Slower to Pull the Trigger on Fungicides, U.S. Growers Asking More Questions
Selectivity remains the name of the game in 2017.
“People that were more selective last year and didn’t get burned by Northern corn leaf blight can justify it in their mind. If you believe the rumors, it’s supposed to be drier this year so they might get away with it a second year,” Daren Mueller, Assistant Professor and Extension Specialist at Iowa State University, says. Nor were growers too quick to pull the trigger on spraying for frogeye leaf spot, despite a slight increase of it in the state.
The many requests he is getting for a corn fungicide efficacy table signals to him that people are looking for other options.
Selectivity is great, but, he says, it’s also good to have flexibility in the plan. Didn’t prepay for fungicides? That’s fine, but know your genetics, and know the season. Have resources in place to make in-season decisions that are responsible.
“I heard from more people this year, especially on the consultant side of things, where they were out there scouting trying to make that decision (on whether or not to spray). I think some of them saw that if they didn’t put a fungicide on fields when they didn’t need it last year they felt they did okay, and saved themselves some money. So I think they may be a little more selective than perhaps 2016,” Damon Smith, Assistant Professor with the University of Wisconsin’s Plant Pathology Department, says.
On the other hand, if it is a wet, early summer, people may go ahead and spray anyway. As always, mindsets can shift and decisions will hinge largely on weather.
Smith shared results of his recent ROI research with AgriBusiness Global‘s sister publication CropLife. The study showed that if disease levels are low around tasseling time, when fungicides are typically applied, the probability of returns on that application in Wisconsin is in the 10% to 20% range. If diseases are active, that goes up to 60% to 65%.
“I think people might try to think more along those lines,” he says. “They will try to do some scouting and decision-making on whether they really need that product or not based on probability of return.”
Growers who adopted the wait-and-see approach amid the low commodity price environment, however, might change their tune especially coming out of last season in the mid-South, Megan Andriankaja, Product Manager with BASF, says. She describes how even progressive growers were caught off-guard by a tremendous amount of Southern rust in corn, which moved in earlier than normal, as well as target spot in soybeans.
“There were some fields I walked in late July in southern Illinois and northern Arkansas where Southern rust had completely demolished the corn crop.” She also visited soybean plots in Arkansas, Mississippi, and Tennessee where target spot had caused 65% defoliation. Yet in the plots where growers had applied BASF’s Priaxor D (AIs: fluxapyroxad+pyraclostrobin+tetraconazole), the soybean plants had kept their leaves and saw a 13-bushel-per-acre yield increase.
“The downside for the growers there is that both of those diseases had taken over faster they could react to it. If we wait and see the disease before taking action, then oftentimes it’s too late, so they spend rest of season playing catch-up,” she says.
To control Southern rust, a strong triazole fungicide like Headline AMP (AI: pyraclostrobin+metconazole) from BASF is effective in corn, says Andriankaja. Apply it at-tassel or earlier in the South — prevention is key, because if you see it, it can eat up fields within a week.
For target spot, 2016 was the first year it popped up in soybeans in the Mid-South, and the second straight year pressure increased in cotton. Andriankaja attributes it to a combination of weather conditions and more inoculum accumulating in fields. Not only were growers not used to scouting for it in the geographies where it was found, it is also a difficult disease to spot because it favors the high-humidity environment found only deep in the canopy. Driving by a plot won’t reveal much on the edges.
“My advice is to be proactive, and make sure (to apply fungicides) preventively, because almost every fungicide is going to be much more effective when applied preventatively rather than curatively.”
Andriankaja says that many of the growers with whom she’s been talking assert that the bushels they lose by not applying a fungicide hits their bottom line worse than anything they save by cutting inputs. “I’ve already heard some of that talk taking place in the beginning of 2017 as well; most are sticking to their guns. I don’t think anybody right now is trying to cut inputs that are going to cost them bushels. They definitely understand there’s a trade-off there.”
If anything, growers are asking more often for products that deliver consistently, no matter the conditions of any given year, she says.
“One thing that has really shown up in our fungicide trials is the consistency of yield response for VT-R1 (tassel-silking) applications in corn as compared to earlier applications,” says Chris Reat, FMC Corn Segment Manager. “Pathogens are present every year, but environmental conditions determine how each year plays out.”
In Wisconsin, interest is high in weighing the risk for white mold for good reason. The three programs that work well on the state’s major disease are very expensive — one 8-oz. application of BASF’s Endura (AI: Boscalid) runs $40. However, in 2016, all of the products paid for themselves and then some, according to Smith.
In a trial he conducted last year, the pricier programs were applied at different timings. The Endura 8-oz. program applied at R3 went 15 bushels better than the non-treated check. “It can be a substantial return if you get the timing right. But it can be a gamble, too.”
Smith described his work on a white mold prediction system, on which he ran a pilot validation study in Wisconsin, Iowa, and Michigan in 2016. The model, which boasted up to an 80% success rate in Wisconsin, uses weather information to determine the presence of small mushrooms called apothecia, without which there is no infection.
“There’s a critical window for spraying soybeans. Those mushrooms have to be present during the soybean bloom period. Our prediction system hinges on whether the weather is going to be favorable for formation of mushrooms during that bloom time.”
He is hoping for a full-scale launch of the prediction system in 2018 so that growers can independently use it.
Other diseases catching the attention of Wisconsin growers: Southern rust of corn moved into the state last year, and although it arrived two weeks too late to cause yield impact, the extra caution that comes with the sense of having just dodged a bullet will stick around. Last year also dealt growers in the state a tremendous amount of stripe rust on wheat.
Generics, Good Stewardship
Andrew Friskop, Assistant Professor with North Dakota State University’s Department of Plant Pathology, also remarked that questions from growers have taken on a decidedly more economic-minded tone as 2017 gets underway, especially as they have been relying on a consistent group of modes of action in their fungicide toolkit for some time.
“I can safely say there have been more questions on generic formulations. They are looking at more inexpensive options for crops grown here. They want to make sure they are not sacrificing efficacy and getting confused (by additional products coming off patent).”
He adds: “Fungicides are never going to go away as far as a management tool. What’s becoming more important now is scout-based spraying. You are seeing more information on when applications should be made — how to save a few dollars here and there. There is more risk assessment,” in contrast with the holistic approach of five to 10 years ago.
North Dakota has been fortunate to escape resistance issues in soybeans and small grains thus far, but Friskop stresses to growers that one of the most important management tools is to use fungicides in combination with crop rotation and resistant varieties. There’s no replacement for good stewardship with so few modes of action. “We are trying to preserve them as long as we can,” he says.
If there is one disease that concerns wheat and barley growers in the Dakotas and Minnesota the most it is scab. Friskop is amping up efforts to evaluate fungicides and fungicide timings to answer grower questions for this disease.
To illustrate how difficult a balancing act disease management can be, he brings up a “trainwreck situation” that has arisen in the northwest corner of the state. There sits a towering amount of durum, because of the Fusarium head blight (scab) pathogen creating levels of mycotoxin too high for market. “They’re trying to find a way to get rid of the grain — it’s a difficult topic. You can’t burn it; you can’t find a hole big enough to bury it.”
Be on the watch for bacterial leaf streak in corn, a new disease that was confirmed in nine states in 2016 including Nebraska, Iowa, Illinois, Texas, Colorado, and Oklahoma. Confusingly, it looks extremely similar to gray leaf spot. “If that continues to spread it may be confusing and people might be spraying a bacterial disease with fungicides,” Mueller says. Caused by the bacterium Xanthomonas vasicola, little on its disease cycle is known, according to the Crop Protection Network.
One of the most buzzed-about fungicides right now is Trivapro from Syngenta. Trivapro contains three active ingredients — azoxystrobin, propiconazole, and Solatenol (benzovindiflupyr) fungicide — that combine to provide both preventive and curative disease control. Solatenol binds tightly to the waxy layer of the leaf, which increases the length of control through the season.
“In several on-farm trials, Trivapro residual lasted 15 to 20 days longer than competitive brands. That type of result from a fungicide does more than pay for itself; it helps add to your bottom line,” said Andrew Fisher, Fungicide Brand Manager at Syngenta.
Across the Midwest and South, Syngenta reported Trivapro-treated acres produced in 2016:
- An average of 27 bushels per acre (bu/A) more corn than untreated, based on 48 non-replicated trials.
- An average of 8 bu/A more soybeans than untreated, based on nine large plot trials.
- Between 11 and 27 bu/A more wheat than untreated and competitive brands, based on five trials.
The company will have a premix registered in the U.S. for Trivapro this year, Eric Tedford, Technical Manager, Fungicides, said at Syngenta’s Media Summit in October.
Also at the Media Summit, Trish Malarkey, Head of R&D, described plans for Syngenta’s “next blockbuster” broadspectrum carboxamide fungicide with an SDHI mode of action, Adepidyn (AI: pydiflumetofen), which made its debut launch in Argentina in November.
Adepidyn provides effective control of leaf spot and powdery mildew, as well as Fusarium head blight, Botrytis, Sclerotinia, and Corynespora. “We are a Swiss company — this is the Swiss army knife of fungicides,” Malarkey said.
Products based on Adepidyn will be sold under the global umbrella brand name Miravis. The active ingredient is currently under review with EPA, and four products containing it are expected to be brought to market in 2017. “It will be exciting because one of the fungicides will play into the row crops very well, and provide benefits above and beyond what we see with Trivapro,” Tedford says.
For wheat growers, BASF received EPA registration for Nexicor, a triple mode-of-action fungicide (AIs: fluxapyroxad+pyraclostrobin+propiconazole) in November. The product, which has multiple tank mix options, offers long-lasting preventative and post-infection control of powdery mildew, tan spot, rusts and other diseases frequently found in cereals. In addition, it can maximize key plant attributes leading to stronger roots and stems, healthier leaves and a cleaner flagleaf.
Introduced for the 2017 growing season, Topguard EQ fungicide from FMC is a new dual mode of action fungicide for corn, soybeans, wheat, pecans and more than 20 other crops. The only premix of azoxystrobin and flutriafol, it protects crops from yield-robbing diseases like leaf spot and blight, especially when facing strobilurin resistance issues.
With one season under its belt, FMC reports a strong performance from its Preemptor SC (AIs: fluoxastobin+flutriafol) fungicide and expects a doubling of acres. It can be applied from V5 to R4 in corn and from R1 to R5 in soybeans and protects against a wide range of diseases, including SDS and white mold.
FMC also recently submitted registration for Bixafen, a new SDHI AI that will be included in a suite of products and will help with resistance.
“Resistance management and search for unique modes of action is driving innovation. Biologicals are playing an important role in some of our new fungicide offerings including Fracture fungicide and Ethos XB insecticide/fungicide,” Kaustubh Borah, TFV Product Manager for FMC, says.