03/16/1993

AU-PNUTS System Looks Promising for Management of Peanut Leafspot

AUBURN, Ala. - Peanut producers interested in protecting their crops, their profit margins, and the environment don't have to exhaust their pest defense budgets on high-tech weapons. They can enlist the help of two long-time agricultural allies - a rain gauge and a weather forecast.

That's the word from Auburn University researchers who have drafted these ordinary tools to help carry out an effective and affordable attack on peanut leafspot. Their strategic plan is part of an overall pest management program known as AU-Pnuts that is now being developed by the Alabama Agricultural Experiment Station at Auburn. AU-Pnuts is a rule-based "expert system" that utilizes the same logic an expert would apply to make management decisions.

According to Paul Backman, professor of plant pathology at Auburn and a member of the research team, AU-Pnuts is an integrated pest management (IPM) system that allows producers to combine pest management decisions into one program, resulting in more effective and efficient pest management.

"AU-Pnuts began in about 1988 when we started dabbling with some efforts to better predict when leafspot fungicide treatments were needed," explained Backman.

"There were some new products out there, including the Envirocaster (a computerized instrument that costs about $7,000 per unit), that were being sold to peanut farmers," said Backman. "We thought we could develop a rule-based model that could provide the same predictive qualities as this equipment at a fraction of the cost."

Expert systems are certainly not new to peanut production. Jim Jacobi, research associate in Auburn's Department of Plant Pathology who has been working on the AU-Pnuts project, noted that growers in Virginia and the Carolinas now use leafspot advisories based on a model developed in the 1960s. However, the need for these systems has become more acute, for both financial and environmental reasons.

"There is a general vision coming from the Environmental Protection Agency (EPA) and the U.S. Department of Agriculture (USDA) that we are going to have to evolve to prescription or predictive use of pesticides and move away from the calendar-based spray programs that do not take into account weather and pest population factors," said Backman.

"EPA is concerned that the 14-day spray calendar, where producers apply pesticides every 14 days regardless of the need for those chemicals, is causing producers to treat at incorrect times," he continued.

"It is a problem," Backman admitted. "When we are doing it by calendar there are times when we are spraying and there is no infection taking place and there are other times when we are not applying, but all hell is taking place. It makes sense to treat only when there is a need."

What's more, restrictions on chemical usage may soon be mandated. Backman noted that many other countries already have ordered reductions in chemical usage. "How do you reduce chemicals and still produce? You make what you do use count," said Backman. "And that's what our system is all about."

The AU-Pnuts system has been developed through support from the Experiment Station, the Alabama Peanut Producers Association and a USDA Southern IPM grant. The goal of the project is to develop and evaluate a system to manage insects, diseases and nematodes attacking peanuts in Alabama.

The total AU-Pnuts program eventually will encompass management schedules for leafspot and other diseases such as white mold and limb rot, and also for other peanut pests, such as nematodes.

For the plant pathologists involved in the leafspot module of the system, the first step in establishing a system was to determine the ideal spray schedule based upon weather conditions and incidence of disease. Research showed that the first application should be made when six rain events of 1/10-inch or greater have occurred following emergence of the plants.

"We used that as the basis in 1989," said Jacobi, who conducted much of the preliminary work. "We decided that subsequent sprays should be made following the 10-day protection window when it has rained or is predicted to rain for three days. That initial model has seemed to work well."

"We've tested it several years since then at numerous locations and we also have tested the incorporation of some newer fungicides, mainly using those fungicides to get at soil-borne diseases," added Jacobi. "Incorporation of the rules for these new fungicides will be added to the AU-Pnuts model as the fungicides become available."

"Our first stab at the rules looked pretty good," said Backman. "By using the rules, we could save sprays and the rule- based program did as well and often better than the $7,000 computerized model."

The next step was to test the system on farms to see if AU-Pnuts would work in the "real world." Last year, Phil Brannen, an Extension research assistant in plant pathology, established on-farm validation tests at sites in five counties in Alabama's eastern peanut belt in the southeastern part of the state.

On farms where AU-Pnuts was used correctly, the program significantly improved season-long disease control and also increased yields an average of 258 pounds per acre in four of the five fields where yields were compared.

"These tests showed us that farmers can use AU-Pnuts without too much trouble," said Brannen. "It does take a training session to explain the rules, but once they understand the program, it is usually not difficult for producers to grasp."

In addition, the research team has been working with scientists in other states, including Oklahoma, Georgia and Florida, to test the system.

"Almost all locations in all years have shown that we can get equal or better control, and usually with less fungicide usage," said Brannen. "Last year it only saved us half a spray, but we obtained better control from our sprays because we had more timely applications."

"We found that this system actually did better than the 14-day schedule," Brannen added. "One reason we found that we did better is that this gives farmers a trigger on when to start spraying. If your first spray is done in a timely manner, it makes a big difference in the amount of disease control you obtain at the end of the season."

Brannen believes another plus for the system is that it allows farmers to spray ahead of weather fronts. "A lot of times farmers are spraying after a rain, when infection already has taken off. This system lets you treat before rain so you get better control," he explained.

"It does require some record keeping," Brannen added. "That may be a drawback for farmers who don't like to keep records, but record keeping is becoming increasingly important for any chemical use."

Though the total AU-Pnuts system is not yet ready for use, the researchers are optimistic that this will soon provide peanut growers an effective option for pest management at a cost that is peanuts compared to the computerized models.

For more information on AU-Pnuts or for detailed rules, contact Austin Hagan, Extension plant pathologist, at (205) 844-5503 or your local Cooperative Extension Service office.

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Office of Ag Communications & Marketing

Auburn University College of Agriculture
Alabama Agricultural Experiment Station
3 Comer Hall, Auburn University
Auburn, AL 36849
334-844-4877 (PHONE) 334-844-5892 (FAX)

Contact Jamie Creamer, 334-844-2783 or jcreamer@auburn.edu
Contact Katie Jackson, 334-844-5886 or smithcl@auburn.edu

03/16/93