Finding The Right Fit

It can take years of research to not only bring a fungicide to the market, but also to find how it will fit in growers’ programs.

By Amanda Huber

Abraham Fulmer, who spent seven years as a graduate student at the University of Georgia under Bob Kemerait, Extension plant pathologist, and is now BASF technical marketing manager, has been around peanuts long enough to see how changes in weather patterns, production practices and prices can affect disease problems and fungicide selections. That experience has also underscored that it can take several years of research and collaboration to know where a product has the best fit, which is critical in his current role. Then again, the way Fulmer looks at it, the goal is to help producers, no matter whether the solution is from BASF or another company.

“The best conversations with growers are when you get down to their unique situation and then help them figure out a solu- tion,” he says. “That’s where I think boots on the ground are so important, along with our relationships with universities, cooperative Extension, specialists, crop advisors and consultants.”

It takes everyone working together to keep up with the changing landscape that is peanut production. One example is the change in the type of leaf spot found in peanuts.

Increasing Late Leaf Spot Pressure

“Early leaf spot was predominant through Georgia Green until 2008-2010,” Fulmer says, although prior to the Georgia Green variety, it was late leaf spot that growers encountered more. Now, it’s back to late leaf spot found often, which is likely a combination of factors, such as later planting dates, introduction of new varieties, extended spray intervals and frequent rainfall, plus a lot of higher-risk fields.

Another possible reason for the increasing late leaf spot pressure is shorter rotations.

“Crop rotation is the best and most critical factor in crop pest management,” Fulmer says. “That’s why it’s weighted heavily on the Peanut Rx. Crop prices have forced growers to go to peanuts more often because they don’t have many options to rotate to. There’s a lot of cotton-peanut-cotton-peanut rotations and significantly fewer that can put three, or even better four, years between peanut crops.

More Rain Events, Stretched Spray Intervals

Not only has the type of leaf spot changed over time, but it has also become a more significant problem, especially in the past few years. Besides shorter rotations, more rainfall during the season led to trouble getting into the field in a timely manner to apply fungicides.

“In 2021, there was a complete leaf spot blowout because of all the rain,” Fulmer says. “The past couple years, there were 10 to 12 rain events, which is typically defined to be greater than 1/10 inch, during June and July. Plus, you’ve got dew. That leads to a long leaf wetness period and will definitely have an impact on disease. We’ve had several years back-to-back that were very conducive to leaf spot.

“When conditions are wet, growers are not able to get into the field at the appropriate timing. It is naturally stretching spray intervals,” he says.

Starting out already behind is also not a good place to be.

“If you’re in a situation where your planting date has gotten pushed back and now it’s mid-May to the first of June, your leaf spot risk has been raised to a whole other level,” Fulmer says.

“The planting date effect is real for leaf spot and white mold.”

Most times, it is too wet to plant, or you are waiting on rain to plant, but if it’s neither of these, then it is a tradeoff of risks.

“Is it worth avoiding Tomato Spotted Wilt Virus and accepting the higher risk for leaf spot and white mold? Most growers know, if they get delayed on planting date, they’ll have to really stay on top of disease control,” he says.

Few Fields Are Low Risk

Fulmer spent most of his time in graduate school working on Peanut Rx, which he says growers can use to help plan what type of disease program they are going to apply.

“Even if you don’t use it to make a field prescription, Peanut Rx is an important tool to help you understand the factors that impact disease potential in a field. It can be more of an internal check to say, ‘Where am I at in my risk?’ and to get a holistic view of the tradeoffs of focusing on TSWV versus leaf spot.

“Every fungicide company has a Peanut Rx program that can be utilized in low, moderate and high-risk situations. BASF has one as well that we’ve developed with our university cooperators.”

But Fulmer says very few growers can calculate a low-risk field.

“If you go back to my doctorate work, it was shocking to me how few fields that I evaluated out of the hundreds in those years were actually low risk. It is difficult to achieve a low-risk field. Most fields are moderate or high risk, and I would say most are in the high-risk area.”

“There are occasional growers who have a four- to five-year rotation and plant at the right time.

However, most varieties are at least somewhat susceptible to spotted wilt, leaf spot or white mold. Georgia-06G is moderately susceptible. That’s why low risk is hard to achieve.”

Varieties And Seed Treatments

Another benefit of Peanut Rx is that it is an added resource to help farmers choose potential varieties to plant.

“It helps you decide, ‘Am I looking to expand my footprint in varieties this year?’ I know growers are looking beyond Georgia-06G wondering what will be next,” Fulmer says. “Some are going to Georgia-12Y. They like the disease resistance from a white mold standpoint, although you need to keep the growth regulator handy.”

Seed treatments, too, are an important step in starting the crop off with good protection from seedling and other diseases.

“Seed treatments are doing a great job protecting seedlings from Aspergillus sp., and keeping Rhizoctonia and white mold at bay, but it’s very important to follow that up with something strong out of the gate,” he says.

“I always go into the season thinking white mold will strike early, and from the time you close the furrow to the time you begin making applications, that is the time to lay the groundwork for a strong white mold program.”

45-Day Fungicide Application

Fulmer says a lot of research goes into finding the right fit for fungicide products.

“Based on work we’ve done the past few years, I think we know better how to position some of our products. Priaxor is a key foundational fungicide option at the 45-day spray,” he says. “It is good on white mold and Rhizoctonia and is from the Fungicide Resistance Action Committee Group 7 and Group 11.

“Based on Dr. Tim Brenneman’s studies, it’s hard to beat Priaxor on Rhizoctonia. It’s also a great white mold product when you get it down to the soil.”

Fulmer says white mold is one of those diseases you need to always assume is going to be present, and if it doesn’t show up, then take it as a win. At the 45-to-50-day timing, he says it is still fairly easy to penetrate the canopy and get Priaxor down to the soil line where it matters.

“On top of that, you also get leaf spot control that provides a foundation for a solid program, as well as additional plant health benefits. We have seen in peanut, cotton and other crops, that when you make an application of Priaxor, you tend to get a greening effect. What that tells me is there is just a little bit extra insurance toward a healthy plant,” Fulmer says.

60- and 90-Day Sprays

After providing a foundational spray for white mold, Rhizoctonia and leaf spot, the 60- and 90-day sprays are looking to continue white mold coverage, Fulmer explains.

“We’re blessed to have a lot of good products for this. From Convoy – a longtime product – to a new product like Excalia, to a tried-and-true product like Elatus – all of these are excellent white mold products that can stand on their own.

“However, I like mixing Bravo with a lot of these, simply because we need to keep chlorothalonil in the system. The more tankmixes we can make, the more pressure we’ll keep on any building resistant populations.”

Fulmer says there are a lot of possible products for this spray timing, but most white mold products are Group 7s or Group 7s + Group 11s, and rotating product modes of action needs to be kept in mind.

A Good Fit At The 75-Day Mark

Because most white mold products are FRAC Group 7s and 11s, a change in the mode of action is a good idea at the 75-day spray.

“What I think we as an industry are starting to realize is we need to work together to position all of our products in such a way that makes sense from a resistance management strategy,” Fulmer says. “We want to incorporate as many different products in a program as possible.

“That’s what I like about Provysol, it’s kind of a new and improved Group 3. It’s a different MOA that has excellent leaf spot control but also white mold suppression and that’s key,” he says.

“In some of our studies, we mixed 3 ounces of Provysol and 7.2 ounces of tebuconazole together and found that when these are put together, it kind of revives the tebuconazole, plus provides a quick uptake, long residual control with the Provysol and enhanced leaf spot control. It also breaks up the Group 7 and 11 combo and provides a solid bridge of leaf spot control and a dose of white mold suppression.

“We looked at Provysol a lot of ways before determining that was the best fit,” Fulmer says. “That’s what’s good about working with the universities like UGA, Auburn and others. We can work collaboratively to bring a product to the market, and by then, everybody is comfortable with where it fits.

“That process took three to four years, but now we feel that Provysol at the 75- and 105-day sprays are our two primary pillars for good disease management. It is also a flexible product, and you can safely mix it with a lot of products. You can mix it with fungicides, herbicides, nutritionals and adjuvants. It doesn’t cause any burn and is incredibly rainfast. As soon as it dries on the leaf, it’s in the leaf. So having a tool like that in your arsenal, it can be used in any program, anywhere.”

No Typical Fungicide Program

The typical spray program doesn’t exist because there are a million iterations of it, Fulmer says. “What we try to do with our research is figure out all the ‘if, then’ scenarios, and that’s why it’s great that we have so many people in the field. If we haven’t answered your exact question, give us a call. We can talk through your situation, whether it is on the farm or the retail store or the county Extension office, we’d be glad to help

Disease Management Tips:

• Crop rotation is the best and most critical factor in crop pest management.

• Planting from mid-May to early June increases leaf spot risk.

• Peanut Rx can help you understand the factors that impact disease potential.

• Most varieties are somewhat susceptible to TSWV, leaf spot or white mold.

• Years of research go into finding the right fit for fungicide products.

• Rotating modes of action and tankmixes keep pressure on any resistant populations.

• The last spray is an opportunity to use a product that hasn’t been used all season.

you think through your situation with a product like Provysol or any others.

“It’s a product that can be used in a lot of different situations, which can lead to confusion. But what I like about it, I feel like it is providing a very important tool for controlling late leaf spot and early leaf spot and contributing to the suppression of white mold in a playing field that is reliant on Group 7s and Group 11s. Being able to bring a Group 3 to the market is exciting,” he says.

The Last Spray

Another quandary for growers is knowing when to pull the trigger on that last spray of the season.

“It depends on your scenario and what your conditions are,” Fulmer says. “With varieties going longer and taking more days to reach maturity, I can see another spray at 130 days.”

At this point, the goal is to keep the vines in good enough shape for the kernels to reach maturity and to keep the pegs strong to hold on to the pod for digging. As for fungicides, it is also an opportunity to practice resistant management and/or use products that have not been used during the season.

“Bravo could be used at 120 days for resistance management. If you haven’t used Provysol, you can use it here. A lot of growers still like Bravo and Topsin as a last spray, and some people think it helps with peg strength.

“In many scenarios and if the field is in good shape, a tebuconazole+Bravo tankmix has looked really solid in this timing to finish out the season.”

Fulmer says some growers in that southwest Georgia hot spot have done well with Provost Silver as the last spray.

“At 120 to 130 days, if you are in a situation where you have already used Priaxor and Provysol and other products, but haven’t used Provost Silver, I would be in favor of using a product like that.”

If all has gone relatively well with the fungicide program: applications were timely at 14-day intervals, different modes of action were used and rain nourished the crop more than it kept farmers out of the field, then vines should be in good enough shape for the crop to reach maturity and digging to take place.

Fulmer says, “My hat is off to growers who juggle all the scenarios and figure out what’s best for their situation.” PG