Everyone can agree there’s a difference between any two peanut fields – five years behind peanuts is different from continuous peanuts. So why not treat them differently?

That’s the premise behind Peanut Rx — a risk index that helps Southeastern growers make smarter disease management decisions. The program is based on years of studying the effects of reduced-fungicide spray programs on disease control and pod yields.

“We can treat fields differently, and growers can maximize profits with a prescription fungicide program,” says Bob Kemerait, University of Georgia Extension plant pathologist.

Peanut Rx was developed by researchers and Extension specialists at the University of Georgia, the University of Florida and Auburn University.

In 2013, Peanut Rx prescription fungicide programs will be supported by Syngenta Crop Protection, Nichino-America, Arysta LifeScience, BASF, Bayer CropScience, DuPont and Sipcam Agro.

Speaking at the recent Georgia Peanut Farm Show in Tifton, Kemerait says he’d like to see more producers using Peanut Rx.

“I don’t care what fungicide program you use, he says. “What I do care about is that you have the information you need to make the best decision for you based on cost of production and the efficacy of chemicals,” he says.

It’s difficult to control peanut diseases in the Southeast for two reasons, says Kemerait. “One, we’ve got a number of diseases — leafspot, white mold, limb rot, CBR, nematodes — every part of the plant and every part of the fruit or pod is affected. The second thing is if we’re trying to protect against leafspot, we’re making foliar applications, and protecting against soil-borne diseases can be very difficult.”

Peanut Rx considers the three most important diseases of the crop — early and late leapspot, tomato spotted wilt virus, and white mold.

“In certain areas, CBR can be more of a problem, but on the whole, white mold is our biggest disease problem statewide. These three diseases are the ones we want to manage better and more cost-effectively using Peanut Rx. 

“As we collect additional results from research, we hope one day to be able to include Rhizoctonia limb rot, CBR and the peanut root not nematode in Peanut Rx.”

Better management, says Kemerait, doesn’t mean you always get the best disease control. “In my opinion, the best management is when we make the most money as a farmer.

Trying to make more peanuts

“We’re not here so much to eliminate leafspot as we are to make more peanuts, and we’re not here so much to eliminate white mold as we are to make more peanuts.”

Kemerait says while he won’t guarantee growers will always have the absolutecleanest fields with Peanut Rx, but in these fields diseases will be managed effectively and profits will be maximized.

“Will all peanut fields have the same pressure? No. In some fields you are farming, you’ll need less disease control and some fields willhave higher risk. If you believe fields need different levels of control, Peanut Rx is an important tool that allows you to predict the risk ineach field.

“We can make predictions today about the potential for disease pressure in July. With accurate predictions we can maximize profits by tailoring our fungicide programs.”

If you know you had cotton in a field the previous year, and you know the field will be conventionally-tilled, then you can already make predictions with regards to the impact of disease in the field in the coming season. This is where Peanut Rx comes into play, says Kemerait.

There are two components to Peanut Rx, with the first being educational or the actual risk index itself. “It’s based on the original TSWV Index, and it’s based upon research and our experience. It’s designed to help every peanut farmer in the Southeastern United States, whether they use a prescription fungicide program or not.  This tool allows you to assess your risk, and it takes only minutes to go through it.

“We continue to improve this index every year with cooperation from researchers and Extension specialists from the University of Georgia, University of Florida, Auburn University, Mississippi State University, and the USDA-ARS.

“Whenever a new cultivar becomes available, and whenever we get new data, we tweak this scale to assess the impact of different factors on disease severity. We work with the various companies that cooperate with Peanut Rx and support it to provide them data on the efficacy of their prescription fungicide programs.”

It’s common knowledge, says Kemerait, that rotation is important and that varieties have different disease resistances.

“The true importance of this index is that it allows us to quantify certain values,” he says. “What’s the value of being five years out of peanuts as opposed to one year out of peanuts? More is better, but this index helps us to quantify that.

A package you can use

“What’s the difference in resistance to white mold between Georgia-07W and Georgia-06G? This program helps you put this information into an overall package you can use.”

Factors considered by Peanut Rx include variety, crop rotation, planting date, final plant stand, tillage, irrigation, field history and insecticides.

“With Peanut Rx, we can go in and assign a total risk of leafspot, white mold and TSWV, and the supporting companies can offer a specific program. The value of a specific program is that you’re putting out the right amount of fungicide where you need it, and you’re spending the right amount of money.”

Peanut Rx changes every year and gets better, says Kemerait.

“We get new varieties, new data, and sometimes we get a new fungicide. Our index continues to evolve. We no longer include limb rot in the index because it hasn’t been a big enough problem over the past 10 years that we can get good data. If we can’t get good numbers, we don’t put a disease in the index.”

The more points assigned by the index, the greater the risk. A variety with 50 points is much more susceptible than a variety with five points. All factors contribute to risk, but the most important are how long it has been since you’ve had peanuts in the field, what variety you are planting, when you planted, and what kind of plant stand you ended up with. The other factors have an impact but not as great as these, says Kemerait.

“After total risk points are determined for a field, the next step it to break the point totals into low-risk, medium-risk and high-risk fields.

“Low-risk means you’ve probably been out of peanuts for awhile, you’ve got a good resistant variety, you’ve got good rotation, tillage practices that work, and your planting date is right. If you’re high-risk, you’re planting peanuts behind peanuts or every other year, and you’ve got a weaker variety as far as resistance goes.

“You don’t need the same amount of fungicides in a low-risk field as in a high-risk field, but growers tend to spray it the same. Why would growers spray a field seven times when four or five sprays are sufficient in reduced-risk fields?

“The first reason is that it’s easier to remember what you’re going to spray and it takes less time to think about it. The other reason is that you’ve got a lot confidence in the fungicide programs you have always used.

Need a good funcicide program

“We’ve spent a lot of time convincing growers that if you want to make top yields and stay in business, you need a good fungicide program. And sometimes it’s hard to let go of something that has worked for you.”

Peanut Rx allows growers to go through each of the categories with their fields and come up with a point total or risk, says Kemerait. Then, they can make choices based on that total.

In 2012, Georgia Green was rated at 30 points and Tifguard was at 10 points on TSWV. This means that Georgia Green is three times more susceptible to TSWV than Tifguard.

Also, Georgia-06G is twice as susceptible to white mold as Georgia-07W.

“There’s a difference in 10 points between the varieties and that’s the difference of one year of rotation. By planting a white-mold-resistant variety, you have flexibility in the other categories to maintain the same risk.

“If you plant Georgia-07W instead of Georgia-06G, the effect on white mold will help offset the negative impact of a shorter rotation. You don’t want that, but that’s what it makes up for. You can transfer those points.”

While there’s nothing in the index that assigns points to the amount of rainfall received or the lack of rainfall, Kemerait says growers should follow their common sense when it comes to this factor.

“Rainfall increases disease. If your weather situation is changing and significant rain is forecast as in a tropical storm, tighten up. This index has never failed us in a commercial field, but if a tropical storm is coming in, use your common sense. If weather stays warm, you have to look out for nematodes, thrips and white mold.”

Kemerait says he want growers to use the right combination of fungicides that make the most money.

“Spending the least amount of money up front on a fungicide program might not make you the most amount of money in the end.

“Tebuconazole will be very popular this year, but just remember it doesn’t solve all your problems. If you have decided that you’re going to spray seven times on a 14-day schedule come hell or high water, then you don’t need the index.

“Prescription fungicide programs can make you money if you calculate your risks and determine the right timing. The goal is to have an adequate fungicide program and maintain disease control.

“You won’t win a beauty contest with leafspot control every year, but you’ll have good-enough control. The goal is to maintain yields and maximize profits.

“If you do your risk index and find you’re at a low risk, you can spray fewer times.”

The updated 2013 Peanut Rx can be found in the Georgia Peanut Production Guide at:

http://www.caes.uga.edu/commodities/fieldcrops/peanuts/documents/2013UGAPeanutProductionGuide.pdf.

phollis@farmpress.com