Insecticides: How To Win With A Smaller Arsenal
There’s no way around it: Loss is a central theme this year in dealing with insect pressure in the U.S.
“My biggest problem with losing [insecticide] products is we don’t know what we’re going to lose next. We don’t know what we’re going to have resistance to,” says Dr. Scott Stewart, Professor of Entomology and IPM Extension Specialist at the University of Tennessee. “We need options in the tool chest.”
EPA’s decision to cancel the registration for Bayer CropScience’s Belt (flubendiamide), was upheld over the summer.
The label for Dow AgroSciences’ Transform (sulfoxaflor), too, is now lost on several important crops due to lawsuits about pollinators, a temporary Section 18 exemption was granted in 2016 for certain crops in certain states, namely sorghum and cotton through the South. As cotton acres are set to increase across the South, a Section 18 request will be submitted again this year for tarnished plant bug in the mid-southern states, Stewart says.
There is the potential loss of uses for another key chemistry — pyrethroids — as EPA recently published preliminary risk assessments indicating a concern. The 60-day public comment period on this draft risk assessment ends on January 30.
For others, such as soybean growers battling pyrethroid-resistant aphids in Minnesota, options are few and far between. The state’s department of agriculture turned down a Section 18 exemption request for use of Transform on soybean aphid in 2016, but concerned growers will likely be pushing for it once again this year, says Bruce Potter, Extension Integrated Pest Management Specialist with the University of Minnesota.
An exemption may prove more critical given that chlorpyrifos, sold under Dow’s Lorsban name, is now also under threat.
In November, EPA announced a notice of additional data availability (NODA) for its proposed revocation of all chlorpyrifos food residue tolerances, and reopened the public comment period. “We relied on it heavily, particularly where we were dealing with pyrethroid-resistant soybean aphid,” Potter says.
Dow AgroSciences strongly criticized the NODA. Phil Jost, Dow’s U.S. Insecticides Marketing Leader, tells CropLife®: “The assessment lacks scientific rigor, is contrary to EPA and administration policies of data access and transparency in scientific decision-making, and falls short of the FIFRA requirement that decisions be based on valid, complete and reliable scientific data. However, it is important to note this NODA is not a final decision.” Chlorpyrifos is a critical tool for growers of more than 50 different types of crops in the U.S., he adds.
“I’m a little nervous about [chlorpyrifos’ future],” Potter admits.
The problems, however, reach beyond aphids and pyrethroid treatments. Dow and DuPont Pioneer’s Herculex above-ground trait is failing to provide control of Western bean cutworm. Western corn rootworm populations resistant to multiple Bt proteins are well-documented in Minnesota and several other states. Migratory insects present challenges in predicting insecticide or trait performance from year to year; resistance to some Bt proteins has been found in southern populations of fall armyworm and suspected in corn earworm.
“The battle we’re fighting right now is trying to steward these (insect control tools) as long as we can. I think that’s one reason IPM concepts are important right now, and this whole concept of economics and treating only when you need to just to keep some of the pressure off,” Potter says.
Save, Trade, Rotate
More growers are planting non-Bt corn to save on seed costs, and that practice is expected to expand in 2017. “They are trying to pick and choose fields that are lower risk before planting, and scouting for corn borer, leaving rootworm management to rotation,” Potter says.
Traits figure heavily in conversations with customers these days, says Rick Ekins, FMC Portfolio Manager, Fungicides and Insecticides. There will be an increasing number of growers that reduce traits and then augment with an insecticide treatment either in-furrow or foliar, or a combination of the two — and they will see a cost savings to produce their corn crop, according to Ekins. “There is room in there, if you reduce the trait, to protect where the trait is now absent and still decrease your input costs while maintaining an economic level of control,” he says.
No doubt, growers will continue to look for cheaper insecticide alternatives to brand names as commodity prices lag, and more products fall off patent with fewer new chemistries to replace them. “If growers feel they can get the same quality on the generic market for cheaper they will do it for sure. You will see that continue to expand,” Stewart says.
According to Keith Jarvi, Associate Extension Educator at the University of Nebraska-Lincoln, from 2015 to 2016, prices dropped 10% to 15% on generics. “I see a lot of guys, at least in northeast Nebraska, using generics now.”
One example: Bifenthrin EC formulations run one-third of the cost of FMC’s liquid fertilizer ready (LFR) products, although they may come with additional expenses.
According to Jarvi, the active ingredient has run into resistance problems in Nebraska, where it has commonly been used for controlling beetles, Western bean cutworm, and spider mites since the 1990s.
Nebraska growers will likely begin to trade bifenthrin for other products, such as FMC’s Mustang Maxx and Syngenta’s Warrior, but problematically, all are synthetic pyrethroids. “We’re hoping we’re not going to have a lot of cross-resistance,” he says.
Corn rootworm, of course, remains the Corn Belt’s No. 1 pest. It also happens that it, and the soybean aphid, overwinter very well.
Jarvi recommends putting more crops into rotation as the best defense, while he admits that is not a sure bet in places like the Eastern Corn Belt, where rotation-resistant rootworms are present.
Now that rootworm resistance to the Monsanto Cry 3Bb1 protein gene is well known, growers have increasingly opted for double-stacked traits with two different Bts. “That’s holding up for now, but there are some rumblings it’s already not looking as good as it used to …. It’s my prediction that the double stack isn’t going to work sooner or later — probably sooner,” Jarvi cautions. “That’s why you have to work rotations in, not only crop rotations but trait and insecticide rotations.”
Christa Ellers-Kirk, Technical Market Manager with BASF, reminds growers that doing an investigation of their fields can be hugely beneficial. Don’t take anything for granted.
“Don’t just assume that because you sprayed and still have insects in your field that the product didn’t work,” she says. If you spray a pyrethroid and later notice you have soybean aphids, it doesn’t necessarily mean that the product didn’t work. “If the aphids have wings, those are migratory, and have moved in after you sprayed. It’s something the grower needs to be cognizant of.”
Likewise with traits. “Traits are a big deal right now — it’s the main way of controlling corn rootworm. Check your traits. Go back, dig up some corn, look at the roots. Is it working? Get a feel for what’s working in your area. It’s going to be very area-specific,” Ellers-Kirk advises.
Products that are compatible with beneficials are of particular importance right now, as regulatory anxieties around pollinators and resistance escalate. It’s the reason Ellers-Kirk is so adamant about good stewardship. Regulatory demands on chemical companies in the past five to 10 years have become such that the entire process is slowed down, and the industry can no longer respond to new issues as they come up in the fields.
“We are not going to be able to quickly turn out new products anymore. That’s a thing of the past. So we need to make certain we are using what we have in our toolbox correctly to discourage resistance,” she says. This includes rotating modes of action, using the correct rates of application, considering beneficials, and ensuring that the product sprayed is appropriate for the pests in the field at that time.
BASF is launching its safer-handling pyrethroid product, Fastac CS, nationally this year.
For the in-furrow market, FMC and BASF announced they will integrate their market-leading insect and disease protection technologies into new products formulated with FMC’s patented LFR technology. For 2017, BASF will launch Manticor LFR in-furrow fungicide/insecticide. FMC will launch Temitry LFR insecticide/fungicide.
The catalyst for the collaboration, says Ekins, is higher demand for insect and disease control combined in the same in-furrow product. He reports “very positive” yield results from FMC’s Ethos XB insecticide/fungicide, launched in 2016, when the cold, wet spring translated to high disease pressure in the soil. In a number of instances where the product was used in the field it was the difference between having to replant and not having to replant, he says.
“This is about getting the crop off to the best possible start. Insect protection as we have traditionally thought about it is moving to more complete crop protection with insect and disease products being developed at an increasing rate,” Ekins says.
Two new products for control of spider mites are newly registered for use on soybeans: Zeal miticide (etoxazole) from Valent, which was labeled for field corn, cotton, and melons, received an expanded label for soybeans this year; and Agri-Mek miticide/insecticide (abamectin) from Syngenta, was launched for mite and insect control on nuts, fruit and vegetables, and soybeans.
The pursuit of the new registration was sought when Valent noticed an increasing demand for a true miticide for soybeans.
“Mite damage in soybeans is prevalent in drought and dry conditions, which for many soybean geographies, is an annual occurrence,” says Carlos Granadino, Product Development Manager for Valent.
Dr. Kelley Tilmon, Associate Professor of Entomology at The Ohio State University, says the new registrations are exciting given the very limited existing choices.
“Some of the go-to products for corn and soybean have registration futures that are highly uncertain. One is Lorsban, which is under review, but the other issue with Lorsban is that we’ve had indications that some spider mite populations are resistant. It’s good to have some new miticides on the shelf,” she says.
Looking forward, Tilmon says that the North-Central region can expect to have increasing problems with stink bugs in the next several years, most notably the brown marmorated, which is gradually working its way westward. The pest has become an economic problem in some parts of Ohio, she says.
Tilmon also offers a caveat on the soybean aphid, infestations of which have been deemed an every-other-year phenomenon. But 10 years of data attained from aerial trapping of migrating soybean aphids in the Midwest show otherwise, she says. “The every-other-year pattern is breaking down in many places; I no longer trust that. It can be every year, depending on the year and the conditions.”
According to Ekins, growers are moving more toward applying insecticide in soybean acres in addition or in lieu of seed treatment. This is where the benefits of a liquid starter system show up. When growers are planting corn and soybean with the same planter, and as they convert to insect-and-disease combination products, they can plant their soybeans while controlling disease in the furrow and reduce or augment seed treatment.
“It is a much more attractive offer to the soybean grower, because they have a lot more issues with disease pressure in the soil than insect pressure in the soil,” Ekins says.