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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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Saturday, 19 November 2022 15:31:49

Grahame Jackson posted a new submission ‘Effect of marigold (Tagetes erecta L.) on soil microbial communities in continuously cropped tobacco fields’

Submission

Effect of marigold (Tagetes erecta L.) on soil microbial communities in continuously cropped tobacco fields

Nature Scientific Reports

Scientific Reports volume 12, Article number: 19632 (2022) Cite this article

Abstract

Root-knot nematode disease is a catastrophic soil-borne disease in tobacco production. The regulation of natural microbial communities is considered a good disease management approach to suppress the incidence of soilborne diseases. In this study, the effects of tobacco (Nicotiana tabacum L.)-marigold (Tagetes erecta L.) rotation on the diversity and structure of soil microbial communities in continuously cropped tobacco fields were analyzed to manage this devastating pathogen. The results showed that the soil bacterial OTUs increased after marigold rotation and that the bacterial Shannon, ACE, Chao1 index, and fungal Shannon index were higher in the tobacco-marigold rotation fields than in the continuously cropped tobacco fields by 3.98%, 10.37%, 5.46%, and 3.43%, respectively. After marigold rotation, the relative abundances of Actinobacteria, Acidobacteria, and Ascomycota increased by 28.62%, 107.50%, and 57.44%, respectively, and the proportion of beneficial bacterial genera such as NocardioidesGemmatimonas, and Bradyrhizobium increased. In addition, our results also showed that rotation of marigold could effectively reduce the incidence of root-knot nematodes in the next crop of tobacco. These results indicate that marigold rotation had a positive effect on the soil microecological environment of continuously cropped tobacco fields, reducing the obstacles to continuous cropping of tobacco.

Read on: https://www.nature.com/articles/s41598-022-23517-x

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Verdure: Lance nematodes play hide-and-seek

Most lance juveniles are migratory and feed inside the root, making them difficult to uncover from soil samples and control with a contact nematicide.

November 2022 | Mike Fidanza 

Filed to: VerdureNematodes

The dreaded lance nematode is a microscopic roundworm that feeds both outside of (ectoparasitic) and inside (endoparasitic) turfgrass roots. Also known as the crown-headed lance nematode, this organism can infest creeping bentgrass and bermudagrass putting greens, which leads to a decline in turf quality and function, especially during periods of drought and heat stress. Turfgrasses aren’t alone, as plant parasitic nematodes are responsible for over $157 billion annually in crop loss globally (https://tinyurl.com/2p9c5cc2).

The botanical species name for lance is: Hoplolaimus galeatus (Cobb, 1913) Thorne, 1935. Hoplolaimus means weapon, and galeatus means helmet-shaped. But who are Cobb and Thorne? They are the “authority” or person(s) who named the species. Nathan Cobb, Ph.D., (1859-1932) is considered the “father of nematology” for his pioneering work with nematode taxonomy. Gerald Thorne, Ph.D., (1890-1975) worked under Cobb and wrote the classic “Principles of Nematology” textbook in 1961.

Derek Settle, Ph.D., studied the lance nematode as a doctoral student at Kansas State University in Manhattan, Kan. He wanted to learn more about their population densities and seasonal fluctuations in turfgrass root zones, so he monitored lance populations in a creeping bentgrass putting green. Sites and conditions (or treatments) were: four cultivars (Penncross, Crenshaw, L-93 and Providence), two mowing heights (0.125 or 0.157 inches [3.175 or 3.988 millimeters]), and two irrigation water amounts (1.2 or 2.4 inches [30.5 or 61.0 millimeters] per week.

The test site root zone was 98% sand with 2.1% organic matter and pH of 7.3 and naturally infested with lance. All treatments were arranged in a representative experimental design with three replications. Lance populations were intensively measured every month from July 2001 to October 2003, by collecting soil cores of 0.5-inch (1.3-centimeter) diameter × 2-inch (5.1-centimeter) depth and utilizing the sugar-flotation centrifuge method for nematode extraction and then microscopic identification. Lance nematodes collected were classified as juveniles or adults (male or female).

What did Settle— as a young, ambitious graduate student — find? For creeping bentgrass putting greens, lance populations tend to increase from late spring into the summer, peak about midsummer, decline in late summer, increase again by midautumn, then decline later in autumn going into the winter. Lance populations in the root zone are density-dependent, meaning they tend to aggregate or “clump” together and do not uniformly disperse throughout a sand root zone.

For creeping bentgrass putting greens, a good time to collect soil samples and monitor for lance populations is during May or June, prior to their midsummer peak. Keep in mind, those samples would only reveal lance adults, especially the females that feed on root surfaces. Because most lance juveniles are migratory and feed inside the root, they are nearly impossible to uncover from soil samples and nearly impossible to control with a contact nematicide.

Within the same putting green, sample from an area showing signs of wilt and poor roots and compare with a sample from a healthy area. This is the best way to determine any negative effects from lance and doesn’t depend on damage thresholds, because the weakest greens are most likely to suffer damage, while the healthiest greens may be tolerant of even the highest lance populations.

What about creeping bentgrass cultivars, mowing height or irrigation? Lance populations were similar in all sites and conditions, so those cultural practices tested didn’t affect lance populations. Unfortunately, lance nematodes are not effectively controlled by current nematicides. Therefore, cultural practices that promote healthy rooting and alleviate abiotic stress are recommended — for example, mitigating midday wilt stress by hand watering, using soil surfactants for root zone moisture management, raising mowing heights, rolling instead of mowing, avoiding excessive equipment wear in areas such as clean-up laps, and alleviating concentrated foot traffic by golfers via regular rotation of pin placement.

Settle is senior director of turfgrass programs at the Chicago District Golf Association (Lemont, Ill.). When he’s not chasing nematodes or tweeting nematode photos as @turfdom, he’s chasing his French bulldogs, Ralph and Leo.

Source: Settle, D.M., J.D. Fry, T.C. Todd and N.A. Tisserat. 2006. Populations dynamics of the lance nematode (Hoplolaimus galeatus) in creeping bentgrass. Plant Disease 90(1):44-50 (https://doi.org/10.1094/PD-90-0044).


Mike Fidanza, Ph.D., is a professor of plant and soil science in the Division of Science, Berks Campus, at Pennsylvania State University in Reading, Pa. He is a 21-year member of GCSAA.

Filed to: VerdureNematodes

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Closer look reveals

https://s.tribalfusion.com

URBANA, Ill. – Nematodes, an abundant group of roundworms that exist in nearly every habitat, have long been used as model organisms for studying the function of neurons – the basic unit of animal nervous systems. For years, it was assumed that neuron anatomy was remarkably similar across this large and diverse group. A recent study by University of Illinois researchers turns that assumption on its head.

“It was a comparative study looking at all of these different species of nematodes, including some parasites, and seeing that there are some substantial differences in the number of neurons in the ventral cord,” says U of I nematologist Nathan Schroeder.

According to Schroeder, discovering this degree of variation across the group suggests that neuron number and anatomy may have changed numerous times during nematode evolution. This is significant because the evolution of nervous systems is notoriously difficult to study in complex higher animals. Being able to study the relatively simple nervous system in nematodes can shed light on some basic research questions in nervous system evolution.

pic This image shows a soybean cyst nematode hatching. Credit: Nathan Schroeder

“This group of animals has the simplicity that makes it easy to work with in the lab, but there are these differences across species. So, we can target that and figure out how nervous systems are evolving.”

On a more practical level, the results of this study may lead to development of new nematicides – pesticides that target plant-parasitic nematodes.

“We know from some of the old nematicides that the nervous system is a very effective target. Unfortunately, some of those nematicides were very broad spectrum and would target anything with a nervous system, including us,” Schroeder noted.

The study showed that soybean cyst nematodes, a major crop pest in Illinois, may have unique neurons that could be targeted by new nematicides to avoid harming beneficial soil organisms. More research will be required to determine whether such a product could be developed, but the study indicates that the potential may exist.

The authors are now focusing their attention on soybean cyst nematodes to identify unique neurons and to learn more about how those neurons affect the movement of the microscopic roundworms in the soil and in soybean plants.

source: University of Illinois College of Agricultural, Consumer and Environmental Sciences

January 14, 2016

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Registrations open to attend Pan-African Nematology Network workshop,
1-3 March 2023

From 1-3 March 2023, the second international PANEMA workshop will take place in Mbombela,
South Africa. This 3-day workshop, hosted by the University of Mpumalanga (in cooperation with
North West University, the Agricultural Research Council and with support from Syngenta), will bring
together trained nematologists, early-career researchers, students, agricultural extension workers,
farmers and other stakeholders from across South Africa, Africa and beyond. This event builds on the
success of the first PANEMA workshop, held in Eldoret, Kenya in February 2022, where more than
100 participants travelled from across Africa to attend the event.
Established in 2021, in the framework of the Erasmus+ project Capacity Building in Higher Education
(CBHE): Nematology Education in Sub-Sahara Africa (NEMEDUSSA), PANEMA (Pan-African
Nematology Network) aims to promote networking and academic exchange between nematologists
working in Africa. The focus of the network and workshop is on sharing good educational practices,
creating and strengthening networks between higher education institutes (HEIs) and other
stakeholders, and providing additional educational opportunities for those working in agriculture and
nematology.
The workshop aims to have a good balance between seminars and hands-on practice in the field and
lab, to enhance life-long learning and create opportunities for interactive discussions and networking
between stakeholders. It is also a platform where students and African nematologists can showcase
their projects and research. Next to nematode-related topics such as ‘Nematology and the One Earth
Approach’, this workshop will focus on training in scientific communication skills to create better
awareness about nematodes.
This workshop is open to farmers, agricultural extension workers, students, researchers,
nematologists and interested parties. Tthey are invited to register to attend this event in Mbombela,
which can also be followed free online. For the programme and registration link, please go to
https://nemedussa.ugent.be/2nd-panema-workshop-1-3-march-2023-2/ .
For more information about the NEMEDUSSA project and upcoming PANEMA events, please see
http://www.nemedussa.ugent.be. This project is funded with support from the European Commission.
Nematology Coordination Office: Erasmus+ CBHE project Nematology Education in Sub-Saharan
Africa (NEMEDUSSA)
For more information, reach out to: nemedussa@ugent.be
28/10/2022
What are nematodes?
Nematodes or roundworms cause significant damage and yield loss to a wide variety of crops, often together with
other pathogens. At the same time, nematodes can also be used as bio-control agents against insect pests and/or as
bio-control agents for environmental health and biodiversity. The NEMEDUSSA project aims to increase awareness
about nematodes and expand educational and research capacities in HEIs in Sub-Saharan Africa (SSA) in this field,
and is a joint effort by a consortium of Universities from Sub-Sahara Africa and Europe. The PANEMA workshop is the
next step in bringing nematologists together to collaborate on ways forward to address this pressing agricultural

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Guava root-knot nematode has been detected in Australia for the first time — so how concerned should farmers be?

ABC Rural

 / By Lucy Cooper and Matt Brann

Posted Mon 31 Oct 2022 at 1:47amMonday 31 Oct 2022 at 1:47am

A women sorts sweet potatoes in a packing room.
The guava root-knot nematode is one of the most damaging root- knot nematodes in the world. (ABC Wide Bay: Brad Marsellos)

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Guava root-knot nematode has been detected for the first time in Australia in the Northern Territory — leaving farmers with questions about what to do next. 

Key points:

  • Guava root-knot nematode has arrived in Australia for the first time in the Northern Territory
  • A expert from the United States is not surprised it has been found here
  • Sweet potato growers have been urged to stay vigilant and report suspected cases

The pest severely impacts sweet potatoes by damaging their roots.

It also stunts the growth of a wide range of other crops, including cotton, cucumbers, capsicums, pumpkins and zucchinis. 

The Northern Territory’s chief plant health officer said the pest had been found in four locations in the territory and the likelihood of eradication was quite low.

So how worried should farmers be and what should they do if they find it on their property?

Fumigation used in the United States

man in black shirt and hands on hips smiles at camera
Dr Johan Desaeger says fumigation is a common control method.(Supplied: University of Florida)

Johan Desaeger, an associate professor from the University of Florida, said he was not surprised to hear the pest had been found in Australia.

“Australia was the last continent, except for Antarctica, where this nematode had not been reported yet,” he said.

“It was first identified in the 1980s in China … but I believe this nematode has been around the tropics and sub-tropics across the world probably for millions of years.”

The nematode was first detected in the United States in 2004.

Mr Desaeger, who co-authored a report on the pest this year, said the nematode liked warm weather and sweet potato farmers in the United States were using fumigation to control it.

“I don’t think it’s had a big impact yet in Florida where I am, although it’s had an impact in North Carolina where it’s been impacting the sweet potato industry — but that’s more of a quarantine issue because the tubers are an ideal (host) to spread this nematode,” he said.

“My advice is to keep monitoring it, keep sampling.

“I wouldn’t go into panic mode, just be cautious and if you see root-knot on any crops, get it properly identified … the more information you have the better.”

He said he doubted it would spread to the temperate climates of Australia.

Keep an eye out for signs

The University of Southern Queensland’s Gavin Ash has been studying sweet potato pests and diseases in Australia and Papua New Guinea for the past decade.

He said root-knot nematodes were like “little tiny eels that live in the soil” and in general were one of the “highest-problem” pests for sweet potatoes.

Sweet potato in a bucket, on the ground in a paddock of rich brown soil.
Guava root-knot nematode has had a severe impact on sweet potato production in the United States. (ABC Wide Bay: Eliza Rogers)

“The problem with nematodes is they’re quite insidious — they’re small, you don’t notice them and then all of the sudden you realise you’re not getting as much yield as you used to get and your yield declines over time,” he said.

“The other really important thing with sweet potato, is that any sort of damage or blemish on the potato makes it unsaleable, because people don’t want to buy a potato with black marks or lumpy bits on them.”

He said there was a risk the guava root-knot nematode was already in Queensland and that it was important for growers to keep and eye out for signs.

“We have other (types of) root-knot nematodes in sweet potato and they’re seen as number one or number two in terms of pests and diseases on the roots, and because they’re in the soil they’re more difficult to manage.”

Queensland farmers concerned

With the threat right on their doorstep, Queensland’s sweet potato growers feel they have been left in the dark.

Wolfies Farms is a major sweet potato producer based in Rossmoya, near Rockhampton in Central Queensland. 

Manager Rodney Wolfenden said he was taken by surprise by the news of the pest.

man stares into camera
Farmer Rodney Wolfenden feels left in the dark about the pest.(Supplied: Rodney Wolfenden)

“I’m not familiar with it at all, it’s not something that we’ve had here previously” he said.

Mr Wolfenden first heard about the pest from a fellow member of the sweet potato industry and said he was yet to receive contact from the Department of Agriculture and Fisheries.

“There has been no contact from the department, the only thing that we’ve seen is a press release, but essentially no information about it — nothing,” he said.

Mr Wolfenden said he was unsure of his next steps.

“I’d like to think that there are attempts made to eradicate it or at least contain it — I’m pretty disappointed that it’s there,” he said.

“The only good thing I can see … is that it has actually been spotted and now we can do something about it.”

Mr Wolfenden said it was the last thing the industry needed.

“We’ve been through a hard time over the last couple of years, we don’t need something like this to turn up,” he said.

“It’s going to affect a wide range of other crops as well — no one needs that sort of thing.”

Farmers urged to report suspected cases

In a statement provided to the ABC, Biosecurity Queensland urged growers in the state to remain vigilant.

“Guava root-knot nematode is a significant threat to horticultural industries as it can be more destructive than other root-knot species on many crops,” it said.

“The risk of spread from the Northern Territory into Queensland and other jurisdictions for plant products and commodities currently traded is considered very low, although the risk for nursery plants is likely to be higher.”

Farmers with suspected guava root-knot nematode on their property were told to report it immediately to Biosecurity Queensland on 13 25 23, online at daf.qld.gov.au or to the Exotic Plant Pest Hotline on 1800 084 881.

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Parasitic behavior of the root-knot nematode is negatively regulated by root-derived volatiles of C. metuliferus

by Nanjing Agricultural University The Academy of Science

<img src="https://scx1.b-cdn.net/csz/news/800a/2022/parasitic-behavior-of.jpg&quot; alt="Parasitic behavior of the root-knot nematode is negatively regulated by root-derived volatiles of the cucumber wild relative Cuc" title="Behavioral response of J2 nematodes to XTMC and CM3 root tips. a Schematic representation of XTMC and CM3 root tips for in vitro chemotaxis assays. b Comparison of the number J2s per root tip of XTMC and CM3 at 6 hours post-inoculation. Data are presented as means ± standard deviation (n = 33). **P 
Behavioral response of J2 nematodes to XTMC and CM3 root tips. a Schematic representation of XTMC and CM3 root tips for in vitro chemotaxis assays. b Comparison of the number J2s per root tip of XTMC and CM3 at 6 hours post-inoculation. Data are presented as means ± standard deviation (n = 33). **P < .01 (Wilcoxon signed rank test). c J2s around root tips of XTMC and CM3 at 6 hours post-inoculation. Credit: Nanjing Agricultural University

Recently, scientists from the Institute of Vegetables and Flowers of the Chinese Academy of Agricultural Science provided new insights into the correlation between cucurbit root volatiles and root-knot nematode parasitism, paving the way for development of more sustainable cucumber production.

The researchers used the resistant C. metuliferus line CM3 and the susceptible cucumber line Xintaimici (XTMC) as study materials. CM3 roots repelled second-stage (J2) larvae of Meloidogyne incognita, whereas the roots of XTMC plants attracted the larvae. CM3 and XTMC were found to contain similar amounts of root volatiles, but many specific volatiles, including nine hydrocarbons, three alcohols, two aldehydes, two ketones, one ester, and one phenol, were detected only in CM3 roots.

One of these specific volatiles, (methoxymethyl)-benzene, repelled M. incognita, whereas creosol and (Z)-2-penten-1-ol attracted it. Interestingly, creosol and (Z)-2-penten-1-ol effectively killed M. incognita at high concentrations. The researchers also found that a mixture of CM3 root volatiles increased cucumber resistance to M. incognita.

“This is the first study on volatile compounds in the roots of cucurbitaceous crops. The results provide insights into the interaction between the host and plant-parasitic nematodes in the soil, studying why C. metuliferus repels nematodes and whether there are any substances that can help cucumber avoid nematode infection or kill nematodes around roots is of great significance to cucumber production, which can be used to manage nematodes,” said the authors.

The study was published in Horticulture Research.


Explore further

Tomato plants are more resistant against nematodes when colonized by a fungus


More information: Xiaoxiao Xie et al, Negative regulation of root-knot nematode parasitic behavior by root-derived volatiles of wild relatives of Cucumis metuliferus CM3, Horticulture Research (2022). DOI: 10.1093/hr/uhac051

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Soil Health and Pest Management: Challenges in the European Union

CERTIS

05/07/2022

Jackie Pucci of AgriBusiness Global sat down with Dr. Arben Myrta, Corporate Development Manager with Certis Belchim B.V., based in Italy, to discuss developments in soil health and pest management solutions at the company and wider trends he is witnessing in the space.

Dr Arben Myrta, Certis Belchim B.V.
Quality produce with good soil pest management
Damage by Fusarium wilt in melon
Destroyed tomato plants from the attack of Meloidogyne spp.
Damaged roots of tomato by the nematode Meloidogyne spp.
Nematode damage in carrots from Meloidogyne spp.

Can you talk about some of the key developments in ‘soil health management’ in agriculture and what is driving adoption in Europe?

Soil health in its broad scientific definition considers its capacity, thanks to biotic and abiotic components, to function as a vital living ecosystem to sustain plants and animals. A soil may be healthy in terms of the functioning of its eco-system but not necessarily for crop production. In agriculture, good soil pest management remains a cornerstone for the quantity and quality of production at farm level. When farmers cultivate the same plants for a long time in the same soil without crop rotations or other agronomic measures, the soil starts to evidence nutritional and phytopathological problems for the plants. This is more evident in horticulture, and particularly, in protected crops in Europe, where this problem is of major importance.

In the past, in Europe, soil pest management in horticulture was mostly covered by chemical fumigation, lead first by methyl bromide (MB). MB was later globally banned for depleting the ozone layer, while other fumigants, which were intended to replace it, were not approved during the regulatory renewal process, thus creating a gap between the farmers’ needs and the possibilities to have adequate solutions for their cropping.  Meanwhile, in the last decades there has also been huge progress in research and technology, developing more effective biorational soil products (beneficial microorganisms, such as fungi, bacteria, etc.., plant extracts, etc..) and increased public awareness around human health and the environment, followed by more restrictive legislation on the use of chemicals in agriculture.

Driven by the legislation and the general attention of society on the use of plant protection products in agriculture, the industry has been proactive in looking for new solutions with safer tox and eco-tox profile, focusing on biorational products, whose number, as new plant protection products for the control of soil-borne pests and diseases, is continuously increasing in the EU.

How important do you see soil health and soil pest management in the complete picture of agricultural productivity, and how has that view changed?

Soil health and good soil pest management practices in crop production have always been considered important. In Europe, the level of attention and knowledge on this topic has been higher among professionals and farmers working in horticulture, the ornamentals industry, nurseries and particularly protected crops, basically everywhere where long crop rotations are not easily practiced, and pest-infested soils become a big problem for the farmers.

The rapid banning or limitation of several traditional synthetic products used to control soil pests raised the question for field advisors and farmers of how to deal with soil problems in the new situation. In recent years European farmers have been facing particular difficulties in controlling plant-parasitic nematodes.

Biorational products available today in EU countries represent a very good tool for the management of several soil pests in many crops and targets, but are still not sufficiently effective to guarantee full satisfaction to the growers in important crops like protected fruiting vegetables, strawberry, carrots, potato, ornamentals, etc., which explains why ‘emergency uses’ are still granted at EU country level following the request of grower associations to cover the needs of their farmers. The continuous increase in the numbers of new biorational products in the future, and particularly the innovative formulations that will follow, will be of paramount importance for their role in soil pest management.

A second, but important obstacle, is the generally limited knowledge on soil components (including its fertility and capacity to suppress pests by beneficial microorganisms) and the correct use of the biorational products, which cannot be expected to be effective quickly or be used as solo products, as the ‘old’ chemicals were. They should be seen more in programs with other soil management solutions, as recommended by the integrated production guidelines. Here, a further important obstacle is the lack of an effective public extension service to advise farmers, which is limited or totally lacking in many European Countries.

Everybody in the EU is now convinced that soil management in the future will rely on biorational and integrated solutions, but the question is how to reach this objective gradually, being pragmatic and reliable, balancing the environmental, economic and agricultural perspective. Legislation always steers the direction of progress but should be carefully considering the real product capabilities to make it happen in a short time and not focusing on ‘emergency situations’ as has now been the case for more than a decade.

What are some of the perceptions, either correct or incorrect, and other challenges you are dealing with in the region with respect to products for soil health?

This market has seen a rapid change from chemistry to biorational solutions, but in the meantime is facing a lot of challenges in order to meet the expectations of the farmers for quantity and quality of produce. This topic is widely discussed in dedicated scientific forums like that of the International Society of Horticultural Sciences, of which the last International Symposium on Soil and Substrate Disinfestation was held in 2018 in Crete, Greece. A dedicated round table was organized with soil experts to discuss the important challenges faced by the European growers due to the lack of plant protection solutions for an effective control of several soil pests, most of all nematodes. I participated in that round table discussion, whose main conclusions were the following concerns, considered as target actions for the scientific community:

  • the farmer needs various tools for soil disinfestation (SD) in the light of the limited current arsenal of SD tools;
  • the lengthy and unpredictable European registration process (sometimes more than 10 years from dossier submission to the first national approval) of new plant protection products (including biorational) and the cautious approach of EU regulation, as well as restrictions imposed, has led to a reduction of active ingredients available in the past years;
  • a more effective and faster evaluation system is needed, especially for naturally occurring and low risk products (biological, plant extracts, etc.). That is, all products which are essential for Integrated Pest Management (IPM) programs;
  • following the implementation of Regulation EC 1107/2009, the only tool available to fill the gaps in local production systems is Art. 53 of the above-mentioned Regulation, which provides “derogations” for exceptional authorizations of plant protection products. Such authorizations increased exponentially in the last years, indicating that existing solutions in the European market are not considered sufficient;
  • the above-mentioned EU Regulation has a high socio-economic impact on various production systems in Europe and a Spanish case shows clearly the importance of maintaining a sustainable agricultural activity in local communities that, in the case of protected crops area, includes 13% of the active population employed in agriculture;
  • several European agricultural sectors are affected as the EU authority is allowing increased importation from extra-EU countries, considered unfair competition due to their more flexible registration system for plant protection products than that of the EU;
  • reduced capacity of soil pest research, where experts are retired and not being replaced, alongside weak, or in many areas non-existent, extension services together are causing the loss of soil knowledge and good advice for our farmers. Today, soil diagnosis is frequently completely lacking or insufficient before any soil pest and crop management decisions are taken.

The clear message from the scientific experts at that meeting was that these issues must be correctly addressed at all levels of stakeholders, in such a way that all available tools, including sustainable use of soil disinfestation, may be used in a combined IPM system to allow sustainable production in Europe.

What are some of the most exciting developments at Certis Belchim in soil health and pest management?

Since the establishment of Certis Europe in 2001, we have focused on soil pest and disease management. In 2003, Certis built the first CleanStart program providing integrated solutions for sustainable soil management, combining cultural, biological and chemical approaches. After more than a decade, in the mid-2010s, the CleanStart integrated approach started combining biological and chemical inputs with agronomic services (training to farmers and field advisors, soil pest diagnosis support for partner farms and stewardship product advice for applicators and/or farmers) to provide sustainable soil management for the future, aligned with the principles of the Sustainable Use of pesticides as per the EU Directive. All these activities were carried out successfully thanks to a wide international network created with many research institutes across Europe on soil pest management topics. This approach facilitated our participation in soil research projects funded also by the EU. Thanks to this experience we have been able to prepare and share many publications and communications, in particular the coordination for several years of an International Newsletter on Soil Pest Management (CleanStart).

Last year we were also granted a SMART Expertise funding from the Welsh Government, which is co-founded by Certis, in a research project lead by Swansea University, with Certis Belchim B.V. the industry partner, alongside major Welsh growers, Maelor Forest Nurseries Ltd and Puffin Produce Ltd. This project, now ongoing, looks to develop new and innovative products to control soil pests, primarily nematodes.

Thanks to this team involvement on soil topics, our present soil portfolio includes several biorational solutions such as Trichoderma spp. (TriSoil), Bacillus spp. (Valcure), garlic extract (NemGuard), etc. and this is continuously increasing through our research and development pipeline. With the soil biorational products we have developed a good knowledge not only on the products, but also in their interaction with biotic and abiotic soil components and with other similar products.

Our new company, Certis Belchim, in the future will continue to be particularly interested in this market segment and will be focusing mostly on biorational products. Our plans mainly encompass: (i) label extension to more crops and targets for the existing products; (ii) development and registration of new active ingredients for the control of soil borne pathogens, insects and nematodes; (iii) development of innovative formulations for soil use with focus on slow-release; (iv) field validation of effective programs with bio-solutions and other control methods.

In all these research and development activities, supported by the long experience we have in such topics, we are looking to generate our own IP solutions for soil pest management.

How have you seen this space evolve over the past of years, and what are you expecting the next years will bring?

From a technical perspective, we expect the nematode problems to increase globally in the future. This is due in part to the gradual global increase in average temperature, now recorded over recent decades, which will allow the most damaging nematodes, Meloidogyne spp., to establish at higher elevation and higher latitudes while in areas already infested, they will develop for a longer damaging period of time, thus leading to larger nematode soil population densities by the end of the crop cycle and, in turn, to greater damage to the succeeding crops.

From a regulatory perspective in Europe, if the approval process for new effective nematicides is not shortened and remains as restrictive as today, less effective solutions will be available, and there will be more reductions in rates and crops on which their use is permitted (e.g. not every year). This again will certainly lead to an increase in the severity of the nematodes that in many areas could be overlooked.

From a quarantine perspective, the globalization of trade has facilitated the introduction into Europe of new damaging nematodes and diseases and pests in general, events which are expected to increase in the future. The most critical situation can occur in protected and nursery crops, and for the production of healthy propagating material of annual crops, such as potato seed, bulbs and seeds of bulbous plant crops, including flowers, strawberry runners, woody nursery plants, of both crop and ornamental plants, and in all crops for which quarantine issues must be considered, especially when seeds, bulbs and any kind of plant propagating material are to be exported out of the EU.

The expectation is also that positive results will come from public research (more focus on resources is needed) and private industry where work is ongoing to bring to the market new biorational solutions and innovative methods with higher efficacy in controlling soil pests and to fulfill the increasing needs of this market. However, this will only be realized if regulatory hurdles are reduced in the EU, for example for low risk biorational solutions.

How are external factors (e.g., soaring input costs) impacting the adoption of these products?

Today agriculture and plant protection products, like the whole economy, are affected by higher prices due to the increased cost of energy and raw materials globally. Considering that the costs in agricultural production are already high and sometimes, those of soil pest control are not applicable for several crops, any further increase in production costs may lead to the abandonment of effective solutions, resulting in additional increase in the complexities of soil problems on our farms. This trend, if allowed to persist, will severely affect our agricultural sector.

This said, there will also be a potential increase in the new solutions entering the market in the coming years, which will face higher costs during development and the registration process as well.

From a technical perspective, the only way to reduce such risks is to support farmers with the right knowledge on how to use new soil products correctly (dose rate, timing and method of application, etc..) and increase cost effectiveness.

Can you share highlights of research and case studies that your company has conducted with respect to soil health?

Our company has been involved in many research and market studies dedicated to the soil pest management sector. The last important one was ‘Sustainability of European vegetable and strawberry production in relation to fumigation practices,’ prepared by a European team of independent soil experts. The aim of the study was to understand technically the role and economic impact of chemical soil fumigation in key European areas of vegetable and strawberry production. Three cases of representative crops were investigated: strawberries, solanaceous/cucurbitaceous crops cultivated under protected conditions and carrots as a relevant open field crop.

The study concluded that vegetable production is a key agricultural sector in Europe: including high-value crops like solanaceous and cucurbitaceous crops produced under protected conditions (tomatoes, peppers, aubergines, courgettes, cucumbers and melons), carrots and strawberries, the production value at farmer level is €12.5 billion; the cultivated area involved is roughly 330,000 ha. The importance of these crops is even greater when the entire food value chain, in economic and social terms, is also considered.

High standards in terms of food quality/safety and certificated production, along with affordable consumer prices and consistent availability across the seasons are demanded of European vegetable production and, as a consequence, are the drivers for the growers who have to protect such crops effectively and economically. The growers face very significant issues deriving from soil-borne pests, which are the key limiting factor to achieving quality and economically sustainable yields. As strongly indicated by farmers and crop experts, among the soil-borne pests, nematodes present the most impactful and frequent challenges.

According to the survey carried out in key EU countries (Spain, Italy, France, Belgium,…), the most common soil management practices for vegetable crops and strawberries are: chemical fumigation, crop rotation, resistant cultivars and rootstocks, followed by soil-less systems, non-fumigant treatments, soil solarization, biological products, organic soil amendments, catch and cover crops.

This shows clearly that soil pest management today and in the near future will rely on IPM systems combining and rotating different management practices, with a different degree of implementation depending on the cropping system.

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Potato farmers conquer a devastating worm—with paper made from bananas

Low-tech approach can quintuple yield and slash need for soil pesticide

Female Golden Nematode (Globodera rostochiensis)
These yellow cysts, attached to potato roots, each contain several hundred eggs that hatch into microscopic worms.USDA/SCIENCE SOURCE

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Potato cyst nematodes are a clever pest. These microscopic worms wriggle through the soil, homing in the roots of young potato plants and cutting harvests by up to 70%. They are challenging to get rid of, too: The eggs are protected inside the mother’s body, which toughens after death into a cyst that can survive in the soil for years.

Now, researchers have shown a simple pouch made of paper created from banana tree fibers disrupts the hatching of cyst nematodes and prevents them from finding the potato roots. The new technique has boosted yields five-fold in trials with small-scale farmers in Kenya, where the pest has recently invaded, and could dramatically reduce the need for pesticides. The strategy may benefit other crops as well.

“It’s an important piece of work,” says Graham Thiele, a research director at the International Potato Center who was not involved with the study. But, “There’s still quite a lot of work to take it from a nice finding to a real-life solution for farmers in East Africa,” he cautions.

Soil nematodes are a problem for many kinds of crops. For potatoes, the golden cyst nematode (Globodera rostochiensis) is a worldwide threat. Plants with infected, damaged roots have yellowish, wilting leaves. Their potatoes are smaller and often covered with lesions, so they can’t be sold. In temperate countries, worms can be controlled by alternating potatoes with other crops, spraying the soil with pesticides, and planting varieties bred to resist infection.

These approaches aren’t yet feasible in many developing countries, in part because pesticides are expensive and resistant varieties of potatoes aren’t available for tropical climates. In addition, small-scale farmers, who can make decent money selling potatoes, are often reluctant to rotate their planting with less valuable crops.

In Kenya, the potato cyst nematode has expanded its range and thrived. “The nematode densities are just so astonishingly high,” says Danny Coyne, a nematode expert at the International Institute of Tropical Agriculture. This is leading to an additional problem of biodiversity loss: Potato farmers are cutting down forests to create new fields free of the nematodes.

The idea that banana paper could help farmers rid their soil of nematodes was hatched more than 10 years ago. Researchers at North Carolina State University (NC State) were looking for a way to help farmers in developing countries safely deliver small doses of pesticides. They experimented with various materials. What works best, they found, is paper made from banana plants. Their tubular, porous fibers slowly release pesticides in the soil for several weeks before breaking down. By then, the plant has developed enough so that even if it does get infected, it already has a healthy root system.

In a field trial, researchers added abamectin, a pesticide that kills nematodes, to the paper. They also planted potatoes in banana paper without abamectin as a control. To their surprise, those plants grew nearly as well as the ones with pesticides. Coyne mentioned this puzzling result to a colleague, a chemical ecologist named Baldwyn Torto who studies the interactions between pests and plants at the International Centre of Insect Physiology and Ecology. “This is fascinating indeed,” Torto recalls thinking.

Together with Juliet Ochola, now a graduate student at NC State, Torto devised several experiments to figure out what was going on. The duo discovered the banana paper holds onto key compounds released from the roots of young potato plants, some of which attract soil microbes that benefit the plant. Nematodes have also evolved to notice these compounds. Some, such as alpha-chaconine, are a signal for nematode eggs to hatch. “If a lot of them hatch at the same time, they’re able to bust open the cysts,” Ochola says. After hatching, the young nematodes sense the compounds and use them to seek out the tender potato roots.

Banana fibers absorbed 94% of the compounds, Ochola and colleagues found. When they exposed nematode eggs to the exudates using the paper, the hatching rate decreased by 85% compared with not using the paper, the team reports today in Nature Sustainability. Other experiments suggested the nematodes that do hatch are far less likely to be able to find potato roots enclosed in the paper.

In nematode-infested fields in Kenya, Coyne and colleagues showed planting potatoes wrapped in plain banana paper tripled the harvest compared with planting without the paper. A tiny dose of abamectin in the paper—just five-thousandths of what would normally be sprayed on the soil—boosted the harvest by another 50%. Presumably, any nematodes that happened to come across the potatoes were then killed by the abamectin. “We’ve got a win here,” Coyne says.

Now, researchers are figuring out how to bring the wrap-and-plant paper to potato farmers in East Africa. Banana plantations in Kenya and nearby countries could supply the fibers, which are now discarded as a waste product. Paper manufacturers could then make the pouches. The biggest challenge, Coyne suspects, will be convincing farmers to buy the paper for the first time.

Once the farmers try the pouches, they’ll find them easy to use, the researchers say. “It’s just wrap and plant,” Ochola says. Simple, yes, but wrapping a lot of potatoes will still be laborious, notes Isabel Conceição, a nematode expert at the University of Coimbra. If a machine is developed to wrap the potatoes, she says, it’s possible the approach might also be feasible on larger farms that use mechanical planters.

Meanwhile, Coyne and his colleagues say they have encouraging results from trials with other tuber crops, such as yam and sweet potato. He also hopes many kinds of vegetables, planted as seeds or seedlings, could be protected from soil pests and pathogens with small pots or trays made from banana fiber, impregnated with various pesticides or biocontrol agents.

The appeal is natural: Banana paper is a biodegradable product, recycled from waste, and it could help protect both farmers and the environment. “We are reducing the amount of pesticides by so much,” Ochola says. “To me, I feel like that’s amazing.”


doi: 10.1126/science.ada1727

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PLANTS & ANIMALS

ABOUT THE AUTHOR

Erik Stokstad

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Erik is a reporter at Science, covering environmental issues. 

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LSU awarded $5 million to look into invasive species harmful to sweet potatoes

A team of LSU AgCenter researchers, collaborating with scientists from four other universities, have been awarded a USDA National Institute of Food and Agriculture grant of more than $5 million, aiding them in developing sweet potato varieties resistant to the invasive guava root-knot nematode.

The AgCenter team is spearheaded by nematologist Tristan Watson. It has also received a sub-grant for $990,000 to support research on sweet potato breeding and characterization of resistance mechanisms and associated genes as well as extension of research findings to regional and national stakeholders.

Watson: “Root-knot nematodes are particularly damaging to the sweet potato. The overall goal of this project is to provide Louisiana sweet potato growers effective tools for the management of established and emerging root-knot nematode species.”

Source: lsuagcenter.com

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Dear Colleagues and Friends,

I want to announce that the handbook I developed together with to other editors and 70 chapter authors on: “Integrated Nematode Management: state-of-the-art and visions for the future”

is now officially available, gratis, in open-access format on the CABI website.

The book can be download for direct viewing on your computer or smart phone or both or saved as a pdf for future use.

Please forward this link to anyone you know who might be interested in what we feel is an important hand book on applied plant pathology and nematology.

The link to the e-Book is available on the CABI website at:

https://urldefense.com/v3/__https://www.cabi.org/bookshop/book/9781789247541/__;!!PvXuogZ4sRB2p-tU!WR2OAeEqidoosMzpHs-bVXo8jPYGPd3SSlo9hVPa2C09W-DLj0A5szz2OSyyOczDLg$

The editors put together the 500 pages of science in 65 chapters with over 250+ figures in the 12 month window we set. Good collaborators.

I look forward to any comments you have and hope the vast majority are positive! Of course nothing is perfect.

All the best over the holiday season whether Thanksgiving, Christmas, New Years or other special occasion.

Sincerely yours

Richard Sikora

rsikora@uni-bonn.de

——————————————————————————

Richard A. Sikora, Prof. em.

Institute for Crop Science & Resource Conservation Consultant Plant Health Management University of Bonn, Germany

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