Plantations around the world have been hit by black Sigatoka, an airborne fungus. In addition to this destructive disease, Asian countries and three South American countries are affected by Panama disease (Fusarium oxysporum f.sp. cubense tropical race 4, abbrev. TR4), a Fusarium fungus that can destroy plantations and contaminate soils, rendering them unsuitable for banana production for at least 20 years.
Farmers have increasingly reached for more chemical products to combat these diseases, but biocontrol products could offer a solution as well as providing longer term benefit in building resilience in soils.
New AG International spoke to Lieselot Van der Veken of Pro Terra-Agro, who has spentthe last 20 years of her career studying this vital crop, buildingan in-depth knowledge of Central and South America.
To begin with, please tell us a little bit more about the problem – what are the main diseases banana growers face globally, have there been new diseases in recent years and how do they spread? The main disease globally in banana is black Sigatoka a fungal leaf disease. It's an airborne disease that attacks the leaves and then renders the leaves insufficiently productive to photosynthesize, so you have a yield loss attached to it and premature ripening, which is huge problem in transport. This is the most widespread disease where in terms of pesticide budgets, it's the biggest cost to farmers.
It's present almost everywhere inthe world, except for Peru for now, because it's a desert area andquite dry. The pressure of black Sigatoka is very much linked with rainfall conditions.
That means that to be able to produce organic bananas, you must go to areas where the rainfall is less than 400 millimetres on a yearly basis to be able to control your black Sigatoka in an organic way. That’s how the organic banana production is actually situated around the world, just through the precipitation levels.
Then there is the Panama disease, tropical race 4 (TR4). That's the Panama disease, Fusarium, sothat's a vascular disease, which is very devastating.
The growers in the east of the world, India and all the eastern partsof the world, Philippines, which isof course the centre of origin of banana, have been suffering from that for many years.
Since it's a vascular xylem blocker, it just terminates the plantation when there is not enough soil biology present. It causes a wilting of the plant, through the blocking of the vascular system of the plant. The progressive wilting and other symptoms don't allow you to produce anymore in the field. Also, the spores stay around for 15 to 20 years in your soil.
So that means a huge loss of investment in capital in terms of banana production, unless you have some management strategy in place, which involve creating “living soils” to prevent this disease from having its own party in what we might call “dead soils” in conventional systems.
So, they are the main two diseases, and then there are some insect pests that are more specific to areas and periods, so bit more punctual in the banana growing season and climate related.
How do those fungal diseases spread? What added long-term problems can they cause? Black Sigatoka spreads by ascospores carried on the wind. The disease has an asexual-sexual cycle, so growers tend to cut off the affected leaves. The leaf material that stays on the ground can also carry the spores. But since it's so labour intensive to remove all those leaves, they tend not to do this.
Some have tried to find a business model for these old leaves. They provide organic fibre, but they are also a source of this foliar fungus.
The Fusarium spreads in a different way, by its spores in soil and infected plant material and attaching itself to animals, or even equipment. This has been the case in spreading the disease from Asia to Central America and then Latin America. When we had the first report in Colombia and then Peru, it apparently had something to do with a bulldozer that came from Asia to do some farming works. There's a lot of pathways, so that makes it really hard to contain, and if you go to banana producing countries, in the airport you will see signs asking for help in preventing TR4. Even shoes can be a source of contamination.
So why is TR4 difficult to treat? It's a vascular disease, meaning that it gets inside the plants. Why does it get easily inside of the plants? It doesn't have its own equipment to do so, so the fungus enters via damaged roots. Damaged roots can be caused by weevils or by nematodes. Or by equipment causing damage to the roots by aerating the soil, which is not so often done.
Fusarium is a secondary disease – it comes into the plant by openings that are already there. Its origin was as an endophytic fungus, meaning there are Fusarium strains that actually provide profit to plants in terms of growth promotion. I've seen it in trials. Originally it must have been a co-evolution between the plants and the fungus. That's why the plant lets it enter and once it enters the vascular system, it is able to grow there.
Under the pressure of pesticides and systemic fungicides to treat black Sigatoka, our hypothesis is that this fungus has been under a lot of stress chemically and it has switched on its pathogenicity genes.
The plant is tricked in a way because it's a fungus that is adapted to growing in the vascular system.
Once it's in the vascular system, it is hard to treat the fungus chemically because you won't be injecting your plants with chemicals.
It's really a kind of an endpoint in our conventional programs in treating Fusarium. It's not only a problem in banana, you see it in most of the intensively grown crops.
We see lettuce or fruiting vegetables like a tomato and sweet pepper coping with Fusarium but it's usually a bit of an endpoint in the sense when your soil is really in a bad condition and not a lot of life anymore around, then the crop becomes sensitive and under pressure from your fungicide. You get yourself a strain that is pathogenic instead of helping your plant out.
Biologically speaking, this fungus doesn't even have the apparatus that other pathogenic fungi have in order to penetrate the roots. This means that it has always been able to enter the roots through existing holes and that the plant has allowed it. It never switched on its defense system and has benefited from growth promotion.
What are other aspects of fertilization can encourage pests and diseases?If we talk black Sigatoka, so a foliar fungus growing on your leaf tissue, the usual fungal pathogens or insects come and feed on a plant because they are in search for nitrogen, for example. But they have to find it in a digestible way for them. So, with our current fertilizer systems being nitrate and urea being applied, we get a very incomplete amino acid incorporated into our leaves, which makes it highly digestible for pest and diseases.
It's known with big agro producers in banana that they have to be careful with their nitrate fertilizer because otherwise they know that the black Sigatoka really gets out of control, so it's something that has been observed for years in the field and the people know.
Tell us about biocontrol treatments that you have either worked with or researched, and how effective have those biocontrol treatments been?Typically when we have foliar diseases, we look for a mycoparasitic organism, which can be a Trichoderma that's used in grape on fungal diseases, or botanical that eradicates bacteria or diseases, such as neem or tea tree oil.
Among the disinfectant, oily substances that can be used against black Sigatoka today, the biggest product is paraffinic oil that is allowed in organic agriculture. It has a fungistatic effect, and that's how they rotate with biologicals, like for example the botanicals. Or, if you go for something living in an organic system, that might be a Bacillus bacteria. Some Bacillus species produce lepidopeptides that induce the plant’s resistance and also kill off the fungal disease on your leaf surface.
These products are applied by air over the plantation. Depending on the pressure, it's sometimes twice a week, such as in Costa Rica, where there are high levels of precipitation. Usually it's every 10 days or every two weeks, depending on precipitation levels.
Can you clarify the importance of precipitation levels? The germination of the fungus goes faster and you get a faster disease cycle and thus a higher disease pressure at higher precipitation levels.
Another approach that we’ve seen in the field involves biological nitrogen. The workers in the plantation came to see me to discuss what I had used because they had observed that in the plots where we had used free-living, nitrogen bacteria, the plots were much less affected by the black Sigatoka.
This confirmed my hypothesis, and it's also not only my hypothesis, but we start to see that if we feed simple nitrogen to plants, then they become very prone to pests and diseases. And we get into a vicious cycle because then you need the chemical pesticides to treat the pests and diseases.
Do you see a place for integrated pest management (IPM) that uses chemistry and biocontrol? I'm convinced that it's a transition that needs to happen towards more resilient, more biodiverse banana cropping systems, and it's a
stepwise approach. I'm sure that there will be a stepwise approach to first botanicals, which are easy transition products because basically they are from natural origin. They also eradicate just like we are used to with chemicals in a farmer's mindset.
That's the first phase of our transition, and by the time the farmers get the confidence and the experience with our biologicals, our system can be more conducive to life stepwise as well. Since we have less harsh chemicals, all the biocontrol agents you insert or you bring into the system have a higher chance to actually proliferate and do their job properly.
For sure it won't be overnight; let's say a switch from conventional chemical inputs to all of a suddena regenerative approach, ororganic system at the other endof the spectrum.
Is it likely that chemistry will be required along with biocontrol in the near future? I’ve worked for seven years alongside some organic banana farmers and they actually reached the same production potential as they would reach conventionally, being 3,000 boxes per hectare, which is a good production if we talk about the Caribbean area.
You can actually do the job and do it in a way that is profitable for the farmers, reducing their input costs. So, it's no longer an argument to say we have to keep doing it theway we do it, because otherwiseit's not profitable.
The organic farmers that you mentioned, are they using manure from local farms? The farm I was talking about is 200 hectares, so it's not a small farm. What they basically do is the same management principles of a conventional farm but replace the input for an organic one and manage it that way. That means if you go with biofertilizer instead of mineral fertilizer, that means applying your fertilizer a bit earlier because it's a slow release.
Typically, organic fertilizer is slow release, so it requires some adaptations of your management in terms of timing of application, and you feed your soil microbes, which in turn feed your plant.
They substitute their inputs with organic inputs where possible, but not everybody has access to that.
In terms of phosphorus and potash potassium, is that coming from manure as such? The farms I was working with had an organic fertilizer – an NPK from organic origins, and from what I understand it includes animal origins, such as feather, bloodmeal, the bones, so all the waste of animal slaughtering.
And also cocoa pods. Let'ssay waste streams that you putinto a granule, just as if it were a mineral granule.
What's in the pipeline for biocontrol products, and what innovation are you seeing that excites you? What I am seeing is that biocontrol companies have become aware of the outdoors, because historically we were born in greenhouses as a biocontrol industry in terms of natural enemies, and then microbials
are being used. If I talk about Latin America, there is more of a history of using microbials than macrobials.
More and more companies are becoming aware of better formulations. There is, for example, better Bacillus species or strains coming on the market, and a combination of Bacilli that are coming on the market for leaf application where we see very good results against black Sigatoka comparable with chemicals.
Not only the soil has a microbiome, but also the leaves have a phyllo sphere microbiome. So, if we can work with living preparates, adding biodiversity that is functional for a system in eradicating pathogens, then we have a gain in biodiversity and a control or management of our disease, which is a double win compared to something that eradicates the disease and maybe has a lot of collateral damage around it as well.
As a first step, I would see these botanicals being a transition product for these fungal leaf diseases in a rotation, and stepwise we can go towards a more biological system where also a Bacillus would grow well or Trichoderma can grow well and actually make sure that your leave surface gets covered again with a good microbiome to protect itself. ●
Do have you had any experience using drones for either broadcasting a biocontrol product or possibly surveying the health of a crop? Yes, we do. We are thankful for this technology advancing because banana farms can be 200 to 900 hectares.
In Central America, a drone is developed where we can spread predatory mites against the banana rust thrips, which is attacking very heavily there and damages the fruit.
It does not damage the nutritional value of the fruit, but due to aesthetical damage there is no market acceptance. The rust thrips produce brownish blemish on the fruits, which is not accepted. To control these thrips, we can just add predatory mites at a rate of one hectare a minute by drone, so that makes it very feasible also to apply biocontrol in these outdoor crops. The nice thing is that we see our predatory mites establishing in the crop when not too many chemicals are being used.
And microbials you can apply by drone as well and what? Yes, there has been some examples of microbials being applied as a powder since they drop on the leaf and the leaf surface is moist. It's tropical humid conditions.
When it’s a liquid that you want to apply, you usually use an airplane and that's really the way to do it. It's a kind of ultra-low volume. You create a mist.
The blue plastic is known as a bunch bag, conventionally impregnated with bifentrine against insects, and also serve to get some extra grade at lower temperatures. Organic growers use other bags that are not impregnated or impregnated with sulphur or plant extracts.
Biocontrol products could offer a solution as well as providing longer term benefitin building resilience in soils.
Banana plantation in Costa Rica. Black Sigatoka levels are dependent on precipitation levels.
Among the disinfectant, oily substances thatcan be used against black Sigatoka today, the biggest product is paraffinic oil that is allowed in organic agriculture.
All the biocontrol agents you insert or you bring into the system have a higher chance to actually proliferate and do their job properly.
The findings are published in Nature Communications by researchers from the University of Southampton, China and Austria.
Plants host a huge variety of bacteria, fungi, viruses and other microorganisms that live in their roots, stems and leaves. For the past decade, scientists have been intensively researching plant microbiomes to understand how they affect a plant’s health and its vulnerability to disease.
“For the first time, we’ve been able to change the makeup of a plant’s microbiome in a targeted way, boosting the numbers of beneficial bacteria that can protect the plant from other, harmful bacteria,” says Dr. Tomislav Cernava, co-author of the paper and associate professor in plant-microbe interactions at the UK’s University of Southampton. “This breakthrough could reduce reliance on pesticides, which are harmful to the environment. We’ve achieved this in rice crops, but the framework we’ve created could be applied to other plants and unlock other opportunities to improve their microbiome. For example, microbes that increase nutrient provision to crops could reduce the need for synthetic fertilizers.”
The international research team discovered that one specific gene found in the lignin biosynthesis cluster of the rice plant is involved in shaping its microbiome. Lignin is a complex polymer found in the cell walls of plants – the biomass of some plant species consists of more than 30 percent lignin.
First, the researchers observed that when this gene was deactivated, there was a decrease in the population of certain beneficial bacteria, confirming its importance in the makeup of the microbiome community.
The researchers then did the opposite, over-expressing thegene so it produced more of one specific type of metabolite – a small molecule produced by the hostplant during its metabolic processes. This increased the proportion of beneficial bacteria in the plant microbiome.
When these engineered plants were exposed to Xanthomonas oryzae – a pathogen that causes bacterial blight in rice crops, they were substantially more resistant to it than wild-type rice.
Bacterial blight is common in Asia and can lead to substantial loss of rice yields. It’s usually controlled by deploying pesticides, so producing a crop with a protective microbiome could help bolster food security and help the environment.
The research team are now exploring how they can influence the presence of other beneficial microbes to unlock various plant health benefits. ●
Bacterial blight Xanthomonas oryzae disease lesions on rice crop
Scientists have found naturally occurring pathogenic fungi infecting the Eucalyptus snout beetle in Eucalyptus forest plantations, and characterized them to develop a biopesticide for controlling the beetle.
Gonipterus platensis, or the Eucalyptus snout beetle, has a heavy impact on Eucalyptus forest plantations worldwide, and it is mostly controlled using the micro wasp Anaphes spp., although control rates rarely become financially viable. This led a team of scientists to look for naturally occurring pathogenic fungi to tackle the Eucalyptus snout beetle problem.
Worldwide, the Eucalyptus forest covers more than 20 million hectares. In the Iberian Peninsula, the Eucalyptus snout beetle could cause defoliation levels of 100 percent and produce wood volume losses of up to 86 percent. Although Eucalyptus wood is important for paper pulp production, the biological control of the Eucalyptus snout beetle is far from total, and on some occasions chemical control is needed, too.
The identification of fungi pathogenic to the Eucalyptus snout beetle is not new. What is remarkable in this new research is that the scientists collected the fungi from naturally infected beetles in the current distribution area in Colombia, so the fungi will be well-adapted to the environmental conditions, which is promising for controlling the beetle in forest plantations.
To ensure that the recovered fungi are suitable for developing a biopesticide, the scientists characterized them in terms of insecticidal activity, UV-B radiation tolerance and other parameters. This characterization ensures that the fungi are suitable for mass production of a biopesticide and, when used in forest plantations, are resistant to the environmental conditions. Beauveria pseudobassiana and Metarhizium brunneum were the most virulent fungi. B. pseudobassiana was the most adapted for producing a biopesticide and tolerant to the environmental conditions.
The fungi could be used to develop a biopesticide, after trials in Eucalyptus forests. For this step the researchers are looking for new funding. After this, the fungi could be used in other countries where the insect causes severe damage. The paper is published in the journal Biological Control. ●
Photo
A Eucalyptus snout beetle in Colombia, infected with pathogenic fungi. Photo: Cindy Mejía.
According to a story by André Julião with the São Paulo Research Foundation, FAPESP, a study that was supported by FAPESP and described in an article published in the journal Environmental Science and Pollution Research, shows that this recognition does not happen in paper wasps of the species Mischocyttarus metathoracicus infected by a biopesticide based on the fungus Beauveria bassiana.
The group of authors, led by researchers at the University of São Paulo’s Ribeirão Preto School of Philosophy, Sciences and Letters (FFCLRP-USP) in Brazil, determined through molecular, survival and behavioural assays that the biopesticide kills wasps, which benefit plants by feeding on pests and performing pollination. They also confirmed that wasps infected by the substance are not detected by nestmates.
The authors include scientists affiliated with the Luiz de Queiroz College of Agriculture (ESALQ-USP), São Paulo State University (UNESP) and the Federal University of Viçosa (UFV), also in Brazil.
“The synthetic insecticide [based on imidacloprid] kills in 24 hours and can quickly wipe out entire wasp colonies. The biopesticide is less lethal initially but kills over a period of 19 days, potentially infecting all the insects in a colony and threatening the long-term survival of the species,” said André Rodrigues de Souza, a researcher at FFCLRP-USP supported by FAPESP and corresponding author of the article.
The biopesticide has an advantage over the synthetic insecticide in that it contains spores of the fungus B. bassiana, which infects only insects, sparing mammals and other animals. The synthetic pesticide tested by the researchers is one of the most widely used and toxic to mammals. It is hazardous to humans if not properly used.
Defensive behaviourIn the survival assay, about half the wasps exposed to the biopesticide died. The entire group exposed to the synthetic compound died. The imidacloprid-based pesticide was 50 times less concentrated than the biopesticide, showing how much more toxic it was to these insects.
A control group was exposed to an inert product or water. Under a quarter of these wasps died, further demonstrating the significant lethality of both pesticides.
In the behavioural assays, which were designed to find out whether wasps infected by the fungus were recognized (more attacked or avoided) by nestmates, the researchers used dead wasps as lures on sticks, which they brought near the nest so that resident wasps could interact physically with them. The resident wasps were able to distinguish nestmates from individuals belonging to other nests, which they attacked by biting and stinging.
They recognized nestmates by detecting the odor of their cuticular hydrocarbons, chemical messengers present on the surface of these insects’ bodies and used for communication. Nest invasions are common in this competitive species, which defends itself aggressively.
In the study, nestmates infected by the biopesticide and hence bearing fungal spores on the surface of their bodies continued to be accepted by the rest of the colony. “If they also attacked infected nestmates, the biopesticide wouldn’t be such a problem for the colony. They were allowed into the nest and probably remained there, so the 19-day period during which they coexisted with the fungus could be sufficient to transmit spores and infect other adults and larvae, potentially endangering the entire group,”Souza said.
Threatened allies The biopesticide containing many fungal spores is sprayed onto crops so that the fungus can colonize and kill in a few days such pests as caterpillars, coffee borer beetles, red spider mites, eucalyptus weevils and silverleaf whiteflies, all of which feed on a wide array of crops.
The wasps feed on caterpillars and can be key allies in the biological control of pests. Social insects are also important pollinators of both crops and wild plants.
For Souza, the results of the study serve as a warning not to avoid using biopesticides, but to test them as rigorously as synthetic pesticides and manage them adequately.
For example, it would be advisable to avoid applying this biopesticide during the day, when the wasps go out to forage and could carry the spores back to the nest.
In recent years, research has shown that mortality testing alone is insufficient to assess the hazardousness of any pesticide, synthetic or biological, for species other than those deliberately targeted by the product. Some compounds may not kill animals immediately but cause loss of fertility, for example, affecting survival of the species in the long run. In light of these findings, the researchers are now studying the effect on wasp fertility of an essential oil widely used as a biopesticide. ●
READ:
Biopesticide resistance
The arrival of various biopesticide options on the market in recent years has meant that farmers could sleep a little more soundly, but it was inevitable. Resistance is now emerging for these products, as it has for conventional insecticides. Treena Hein WRITES.
Rows of bell peppers at AAFC’s Harrow Research and Development Centre, Harrow, Ontario. Photo: Jacob Basso, University of Guelph
For the first time, researchers in Canada have investigated the use of the sterile insect technique (SIT) for controlling populations of the pepper weevil, Anthonomus eugenii. The paper, published in the SCI journal Pest Management Science, revealed compelling findings on the use of gamma irradiation as a sterilization technique to improve the sustainability and effectiveness of pepper weevil management worldwide. The study was a collaboration between Bruce Power, Nordion Inc, the University of Guelph (UofG), Agriculture and Agri-Food Canada (AAFC) and the Fruit and Vegetable Growers of Canada.
The pepper weevil, Anthonomus eugenii, is one of the most important pests of pepper crops in North America. Photo: AAFC, Harrow Research and Development Centre
A. eugenii poses a significant challenge to pepper growers across much of North America, causing millions of dollars’ worth of crop damage annually. The beetle larvae damage the flowers and immature fruit of capsicum plants, with infestations causing yield losses of up to 90 percent. Managing A. eugenii populations is particularly challenging as the development of beetle larvae takes place in the protective confines of pepper fruits.
Roselyne Labbe, greenhouse entomologist at AAFC.
Roselyne Labbe, greenhouse entomologist at AAFC, and
corresponding author of the study, explained the challenges in identifying effective strategies to manage populations of A. eugenii. “In prior research, we found that few conventional, reduced-risk or microbial pesticides could effectively knock down adult populations of the pepper weevil on greenhouse pepper crops. Even assessments of parasitoids that attack larval stages of the pepper weevil had limitations, as they sometimes had trouble accessing hosts deep within the pepper fruit cavity,” she said.
Lead author, Jacob Basso, University of Guelph,at AAFC’s Harrow Researchand Development Centre, Harrow, Ontario.PHOTO: Jacob Basso
The team, led by Jacob Basso, a researcher at the UofG, turned their attention to the SIT, a genetic control method where large numbers of sterile insects are released into the wild to reduce the reproductive success of the pest. Labbe noted that the SIT seemed promising as prior research was conducted with this technique for control of the cotton boll weevil (Anthonomus grandis), a congeneric of pepper weevil.
Key to a successful SIT program is the selection of an appropriate radiation dose for sterilization of the target species. The authors note, “It is critical to determine the minimum radiation dose at which insects are effectively sterilized but maintain their ability to successfully find and mate with wild individuals.” An analysis of the effects of different gamma radiation doses on A. eugenii pupae revealed that irradiation of both males and females at 110 Gy resulted in completely sterile individuals that could not contribute to offspring production if released in field sites.
The researchers noted that the lifespan of the irradiated beetles at this dosage was reduced to under two weeks and therefore recommended that A. eugenii SIT programs should schedule repeated releases of sterile insects no more than two weeks apart, to compensate for their mortality. For the SIT to become a viable A. eugenii management strategy for growers, numerous practical considerations need to be addressed, according to the researchers. “We still need to examine the dispersal capability of irradiated weevils in the field, and, crucially, to evaluate sterile males for their mating competitiveness against non-irradiated male weevils,” noted Labbe.
The team now hopes to apply SIT to control other pests of horticultural crops. “There is still quite a bit of information lacking with these regards. We are for instance interested in applying this strategy for control of lepidopteran pests that routinely invade greenhouse crops,” said Labbe. ●
Tray of Anthonomus eugenii pupae.Photo: Jacob Basso, University of Guelph
A new campaigning coalition advocating increased access to biocontrol within the European Union (EU) was launched in January.
The Biocontrol Coalition already has a number of leading companies among its membership and aims to capitalize on EU elections that are coming up this year. The elections mark the beginning of a newfive-year policy cycle, providingan infrequent opportunity to influence the agenda shaping agrifood innovation.
Prospero & Partners, a management consultancy based in Belgium, is spearheading the secretariat role for the coalition.
“We have three types of members: Leading Members who are biocontrol producers; Supporting Members who are associations, NGOs, companies from other sectors, etc. who want to participate actively in defining the advocacy strategy; and Innovation Allies who are organizations that support our general call for an enabling framework, but who don’t want to be as involved on an ongoing basis,” said Prospero Consulting Partner Kristen Sukalac.
“Our focus at the moment is on recruiting Supporting Members and Innovation Allies, although we would certainly welcome other Leading Members. The founding Leading Members are Aphea.Bio, Atlántica Agrícola, Certis Belchim, Diachem, Evergreen Garden Care, Lallemand Plant Care, Rovensa Next, and Syngenta.”
The full interview can be accessed by subscribing to 2Bmonthly, co-produced by New AG International and DunhamTrimmer. ●
University of California-Riverside (UCR) scientists have discovered a tiny worm species that infects and kills insects.
This new species is a member of a family of nematodes called Steinernema. UCR nematology professor Adler Dillman, whose lab made the discovery, said they are “always on the lookout for new [Steinernema species] because each has unique features. Some might be better in certain climates or with certain insects.”
Hoping to gain a deeper understanding of a different Steinernema species, Dillman’s laboratory requested samples from colleagues in Thailand. “We did DNA analysis on the samples and realized they weren’t the ones we had requested. Genetically, they didn’t look like anything else that has ever been described,” Dillman said.
Dillman and his colleagues have now described the new species in the Journal of Parasitology. They are nearly invisible to the naked eye, about half the width of a human hair and just under 1 millimeter long. They’ve named the new species Steinernema adamsi after the American biologist Byron Adams, Biology Department chair at Brigham Young University. “Adams has helped refine our understanding of nematode species and their important role in ecology and recycling nutrients in the soil,” Dillman said. Adams, who is currently doing research on nematodes in Antarctica, said he is honored to have such a “cool” species bear his name in the scientific literature.
As juveniles, nematodes live in the soil with sealed mouths, in a state of arrested development. In that stage, they wander the soil looking for insects to infect. Once they find a victim, they enter the mouth or anus and defecate highly pathogenic bacteria. Within 48 hours of infection, the insect dies. “It essentially liquefies the insect, then you’re left with a bag that used to be its body. You might have 10 or 15 nematodes in a host, and 10 days later you have 80,000 new individuals in the soil looking for new insects to infect,” Dillman said.
The researchers are certain that S. adamsi kills insects. They confirmed this by putting some of them in containers with wax moths. “It killed the moths in two days with a very low dose of the worms,” Dillman said. Going forward, the researchers hope to discover the nematode’s unique properties. “We don’t know yet if it can resist heat, UV light, or dryness. And we don’t yet know the breadth of insects it is capableof infecting.”
However, S. adamsi are members of a genus that can infect hundreds of types of insects. Therefore, the researchers are confident it will be beneficial on some level whether it turns out to be a specialist or a generalist parasite of multiple types of insects. “This is exciting because the discovery adds another insect-killer that could teach us new and interesting biology,” Dillman said. “Also they’re from a warm, humid climate that could make them a good parasite of insects in environments where currently, commercially available orchard nematodes have been unableto flourish.” ●
Close-up look at the new nematode species, Steinernema adamsi.Photo: Adler Dillman / UCR
Australia’s national science agency, CSIRO, announced that field trials have confirmed the successful establishment of Venturia paralias, a biocontrol agent for sea spurge.
Sea spurge is a serious environmental weed along the whole of Australia’s southern coastline. It is found from Western Australia all the way around Tasmania to mid-New South Wales. It threatens nesting sites of native shorebirds and little penguins (Edyptula minor), and it displaces native plants and changes natural patterns of sand movement.
CSIRO identified a targeted biological control agent for sea spurge: a fungus called Venturia paralias from France. It infects the leaves and stems of sea spurge, reducing its growth and reproduction.
CSIRO began by commissioning comprehensive host-specificity testing of the biocontrol agent. The purpose was to confirm that the fungus, chosen to combat sea spurge, would not harm native plant species. After confirming the fungus was safe and only targeted sea spurge, it received approval for use in the environment.
Senior research scientist Gavin Hunter was project lead. “We worked with Aboriginal Land Councils, Bushcare, Coastcare and Landcare, state government agencies, and the Sea Spurge Remote Area Teams (SPRATS) volunteer group in Tasmania and Victoria, to release the fungus in areas infested with this weed.” The release program across Tasmania and Victoria was supported by the New South Wales government through its Environmental Trust.
Caroline Delaisse is a research technician with CSIRO. She said it was interesting trying to develop field application methods for the fungus. “In the laboratory, we spread the fungus over a plate of agar to grow a ‘lawn’ of mycelium,” she noted. “We dry this out and package it into plastic tubes to mail out to community partners. They then mix it up in a solution to be sprayed onto sea spurge plants at release sites.”
In total, the biocontrol agent has now been released at 182 sites across 40 locations by 26 registered community groups. So far, data from community participants confirms that the fungus has established at 60 release sites. Field surveys have also confirmed the fungus has established in Tasmania.
The fungus has also been released by Parks Victoria at the London Bridge, a natural offshore arch in Port Campbell National Park.This includes nesting sites forlittle penguins.
CSIRO conducted initial assessments seven months after the release. They showed the fungus had infected sea spurge plants at six dedicated monitoring spots around Victoria’s coastline. Stem lesions were observed at all six spots and leaf lesions observed at five out of the six sites. The sea spurge plants at most of the plots showed decreased health.
The most recent field data is from October 2023. It confirmed that stem and leaf lesions were affecting sea spurge plants at all six monitoring sites. And surveys showed the biocontrol agent had naturally spread further afield at all of the monitoring sites. ●
Sea spurge close up in Tasmania showing brown spots on the leaves. These leaf lesions are the biocontrol fungus at work.Photo: CSIRO
The government of the Australian state of New South Wales (NSW) is taking action to combat invasive weeds by investing nearly AUD$500,000 into a program that manages two weeds of national significance with biocontrol agents.
Funding from the NSW Environmental Trust will see the CSIRO and NSW Department of Primary Industries (DPI) use two recently approved biocontrol agents to target two weeds. One biocontrol agent is a weevil targeting cabomba, the other is a fungus which attacks African boxthorn.
Stem-boring weevils (Hydrotimetes natans) will be bred at the DPI’s biocontrol rearing facility in Grafton. They will be introduced to five nursery sites across New South Wales and the CSIRO will monitor their effect on the sites. Cabomba was introduced to Australia in 1967 as an aquarium plant and has since spread along the coast from Cairns to Melbourne, where it can grow up to five centimetres a day.
A pathogenic rust fungus (Puccinia rapipes) will be mass-reared in the CSIRO Black Mountain Laboratories in Canberra. Fungal spore packages will be sent to community members for release in areas across New South Wales which contain African boxthorn and the CSIRO will monitor damage to the weed. African boxthorn is a shrub introduced to Australia in the mid-1800s as a hedge plant.
Following detailed research, testing and risk assessment, the release of these biocontrol agents was approved by the federal Department of Agriculture, Forestry and Fisheries in 2021. ●
The cabomba weevil is smaller than a grain of ricePhoto: CSIRO
Australia-based New Edge Microbials (NEM) has formed a partnership with Lallemand Plant Care, the global biocontrol and biofertilizer business unit of Lallemand Inc.
Lallemand Plant Care develops and markets microorganism-based products for biocontrol, biostimulation and biofertilization, with operations in North America, South America and Europe.
Under this exclusive partnership, NEM will introduce an extensive range of Lallemand products to the market, starting with field trials in 2024 and leading to a steady stream of new product launches from 2025 onwards.
NEM is majority Australian-owned, and regionally based (Wodonga, Victoria). The collaboration with Lallemand will expand NEM’s range of biological inputs, bringing key distribution partners a broader range of science-based biological products for farmer clients.
The partnership includes sharing of intellectual property, and ongoing innovation and new product development. It will also leverage NEM’s new factory and logistics facility in Wodonga which has expanded the company’s product development, formulation, fermentation, production, and logistics capacities. ●
MustGrow Biologics Corp. announced the signing of a collaboration agreement with Bayer AG covering soil applications of MustGrow’s mustard-based biocontrol technologies in Europe, Middle East and Africa, excluding home and garden, turf and ornamental applications.
Under the terms of the agreement, MustGrow will receive an initial upfront payment as well as additional payments linked to the achievement of certain business milestones. Upon the commencement of commercial sales, MustGrow will also be entitled to fees from royalties and manufacturing sales. Additionally, Bayer will be responsible for regulatory and market development work in the respective field of use necessary to commercialize MustGrow’s mustard-based biocontrol technologies, including the development of the formulated product, conducting relevant regulatory data studies for regulatory submissions, filing regulatory submissions, registration with relevant regulatory authorities, and support, marketing, and commercial sales activities.
MustGrow anticipates that the value of the upfront, milestone payments and development work could approximate USD $35 to $40 million over the next several years (not including additional fees from royalties and manufacturing sales).
Pursuant to the agreement, Bayer has also been granted a right-of-first-negotiation for a license to use MustGrow’s mustard-based biocontrol technologies for use in bananas in particular applications, excluding postharvest applications.
MustGrow expects to continue collaborating with Bayer to consider other potential applications of MustGrow’s mustard-based biocontrol technologies, including potentially testing in regions not currently covered by the agreement. ●
Agrivalle, a Brazilian agricultural biologicals company, announced a new partnership with Ginkgo Bioworks which is building a platform for cell programming and biosecurity.
Together, the companies will collaborate on building technologies to advance Agrivalle's biological products, including next-gen fertilizers and biocontrol agents.
Ginkgo will leverage its Strain Optimization Services to improvethe efficacy of Agrivalle's biocontrol products.
In planned future projects, Ginkgo intends to work with Agrivalle to discover and optimize plant-compatible microbes that can provide crop nutrition, and to engineer organisms that can make compounds to specifically target certain pests. This, in turn, could help Agrivalle enhance the breadth and efficacy of their novel biological products and enable them to sell and license products to major players in agriculture acrossthe globe. ●
Summit Agro USA has extended its field trials for its hybrid fungicide REGEV to a variety of crops – potato, grape, apple, blueberry, tomato and watermelon.
Summit Agro USA is the exclusive distributor of STK Botanical Biopesticides and Innovative ‘Hybrids’ in the U.S.
REGEV is STK’s first hybrid fungicide product, which comes in a ratio of 2:1 of tea tree oil (TTO) and difenoconazole. The company also has another formulation of Regev, known as Regev HBX, which comes in a 1:1 ratio, and is registered for use on pecans, soybeans and rice.
Dr. Eric Tedford, Field Research Manager of Summit Agro USA has been sharing new field results on a wide variety of fruits and vegetables using Regev, which is used in 14 countries, including the U.S. Regarding potato, Tedford told New AG International that the product had performed well and showed “good control of early blight.”
The company commissioned trials on grape against black rot and powdery mildew. The results were collected during trials in 2022 in New York state, performed by Assistant Professor of Grape Pathology at Cornell University Katie Gold. Regev was found to be effective against black rot in both clusters and leaves.
The trials for powdery mildew were performed at three sites in California in 2022, at various application rates of Regev, one being 8.5 oz/acre. Some of the trials were also combinations with specific adjuvants, such as Regev plus Dyne-Amic at 0.125 percent, or Kinetic 2.58-3 oz. Regev was also effective against powdery mildew in watermelons, early blight on tomatoes, and efficacy against shoot strikes on blueberry.
Tedford explained in an earlier interview that TTO contains eight different terpene hydrocarbons and so is more akin to conventional chemistry. “TTO has eight active ingredients with multiple mechanisms for its activity.” (See more here on the launch of STK’s second hybrid product, which contains TTO.)
Tedford told New AG International that Summit Agro USA was carrying out more trials with Regev in 2023. “We put out 66 trials with Regev or Regev HBX in 2023.”
The trials for almond covered the following diseases: Alternaria, brown rot, gray mold, bacterial spot, scab and hull rot. Cherry, citrus, peach, onion, peanut, pecan, strawberry, rice and soybean were among the tested crops
“We had excellent results in most of these trials, with efficacy equal to many of the standard fungicides for these crops,” said Tedford.
Classification benefits “With many of the fungicides on the market today being either 3s, 7s or 11s, or combinations of two or three of these, Regev is an excellent new product for resistance management purposes. TTO has been designated by the Fungicide Resistance Action Committee (FRAC) as a BM01 fungicide. This classification is different from the 3s, 7s and 11s, and it has low resistance risk.”
Regev can be used in programs to help reduce the risk of fungicide resistance development, explained Tedford. “The TTO does not impart a residue, so the only residue growers need to concern themselves with for MRL considerations are for the triazole component of Regev.” ●
