Plant health key to reducing world hunger

By Katie Tomlinson

On the 16th October, World Food Day events will take place around the globe to draw attention to the growing problem of world hunger and malnutrition.

34Nairobi-Market (1)

Shockingly, the FAO has reported that 10% of the global population experienced severe food insecurity in 2017 and that world hunger has increased for the third consecutive year. Key drivers in this trend have been recent climate variations and extreme weather events and increasing impacts of pests and diseases.

Plant health has always been tightly linked to human health. There are infamous cases where a decline in plant health has contributed to food shortages and caused severe human suffering. Plant diseases not only reduce the quantity of food plants produce but also the quality of food. For instance, species of Aspergillus fungi produce alfatoxins that contaminate oilseeds, cereals, grains, legumes and tree nuts. Continued exposure to aflatoxins in contaminated food can lead to liver cancer, immune suppression and stunted growth in children. The fungus grows particularly well in warm, humid climates common to areas of sub-Saharan Africa. A study has shown high levels of alfatoxin contamination on grains and nuts in central Tanzania and in the Iringa, Tabora, and Kilimanjaro regions, 67% of children were reported to have ingested relatively high levels of alfatoxins. Interventions, such as training farmers in the dangers of alfatoxins to human health and the benefits of drying grains can significantly help to reduce the damage caused by the fungus.

Global plant health is now under threat from a multitude of pests and diseases, which are introduced to new areas through the global trade of plants and can rapidly adapt to favorable climate changes. Examples of emerging threats to plant health include Xanthomonas Wilt of Banana, a bacterial disease which is threatening the food security of about 70 million people in sub-Saharan Africa and the Puccinia graminis f. sp. tritici fungus which is having a devastating impact on wheat in Uganda, and is also threatening most of the wheat-growing countries of the world. These threats to plant health directly affect human health.

To tackle global hunger, the UN launched the Zero Hunger Challenge in 2012, which aims to eliminate all forms of malnutrition and build inclusive, sustainable food systems. This has called for renewed focus to improve responses to food crises, building capacity and resilience and long-term proactive strategies. Through pledging to be a part of the Zero Hunger campaign, 57 countries have implemented measures to prevent and reduce food insecurity risks. Although promising, this progress needs to be scaled up, with increased investment and policy coherence if the goal of ending world hunger by 2030 is to be achieved. World Food Day on the 16th October is driving social and political momentum and attracting attention to the world hunger problem. Events are taking place in around 130 countries and include marathons, hunger marches, exhibitions, cultural performances and concerts. You can take part by attending a World Food Day event and pledge your support for the Zero Hunger campaign.

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About the author
Katie Tomlinson has recently finished her PhD and is about to start a post-doc at the University of Bristol, UK where she will be researching Cassava brown streak virus transmission with Dr. Andy Bailey and Prof. Gary Foster. Her project is funded by the Connected Community Network  for African Vector-Borne Plant Viruses, which is part of the UK government Global Challenges Research Fund. You can read her first-hand experiences of how cassava viruses affect plant health in Uganda in her blogposts for the Cabot Institute.

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The Umatui amazing site women group tackle Tuta absoluta



Located in semi-arid Eastern Kenya, Machakos county is home to the Umatui amazing site women group. The group comprises 15 members who mainly grow tomatoes, cowpeas, pigeon peas, and maize. It is among eight other women groups working with Katoloni Community Based Organisation (CBO),  a non governmental organization under infonet biovision. The CBO runs a mobile Plant Clinic in Machakos county, Kenya and mostly targets organized farmer groups.

Umatui amazing site women group has benefitted from the county project of green house allocation to farmer groups, where they cultivate tomatoes, employing the basic skills provided by an extension officer from the Ministry of Agriculture. Initially the crop was doing well but just before harvest they noticed big leaf mines, and assuming that they were caused by leaf miners, sprayed chemical insecticides. The tomato plants however started  drying up, with the fruits developing black spots which later turned into caterpillar-infested rots. They further misdiagnosed this as tomato blight and applied fungicides which did not work and the tomato crop deteriorated even further leading to worry and frustration among the farmers.

It was at this point that one of the group members said she had discussed the issue with one of her friends and was told the problem could be solved in a ‘Plant Clinic’. This was a new concept to the group, not having heard about it before. However, they decided to give it a try, having exhausted all other options. Armed with a leaf sample of the affected crop, the group’s chairlady Mrs. Florence Koki attended a plant clinic session organized by Katoloni CBO at Mutituni Market. The plant doctor, Mr.  Anthony Musili, who also doubles up as a Biovision Community information worker diagnosed the problem as Tuta absoluta. Together they organized a farm visit to assess the extent of damage by the pest and consequently find recommendations for management.  At the time of the visit to the greenhouse, the tomatoes were already at the harvest stage which meant that sadly the crop for that season could not be rescued.


However, the plant doctor recommended crop rotation with kale in the subsequent season and advised the farmers on various cultural practices to control pests and diseases in the green house. Among these were: preparation of plant extracts and spraying them on infested crops, regular monitoring for pests and diseases, and proper spacing. Upon harvesting the kale, the farmers planted their tomatoes, this time following the plant doctor’s advice. They used a Tuta trap at germination stage  to monitor the presence of the pest as well as control its invasion. Together with the plant doctor’s assistance, they prepared plant extracts from African marigold, Tithonia, Lantana camara, and garlic which they used for spraying. The tomato crop was also infested with Thrips and White flies, and so the plant doctor advised the use of blue sticky traps and yellow sticky traps for control of these two pests, respectively. These technologies worked very well and the group doubled their income from KES 15,000 in the previous season to KES 30,000.

Since then, the members of the Umatui amazing site women group have shared their experiences and the benefits of plant clinic advice with other groups. As a result, other farmer groups have also had sessions with the plant doctor and visited the plant clinic. In addition, the group now use organic pesticides made from plant extracts as opposed to the chemical pesticides they were using before.

Plantwise strives to empower rural communities from within by giving all farmers the knowledge and skills they need to lose less and grow more.


This article has been written in support of International Day of Rural Women, recognised on 15th October.

“The empowerment of rural women and girls is essential to building a prosperous, equitable and peaceful future for all on a healthy planet.”
— UN Secretary-General, António Guterres


J & E/Flickr (CC BY 2.0)

Several species of insects have almost completely vanished from some tropical forests

Insects and other arthropods have declined by up to 99% over 4 decades in a Puerto Rican forest, apparently because of climate change, according to new study. And that’s not the only bad news.

Previously, most insect declines have been documented in temperate ecosystems and blamed on habitat destruction, insecticides, and climate change. In 1976–77, one of the authors of the new study surveyed insects and other arthropods—such as millipedes and pillbugs—in the protected Luquillo rainforest of Puerto Rico with sticky traps and nets. He returned several times between 2011 and 2013 to see how the populations were faring. The weight of arthropods collected in traps on the ground was 97% less than before, he and a colleague report today in the Proceedings of the National Academy of Sciences. The 10 most common species living in the forest canopy also declined, as did the population of walking stick insects (photo).

Something similar happened in the Chamela forest of Mexico when the two researchers compared the abundance of arthropods in 2014 with their previous survey in 1987–88. Meanwhile, the average maximum daily temperatures in the Puerto Rican forest have risen 2°C, and by 2.4°C in the Mexican forest. Ecologists know excessive heat can harm animals, especially those that have evolved to live in relatively constant tropical temperatures.

The damage hasn’t been limited to arthropods. As their biomass declined in Puerto Rico, so did numbers of animals that eat them. In their study of the Luquillo forest, the researchers found that the average density of anole lizards fell by half, for example, and they note that others have found that the more a bird species depends on insects, the harder it has become to find. Indeed, the population of the Puerto Rican tody, a bird that eats only insects, has dropped by 90% between 1990 and 2015. The researchers say climate change, by driving down arthropod populations, could disrupt tropical forests even more than previously thought.

tuta larva on tomato (2)                                    IAPPS tuta wkshop bangalore 2018

From September 27 – 29, the First International Conference on Biological Control: Approaches and Applications took place in Bengaluru, India. In congruence with the International Organization for Biological Control’s (IOBC) Parthenium symposia, the Feed the Future Innovation Lab for Integrated Pest Management hosted a symposia on Tuta absoluta. Tuta is a South American tomato leafminer that was introduced to Spain in 2006, and has now spread across Asia and Africa, with the potential to wipe out 100% of tomato crop yields.

The symposia, led by the International Association for Plant Protection Sciences (IAPPS) Working Group, was conducted on September 28 where 11 presentations addressed topics such as biology of the pest, modeling distribution, biocontrol involving parasitoids and predators, and more. Fifty people representing five continents participated, offering recommendations for future modes of control of the pest.

“Not only did this conference bring together people from all over the world,” Muni Muniappan, director of the Innovation Lab, said, “but it united us in what we should do for further management methods. Some of our final recommendations include pheromone traps, host plant resistance, to continue modeling Tuta’s movement, and to push donor agencies to support Tuta management research and outreach.”

The Innovation Lab currently has a project led by Abhijin Adiga, who presented at the conference, on tracking Tuta absoluta by its movement throughout domestic markets and has already conducted 18 workshops involving 55 countries on management of the pest.

R. Muniappan

IAPPS North America Coordinator


SW FarmPress

boll-weevil_cotton_GettyImages-485779936 alffoto/iStock/Getty Images Plus

Origin of boll weevils in Mississippi under investigation; Texans urged to be diligent

Harvest equipment closely scrutinized to prevent weevil movement to eradicated zones.

Shelley E. Huguley | Oct 12, 2018

Recently two Mexican boll weevils were trapped near Batesville, Miss., in Panola County. How they got there no one knows for sure but boll weevil personnel have increased trapping schedules near the spot where the two weevils were found.

“We know they were identified as boll weevils and they were two males,” says Larry Smith, Texas Boll Weevil Eradication program director, who’s been in contact with some of the Mississippi program managers about the origin of the weevils. “Right now, it’s in the investigative stage.”

Smith says investigations conducted throughout the years have revealed how re-infestations occur, often traced back to vehicles, module trucks or harvest equipment that have previously been in an active boll weevil zone.  “You never know how weevils can move. Everybody automatically thinks equipment, but they can move in many different ways.”

Wind also can be a culprit. For example, along the Rio Grande Valley, where the summer winds primarily blow southeast to northwest, Smith says there is a migration effect from active zones in Tamaulipas, Mexico, to nearby Texas fields, an issue both Mexico and the U.S. are working to resolve.

Boll weevil traps are not only strategically placed in fields but at truck stops and roadside parks and in areas where migration of field laborers occurs, moving from one field to another.

Female weevils can lay up to 200 eggs, laying each egg in a separate cotton square or boll. The entire life cycle, from egg to adult, can be completed in three weeks or less resulting in five or more generations per year.

While 97 percent of the cotton grown in the U.S. is weevil free, Smith says everyone must be diligent to make sure weevils don’t repopulate.

“In Texas, we work in cooperation with USDA and TDA to inspect equipment coming out of weevil areas,” Smith says. “We have over 7 million acres that are eradicated and we don’t want weevils moving into those areas, so we closely scrutinize all the equipment moving out of the quarantined areas. And with all the equipment movement we’ve had this year, luckily, we have not seen anything, but I think part of that is our thorough inspection to make sure there is no cotton material present.”

The Texas quarantine laws help protect our weevil-free areas from someone moving regulated articles from the Lower Rio Grande Valley into all the other cotton growing areas which have been declared eradicated, says Smith.

According to the Texas Boll Weevil Eradication website, cotton harvesting equipment and other equipment associated with the production and transport of cotton, as well as gin equipment, may be moved through a restricted area provided the equipment is free of hostable material, seed cotton and boll weevils in any stage of development by one of the following methods:

a. removal by hand;

b. high-pressure air cleaning;

c. high-pressure washing; or

d. fumigation of regulated articles as prescribed by the Texas Department of Agriculture.

Once the machinery has been cleared, the owner is issued a certificate. “There are pretty high fees if you’re caught moving out of one of those areas without getting the necessary documentation or cleaning the equipment,” Smith says.

While TDA monitors the highways for dirty harvest equipment, Smith says, local producers are often some of our best eyes and ears. “They don’t mind picking up the phone and calling us and saying, ‘Hey, I saw some equipment moving down this road.’ And we’ll check it out, make sure they’ve been inspected.”

Just because harvest equipment is dirty, doesn’t necessarily mean it’s weevil free, it may have been fumigated, which also kills any insects on the machine, says Smith.

To keep custom harvesters on the road and in the field harvesting Texas cotton, Smith says his personnel inspect seven days a week. “Most custom harvesters know to call the foundation,” he says. “And with the wet harvest season we are having, every second is very important. We don’t want to delay them by making them wait until Monday to get an inspection.”

You can hear more from Smith about the Texas Boll Weevil Eradication Program at the 2019 Beltwide Cotton Conference next January 8-10 in New Orleans, La. For more information about the foundation or program, visit: https://www.txbollweevil.org/protect.html.

TAGS: Insects

Thailand: Biological control

Parasitic wasp saves Thai farmers money

11 Oct 2018
Photo of Anagyrus lopezi
Anagyrus lopezi (Courtesy: by CIAT (Anagyrus lopezi) CC BY-SA 2.0 (https://creativecommons.org/licenses/by-sa/2.0), via Wikimedia Commons

Biological control – the use of non-native species to control invasive pests – rings alarm bells for many. The release of cane toads in Australia in the 1930s to control pests devouring the sugar cane crop became infamous, with native wildlife suffering serious declines and the pests largely carrying on strong.

Yet high-profile failures like this are outweighed by more than 250 success stories such as the 1889 introduction of the vedalia ladybird beetle into California’s citrus groves that brought the “cottony-cushion scale” pest under control, or the release of plant-feeding weevils to clean up the invasive water hyacinth choking Africa’s Great Lakes. Analysis of a recent success story has revealed how valuable biological control can be, both financially and through its hidden environmental and human-health benefits.

Back in 2008, the cassava mealybug Phenacoccus manihoti, an aphid-like pest that feeds on sap, arrived in Thailand. Over the next two years, the nation’s cassava crop yields plummeted by more than one quarter. The export price of cassava-derived commodities such as starch surged by 162% and the global cassava trade saw a drastic restructuring, with markets importing cassava-derived products from other countries and substituting different crops.

“Local farmers resorted to insecticides – including products that have recently been banned in Europe,” says Kris Wyckhuys of China Academy of Agricultural Sciences and the University of Queensland, Australia.

In 2009 the Thai Royal Government authorised the release of a South American parasitic wasp, a biological pest control already proven successful across Africa during the 1980s. Around a millimetre long, Anagyrus lopezi solely attacks cassava mealybug, and does not cause any undesirable environmental impacts.

The wasp rapidly brought the cassava mealybug under control and restored crop yields to their pre-invasion levels by 2012.

“It is an entirely cost-free pest control service which naturally propagates from field to field and does not require any intervention on behalf of individual growers, except for refraining from using pesticides,” says Wyckhuys, who published his findings in Environmental Research Letters, Journal of Pest Science and PeerJ. “In many countries, chemically-synthesised pesticides continue to be the first line of defence when addressing invasive pests. For decades those pesticides have been shown to inflict damage on human health and the environment, but with effective biological control in place we simply no longer need them.”

Wyckhuys and colleagues estimate that the introduction of the insect saved Thai farmers as much as $700 per hectare as well as bringing stability to global cassava (starch) markets. Cassava is used for human food, animal feed and biofuel, as starch and to make the artificial sweetener sorbitol and the flavour enhancer mono-sodium glutamate. Thailand is the world’s largest starch exporter, the researchers showed, with 36% of global trade volume. The country is also the biggest supplier of cassava-derived commodities to China.

Awareness of biological control methods is growing; many of Europe’s organic farmers and greenhouse growers rely on the parasitic wasp Encarsia formosa to suppress the greenhouse whitefly and protect valuable tomato and cucumber crops. As history has taught us, we need to exercise caution when using exotic biological pest control organisms, but Wyckhuys and his colleagues believe that with current safeguards, those benefits shouldn’t be underestimated.

Field diagnostic photoguides

Plantwise Photoguides

Photo Booklet montage

The Plantwise training for plant doctors (Module 1: Field diagnostics and plant clinic operation)  is unique in that it is the only international training that focuses on field diagnosis and uses live plant samples in the learning process.  The training takes advantage of the fact that many of the symptoms caused by the different groups of pathogens are often similar irrespective of the host plant.  The training has been widely praised by those just starting a career in field diagnostics as well as those trained to PhD levels as it is rare that the symptoms are laid out in this way.

All too often people will rush into making a diagnosis but Module 1 encourages the trainee to take time and to consider all aspects of the symptoms and to really think about the potential causes.

The training offered in field diagnostics by Plantwise in Module 1  is very generic, focusing on the principles of field diagnosis. The fact is that many of the solutions for the problems, e.g. cultural controls/fungicides/insecticides/etc., are not specific, meaning they are typically effective against all of the species in a pest group. Therefore it is often adequate to identify the group of pathogen or pest.

Since the Plantwise training only goes as far as the general group of the disorder, additional resources are needed for when a more specific diagnosis is required (if biological control was to be used for example). To address this problem Plantwise has produced some photoguides to help guide extension workers to the exact disorder.  Essentially it invites the reader to compare the sample with the photo in the book.

The photoguides are crop specific and each problem often has several photos illustrating the various symptoms (on fruit leaves stems etc) or the various life stages of the pest.  The booklets are divided up so that that similar symptoms are near each other on the page and can easily be compared.  For example even though very they are very different organisms mite damage may look superficially like an viral mosaic and the photos of these symptoms are near one another in the booklets. However the photo of the actual mite would be alongside small insects with which it could be confused. The whole book is cross referenced so that it is possible to navigate around looking at all the photos associated with a particular pest.  Along with each photo there is a brief description of the pest or disease offering additional information useful for diagnosis not seen in the photo.

Booklets on coffee, mango, citrus, onion, cabbage, sorghum, tomato, potato, rice, and Beans have been created thus far with more in the pipeline.

View all photoguides on the Plantwise Knowledge Bank→

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