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The growing urgency of fungal disease in crops

Posted in Control tactics, Cultural control, Fungi, Host plant resistance, Pesticides on May 25, 2023| Leave a Comment »

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Address the growing urgency of fungal disease in crops

More political and public awareness of the plight of the world’s crops when it comes to fungal disease is crucial to stave off a major threat to global food security.

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A dark cloud of dust from smut surrounds a machine harvesting crops on a sunny day
Clouds of dust caused by a fungus engulf a crop field. Credit: Darren Hauck/Reuters

In October 2022, the World Health Organization (WHO) published its first list of fungal pathogens that infect humans, and warned that certain increasingly abundant disease-causing fungal strains have acquired resistance to known antifungals1. Even though more than 1.5 million people die each year from fungal diseases, the WHO’s list is the first global effort to systematically prioritize surveillance, research and development, and public-health interventions for fungal pathogens.

Yet fungi pose another major threat to human health — one that has received even less attention than infections in people.

Hundreds of fungal diseases affect the 168 crops listed as important in human nutrition by the Food and Agricultural Organization (FAO) of the United Nations. Despite widespread spraying of fungicides and the planting of cultivars bred to be more disease resilient, growers worldwide lose between 10% and 23% of their crops to fungal disease every year, and another 10–20% post-harvest2. In fact, the five most important calorie crops — rice, wheat, maize (corn), soya beans and potatoes — can be affected by rice blast fungus, wheat stem rust, corn smut, soybean rust and potato late blight disease (caused by a water mould oomycete), respectively. And losses from these fungi equate to enough food to provide some 600 million to 4,000 million people with 2,000 calories every day for one year3. Such losses are likely to increase in a warming world4,5.

Much more awareness of the plight of the world’s crops as a result of fungal disease is needed, as is more government and private- sector investment in crop fungal research.

Adaptive potential unleashed

In a 2019 list of 137 pests and pathogens (ranked according to impact), fungi dominate the first to sixth places for diseases affecting each of the world’s 5 most important calorie crops6. Wheat, for example, is grown over more land area than any other crop, with production yielding around 18% of all the calories consumed globally each year. Despite mitigation practices, current crop losses worldwide from infections by the Septoria tritici blotch disease-causing fungus Zymoseptoria tritici, the main wheat pathogen in temperate areas, range from 5% to 50%7. Losses caused by the wheat stem rust fungus Puccinia graminis, which frequents more tropical climates, range from 10% to 70% of the harvest3. Commodity crops, such as bananas and coffee, which in many countries generate revenue that is used to purchase calorie crops, are also vulnerable to fungal diseases.Bacterial defence repurposed to fight blight

Fungi are hugely effective pathogens. They produce massive amounts of spores. The spores of some species can persist in soil and remain viable for up to 40 years. In other species, airborne spores can disperse over distances ranging from a few metres to hundreds or even thousands of kilometres. Wheat stem rust, for example, produces airborne spores that can travel between continents8, although many other fungi produce prolific numbers of spores more locally, promoting disease spread within and between adjacent fields.

Fungi also exhibit a phenomenal degree of genetic variation and plasticity9. Over the past decade or so, genome-wide studies have revealed extensive genetic diversity between and within species of fungi. Although some fungal pathogens undergo frequent sexual recombination, genetic variation can be generated through other processes, too. These include mutational changes conferred by transposable elements (DNA sequences that can change their position in the genome), mitotic (asexual) recombination and the horizontal transfer of genetic material — in some cases, between fungal species, or between fungi and bacteria or plants.

A perfect storm

Current problems have arisen because the adaptability of fungi has met modern agricultural practices.

Most monocultures entail vast areas of genetically uniform crops. (The world’s largest monoculture is a field of more than 14,000 hectares of genetically uniform wheat in Canada.) These provide ideal feeding and breeding grounds for such a prolific and fast-evolving group of organisms. Added to this, the increasingly widespread use of antifungal treatments that target a single fungal cellular process (for example, compounds called azoles target an enzyme needed for the formation of fungal cell membranes) has led to the emergence of fungicide resistance.

Ever harder to control. A line chart showing the increase of antifungal use in agriculture leading to higher resistance.
Source: T. M. Heick et al. in Applied Crop Protection 2018 Ch. 4 (DCA, 2018)

Together, the azoles, the strobilurins and the succinate dehydrogenase inhibitors (all of which are single-target-site antifungals) comprise more than 77% of the global fungicide market10. Moreover, between 2021 and 2028, the market for fungicides is projected to grow by around 4.9% per year — largely thanks to increasing use in low-income countries.

An open question is how the impacts of fungal diseases on crops will be affected by climate change. Although little is known about the response of major plant pathogens to climate change, increasing temperatures in the Northern Hemisphere will drive the evolution of new temperature tolerances in fungal pathogens, and the establishment of pathogens that previously were restricted to more southerly regions4,5. In fact, since the 1990s, fungal pathogens have been moving polewards at around 7 km per year4. Growers have already reported wheat stem rust infections — which normally occur in the tropics — in Ireland and England.

Increasing temperatures might also affect interactions between plants and their microbiomes, including endophytic fungi (symbionts that live in plants). Harmless endophytic fungi could become pathogenic as plants change their physiologies in response to environmental stresses11, which has been demonstrated in studies of the model plant Arabidopsis thaliana12. Moreover, tolerance to higher temperatures in fungi could increase the likelihood of opportunistic soil-dwelling pathogens hopping hosts, and becoming pathogenic in animals or humans13.

With the pressures on the food system from a growing human population added to these problems — over the next 30 years, the global population is projected to grow to 9.7 billion — humanity is on track for unprecedented challenges to food production.

Early promise

Better protecting the world’s crops from fungal disease will require a much more unified approach than has been achieved so far — with closer collaboration between farmers, the agricultural industry, plant breeders, plant-disease biologists, governments and policymakers, even philanthropic funders.

It is no longer enough to focus on crop husbandry (such as the clearing or burning of diseased plant tissues), conventional methods of breeding plants for single disease-resistance genes, or the spraying of predominantly single-target-site fungicides. Growers and other stakeholders must exploit various technical innovations to more effectively monitor, manage and mitigate plant disease. Several approaches are already being developed or used to limit disease impacts and protect crop yields; in combination, these approaches could help farmers to sustain their yields in the coming decades.

Discovery and development of antifungals. The development of fungicides has been largely orchestrated in the agrochemical crop-protection industry. It has so far relied on the serendipitous discovery of antifungals following large-scale screening of compounds, such as the by-products of the pharmaceutical industry — and, since the 1980s, on the synthesis of chemical variants of known compounds, such as the strobilurins and the azoles.

However, it is time to move away from reliance on single-target-site fungicides, and to search for compounds that target multiple processes in the pathogen. In 2020, an inter-disciplinary research team at the University of Exeter, UK, revealed an interesting candidate molecule — a lipophilic cation (C18-SMe2+) that targets several fungal processes (including the synthesis of the energy-carrying molecule ATP, as well as programmed cell death)14. This molecule provides significant crop protection against Septoria tritici blotch in wheat, rice blast in rice13 and Panama TR4 disease in bananas15.

A close-up of corn smut in a field of corn
Corn smut, a disease caused by the fungus Ustilago maydis, affects maize (corn) crops.Credit: Getty

Increasing diversity in agricultural fields. Planting seed mixtures that combine several crop cultivars carrying different resistance genes could provide an important way to slow down pathogen evolution.

In 2022, around 25% of the total wheat production in Denmark used mixed cultivars, selected because they grow at a similar pace and carry complementary disease-resistance genes. This collaborative venture (involving breeders, farmers, environmentalists and scientists) provided promising results in terms of reducing the severity of both Septoria tritici blotch and yellow and brown rust in mixed cultivars without incurring yield loss (L. Nistrup Jørgensen, pers. comm.).

Indeed, these cultivars could reduce the spread of disease and the erosion of crop-resistance genes16.

Early disease detection and surveillance. Artificial intelligence (AI), satellites, remote- sensing tools (such as drones), incentives to persuade farmers to report disease and community-science projects that engage the public in the reporting of plant diseases (both in crops and in wild species) are beginning to engender more effective surveillance of fungal disease.

A collaborative scientist initiative called OpenWheatBlast aims to collect research outputs and data on the emerging wheat blast disease. The fast and easy data sharing allows discoveries to be made, resulting in faster disease control (see go.nature.com/42s25a3). Meanwhile, for the Cape Citizen Science project, an initiative funded by Stellenbosch University in South Africa, researchers are asking people who are interested in science to hunt for the oomycete Phytophthora spp. in South African vegetation (https://citsci.co.za/disease/) — to create records of the presence and spread of this pathogen.

Data collected through AI, community- science projects and so on could be integrated with disease records and collated into, for example, the PlantwisePlus programme (see go.nature.com/3mlgxnn) led by the Centre for Agricultural and Bioscience International, a non-profit intergovernmental organization. The results could also be integrated with climate data obtained from meteorological offices (for example, see go.nature.com/3ukk5hu) and so inform the building of models that predict when and where plant fungal diseases will occur5. More accurate disease predictions could, in turn, trigger early interventions to offset the loss of crops.

A biosecurity sign stands in front of a banana farm on an overcast day
A quarantined banana farm near Cairns in Queensland, Australia.Credit: Suzanne Long/Alamy

Disease resistance and plant immunity. Conventional plant-breeding practices have involved introducing into a given cultivar one or two genes that confer resistance to a particular disease, known as R genes. But although pathogens can overcome this R-gene-mediated resistance in a few years, it can take 10–20 years to go from researchers unmasking an R gene to an agriculture company selling the new cultivar. Incorporating two or more R genes (known as R-gene pyramiding or stacking) can broaden resistance to a diversity of pathogens. Yet field studies have documented how resistance achieved through this means can be short-lived17.

Most R genes encode proteins with a nucleotide-binding site and a leucine-rich repeat region, which act as receptors in the plant cell. These receptors recognize particular pathogen-produced molecules. However, plants possess an earlier detection system for pathogens, involving extracellular receptor proteins that recognize pathogen elicitor molecules, such as chitin and glucan. (Chitin and glucan are present in the fungal cell wall.) These receptors are known as pattern-recognition receptors (PRRs). This type of ‘immune boosting’ could be combined with new R-gene-edited cultivars or through R-gene pyramiding using conventional breeding to provide more durable and broader resistance to major pathogens.

A significant barrier to exploiting this approach in a way that is fast and efficient — particularly in Europe — is public and political resistance to the use of transgenic plants. In March, however, the UK Genetic Technology (Precision Breeding) Act was passed into law; this will enable the development and marketing of gene-edited crops in the United Kingdom. In principle, practices such as ‘immune boosting’, combined with the incorporation of two or more R genes into crops, could endow more durable and broader disease resistance.

Exploiting biologics and crop biotics. Biologics are a broad category of products derived from living organisms. Just as interest in probiotics in medicine has grown over the past decade, so too has interest in the use of biologics in crop protection. This is evidenced by the projected rise in investment by governments and stakeholders.

Strategies currently being explored include the exploitation of living antagonists of plant pathogens, such as the fungus Trichoderma spp., and spraying crops with natural antimicrobial compounds, such as polyoxins, which inhibit the synthesis of chitin (for example, polyoxin D zinc salt)18. Trichoderma strains can impede fungal phytopathogens either indirectly, for example by competing for nutrients and space, or directly, by parasitizing fungi. And in the past decade, researchers have identified other fungal and bacterial endophytes that can help to suppress disease.Indigenous knowledge is key to sustainable food systems

Plants do not grow alone — they associate with diverse microbial communities, which can play a part in plant development, stress tolerance and disease resistance. Over the past decade, new methods for profiling microbes have revealed the existence of beneficial microbial networks. The discovery that some microbial species always co-occur, whereas others never do, is essential knowledge in the design of consortia of microbes that can be applied to soil to promote plant growth and enhance disease protection. Indeed, the challenges ahead will include translating these discoveries from laboratory settings to fields of crops, and ensuring that synthetic, beneficial microbial communities persist once they are introduced, and do not adversely affect the native microbiota, or become pathogenic themselves18.

RNA trafficking between plants and fungi. In 2013, a research team showed that small RNAs (sRNAs) from the grey mould fungus Botrytis cinerea can silence plant host genes involved in immunity19. Some of the researchers then showed that double stranded RNAs (dsRNAs) and sRNAs from the fungus could protect vegetables and fruit against grey mould disease for up to ten days20. However, RNAs (usually encapsulated in tiny vesicles) are not only transferred from the fungus to the host — plant hosts also dispatch vesicles to suppress fungal virulence genes.

A growing number of researchers and newly founded technology companies are now looking to harness these naturally occurring RNA interference (RNAi) based trafficking systems to better protect crops against fungal disease. Currently, investigators are exploring two possible ways of using RNAs. One of these, called host-induced gene silencing or HIGS, relies on the genetic modification of crops. But this approach is lengthy, costly and can’t be implemented in the many countries where genetically modified plants remain banned. Therefore the main focus is now on spray-induced gene silencing or SIGS, in which sRNAs or dsRNAs are directly applied to plants, as a new, environmentally friendly and non-genetically modified crop-protection strategy21.

Several studies have documented the efficacy of RNAi in providing resistance to common fungal pathogens22. However, research is still needed to understand how these external RNAs are taken up and transported between the plant and fungal cells. Moreover, although progress is being made in the application of RNAs to crops, questions remain about the stability of the molecules.

A global body for plant health

Between January 2020 and January 2023, the UK Research and Innovation (UKRI) council allocated around US$686 million to COVID-19 research, and almost 225,000 papers on COVID-19 were published globally. (We conducted a search on the Scopus and Web of Science databases, using ‘COVID’ and ‘SARS-CoV-2’ as keywords.) During the same period, the UKRI spent around $30 million on fungal crop research and, globally, around 4,000 papers on crops and fungal disease were published. (Scopus and Web of Science key words were ‘crops’ and ‘fungal disease’.) Given that food security engenders health and well-being, agriculture and farmers are arguably just as crucial to human health as medicine and health-care providers.

Addressing the threat to human health posed by fungal crop diseases will require greater engagement with the problem, and more investment in research from governments, philanthropic organizations and private companies.

The International Plant Protection Convention (IPPC) is a body supported by the FAO that aims to protect the world’s plant resources from pathogens. It is much less well known than other bodies that deal with threats to human well-being, such as the WHO. The 180 member states that are signatories of the IPPC treaty must work together to change that.

Because viruses and bacteria dominate as agents of human disease, these microbes have received much more attention than have fungi. Yet in crops, fungi are by far the most important agents of disease. The WHO’s list of fungal pathogens that infect humans is a step towards bringing more attention to this extraordinary but understudied group of microbes. But addressing the greatest threats to food security — and so to human health — must include tending to the devastating impacts fungi are having, and will keep having, on the world’s food supply.

Nature 617, 31-34 (2023)

doi: https://doi.org/10.1038/d41586-023-01465-4

References

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Competing Interests

The authors declare no competing interests.

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Can Europe be pesticide free by 2050?

Posted in Biological control, Biotechnology, Cultural control, Pesticides on March 31, 2023| Leave a Comment »

Published: March 27, 2023

Technology Network

| Original story from the INRAE Grass strip and trees at the edge of a wheat field.

Grass strip and hedge at the edge of a field. Credit: INRAE – Christophe MAITRE.

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Harnessing research to speed up the agroecological transition aligns with the objectives of the European Green Deal and addresses the strong demand from public authorities, stakeholders and society at both the national and European levels. For more than two years, over 144 experts investigated possible ways to eliminate pesticides from agriculture on a European scale for the “European Pesticide-Free Agriculture in 2050” foresight study. The three scenarios that were explored to promote changes in the agricultural and food system were presented during a symposium to discuss the findings. Some 1,4200 participants of 64 different nationalities attended the conference on Tuesday 21 March in Paris, where remarks were heard from various French and European stakeholders in the fields of agriculture, regulation and policymaking, environment, and food. This groundbreaking attempt to weave together a larger narrative was bolstered by measured impacts on European food sovereignty and the environment for each scenario. Possible pathways forward are given for each scenario for the European and regional transition of the entire food system based on participatory workshops conducted in four regions in Italy, Romania, Finland and France.

While the negative impacts of chemical pesticides on the environment and human health are well documented, European policies are struggling to make progress towards the target of cutting chemical pesticide use by 50% [1] by 2030. This observation spurred 144 experts, scientists and stakeholders to work together for two years to produce a foresight study that sought to change the model and design agricultural and food systems without any chemical pesticides by 2050.

Chemical pesticides are essential in today’s conventional agricultural systems. Drastically reducing their use to the point of completely eliminating them from agriculture is a thorny issue for which there is no simple solution. This foresight study goes further in terms of the ultimate goal and time frame by asking whether effective crop protection in pesticide-free agriculture is feasible in Europe by 2050 and how to transition to this type of agriculture. Under what conditions would such a transformation be possible? What would the impacts be on production, land use, the trade balance and greenhouse gas emissions? This foresight study, conducted as part of the “Growing and protecting crops differently” Priority Research Programme (PPR) and in conjunction with the “Towards a Chemical Pesticide-Free Agriculture” European Research Alliance,[2] aims to shed light on all these issues and to suggest pathways forward. It offers three scenarios of pesticide-free agriculture for Europe in 2050, each with a transition pathway and examples of these scenarios and pathways in four European regions, along with a quantitative evaluation of their impacts in Europe:

  • Scenario 1: “Global market”: global and European food value chains based on digital technologies and plant immunity for a pesticide-free food market.
  • Scenario 2: “Healthy microbiomes”: European value chains based on plant holobiont, soil and food microbiomes for a healthy diet.
  • Scenario 3: “Embedded landscapes”: complex and diversified landscapes and regional food value chains for a one-health food system.

For each scenario, pesticide-free cropping systems make use of crop diversification, biocontrol development, the choice of suitable crops and varieties, digital technology and agricultural equipment, and monitoring systems to anticipate the arrival of pests.

Differentiated impacts measured for each scenario

One of the key aspects of this foresight study is that it quantified the impacts of each scenario on agricultural production, land use, greenhouse gas emissions and trade, based on the results of simulations of a biomass equilibrium model at the European and global scales.

With regard to European agricultural production, calorie production varies from −5% to +12% depending on the scenario, with a balance to be struck between reducing the consumption of animal products and maintaining grasslands. In terms of the trade balance, the overall impact of scenarios 2 (Healthy microbiomes) and 3 (Embedded landscapes) gives Europe room for manoeuvre to secure its food sovereignty and export its products. The three scenarios reduce greenhouse gas emissions by −8% (scenario 1), −20% (scenario 2) and even up to −37% (scenario 3). All three pathways lead to an increase in the carbon stock in soils and biomass, which will contribute to carbon neutrality by 2050 for the agricultural and agri-food sector in scenarios 2 and 3.

The keys to success: coherent European public policies, the involvement of all value-chain players and risk sharing among stakeholders

Effective crop protection without chemical pesticides relies on several levers that must be activated in tandem: crop diversification over time and across space, the development of biocontrol products and biological inputs, appropriate varietal selection, farm equipment and digital tools, and tools for monitoring pest dynamics and the environment. Biological regulation mechanisms at the soil, field and landscape levels should be favoured, as well as preventive measures gainst pests.

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Specific case studies in Italy, Romania, Finland and France helped establish transition pathways that showed that the entire food system must be considered in this redesign and involve all players across the chain, from producers to consumers who must change their diets and authorities responsible for public and regulatory policies. Transitioning to chemical pesticide-free agriculture will require a coherent mix of European public policies to reduce pesticide use articulated with other policies such as food policies, support the transition through a redesign of the Common Agricultural Policy (CAP) and economic instruments that can be leveraged, and create pesticide-free markets through trade agreements. Finally, the transition will need the various stakeholders to share the risk of transforming their cropping systems and the agricultural and agri-food supply.

The scenarios explored in the foresight study should help decision-makers and the scientific community to identify new research avenues to build a future chemical pesticide-free European agricultural and agri-food system by 2050.

Reference: Mora O, Berne J-A, Drouet J-L, Le Mouel C, Mernier C. European Pesticide-Free Agriculture in 2050. https://www.calameo.com/read/006800896f25276a7e498?authid=u7GuXsBiCGyN

This article has been republished from the following materials. Note: material may have been edited for length and content. For further information, please contact the cited source.

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West Africa: Farmers need more ways to combat pests

Posted in Biological control, Biopesticide, Botanical pesticides, Climate change, Control tactics, Cultural control, Emerging/invasive pests, Host plant resistance, IPM, natural enemies, Pests on December 1, 2022| Leave a Comment »

Climate change means farmers in West Africa need more ways to combat pests

by Loko Yêyinou Laura Estelle, The Conversation

worm on corn
Credit: Unsplash/CC0 Public Domain

The link between climate change and the spread of crop pests has been established by research and evidence.

Farmers are noticing the link themselves, alongside higher temperatures and greater variability in rainfall. All these changes are having an impact on harvests across Africa.

Changing conditions sometimes allow insects and diseases to spread and thrive in new places. The threat is greatest when there are no natural predators to keep pests in check, and when human control strategies are limited to the use of unsuitable synthetic insecticides.

Invasive pests can take hold in a new environment and cause very costly damage before national authorities and researchers are able to devise and fund ways to protect crops, harvests and livelihoods.

Early research into biological control methods (use of other organisms to control pests) shows promise for safeguarding harvests and food security. Rapid climate change, however, means researchers are racing against time to develop the full range of tools needed for a growing threat.

The most notable of recent invasive pests to arrive in Africa was the fall armyworm, which spread to the continent from the Americas in 2016.

Since then, 78 countries have reported the caterpillar, which attacks a range of crops including staples like maize and has caused an estimated US$9.4 billion in losses a year.

African farmers are still struggling to contain the larger grain borer, or Prostephanus truncatus Horn, which reached the continent in the 1970s. It can destroy up to 40% of stored maize in just four months. In Benin, it is a particular threat to cassava chips, and can cause losses of up to 50% in three months.

It’s expected that the larger grain borer will continue to spread as climatic conditions become more favorable. African countries urgently need more support and research into different control strategies, including the use of natural enemies, varietal resistance and biopesticides.

My research work is at the interface between plants, insects and genetics. It’s intended to contribute to more productive agriculture that respects the environment and human health by controlling insect pests with innovative biological methods.

For example, we have demonstrated that a species of insect called Alloeocranum biannulipes Montr. and Sign. eats some crop pests. Certain kinds of fungi (Metarhizium anisopliae and Beauveria bassiana), too, can kill these pests. They are potential biological control agents of the larger grain borer and other pests.

Improved pest control is especially important for women farmers, who make up a significant share of the agricultural workforce.

In Benin, for example, around 70% of production is carried out by women, yet high rates of illiteracy mean many are unable to read the labels of synthetic pesticides.

This can result in misuse or overuse of chemical crop protection products, which poses a risk to the health of the farmers applying the product and a risk of environmental pollution.

Moreover, the unsuitable and intensive use of synthetic insecticides could lead to the development of insecticide resistance and a proliferation of resistant insects.

Biological alternatives to the rescue

Various studies have shown that the use of the following biological alternatives would not only benefit food security but would also help farmers who have limited formal education:

  1. Natural predators like other insects can be effective in controlling pests. For example I found that the predator Alloeocranum biannulipes Montr. and Sign. is an effective biological control agent against a beetle called Dinoderus porcellus Lesne in stored yam chips and the larger grain borer in stored cassava chips. Under farm storage conditions, the release of this predator in infested yam chips significantly reduced the numbers of pests and the weight loss. In Benin, yams are a staple food and important cash crop. The tubers are dried into chips to prevent them from rotting.
  2. Strains of fungi such as Metarhizium anisopliae and Beauveria bassiana also showed their effectiveness as biological control agents against some pests. For example, isolate Bb115 of B. bassiana significantly reduced D. porcellus populations and weight loss of yam chips. The fungus also had an effect on the survival of an insect species, Helicoverpa armigera (Hübner), known as the cotton bollworm. It did this by invading the tissues of crop plants that the insect larva eats. The larvae then ate less of those plants.
  3. The use of botanical extracts and powdered plant parts is another biological alternative to the use of harmful synthetic pesticides. For example, I found that botanical extracts of plants grown in Benin, Bridelia ferruginea, Blighia sapida and Khaya senegalensis, have insecticidal, repellent and antifeedant activities against D. porcellus and can also be used in powder form to protect yam chips.
  4. My research also found that essential oils of certain leaves can be used as a natural way to stop D. porcellus feeding on yam chips.
  5. I’ve done research on varietal (genetic) resistance too and found five varieties of yam (Gaboubaba, Boniwouré, Alahina, Yakanougo and Wonmangou) were resistant to the D. porcellus beetle.

Next generation tools

To develop efficient integrated pest management strategies, researchers need support and funding. They need to test these potential biocontrol methods and their combinations with other eco-friendly methods in farm conditions.

Investing in further research would help to bolster the African Union’s 2021–2030 Strategy for Managing Invasive Species, and protect farmers, countries and economies from more devastating losses as climate change brings new threats.

Initiatives like the One Planet Fellowship, coordinated by African Women in Agricultural Research and Development, have helped further the research and leadership of early-career scientists in this area, where climate and gender overlap.

But much more is needed to unlock the full expertise of women and men across the continent to equip farmers with next generation tools for next generation threats.

Provided by The Conversation 

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Explore further

Why African farmers should balance pesticides with other control methods

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Food security: Combatting soil-borne pathogens and nematodes in wheat

Posted in Crop protection, Cultural control, IPM, Nematodes, Plant Pathogens on November 30, 2022| Leave a Comment »

Combatting soil-borne pathogens and nematodes vital for food security

   Delhi Bureau  0 Comments CIMMYT  9 min read

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08 November 2022, Mexico: The International Maize and Wheat Improvement Center (CIMMYT) coordinated the VIII International Cereal Nematode Symposium between September 26-29, in collaboration with the Turkish Ministry of Agriculture and Forestry, the General Directorate of Agricultural Research and Policies and Bolu Abant Izzet Baysal University.

As many as 828 million people struggle with hunger due to food shortages worldwide, while 345 million are facing acute food insecurity – a crisis underpinning discussions at this symposium in Turkey focused on controlling nematodes and soil-borne pathogens causing reduced wheat yields in semi-arid regions.

A major staple, healthy wheat crops are vital for food security because the grain provides about a fifth of calories and proteins in the human diet worldwide.

Seeking resources to feed a rapidly increasing world population is a key part of tackling global hunger, said Mustafa Alisarli, the rector of Turkey’s Bolu Abant Izzet Baysal University in his address to the 150 delegates attending the VIII International Cereal Nematode Symposium in the country’s province of Bolu.

Suat Kaymak, Head of the Plant Protection Department, on behalf of the director general of the General Directorate of Agricultural Research and Policies (GDAR), delivered an opening speech, emphasizing the urgent need to support the CIMMYT Soil-borne Pathogens (SBP) research. He stated that the SBP plays a crucial role in reducing the negative impact of nematodes and pathogens on wheat yield and ultimately improves food security. Therefore, the GDAR is supporting the SBP program by building a central soil-borne pathogens headquarters and a genebank in Ankara.

Discussions during the five-day conference were focused on strategies to improve resilience to the Cereal Cyst Nematodes (Heterodera spp.) and Root Lesion Nematodes (Pratylenchus spp.), which cause root-health degradation, and reduce moisture uptake needed for proper development of wheat.

Richard Smiley, a professor emeritus at Oregon State University, summarized his research on nematode diseases. He has studied nematodes and pathogenic fungi that invade wheat and barley roots in the Pacific Northwest of the United States for 40 years. “The grain yield gap – actual versus potential yield – in semiarid rainfed agriculture cannot be significantly reduced until water and nutrient uptake constraints caused by nematodes and Fusarium crown rot are overcome,” he said.

Experts also assessed patterns of global distribution, exchanging ideas on ways to boost international collaboration on research to curtail economic losses related to nematode and pathogen infestations.

A special session on soil-borne plant pathogenic fungi drew attention to the broad spectrum of diseases causing root rot, stem rot, crown rot and vascular wilts of wheat.

Soil-borne fungal and nematode parasites co-exist in the same ecological niche in cereal-crop field ecosystems, simultaneously attacking root systems and plant crowns thereby reducing the uptake of nutrients, especially under conditions of soil moisture stress.

Limited genetic and chemical control options exist to curtail the damage and spread of these soil-borne problems which is a challenge exacerbated by both synergistic and antagonistic interactions between nematodes and fungi.

Nematodes, by direct alteration of plant cells and consequent biochemical changes, can predispose wheat to invasion by soil borne pathogens. Some root rotting fungi can increase damage due to nematode parasites.

Integrated managementFor a holistic approach to addressing the challenge, the entire biotic community in the soil must be considered, said Hans Braun, former director of the Global Wheat Program at CIMMYT.

Braun presented efficient cereal breeding as a method for better soil-borne pathogen management. His insights highlighted the complexity of root-health problems across the region, throughout Central Asia, West Asia and North Africa (CWANA).

Richard A. Sikora, Professor emeritus and former Chairman of the Institute of Plant Protection at the University of Bonn, stated that the broad spectrum of nematode and pathogen species causing root-health problems in CWANA requires site-specific approaches for effective crop health management. Sikora added that no single technology will solve the complex root-health problems affecting wheat in the semi-arid regions. To solve all nematode and pathogen problems, all components of integrated management will be needed to improve wheat yields in the climate stressed semi-arid regions of CWANA.

Building on this theme, Timothy Paulitz, research plant pathologist at the United States Department of Agriculture Agricultural Research Service (USDA-ARS), presented on the relationship between soil biodiversity and wheat health and attempts to identify the bacterial and fungal drivers of wheat yield loss. Paulitz, who has researched soil-borne pathogens of wheat for more than 20 years stated that, “We need to understand how the complex soil biotic ecosystem impacts pathogens, nutrient uptake and efficiency and tolerance to abiotic stresses.”

Julie Nicol, former soil-borne pathologist at CIMMYT, who now coordinates the Germplasm Exchange (CAIGE) project between CIMMYT and the International Center for Agricultural Research in the Dry Areas (ICARDA) at the University of Sydney’s Plant Breeding Institute, pointed out the power of collaboration and interdisciplinary expertise in both breeding and plant pathology. The CAIGE project clearly demonstrates how valuable sources of multiple soil-borne pathogen resistance in high-yielding adapted wheat backgrounds have been identified by the CIMMYT Turkey program, she said. Validated by Australian pathologists, related information is stored in a database and is available for use by Australian and international breeding communities.

Economic losses

Root-rotting fungi and cereal nematodes are particularly problematic in rainfed systems where post-anthesis drought stress is common. Other disruptive diseases in the same family include dryland crown and the foot rot complex, which are caused mainly by the pathogens Fusarium culmorum and F. pseudograminearum.

The root lesion nematode Pratylenchus thornei can cause yield losses in wheat from 38 to 85 percent in Australia and from 12 to 37 percent in Mexico. In southern Australia, grain losses caused by Pratylenchus neglectus ranged from 16 to 23 percent and from 56 to 74 percent in some areas.

The cereal cyst nematodes (Heterodera spp.) with serious economic consequences for wheat include Heterodera avenae, H. filipjevi and H. latipons. Yield losses due to H. avenae range from 15 to 20 percent in Pakistan, 40 to 92 percent in Saudi Arabia, and 23 to 50 percent in Australia.

In Turkey, Heterodera filipjevi has caused up to 50 percent crop losses in the Central Anatolia Plateau and Heterodera avenae has caused up to 24 percent crop losses in the Eastern Mediterranean.

The genus Fusarium which includes more than a hundred species, is a globally recognized plant pathogenic fungal complex that causes significant damage to wheat on a global scale.

In wheat, Fusarium spp. cause crown-, foot-, and root- rot as well as head blight. Yield losses from Fusarium crown-rot have been as high as 35 percent in the Pacific Northwest of America and 25 to 58 percent in Australia, adding up losses annually of $13 million and $400 million respectively, due to reduced grain yield and quality. The true extent of damage in CWANA needs to be determined.

Abdelfattah Dababat, CIMMYT’s Turkey representative and leader of the soil-borne pathogens research team said, “There are examples internationally, where plant pathologists, plant breeders and agronomists have worked collaboratively and successfully developed control strategies to limit the impact of soil borne pathogens on wheat.” He mentioned the example of the development and widespread deployment of cereal cyst nematode resistant cereals in Australia that has led to innovative approaches and long-term control of this devastating pathogen.

Dababat, who coordinated the symposium for CIMMYT, explained that, “Through this symposium, scientists had the opportunity to present their research results and to develop collaborations to facilitate the development of on-farm strategies for control of these intractable soil borne pathogens in their countries.”

Paulitz stated further that soil-borne diseases have world-wide impacts even in higher input wheat systems of the United States. “The germplasm provided by CIMMYT and other international collaborators is critical for breeding programs in the Pacific Northwest, as these diseases cannot be managed by chemical or cultural techniques,” he added.

Road ahead

Delegates gained a greater understanding of the scale of distribution of cereal cyst nematodes and soil borne pathogens in wheat production systems throughout West Asia, North Africa, parts of Central Asia, Northern India, and China.

After more than 20 years of study, researchers have recognized the benefits of planting wheat varieties that are more resistant. This means placing major emphasis on host resistance through validation and integration of resistant sources using traditional and molecular methods by incorporating them into wheat germplasm for global wheat production systems, particularly those dependent on rainfed or supplementary irrigation systems.

Sikora stated that more has to be done to improve Integrated Pest Management (IPM), taking into consideration all tools wherever resistant is not available. Crop rotations for example have shown some promise in helping to mitigate the spread and impact of these diseases.

“In order to develop new disease-resistant products featuring resilience to changing environmental stress factors and higher nutritional values, modern biotechnology interventions have also been explored,” Alisarli said.

Brigitte Slaats and Matthias Gaberthueel, who represent Swiss agrichemicals and seeds group Syngenta, introduced TYMIRIUM® technology, a new solution for nematode and crown rot management in cereals. “Syngenta is committed to developing novel seed-applied solutions to effectively control early soil borne diseases and pests,” Slaats said.

It was widely recognized at the event that providing training for scientists from the Global North and South is critical. Turkey, Austria, China, Morocco, and India have all hosted workshops, which were effective in identifying the global status of the problem of cereal nematodes and forming networks and partnerships to continue working on these challenges.

Also Read: Agriculture and the agricultural economy is the strength of India: Union Agriculture Minister

(For Latest Agriculture News & Updates, follow Krishak Jagat on Google News)

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Biological control in greenhouses

Posted in Biological control, Biopesticide, Cultural control on August 5, 2022| Leave a Comment »

Integrate Your Insecticide Rotation in the Greenhouse with Biological Control

Juang-Horng (J.C.) ChongBy Juang-Horng (J.C.) Chong|August 1, 2022

  • Greenhouse Grower

Predatory Mite Release biological control

Biological control can be used effectively as a part of an integrated pest management program. This image shows loose bran leftover from a predatory mite release. Photos: Juang Chong

In a perfect world, we can have our cake and eat it, too. Alas, this isn’t a perfect world. As much as we hope biological control can be a complete replacement for pesticides, it’s not. We may need to apply pesticides to prevent damage by a secondary pest. By a secondary pest, I mean a pest that’s not the primary target of your biological control program but can become a problem because it has no effective biological control option (such as lygus bug or striped mealybug) or its biological control agents are in short supply or unaffordable.

Multiple factors decide which pesticides to use when practicing biological control. You can consult Koppert’s Side Effects Database or Biobest’s Side Effect Manual to select compatible insecticides. But, understand that compatibility information isn’t available for all products, and databases from different companies may have different ratings for the same product. You’ll have to do a little homework. When multiple ratings are available, it’s prudent to go with the most conservative one or the “worst-case scenario.” The best aid in selecting compatible pesticides is the representative of your biological control agent supplier, who can help you select the most suitable products and fill information gaps, particularly information on sublethal impact of pesticides.

Today’s topic hasn’t been discussed in detail when folks talk about selecting compatible insecticides — how do you satisfy two critical requirements, i.e., insecticide rotation and compatibility with biological control agents, when selecting which insecticide to use against the secondary pest?

Avoid Pesticide Resistance

As part of an integrated pest management program, biological control is a great way to delay the development of pesticide resistance. Hopefully, a preventive biological control program is so successful that you don’t ever have to use pesticides. If you don’t use or use very little pesticides, then you don’t have to worry about pesticide resistance — as simple as that. But, if you need to make multiple applications to reduce a secondary pest population, you should consider rotating the pesticides you plan to use to avoid resistance development.

The process of developing an insecticide rotation program that’s compatible with your biological control program is the same as developing a rotation program for any other pest. This could be best illustrated by going through the steps of developing such a rotation program, say, against mealybugs (I’m too cheap to buy Cryptolaemus) while being compatible with the predatory mite, Neoseiulus cucumeris, used for thrips management.

Pests on Verbena

Multiple pests can occur on the same plant, such as spider mites and thrips on this verbena. Designing an insecticide rotation program will need to consider both pests and their biological control agents.

The first step is to have a list of insecticides effective against mealybugs. I can find pesticide efficacy information from several resources. I can read IR-4’s Research Summaries or the Comparative Efficacy and Ecotox table from Rutgers University’s Protecting Bees website. Alternatively, I can call or email my favorite entomologist for recommendations. At the end of Step 1, my fictional list includes acephate, bifenthrin, buprofezin, dinotefuran, flonicamid, horticultural oil, insecticidal soap, and pyriproxyfen.

Now, let’s select insecticides that are compatible with cucumeris mite from my list. For this step, I consult with the technical representative of my biological control agent supplier, Do-Good Bug Company. Acephate and bifenthrin are out because they are broad-spectrum and have residual toxicity that may last for weeks. Dinotefuran can be very detrimental to cucumeris mite when sprayed, but is safe as a drench, so I’ll use that as a drench. Horticultural oil and insecticidal soap can also be detrimental when sprayed, but they have short residue, so I can use them just before releasing the predatory mites (the residue becomes harmless by release time) or at the end of the crop to clean up the mealybug population. Buprofezin, flonicamid and pyriproxyfen are compatible.

Steps for Mealybug Program

Here’s my mealybug program: I’ll start with a drench of dinotefuran followed with biweekly sprays of buprofezin, flonicamid, and pyriproxyfen. Remember that a good rotation program includes a sequence of non-repeating modes of action or IRAC (Insecticide Resistance Action Committee) numbers. I can find the IRAC numbers on the first page of the product labels, which are 4A for dinotefuran, 16 for buprofezin, 29 for flonicamid, and 7C for pyriproxyfen. All IRAC numbers in my rotation program are different, so I’m good to go. There you have it — an insecticide rotation program against mealybugs that’s compatible with cucumeris mite.

Of course, the example above is a simplified version of building an insecticide rotation program. Despite its simplicity, the same process can be repeated for any combination of (macro and micro) biological control agents and pesticides (insecticides and fungicides).

It is important to understand that insecticide rotation and compatibility with biological control should be considered within the context of the entire crop. Rarely do we deal with one pest or disease at a time. What we do to manage one pest or disease may have significant impact on the management efficacy against another pest or disease. Therefore, pesticide rotation and biological control programs should be designed carefully to consider multiple plant and pest species. It doesn’t matter how successful a biological control program is in managing the primary pest, a crop can still fail if a secondary pest management program ignores insecticide rotation and creates a resistant population that ultimately destroys the crop.

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India: Eco-friendly pest control

Posted in Biological control, Biopesticide, Botanical pesticides, Cover cropsc, Cultural control, IPM on July 23, 2022| Leave a Comment »

Going the eco-friendly way to control pests

The rainy season brings a slew of problems for fruit growers, who struggle to save their crops from infestation by pests. The application of insecticides is not very effective and also poses environmental hazards, leading to a negative impact on soil health. Amid these challenging circumstances, the adoption of various eco-friendly techniques for managing pests targeting fruit crops has emerged as a viable option among farmers across Punjab.

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  • Updated At: Jul 18, 2022 07:32 AM (IST)
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Going the eco-friendly way to control pests

Bagging of guava fruit

Manav Mander

FRUIT cultivation faces a constant threat from insects. Several pests cause damage to fruit production, leading to a loss of yield. Among the pests that impede quality fruit production, fruit flies Bactrocera dorsalis and Bactrocera zonata can cause up to 100 per cent damage in the rainy season to the guava crop, 85 per cent (kinnow), 80 per cent (pear), 78 per cent (peach) and 30 per cent to mango as well as plum.

The application of insecticides is not much effective and also causes environmental hazards, leading to a negative impact on soil health. Amid this scenario, the adoption of eco-friendly techniques for managing insect-pests of fruit crops has emerged as a viable option among farmers across Punjab.

Prominent among these techniques developed by Punjab Agricultural University (PAU), Ludhiana, are the fruit fly trap and the termite trap, while integrated management of snails in the citrus nursery, integrated pest management (IPM) of mango hoppers and bagging for fruit fly management in guava are also being practised.

Popular techniques for saving fruits

PAU fruit fly trap

Fruit fly trap

The PAU fruit fly trap is the most popular of these techniques. Till date, the university has sold around 52,000 PAU fruit fly traps, while 21,500 have been supplied to the fruit growers and government orchards for frontline demonstrations under the National Horticulture Mission (NHM) projects, thus covering an area of 4,600 acres under fruit fly traps. This trap is being adopted by more than 90 per cent of the fruit growers of Punjab, besides being used in kitchen gardens.

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According to Dr Sandeep Singh, Senior Entomologist (Fruits) and team leader for developing these techniques, fruit growers of Punjab, Haryana, Himachal Pradesh, Rajasthan and Uttar Pradesh are purchasing PAU fruit fly traps from the university’s Department of Fruit Science.

Eco-friendly management of fruit flies can be done by fixing PAU fruit fly traps at the rate of 16 traps/acre in the second week of April, first week of May, third week of May, first week of June, first week of July and second week of August, respectively. Traps can be re-charged after 30 days, if needed, and one trap costs around Rs 100. It is best suited for the management of male fruit flies in kinnow, guava, mango, pear, peach and plum.

“In the rainy season, guava suffer maximum infestation due to the carry-over of fruit flies from other early-ripening fruit crops — peach, pear, mango, litchi, plum, grapes, loquat, jamun, sapota, pomegranate, fig, banana and papaya — and from vegetable crops, especially cucumber. The fruit fly trap is the most effective and economical way of controlling the menace,” says Gurusewak Singh, a farmer from Malerkotla.

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Termite trap

Termite trap

Termites in the fruit crop no longer bother farmers who use earthen pot-based traps. Eco-friendly management of termites can be done by burying gul (maize cobs without grains)-filled 24-holed earthen pots of 13-inch diameter with lid at the rate of 14 per acre in termite-infested orchards of pear, ber, peach, grape and amla during the first week of April and then in the first week of September. These pots should have their necks outside the soil surface. The pots should be removed from the soil after 20 days of installation and the termites collected should be destroyed by dipping in water containing a few drops of diesel.

A total of 4,578 termite traps have been supplied by PAU to the fruit growers and government orchards for frontline demonstrations under the NHM projects, covering 327 acres.

“I have been using termite traps for the past four years in my orchard. It is an eco-friendly technique as there is no pesticide residue in fruits, soil, plants and environment. The cost of fixing of earthen pots in the orchards is quite cheap (Rs 980/acre). A single pot has the capacity to trap more than 100,000 termites,” says Ravinderpal Singh.

Integrated management of snails in citrus nursery

In this technique, papaya leaves are spread in/around the nursery area to attract snails. Then, the snails are collected and put into a bucket containing salt water to kill them. Wet gunny bags are kept in the nursery area as snails try to hide under them.

IPM of mango hoppers

In this method of integrated pest management, the spray of PAU home-made neem extract and PAU home-made Dharek extract (5 litres per acre) is effective in reducing the population of hoppers in mango.

Fruit fly bagging

The mature green and hard fruits of guava should be covered with a biodegradable white-coloured non-woven bags of 9 inch x 6 inch from June-end to mid-July. For proper bagging of fruits, stapler or needle pins can be used. The bagged fruits should be harvested at the colour-break stage.

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Polyphagous menace

Fruit flies Bactrocera dorsalis and Bactrocera zonata are polyphagous pests that damage various fruit crops and multiply profusely. The female adult fruit fly punctures the fruit at the colour-break stage and deposits its eggs below the epicarp. On hatching, the maggots feed on the soft pulp of the ripening fruits. The punctured portion start rotting and the fruit fall down prematurely. The duration of activity of the fruit flies on mango fruits is from the last week of May to the last week of July. These flies also attack peach, plum, kinnow and guava crops. Isolated orchards are less infested by fruit flies. The duo can cause up to 100 per cent damage in the rainy season to the guava crop, 85 per cent to kinnow, 80 per cent (pear), 78 per cent (peach) and 30 per cent to mango as well as plum.

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USA: Timing is everything for weed management

Posted in Cultural control, Herbicides, Weeds on July 1, 2022| Leave a Comment »

JUNE 22, 2022

Timing is everything for weed management

by Jim Catalano, Cornell University

Timing is everything for weed management
Bryan Brown, integrated weed management specialist for New York State Integrated Pest Management, stands in a soybean field that lost 50% of its yield to weed competition, even after several herbicide applications. Credit: Cornell University

Farmers can tailor their efforts to control weeds more effectively by pinpointing when a particular weed will emerge, according to a new Cornell University study.

Researchers in the College of Agriculture and Life Sciences reviewed past studies on the peak timing of emergence for 15 troublesome weed species in the Northeast, as well as potential ways to use this knowledge, in their study, “Improving Weed Management Based on the Timing of Emergence Peaks: A Case Study of Problematic Weeds in Northeast U.S.,” published June 21 in the journal Frontiers in Agronomy.

“There are lot of different weed management tactics out there, and most of them can be improved with some consideration of what weed species you have and when they emerge,” said lead author Bryan Brown, integrated weed management specialist for New York State Integrated Pest Management and adjunct assistant Professor in the School of Integrative Plant Science’s Horticulture Section, in the College of Agriculture and Life Sciences. “In this paper, we provided a framework starting with those tactics that are easiest to tailor or adjust—all the way up to revamping a cropping system—based on avoidance of certain weed species.”

As an example, Brown pointed to common ragweed. “We found that in most of the literature, common ragweed had finished up its emergence by June 1,” he said. “So, if you’re able to wait to till and plant your field until after June 1, then you’ve effectively avoided common ragweed for the season.” Conversely, if a field is riddled with mid- or late-season weeds, planting earlier can help give crops a head start to outcompete them.

When it comes to controlling weed seedlings using herbicides or shallow tilling, control is most effective soon after weeds emerge, so knowing when different weed species grow can help farmers plan ahead.

Farms with flexible crop rotations can leave the ground bare, or perhaps cover-cropped, during the period when their most problematic weed emerges. By controlling that species, they essentially remove its weed seeds from the soil so it will be less of a problem in the future.

The researchers found that the timing of weed emergence varied among previous studies due to factors such as weather, soil temperature and moisture.

“Naturally, that’s going to vary from year to year and from study to study,” Brown said. “But the big surprise to me was that among previous studies that modeled weed emergence, when we input identical weather data, there was still variation in when they expected weeds to emerge. That highlights the regional differences in soils and weed genetics.”

As the models improve by incorporating regional differences, the researchers hope to work with the Network for Environment and Weather Applications to give farmers direct access to weather-based weed emergence predictions.

“As weed management becomes more challenging, I think that this type of planning is going to become more important,” Brown said. “Hopefully, as those emergence models become more accurate we’ll be able to use these tactics to even better use and really fine-tune the timing of our weed management.”

Explore further

Examining the impact of herbicide-resistant crops on weed management

More information: Bryan Brown et al, Improving Weed Management Based on the Timing of Emergence Peaks: A Case Study of Problematic Weeds in Northeast USA, Frontiers in Agronomy (2022). DOI: 10.3389/fagro.2022.888664

Provided by Cornell University 

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USA: Managing rice insect pests

Posted in Control tactics, Cultural control, Host plant resistance, Insects, Pesticides on June 2, 2022| Leave a Comment »

Manage insects and other pests in rice production before they manage you

Brian Irelanddfp-ricefield-bireland (6) copy.jpg

Recently planted rice emerges in fields near Rayne, La.

Insects must be identified and managed in rice production before the effects impact a growers yield.

Brian Ireland | Jun 01, 2022

fps-generic.jpg

Insects and other pests can destroy a crop at any stage, reducing yields and grower profits.  

Over the past few years, Louisiana has experienced a multitude of pests attacking the rice industry. Growers and researchers continue to be diligent in finding ways to combat the issues that arise to have a successful and productive harvest. 

Blake Wilson, a Louisiana State University field crop entomologist specializing in sugarcane and rice, works with the major pests faced by Louisiana farmers, including the invasive apple snails.  

“Pests come in waves and can destroy rice yield if not properly managed,” he said. “From armyworms and weevil in the early season to rice stink bugs in the late season.” 

The LSU Rice Research Station, located in Rayne, La., works with producers to select varieties that are resistant to pests and learn how to properly treat and control pests before they become a problem. 

Rice water weevil 

Rice water weevil is a major concern for the rice industry. According to Wilson, rice water weevil is most damaging in water seeded rice, but it also infests dry or drill-seeded rice. 

The primary treatment for controlling and preventing infestations remains to be insecticidal seed treatments, while certain practices can significantly reduce the impact on rice yield. 

“Rice water weevil can be controlled by a variety of methods,” he said. “Foliar application is less effective once the weevil larvae reach the roots.” 

Adult beetles fly into rice fields to feed on the leaves. This causes narrow scars that run lengthwise on the leaf, while this feeding rarely causes yield reduction. 

Females lay eggs at or below the water line beginning soon after a permanent flood is applied. The larvae feed on the roots, reducing plant growth and rice yields. 

Water-seeded and early flooded rice are the most susceptible to yield losses during infestations.  

“Seed dealers can apply insecticidal seed treatments before planting,” he said.  

Fall armyworm 

In 2021, Louisiana, as well as the rest of the Midsouth, experienced a major outbreak of fall armyworms.  

The armyworm is an early-season concern for rice growers. Larvae feed on the leaves of young rice plants, often resulting in the seedlings being pruned to the ground.  

Infestations typically occur on elevated areas in and around the field, where the worms can escape drowning in high water. Fall armyworms can devastate a field of rice that is too young to be flooded so scouting should occur after the germination of seedlings and continue weekly according to the LSU AgCenter. 

Since adult worms lay eggs on grasses in and around rice fields, larval infestations can be reduced by managing weedy grasses. Flooding-infested fields for a few hours can be effective under the right conditions. Parasitic wasps and pathogenic microorganisms can help reduce armyworm populations.  

“Some states had to apply for emergency approval to utilize new or different insecticides,” Wilson said concerning last year’s worm invasion.  

Rice stink bugs 

Rice stink bugs are a big threat to headed rice later in the season and can reduce yields as well as grain quality. Females lay eggs in two-row clusters on leaves, stems, and panicles.  

Nymphs and adults feed on the rice florets and suck the nutrients from developing rice grains in the early milk stage which can reduce yields. According to LSU AgCenter, the most economic losses arise from a reduction in grain quality that results from stink bugs feeding on developing kernels. 

Insecticides such as neonicotinoid Tenchu (dinotefuran)  can be used before flowering to control stink bugs. There are several insecticides available but be sure to choose the right one for that time as some cannot be applied 21-days before harvest. 

Apple snail 

Another major issue rising throughout Louisiana waterways is the invasive apple snails.  

“Apple snails have existed throughout much of south Louisiana for the last 10 to 15 years,” he said. “Over the past five years, apple snail population growth in rice and crawfish production systems has become an issue.” 

While not an insect, this pest can easily damage seedling rice in water-seeded fields. 

“These snails can be highly detrimental to crawfish production,” he said.  

Apple Snails are believed to be introduced through irrigation with infested surface water.  

“The spread of snails has been slower due to farmers using well water to fill their crawfish ponds or rice fields,” he said. “Flooding events or movement of materials or equipment from infested ponds can spread the snails into new fields.”  

Copper sulfate has been shown to be an effective treatment for apple snails but can be detrimental to aquatic life such as crawfish. 

There remains no shortage of pests. The trick is figuring out how to control all insects and other pests like invasive apple snails while maximizing yield. Remember there are individuals in the agriculture industry who specialize in identifying and controlling insects or other pests. 

TAGS: RICE

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Competitive sorghum crops will dent weed invasion

Posted in Cultural control, Weeds on March 23, 2022| Leave a Comment »

Competitive sorghum crops will dent weed invasion

The Land

Bob Freebairn

14 Mar 2022, 5 a.m.

Cropping

Closer row spacing and heavier sowing rates play a vital part of reducing weeds in grain sorghum crops. Closer row spacing and heavier sowing rates generally have little to no detrimental adverse effect on crop yield.

 Closer row spacing and heavier sowing rates play a vital part of reducing weeds in grain sorghum crops. Closer row spacing and heavier sowing rates generally have little to no detrimental adverse effect on crop yield.

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Grain Sorghum Weed Control Guide, written for Pacific Seeds by nationally recognised weed authority Andrew Summervaille, is a comprehensive and outstanding publication dealing with all control aspects. These include herbicides, with lots of insightful comment, fair but often acknowledging limitation of specific products, as well as the important contribution of agronomic aspects to help combat weeds’ effect on yield.

Contributed by Qld Department of Agriculture and Fisheries research agronomist Michael Widderick, is an important section covering weed suppression by growing a competitive sorghum crop. Research over two years has shown that growing a competitive sorghum crop with increased density and reduced row spacing can significantly suppress growth and seed production of weeds like barnyard grass and Feathertop Rhodes grass.

While trial results were not always consistent, crops sown in 0.5 m rows generally suppressed weeds better than in the more traditional 0.75 and 1.0m row spacing. Increasing sorghum plant density from more traditional 5.0 plants sq/m to 10 plants sq/m also generally contributed to a more competitive crop against weeds.

Different varieties (of those tested) had no impact on suppressing weed growth, suggesting cultivar choice will have a lesser impact on sorghum competitiveness than agronomy. However, the researchers note that impact of cultivar may differ across seasons and locations. Also especially noteworthy, was that at least in favourably growing conditions sorghum at narrow row spacing and increased density, did not have any negative impact on sorghum yield.

Weed control in grain sorghum is important for crop yield, as well as for driving down the soil weed seed bank. A combination approach is important for weed control.

 Weed control in grain sorghum is important for crop yield, as well as for driving down the soil weed seed bank. A combination approach is important for weed control.

Therefore, gains in competitiveness and reduction in weed growth can be achieved without reducing yield. Again the researchers note that rarely will a sorghum crop be grown without herbicides, whether they be residual or knockdown, or a combination of both. Integrating a competitive sorghum crop with herbicides should provide an additive effect on reducing in-crop weed pressures, growth and seed production. Over time, this strategy should deplete the weed seed banks, and reduce their impact on sorghum production.

Also read: Perfect growing season sees great sorghum crops in north-west

A further valuable part of the publication is discussion of the role of Imidazolinone technology in sorghum, developed by Advanta Seeds. Sorghum has well and truly joined the list of crops with varieties that provide tolerance to Imidazolinone (IMI herbicides). Note this is not GMO technology. This technology allows the application of a new range of registered herbicides at recommended rates without causing crop damage.

Intervix (imazamox + imazapyr) is an example of an IMI herbicide. IMI products have broad spectrum activity with variation in the activity of individual herbicides for pre-emergence and post-emergence control. Control of broadleaf weeds post-emergence is normally limited to small weeds and relies to a measure on the effectiveness of crop competition occurring subsequent to application particularly for less susceptible species. While IMI herbicides like Intervix control a wide range of broadleaf and grass weeds it does, like most herbicides, have its limitations like not controlling fleabane or Feathertop Rhodes grass.

Grain Sorghum Weed Control Guide, written for Pacific Seeds by nationally recognised weed authority Andrew Summervaille, is a valuable reference.

 Grain Sorghum Weed Control Guide, written for Pacific Seeds by nationally recognised weed authority Andrew Summervaille, is a valuable reference.

Excellent tables are presented in the publication that covers aspects like effect of various herbicides on specific weeds. These are detailed in tables for pre-emergent and post emergent. Tables also detail aspects like plant back intervals, application timing, rates per ha, rainfall requirement and the like.

Especially valuable is Andrew Summervaille’s discussions about various herbicide products. He highlights advantages and disadvantages of the various herbicides. Planning for control of difficult weeds, like fleabane, Feathertop Rhodes grass, and even well known weeds like barnyard grass and liver-seed grass that have or are developing resistance to some herbicides, requires carful choice of herbicide and their application.

Further details obtain the booklet via http://www.pacificseeds.com.au/wp-content/uploads/2021/07/Pacific-Seeds-Grain-sorghum-weed-control-guide-_Low-Res.pdf

Next week: Ensuring legumes are a vital part of the pasture mix.

  • Bob Freebairn is an agricultural consultant based at Coonabarabran. Email robert.freebairn@bigpond.com or contact (0428) 752 149.

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Report of activities: IAPPS Region X Northeast Asia Regional Center (NEARC) 2020-2021

Posted in Biological control, Biopesticide, Botanical pesticides, Crop protection, Cultural control, Herbicides, Host plant resistance, Mechanical control, Meetings, News, Pests, Plant Pathogens, Webinars, Weeds on November 28, 2021| Leave a Comment »

IAPPS Region X Northeast Asia Regional Center (NEARC)

Present committee members

Dr. Izuru Yamamoto, Senior Advisor

Dr. Noriharu Umetsu, Senior Advisor

Dr. Tsutomu Arie, a representative of the Phytopathological Society of Japan, the chair of Region X

Dr. Tarô Adati, a representative of Japanese Society of Applied Entomology and Zoology

Dr. Hiromitsu Moriyama, a representative of Pesticide Science Society of Japan, the secretary general of Region X

Dr. Rie Miyaura, a representative of The Weed Science Society of Japan

The Phytopathological Society of Japan and Pesticide Science Society of Japan became official partners of IYPH2020 by FAO of UN and Ministry of Agriculture, Forestry and Fisheries (MAFF) of Japan and endeavored to educate the society on plant protection. https://www.maff.go.jp/j/syouan/syokubo/keneki/iyph/iyph_os.html

Annual activities related to IAPPS especially to IPM of plant diseases, insects and weeds, and plant regulation (from April 2020 to March 2021)

The Phytopathological Society of Japan (PSJ)

2020 Kanto District Meeting, Online; Sep 21–22, 2020

2020 Kansai District Meeting, Online; Sep 21–22, 2020

2020 Tohoku District Meeting, Online; Oct 12–14, 2020

2020 Hokkaido District Meeting, Online; Oct 15, 2020

2020 Kyushu District Meeting, Online; Nov 24–26, 2020

2021 Annual Meeting, Online; Mar 17–19, 2021

Japanese Society of Applied Entomology and Zoology (JSAEZ)

65th Annual Meeting, online, March 23-26, 2021

28th Annual Research Meeting of the Japan-ICIPE Association, online, March 25, 2021

Pesticide Science Society of Japan

37rd Study Group Meeting of Special Committee on Bioactivity of Pesticides, online, Sep 18, 2020

40th Symposium of Special Committee on Agricultural Formulation and Application, Yokohama, Kanagawa; Oct 15–16, 2020 (Cancelled due to the spread of COVID-19)

43th Annual Meeting of Special Committee on Pesticide Residue Analysis, online, Nov. 5–6, 2020

46th Annual meeting, Fuchu, Tokyo and Online, March 8–10, 2021

The Weed Science Society of Japan (WSSJ)

2020 Annual Meeting, The Weed Science Society of Kinki, Online; Dec 5, 2020

35th Symposium of Weed Science Society of Japan, Online; Dec 12, 2020

2020 Annual Meeting, Kanto Weed Science Society, Online; Dec 22, 2020

22th Annual Meeting, The Weed Science Society of Tohoku, Japan, Online; Feb 25, 2021

2020 Study Group Meeting of Weed Utilization and Management in Small Scale Farming, Online; Feb 26, 2021

Hono-Kai (means, Meeting who are appreciating agriculture)

35th Hono-Kai Symposium was cancelled due to the epidemic of COVID-19

Japan Biostimulants Association

３rd Symposium, Online; Nov 2–30, 2020

Nodai Research Institute

2020-1 Biological Control Group Seminar, Setagaya; Tokyo; Jun 16, 2020 (Cancelled due to the epidemic of COVID-19)

2020-2 Biological Control Group Seminar, online, Nov 13, 2020

2021-1 Biological Control Group Seminar, online, Jun 15, 2021

2021-2 Biological Control Group Seminar, online, Nov 9, 2021

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Cover Crops Attract Pest Predators

Posted in Cultural control on November 9, 2021| Leave a Comment »

Cover Crops Attract Pest Predators which Reduce Pesticide Use

(Beyond Pesticides, November 2, 2021) Cover crops create habitat that draw in pest predators and help mitigate crop injury, finds research published in the journals Agroecosystems and Biological Control from scientists at the University of Georgia. Expanded predator diversity can reduce pest pressure that drives conventional chemical farmers to apply toxic pesticides, and the authors of the study find the practice to be economically viable within these cropping systems. “There’s a motion of change going on where growers are thinking more about using natural systems instead of just using pesticides,” said co-author Jason Schmidt, PhD in a news release. “Producers must use all tools available to make a profit, so if they can promote beneficial insects in the system to aid in pest control,  fewer inputs are needed and that should lead to reduced costs of production. ”

To determine how beneficial cover crops were to cotton production, researchers began with experimental crops established over two years in 2016 and 2017 in Georgia. Twelve cover crops plots were established with crimson clover and rye, while a plot not planted with cover crops was used as a control. Researchers planted the cover crop in early November after the previous cotton crop was harvested, and terminated and rolled the cover crop 2 weeks prior to a May cotton planting. Cover crop residue was sucked up with a reverse leaf blower the scientists created and sampled six times at random locations. Analysis was then conducted on the gut content of the pest predators retrieved in order to determine what pests they were consuming.

Predator communities were found to be much more diverse (7 to 10x more) in cover cropped fields. While the cover cropped fields contained a range of spiders and other predaceous bugs, control fields mostly contained a specific type of beneficial beetle. Researchers found the benefits of cover cropping to be most pronounced in the early spring. But as the cover crop degrades, differences between cover cropped and control plot predator communities began to even out.

“There are early-season benefits of cover crops when cotton plants are small, said Dr. Schmidt. “The cover crop residue forms a complex habitat matrix with cotton seedlings popping out of it and there are insect predators in there that can defend those young plants from pests.” Dr. Schmidt indicates that the change occurs when there is more of the cotton crop above ground than the cover crop.  “Later in the season, you see similar communities. So, even though there’s a little bit of habitat on the ground from those cover crops, it doesn’t seem to matter in terms of the overall community in the system when cotton plants become the primary habitat available.”

A deeper review of the findings show that thrip populations, which can often hinder cotton crops in early growth stages, are mitigated by increased cover cropping. Cover crops also bring in predators that hamper stink bug damage to cotton bolls. An economic analysis found cover cropping to be a cost effective approach comparable in expense to a completely conventional chemically managed system. “These results suggest that conventional growers utilizing cover crops could reduce insecticide inputs through natural reductions in pest pressure, and overall do not incur additional production costs,” reads the study in Biological Control.

The scientists indicate that they will continue their work to better understand the complex interactions that occur between pest and predator in crop fields. “That’s our ultimate goal, understanding the functioning of diversity and the beneficial roles species play in production systems and best harvest these services for production systems, like cotton,” said Dr. Schmidt.

The study’s results are likely to be unsurprising for organic farmers and even many home gardeners that make certain they keep their soil covered with organic matter year-round. Key to soil conservation are practices that minimize soil disturbance, increase plant diversity, and continually keep soil covered with live plants or roots in the ground.

The study results are encouraging in the context of a system primarily reliant on chemical inputs. Termination of the cover crop utilized an unnamed chemical herbicide, for instance. Although herbicides are intended to target plant material, products like glyphosate threaten a broad range of species. A federal biological assessment published late last year found that glyphosate itself is likely to affect 93% of endangered species. Thus a range of predator insects that may have assisted in further, or more sustained pest management may have been killed off by the use of a chemical to terminate the cover crop. Non-toxic cover crop termination options include mowing, or the utilization a roller/crimper machine that bends plant residue uniformly over the surface of soil.

In study after study, results show that creating habitat that increases diversity enhances plant productivity and reduces toxic pesticide use.  Conventional cotton production can utilize these practices and see some ephemeral benefits, but when properly maintained, these practices decrease pest pressure and create more stable ecological systems that provide lasting ecological and economic benefits. To truly break out of a reliance on chemical inputs, conventional systems must move not only towards cover crop diversity, but crop diversity in general, as multi-crop farming practices produce higher yields than monoculture farmlands.

Most organic farmers, required to maintain or improve soil health under organic standards, are already conducting practices that work with natural systems. Help continue to grow organic, so that more farmers will adopt these safer practices, by purchasing organic products whenever possible. To help become part of the organic solution, join Beyond Pesticides today, and support our fight to maintain the integrity of organic standards from attacks by the conventional chemical industry.

All unattributed positions and opinions in this piece are those of Beyond Pesticides.

Source: Agroecosystems, Biological Control, University of Georgia news release

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