Why the Perception of Fungicides Is Changing
February 28, 2023 The conventional wisdom that fungicides are “nice to have” applications that cannot match “must have” herbicides is being challenged.
From a bird’s-eye view, the segment’s growth speaks volumes: Just about half a million acres of corn were treated with fungicides back in the late ’90s and early 2000s, while today, over 20 million acres are treated. The development of sophisticated “racehorse” hybrids to push the limit on yields and exploit full-season maturity has resulted in much larger windows for disease to come in and become yield-limiting. In addition, troublesome new diseases like tar spot and Curvularia leaf spot have emerged.
“Fungicides are probably more of a must-have than you’re aware of, even though there are years where it may not return very much, if you don’t have disease or abiotic stress,” says Tyler Harp, Fungicide Technical Product Lead with Syngenta US. But in a span of five years, with abiotic stress present in one or two of those years, the average yield bump over the five years is almost always 15 to 18 bushels across any given location, he says.
“One of the things that we’re learning more and more, is that in addition to disease control, certain classes of fungicides — we call them plant health fungicides — have the ability to also increase the productivity and the efficiency of the crop,” Harp tells CropLife®.
Syngenta calls these fungicides, including Miravis Neo, “cleaner and greener.” Cleaner refers to the ability to manage yield-robbing fungal diseases. Greener refers to the prolonged greening of the plant, by which the fungicide ultimately enables the plant to produce more energy for the period that it’s in the field as opposed to a premature senescence or dry down.
“We want to link the fact that it’s cleaner and has good disease control, but it’s greener because of these plant health benefits: Preservation of yield in the presence of abiotic stress, as well as a more efficient and productive crop,” Harp says.
These fungicides can reduce the leaf transpiration rate but maintain photosynthesis — the PS2 efficiency. “We’re conserving and preventing some of the loss of water vapor of the leaf while having no impact on the energy production,” he explains, noting that in a field where a product like Miravis Neo is used compared to an adjacent field where it is not applied, and drought conditions follow, “you’ll get more leaf curl in the untreated.” The leaf is curling because the plant is trying to conserve the water it has.
The advantage of harvest efficiency is more well known, because the results are tangible — the grower sees a better-quality harvest. When a plant has disease in the leaves or abiotic stress, the leaves will pull starches from the stalk, which compromises the integrity of the crop and makes it more prone to lodging or breaking in the field. The combine is forced to drive as much as 2 mph slower; on the flipside, university research indicates the fungicide application could save growers about $23 per acre, Harp says.
BSI CEO Gason Salinas speaking about new Quillibrium botanical-based biofungicide for ag and QS-21 for vaccines, both from Quillaja saponaria trees grown by BSI.
Botanical Solution Inc. (BSI)’s Quillibrium biofungicide — which was first commercialized in 2019 in Chile and in 2021 in Peru through a partnership with Syngenta and will also launch in Mexico — is another example of these products’ multifaceted properties.
This broad-spectrum biofungicide, based on the extract of Quillaja saponaria Molina, a plant native to Chile, has been proven to be highly efficacious and consistent in the prevention and control of Botrytis cinerea, powdery mildew, sour rot, Alternaria, and others, especially for conventional growers of blueberries, vines, and vegetables. It also triggers a systemic acquired response in the plant when used as a preventative treatment, which results in yield gains across different geographies and markets.
Dr. Eric Tedford, R&D Manager for Summit Agro USA, U.S. distributor for STK Bio-Technologies, explains that STK’s tea tree oil-based biofungicide, Timorex ACT, and hybrid fungicide Regev (tea tree oil + difenoconazole), are primarily known for their high efficacy against a broadspectrum of plant-pathogenic fungi with strong prophylactic and curative activities in crops including vegetables, herbs, grapevines, bananas, rice, coffee, and fruit trees.
Yet, tea tree oil has also been found to turn on genes in some crops, such as bananas and tomatoes, to become resistant to disease.
“You can almost equate it to giving a plant a vaccination,” Tedford describes. In addition, tea tree oil is an excellent product for disease control because it contains eight different terpene alkaloids.
“The reason this is important is because all eight of these are having activity against pathogens, and then you’ve got the difenoconazole [in Regev]. You can almost think of it as a combination of nine active ingredients, all working in tandem to kill the pathogen,” he adds.
BioConsortia photomicroscopy – Fungal Root Colonization
Sarah Reiter, who leads Business Development at BioConsortia, points out that between 10% and 40% of all crop yield is lost to disease, and often it’s lost before disease is even recognized to be present.
BioConsortia’s work focuses heavily on bionematicides for fruits and vegetables and increasingly in row crops, delivered as seed treatments. One of the lead products for corn in its pipeline, which it anticipates marketing in 2025, is shown to outperform Poncho Votivo 2.0 and delivers a 10-bushel yield boost.
Its nematode solutions often outperform chemical counterparts — for example, its bionematicide in strawberries delivers 36% better yield than synthetics.
Plant growth-promoting effects, aside from nematicidal modes of action, include production of in-doleacetic acid (IAA) in the root zone and turning on of either induced system resistance or systemic acquired resistance.
“That is the plant defending itself, basically. It may trigger growth cascades inside the plant and the plant sort of outgrows the plant damage. Both of those are impressive secondary benefits of bionematicides,” Reiter says.
‘Less Is More’
Communicating the fringe benefits of fungicides to retailers and end users presents a separate set of challenges.
Tea tree oil, for example, makes plants better able to protect themselves, but “it’s hard to tell that to a distributor, because they’re not used to that,” Tedford points out. “It’s harder, but I think more people are coming around to it, and more growers are coming around to it, because they’ve actually used products and have seen [the results.]”
Gaston Salinas, CEO of BSI, notes that in developing a biofungicidal product, there is a huge temptation to extract the full value of your product in your marketing approach.
“When you are approaching a grower, you’re trying to give a simple, technical recommendation,” he tells CropLife. “For years, natural products would be considered a sort of snake oil. If you are tempted to give a recommendation that the product is going to solve all your problems overnight — that it’s going to not only help you with disease pressure but it’s also going to help you with biostimulant benefits — then you are going to start losing credibility,” Salinas explains that while trying to introduce a product, it is best to be as specific as possible and find your specific value proposition. “In our experience, less is more. It is better to hear directly from the grower all the great additional benefits when you get back to him the next season, instead of us pushing harder to use the product.”
For BSI, the trade-offs are clear. Focusing on the fungicidal aspects of the product and gaining a position in integrated management strategies comes first. “On the other benefits, we still don’t have the answer on how to capture that value. But we know it’s there, and I think it’s probably a challenge for most companies.
Syngenta’s “cleaner and greener” messaging also speaks to the desire to make the science behind fungicidal activity less cryptic.
“It’s not like we haven’t known about these benefits; I just don’t think we’ve done a good job describing them and putting equity on it. That’s been my mission in life over the past year and a half, to help do that,” Harp tells CropLife, “because I really do believe there’s more value out there than what we think.”
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