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Here’s How Insects Coax Plants into Making Galls

24-Feb-2021 10:20 AM EST, by Howard Hughes Medical Institute (HHMI)1favorite_border

Newswise: Here’s How Insects Coax Plants into Making Galls

David Stern

Hormaphis cornu aphids feed on witch hazel leaves and coax the plants into making galls.

Newswise — Insects can reprogram plant growth, transforming ordinary plant parts into intricately patterned shelters that are safe havens for feeding and reproduction.

These structures, called galls, have fascinated biologists for centuries. They’re crafted by a variety of insects, including some species of aphids, mites, and wasps. And they take on innumerable forms, each specific in shape and size to the insect species that’s created it – from knobs to cone-shaped protrusions to long, thin spikes. Some even resemble flowers.  

Insects create galls by manipulating the development of plants, but figuring out exactly how they perform this feat “feels like one of the great unsolved problems in biology,” says David Stern, a group leader at the Howard Hughes Medical Institute’s Janelia Research Campus. “How does an organism of one kingdom take control of the genome of an organism in another kingdom to completely reorganize its development, to produce a home for itself?”

Now, Stern and his colleagues have identified the first examples of insect genes that directly guide gall development. These genes are turned on in aphids’ salivary glands and appear to direct gall formation when the insects spit their saliva into the plants. One gene the team identified determines whether such galls will be red or green, the researchers report in a paper published March 2, 2021 in Current Biology.

“I think they’ve discovered essentially new territory,” says Patrick Abbot, a molecular ecologist at Vanderbilt University who wasn’t involved in the work. There’s a strong likelihood that similar genes are found in other insects, he says. “It makes me want to run to the lab and start looking back through my data.”

Figuring out how to study gall formation has been a longstanding challenge, Stern says – one that’s interested him since he was a graduate student doing fieldwork in Malaysia. Gall-making insects aren’t laboratory model organisms like fruit flies, and not as much is known about their genetics.

A few years ago, while wandering the woods of Janelia’s riverside campus, Stern made a convenient observation. Hormaphis cornu aphids make galls on witch hazel trees, small flowering trees that are abundant on campus. Even on a single leaf, Stern noticed, some Hormaphisaphids were making green galls, while others were making red ones. It set up a natural experiment – a chance to compare two visibly distinct kinds of galls and figure out what’s genetically different between the aphids that make them.

When Stern and his team sequenced the genomes of aphids that made green galls and those that made red galls, they pinpointed a gene that varied between the two genomes. Aphids with one version of a gene that they named “determinant of gall color” made green galls; aphids with a different version made red ones. The finding piqued their curiosity, as the gene didn’t look like any previously identified genes.

To dive deeper, they collected aphids from both witch hazel trees and river birch trees. (Hormaphis cornu aphids live on river birch trees in the summer, but don’t make galls there.) Back in the lab, the researchers carefully dissected out the insects’ tiny salivary glands. In these glands, the team hunted for genes that were turned on only in the aphids that made galls. The researchers found that the gene determinant of gall color was similar to hundreds of other genes that were all turned on specifically in the gall forming aphids. Stern’s team dubbed this group bicycle genes.

The gall-making aphids on the witch hazel trees switch on these genes to make BICYCLE proteins. The insects might spit these proteins into plant cells to reprogram leaf tissue into making a gall instead of normal plant parts, says Aishwarya Korgaonkar, a research scientist in the Stern lab who helped lead the project.

“This is a beautiful bit of biology,” says Sam Mugford, a plant scientist at the John Innes Center in Norwich, England who wasn’t involved in the research. “The exciting work ahead will be to understand the molecular processes that are going on inside the plant when the proteins are delivered by the aphid.”

The team is now working to identify the plant molecules targeted by the aphids’ BICYCLE proteins, says Korgaonkar. That could help them understand just how BICYCLE proteins goad plants into forming galls.

“After years of wondering what’s going on, it’s very rewarding to have something to show for it,” Stern says.

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Relationship between Nitrogen and crop disease

  1. The Crescent News
  2. By Hoorman Soil Health Services
  3. Feb 25, 2021 Updated Feb 25, 2021

Nitrogen (N) is the fourth most abundant plant nutrient with about 80-85% N sequestered in protein, 10% in genetic components (DNA & RNA), and 5% in amino acids (protein building blocks). Nitrogen makes proteins like enzymes (speed up chemical reactions), hormones (regulate plant functions), and N increases cell growth. Nitrogen strengthens plant cell walls (cellulose), is used in plant energy transfer (ATP), and in photosynthesis (chlorophyll); effecting many plant processes. If a plant has balanced N, it has less disease; but when N is either deficient or in excess, expect more disease and insect problems in the field, garden, with ornamentals, or house plants.https://e58b06d6ddf80758d88dccc3cc17f20d.safeframe.googlesyndication.com/safeframe/1-0-37/html/container.html

The rate of N application and the form depends on the plant’s life cycle. Nitrogen deficiency or excess N may change the cell wall to become leaky, promoting more diseases. Early on, plants need more nitrates for growth with ammonium sources increasing as the plant matures to increase yield. N stressed deficient plants can’t make full proteins while excess N lowers plant defenses to both disease and insects. Plants typically absorb N in the oxidized form as nitrate (NO3-) or the reduced form as ammonium ( NH4+). Ammonium is 25% more plant efficient than nitrates because it can be easily converted to amino acids but to avoid toxicity, plants need it in small doses and it is easily converted to soil nitrate. Soil health keeps these N forms plant available to optimize plant growth and yield.

Nitrogen interacts with many other plant nutrients. Potassium (K) promotes the increase of nitrates and plant growth, but too much K decreases yield. Adequate phosphorous plus chlorine decreases nitrates and enhances plant ammonium N forms to increase yield. In soybeans, calcium and cobalt are needed for Rhizobium microbes to fix atmospheric N into protein. Supplementing cobalt (a micronutrient) and calcium in soybeans at the right time may increase soybean yields by 3x. Molybdenum, manganese, iron, and magnesium are involved in nitrogen transformations and protein synthesis. As my high school math teacher (Dave Laudick) use to say: It’s as clear as mud. Soil organic matter is a storehouse of many essential micronutrients and allows soil microbes and plants to thrive in a buffered and safe environment. Yes, it’s complicated but worth knowing if yields improve.

Common N related corn diseases are gray leaf spot, stalk rot due to late season N stress (N deficient), and increased aflatoxin due to high nitrates. In soybeans, to much N increases mosaic virus and Rhizoctonia. In wheat, take-all is increased by nitrates, decreased by ammonium; too much N increased powdery mildew; but higher N levels decreases Stagonospora nodurum. Balanced N fertilization is a key to decreasing most diseases.

Time of N fertilization is important. Corn side dressing reduces N leaching and denitrification losses but also decreases Pythium and Rhizoctonia BUT may increase Fusarium and Gibberella stalk rot. Adding a N inhibitor to fertilizer or liquid manure may decrease corn stalk rot by keeping N in the ammonium form late season. In soybeans, avoid over using glyphosate because it chelates or ties up manganese, iron, calcium, and zinc which can affect plant N fixation. In wheat, delaying N fertilizer until spring promotes take-all but avoids excess winter N when its cold and wet, so less Rhizoctonia. Best solution, put on a small amount of N in fall to promote tillering and delay spring N applications until late spring using granular or urea forms of N to reduce foliar leaf stress from liquid N sources.

There are four strategies to reducing diseases associated with nitrogen. The 4 R’s are the right form, right time, right rate, and right place. Use a balanced N fertilizer program with sufficient N in the right form for optimum growth. For corn starter, 25% nitrates and 75% ammonium, is a good mix but placement (2”X2”, 2”X4”) is critical to avoid root stress. Weather, pH, soil conditions (compaction), soil texture, moisture, biological activity, etc. all affect N transformations and plant uptake. Building SOM buffers soils and helps control or moderate these factors. Make timely N applications to avoid N deficiency, excesses, or losses. Modify the soil environment by changing pH (lime), add cover crops to build soil organic matter, reduce soil compaction, add a N inhibitor, avoid over using glyphosate, or supplement with micronutrients to assist in optimal N utilization and less crop disease. Source: Mineral Nutrition and Plant Disease, 2018.

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Brisbane beekeeper creates editable map to track African tulip trees killing native stingless bees

From PestNet

ABC Radio Brisbane

By Antonia O’Flahert

A Brisbane beekeeper has created a map for the public to locate African tulip trees in a bid to weed out the plant, which kills native bees.

Hobbyist beekeeper Phil Baskerville told Steve Austin on ABC Radio Brisbane there was not an effective mapping system to report African tulip trees, so decided to create one on Google Maps.The tree is native to tropical Africa but was once planted as a street tree and garden tree, and while regarded for its red flowers, it is a serious weed which is toxic to native stingless bees and crowds out native vegetation.

“I’ve labelled it [the map] African Tulip Tree, people should be able to find that and they can actually drop a pin on every tree they identify,” Mr Baskerville said.

“It’s quite prevalent across fairly old suburbs, the inner 15-kilometre radius of those suburbs, they were prevalently planted as a street tree down a number of footpaths.”

Brisbane City Council stopped planting the trees 20 years ago, with about 2,000 older plants left, according to environment, park and sustainability chair Fiona Cunningham.

The exotic tree is a significant weed across coastal Queensland which is “highly invasive, forming dense stands in gullies and along streams, crowding out native vegetation”, according to Department of Agriculture and Fisheries information.

Read on: https://www.abc.net.au/news/2021-02-17/beekeper-creates-tree-map-to-save-native-bees/13156240

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Sunday, 21 February 2021 03:49:05

From PestNet

Locust Hunters On a Mission in Kenya


By Kizzi Asala with AFP

In light of the ongoing desert locust infestations in Kenya, the United Nations Food and Agriculture Organization (FAO) has teamed up with the company 51 Degrees to get control of the situation — via tracking software integrated with a hotline system, scouts and dispatched aircraft.

The software — initially developed for tracking poaching, injured wildlife and illegal logging and other conservation needs, has been reworked to instead trace and tackle locust swarms.

The hotline takes calls from village chiefs or some of the 3,000 trained locals scouts.

The aircrafts are then dispatched according to the data on the size of the swarms and direction of travel are shared with the pilots – as well as governments and organisations battling the invasion in Somalia, Kenya and Ethiopia.

Batian Craig, the Director of 51 Degrees, shared the company’s contribution.

“We’ve been part of the desert locusts surveying and controls side of things from January last year, you know, our approach is completely being changed by good data, by timely data, and by accurate data, and you know with that certainly for Kenya and this way we’ve stopped 80% getting back into the breadbasket where last year we were dealing with a very different situation.”

Desert Locust Storm in East Africa

Notoriously difficult to control and each eating its weight in vegetation daily, the ravenous desert locusts first infested the Eastern Horn of Africa region in mid-2019 — eventually invading nine countries as the area experienced one of its wettest and inopportune rainy seasons in decades.

Jane Gatumwa, a local farmer, hopes to an end to this dire situation.

“Before the locusts, we used to harvest 25 bags from an acre of maize but now we don’t expect to harvest anything this time around because they completely eat everything. Back then when there were no locusts we used to harvest 50 bags of potatoes, harvest 5 bags of beans per acre but now they have eaten everything there’s nothing we will harvest. The government needs to act swiftly and spray pesticides so that we can at least salvage the maize which is the only thing left, there’s nothing else left.”

Kenya had not seen the pest in up to 70 years and the initial response was hampered by poor coordination, plus lack of pesticides and aircrafts.

Second Wave Updated Approach

A slick new operation to combat a second wave of the pests has improved control and co-operation in Kenya, Ethiopia and parts of Somalia.

Cyril Ferrand, the FAO East Africa Resilience Team Leader, outlines the new methods to gain control of the problem.

“We have a lot of swarms, the swarms are much smaller and then the capacity to respond is much higher. So a year ago in February 2020, we had two aircrafts in Kenya able to spray a very very minimal quantity of pesticide. Now in Kenya, we have 10 aircrafts operating, so the time lap between the moment we can spot desert locust and the moment we can treat is much faster, which means that the damage also is very reduced on vegetation and biomass.”

In 2020, the locust infestation affected the food supply and livelihoods of some 2.5 million people — and 3.5 million could be impacted in 2021.

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New Zealand deploys insects to tackle wasp problem

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Sign saying "Wasps"

New Zealand has some of the highest numbers of wasps in the world, and is now taking action to tackle them by introducing two insects from Europe.

The hover fly and wasp-nest beetle were given the green light by the country’s Environmental Protection Authority.

They target the nests of wasps, which have overrun parts of the South Island.

The German wasp was introduced in New Zealand in the 1940s and the common wasp arrived in the late 1970s but is now widespread, the government says.

Tasman District Council, based in Richmond, South Island, had applied for permission to introduce the hover fly and wasp-control beetle as bio control agents.

In its application, the council said the region’s honey dew-covered bean trees had the highest density of wasps in the world – with as many as 30 wasp nests per hectare.

So many thousands of wasps had disrupted the local ecosystem – killing honey bees and other insect life – and costing New Zealand’s economy $133m annually in damages and management, local media reported.

The EPA said it had assessed the impact of introducing non-native species and deemed it to be safe.

“The reason why it’s safe is because these two insects only attack wasps and that’s been established both where they come from in Europe but also elsewhere,” said Chris Hill, the EPA’s general manager of hazardous substances and new organisms.

Tasman District Council’s biosecurity and biodiversity co-ordinator Paul Sheldon said it was one of a number of ways to tackle the wasp problem. “It’s not a silver bullet, but it’s one tool in the tool box,” he said.

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icipe launches mass release of indigenous natural enemies to control fall armyworm

Management of the invasive fall armyworm (FAW), scientifically known as Spodoptera frugiperda in Africa, requires the deployment of all tactics within the context of integrated pest management (IPM). The International Centre of Insect Physiology and Ecology (icipe) has launched mass releases of indigenous natural enemies of FAW in Kenya.

Egg parasitoid, Telenomus remus parasitizing fall
armyworm eggs

In Africa, the cultivation of maize represents one of the most important sources of food security, income generation and employment for over 300 million people. However, the recent invasion by FAW has led to yield losses of 8 – 20 million tonnes of maize on the continent.

Maize is attacked by diverse species of native and invasive stemborer pests in Africa. However, the FAW has become the most devastating. It attacks all the developmental stages of the maize plant attracting an unprecedented scale of broad-spectrum application of chemical insecticides by the growers.  In Ethiopia and Kenya, more than 50% of maize growers that applied chemical pesticides for FAW control reported that they only provide marginal control or they are completely ineffective. These chemical pesticides are not only ineffective but expensive and pose serious detrimental effects to humans, biodiversity and the environment.

Egg parasitoid, Trichogramma chilonis
parasitizing fall armyworm eggs

Since the first detection of FAW in East Africa, icipe, jointly with national and international partners have embarked on basic and applied research to understand the ecology of the pest in Africa to guide the development of sustainable management strategies suited for African conditions. Technologies such as the use of icipe’s Push-pull technology, maize-legume intercropping and biopesticides have proven to be a key part of sustainable management strategy for FAW, particularly under smallholder maize production systems in Africa. These technologies are eco-friendly and compatible with the use of biological control agents.

“Though FAW is an alien invasive pest, our research has unravelled significant information on widely distributed native parasitoid species in Africa (namely Telenomus remusTrichogramma chilonis and Cotesia icipe) and their ability to successfully parasitize and kill the invasive pest” explained, Dr Samira Mohamed, Senior Scientist, icipe.

Our approach focusses on evaluating the performance of these native parasitoids on various life stages of the FAW to identify the most effective one. Further we intend to mass produce these effective parasitoids and release them in the FAW hotspots along with other eco-friendly management technologies to effectively manage the pest and improve maize yield”, added Dr Mohamed.

Larval parasitoid, Cotesia icipe
parasitizing young fall armyworm

In the last quarter of 2020 and following a comprehensive assessment of the performance of the native parasitoids, icipe jointly with national partners in Kenya has embarked on their mass releases.  So far over 140,000 wasps each of Telenomus remus and Trichogramma chilonis that parasitize FAW eggs; and 5,000 wasps of Cotesia icipe that parasitize early larval stages of FAW have been released in five counties (Taita-Taveta, Machakos, Embu, Meru, and Nyeri) of Kenya with very encouraging results.

The initial post release field assessments revealed that parasitism rates of FAW in the field increased by 55%, 50% and 38%, for Trichogramma chilonisTelenomus remus and Cotesia icipe, respectively. “The released parasitoids work synergistically to bring down the population of FAW by attacking different developmental stages (eggs and larvae) of the pest. However, for these parasitoids to be able to effectively contribute to the suppression of pest, they need to be conserved by minimizing application of broad-spectrum chemical insecticides”, added Dr Mohamed.

“There are further plans for mass releases of these beneficial insects in other major maize growing zones across Kenya. Also, plans are under way with the national partners to expand the releases of these natural enemies to other eastern and southern African countries”, concluded Dr Sevgan Subramanian, Principal Scientist, icipe.

Selected references

  1. Akutse, K. S., Kimemia, J. W., Ekesi, S., Khamis, F. M., Ombura, O. L., & Subramanian, S. (2019). Ovicidal effects of entomopathogenic fungal isolates on the invasive fall armyworm Spodoptera frugiperda (Lepidoptera: Noctuidae). Journal of Applied Entomology143(6), 626-634. doi.org/10.1111/jen.12634
  2. Khan, Z. R., Pittchar, J. O., Midega, C. A., & Pickett, J. A. (2018). Push-pull farming system controls fall armyworm: lessons from Africa. Outlooks on Pest Management29(5), 220-224. doi.org/10.1564/v29_oct_09
  3. Kumela, T., Simiyu, J., Sisay, B., Likhayo, P., Mendesil, E., Gohole, L., & Tefera, T. (2019). Farmers’ knowledge, perceptions, and management practices of the new invasive pest, fall armyworm (Spodoptera frugiperda) in Ethiopia and Kenya. International Journal of Pest Management65(1), 1-9. doi.org/10.1080/09670874.2017.1423129
  4. Midega, C. A., Pittchar, J. O., Pickett, J. A., Hailu, G. W., & Khan, Z. R. (2018). A climate-adapted push-pull system effectively controls fall armyworm, Spodoptera frugiperda (JE Smith), in maize in East Africa. Crop protection105, 10-15. doi.org/10.1016/j.cropro.2017.11.003
  5. Sisay, B., Simiyu, J., Malusi, P., Likhayo, P., Mendesil, E., Elibariki, N., Wakgari, M., Ayalew, G., & Tefera, T. (2018). First report of the fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae), natural enemies from Africa. Journal of Applied Entomology142(8), 800-804. doi.org/10.1111/jen.12534
  6. Sisay, B., Simiyu, J., Mendesil, E., Likhayo, P., Ayalew, G., Mohamed, S., Subramanian, S., & Tefera, T. (2019). Fall armyworm, Spodoptera frugiperda infestations in East Africa: Assessment of damage and parasitism. Insects10(7), 195. doi.org/10.3390/insects10070195
  7. Sokame, B. M., Subramanian, S., Kilalo, D. C., Juma, G., & Calatayud, P. A. (2020). Larval dispersal of the invasive fall armyworm, Spodoptera frugiperda, the exotic stemborer Chilo partellus, and indigenous maize stemborers in Africa. Entomologia Experimentalis et Applicata168(4), 322-331. doi.org/10.1111/eea.12899
  8. Mohamed, S. A., Wamalwa, M., Obala, F., Fiaboe K.M., Tefera, T., Calatayud, P-A., Subramanian, S., & Ekesi, S.A deadly encounter: Alien invasive Spodoptera frugiperda in Africa and indigenous natural enemy, Cotesia icipe. PLOS ONE. In press


European Union Funded project “Integrated pest management strategy to counter the threat of invasive fall armyworm to food security in Eastern Africa (FAW‐IPM) (FOOD/2018/402‐634); USAID Feed the Future IPM Innovation Lab, Virginia Tech, Cooperative 341 Agreement No. AID-OAA-L-15-00001; BBSRC research grant BB/R020795/1; USAID-OFDA funded project on “Community–based fall armyworm monitoring, forecasting, early warning and management system”; UKs Foreign, Commonwealth & Development Office (FCDO); the Swiss Agency for Development and Cooperation (SDC); the Swedish International Development Cooperation Agency (SIDA); The Norwegian Agency for Development Cooperation (NORAD); the Federal Democratic Republic of Ethiopia; and Government of the Republic of Kenya.


Kenya Agricultural and Livestock Research Organization (KALRO), Kenya; Ethiopian Institute of Agricultural Research (EIAR), Ethiopia; Rwanda Agriculture Board (RAB), Rwanda; Tanzania Agricultural Research Institute (TARI), Tanzania; National Agricultural Research Organization (NARO), Uganda; Jimma University College of Agriculture & Veterinary Medicine, Ethiopia; Haramaya University, Ethiopia, Nairobi University, Kenya. Ministry of Agriculture Livestock and Fisheries, Kenya; Keele University, United Kingdom, The Food and Agriculture Organization (FAO).

The International Centre of Insect Physiology and Ecology (www.icipe.org): Our mission is to help alleviate poverty, ensure food security, and improve the overall health status of peoples of the tropics, by developing and disseminating management tools and strategies for harmful and useful arthropods, while preserving the natural resource base through research and capacity building.Tags:

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University researchers developing aphid-resistant soybeans

These new plants could make it easier for organic farmers to combat the harmful pests, and could also reduce pollution caused by insecticide use in Minnesota.


Motasem Kadadah

Becca Most, Campus Activities Reporter
February 8, 2021Jump to CommentsShare on FacebookShare on TwitterShare via EmailPrint

Last year, 90% of Matthew Fitzgerald’s 450 acres of soybeans were infested with soybean aphids. An organic farmer in Hutchinson, Minnesota, Fitzgerald is one of many whose livelihoods have been devastated by this tiny insect in recent years.

Since 2016, University of Minnesota researchers have been looking to develop an aphid-resistant soybean crop that will not only cut down insecticide use in the state, but assist organic farmers who cannot combat the bugs using traditional insecticides.

Soybeans make up 30% of Minnesota’s total agricultural exports and remain the state’s top export commodity. In 2016, soybeans accounted for $2.1 billion in exports from Minnesota, and the state ranked third in the nation for soybean production as of 2019.

This is one of the reasons why University researcher and the principal investigator on the project Dr. Bob Koch said their work is so important.

Aphids suck nutrients from the soybean plant and excrete a sticky brown film onto their leaves. This makes it harder for the plant to get its energy from the sun using photosynthesis; it also limits the plant’s ability to grow and produce a bigger crop yield.

As part of their second phase of the project, Koch and his team are looking to breed plants with a natural resistance to the aphids. He is also exploring the best way to incorporate these aphid-resistant varieties into production, as well as test their effectiveness and impacts on other pests besides the aphid.

“The research from Minnesota and other states shows that these varieties can be very effective at protecting soybean plants — protecting their yield, preventing aphid populations from growing. But the challenge is they’re not very widely available,” Koch said.

Another element of their research is using remote sensing technologies to help farmers visualize where infestations are in their fields. Using satellite data, researchers have been able to detect damaging levels of aphids. Farmers can then use this data to determine which crops would benefit from treatment and which would not.

Koch said this will be an important tool for farmers who are applying insecticide to their fields. Knowing which areas need the insecticide reduces the tendency to blanket a field in insecticides, and helps farmers opt for a more tailored application, which can save them money, too.

Excessive insecticide use has contaminated surface waters like streams, lakes and rivers and is harmful for pollinators like bees. It can even leach into drinking water, said University professor and researcher Dr. Aaron Lorenz, who is also on the project.

Although he said this research is not the only solution, Koch said it is important to have these crops as another option farmers can turn to.

Fitzgerald said because he is an organic farmer, he does not have the same tools to control aphids as other farmers do. In order to keep his organic status, he cannot use many traditional insecticides, and the ones he can use are very expensive and sometimes do not even work.

Because it is so hard to grow organic soybeans in the U.S. — partially due to these aphids — Fitzgerald said this is why more organic soybeans are actually imported into the country than exported. Another factor is accessibility.

“The availability right now with aphid-resistance soybeans, especially in northern Minnesota and central Minnesota is really, really limited,” Lorenz said. “In general, the big seed companies really don’t develop aphid-resistant soybeans … so my philosophy is that the more we can develop, the better off we are in terms of options for farmers.”

Carmen Fernholz, who owns an organic farm with his family in western Minnesota, said although his crops have been impacted by aphids less in recent years, he wishes he could plant soybeans without worrying about losing hundreds of dollars.

“Whenever the aphid first started showing up here, it could impact the crop and yield by at least 50%. And so, any way to develop aphid-resistant varieties would be a tremendous boon to organic producers,” Fernholz said. “We live in fear that it could show up with a vengeance anytime.”

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Brazil’s EMBRAPA Announces New “Harmless” Bioinsecticide Against Crop Pests

Unlike chemical pesticides,bacteria-based Acera is harmless to the environment, according to the state-owned Brazilian Agricultural Research Company EMBRAPA.By Iolanda Fonseca -February 8, 2021

RIO DE JANEIRO, BRAZIL – The state-owned Brazilian Agricultural Research Company (EMBRAPA) has announced a new bioinsecticide which, according to the company, fights pests that target soybean, corn and cotton crops without endangering the health of workers who handle the product. The bioinsecticide poses no risks to the environment, nor to other insects, ensures EMBRAPA.

Commercially named Acera, the new pesticide is recommended for the control of pests such as the Fall Armyworm (Spodoptera frugiperda), and the Soybean Looper Moth (Chrysodeixis includens). It consists of two strains of bacteria called Bacillus thuringiensis (Bt), which produce proteins with specific toxic properties . . .

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Using allelopathy as a weed management strategy

February 5, 2021 at 10:07 am

Cover crop residue leaches allelochemicals, which help control weeds. But to achieve good, prolonged results, you will still need to implement effective weed control.

Using allelopathy in a weed management strategy
The effects of Lolium multiflorum (pictured here) and stooling rye as cover crops with maize were recently evaluated. Photo: Matt Lavin

Weed management should focus on combining different methods to prevent and control weed populations.

“[This is] not only in the short term but also in the long term,” says Dr Suzette Bezuidenhout, acting scientific manager of Cedara’s crop protection unit.

She adds that cultural weed management practices are important. These include production practices that improve crop competitiveness such as cover crops in combination with conservation tillage.

Allelopathy is a natural process whereby a plant produces one or more biochemicals that influence the germination, growth, survival, and reproduction of other plants.

Bezuidenhout explains that allelopathic cover crops release allelochemicals into the environment and can be used to enhance weed management.

Researchers are constantly conducting field and tunnel experiments to evaluate the weed control abilities of various cover crops and cultivars in combination with the application of herbicide.

Recently, researchers evaluated the effects of two cover crops, Italian ryegrass (Lolium multiflorum) and stooling rye (Secale cereale), without herbicide use, on the growth of maize and yellow nutsedge (Cyperus esculentus) in the field.

The trial involved three control treatments, namely weed residue left on the soil surface, herbicide application, and weed control by hoeing.

In a tunnel experiment, oats, stooling rye and three cultivars of ryegrass were used to evaluate their influence on maize and yellow nutsedge growth and development.

The field experiment examined the desiccation times of cover crops on their weed-control abilities by spraying them with glyphosate four and two weeks before planting and at planting.

Minimum-till maize was planted into the residue with selected spraying of pre- and post-emergence herbicides, and its growth and development were evaluated.

In the first field experiment, maize emergence and growth were delayed in the presence of residues of both cover crop species, and especially in annual ryegrass residues.

C. esculentus growth was significantly inhibited in the area between the maize planting rows by the cover crops for the first 14 days after maize emergence. This growth-suppressing effect diminished after 28 days.

In the tunnel experiment, maize and C. esculentus growth were suppressed, especially by the root residues of the cover crops. The annual ryegrass cultivar Midmar was the most suppressive.

The field experiment indicates that spraying annual ryegrass at planting reduced weed and maize growth the most.

Adequate weed control was not achieved by applying only post-emergence herbicides.
Combining annual ryegrass residues sprayed at planting with only post-emergence herbicides applied later in the season resulted in the lowest maize yields.

Weed growth can be reduced by the allelochemicals leached from cover crop residues, but to achieve prolonged, effective weed control, a farmer needs to apply herbicide and retain mulch on the soil surface.

“More research is needed to establish principles of cover crop weed management in order to define its role in a weed management strategy,” says Bezuidenhout. “The use of cover crops for weed control should therefore be considered a tool that is supplementary/complementary to standard weed-control practices aimed at managing weed populations in the long-term.”

Source: Bezuidenhout, SR. ‘The use of allelopathy in a weed management strategy’. Department of Agriculture and Environmental Affairs, KZN. Retrieved from kzndard.gov.za/research-reports.

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FEBRUARY 4, 2021

New eco-friendly technique protects rice plants against devastating fungal infection

by Tokyo University of Agriculture and Technology

New eco-friendly technique protects rice plants against devastating fungal infection
Spraying rice flowers with a non-pathogenic fusaria produces seeds carrying the non-pathogenic fusaria and controls seedborne bakanae disease.. disease Credit: Tsutomu Arie, Tokyo University of Agriculture and Technology

Researchers have developed a new technique to protect rice seeds against fungal infections that can ruin up to half of all rice crops in the world. The biocontrol method, which involves inoculation of flowers with a different fungus that doesn’t cause disease and using seeds harvested from the flower to grow crops, is even better at protecting rice plants from diseases than existing fungicide approaches, and could also be used against similar pathogens that affect other staple crops.

The extremely destructive seedborne bakanae disease, which affects rice plants everywhere in the world that the staple crop is grown, is currently typically combatted with either chemical fungicides or by hot-water treatment of seeds, all of which face growing challenges to their effectiveness.

However, researchers have developed a new anti-bakanae technique that actively encourages the spread of a different, non-pathogenic variety of fungus, that has been shown to outcompete the disease-causing fungus on rice seeds. This biocontrol method not only delivers protection against bakanae disease as effectively as traditional methods, but can also prevent bakanae disease from affecting the seeds, which current techniques cannot.

The researcher’s findings are reported in the journal Applied and Environmental Microbiology on January 4, 2021.

The pathogenic fungus Fusarium fujikuroi produces gibberellic acid, a plant growth hormone, on rice plants and drives abnormal elongation and etiolation. The affected plants appear pale yellow or white, produce no edible grains, and suffer from weak stems that topple over, hence the name bakanae, Japanese for “foolish seedling.” Losses in the field are substantial wherever the disease emerges, but particularly severe in Asian countries, where the disease can hit 20-50% of crops.

Throughout agriculture, efforts to reduce conventional pesticide use are widespread in order to limit negative impacts on other organisms, but the additional problems that conventional methods of tackling bakanae disease face only add to the need to come up with an alternative. None of these techniques have been very stable, and thus lead to disease outbreaks. They are also not very efficient at combating deeply infected seed stocks. On top of this, existing chemical fungicides also increasingly face challenges from fungicide-resistant strains of the fungus.

The new biocontrol technique, developed by plant pathologists at Tokyo University of Agriculture and Technology, involves spraying rice flowers with a non-pathogenic strain of the fusaria fungus and produces rice seeds carrying the non-pathogenic fusaria. Testing against conventional techniques showed roughly the same level of effectiveness, both against transmission of the disease to seeds, but also transmission among offsprings.

“Investigation under the microscope suggests that the non-pathogenic strain out-competes its cousin, preventing the pathogenic fungi from colonizing the seed, while the growth of the ‘good’ fungus causes no harm,” said Tsutomu Arie, professor and Hiroki Saito, graduate student at the Laboratory of Plant Pathology, Graduate School of Agriculture, Tokyo University of Agriculture and Technology.

As the spread of the good fungus appears to completely replace the bad fungus, the technique should also work on heavily affected seed stocks.

Because rice seeds are usually stored for about six months over the winter before sowing in Japan, the non-pathogenic fusaria in seeds needed to survive at least this amount of time. So to track how long the protection lasted, the researchers genetically tweaked the fungus to make them fluorescent. Six months later, microscopic investigations found that fungal mycelia were still fluorescent, demonstrating they were still there and out competing their “bad” fungus cousins.

The reproductive mechanics of other staple crops in the Poaceae family of grasses that the rice plant belongs to, such as wheat, barley and corn are similar enough that the technique could work on fungal infestations that affect these plants as well. The researchers now aim to test their new method on these crops, as well as on tomatoes, spinach, lettuce, and carrots.

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More information: Hiroki Saito et al, Spray Application of Nonpathogenic Fusaria onto Rice Flowers Controls Bakanae Disease (Caused by Fusarium fujikuroi) in the Next Plant Generation, Applied and Environmental Microbiology (2020). DOI: 10.1128/AEM.01959-20Journal information:Applied and Environmental MicrobiologyProvided by Tokyo University of Agriculture and Technology

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