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Gaining Ground On Disease

Producers have the upper hand on certain diseases, while others command attention.

By Amanda Huber print email

 
No one would want to jinx the 2010 growing season, but in the last few years, producers have not had the incidence of spotted wilt or losses to some other diseases as has been experienced in the past. However, this isn’t just by chance, but by a concerted effort from researchers and producers to lessen the disease threat and make the most of every disease management dollar spent.

“We are turning the corner on spotted wilt and other disease problems, and it is a combination of varieties and good disease management programs,” says Bob Kemerait, University of Georgia Extension plant pathologist. “Yields in 2009 averaged approximately 3,500 pounds per acre in Georgia, the highest average yield we have ever had.”

Even so, for Kemerait and others, there is no letting up on learning more ways to combat disease pressure.

Best Value For The Money
New information is being discovered in plot testing each year, but producers also need a reinforcement of practices they already know.

“When thinking about how expensive a fungicide program is going to be,” Kemerait says, “the good news is when you put your seed in the ground, whatever seed treatment you use, it is a tremendous advantage and value for the money.

“We estimate that over time, if you don’t have a good seed treatment on your peanuts, you may lose at least 900 pounds per acre to seedling disease,” Kemerait says. “With the hot soil temperatures in 2009, without a seed treatment, you could have lost up to 2,000 pounds per acre.”

Before Dawn’s Early Light
For producers who need to improve the efficacy of their soilborne disease programs, the new conventional wisdom is a pre-dawn spray.

“For leaf spot, it’s best to spray in the day so that the fungicide gets onto the leaves for maximum protection,” Kemerait says. “But for soilborne disease, the best time is early in the morning before the sun comes up. The dew on the leaves helps to move the fungicide down into the canopy where it needs to be.”

Jay Chapin, Clemson University Extension peanut specialist, says in fields at more risk for white mold, such as from previous field history, soybeans in the rotation or in early planting situations, a pre-dawn application can help.

“Where we have a history of severe white mold, spray programs that include Artisan or Convoy at 75 and 90 days after planting tend to excel,” Chapin says.

On the pre-dawn sprays, he says producers may not choose to do it every time unless they are really going after white mold. “If you are only going to do the pre-dawn spray once, do it at that critical 75-day period.”

Producers and researchers in the Virginia-Carolina region, including Chapin, are highly anticipating the release of new varieties that have increased resistance to disease. One of those varieties is Bailey, a Virginia-type with high yield potential and excellent resistance to white mold and spotted wilt disease. It also has reduced susceptibility to Cylindrocladium Black Rot (CBR), a growing problem in peanut production.

Disease Management Thoughts For 2010:

• Select varieties with resistance to problem
  diseases
• Seed treatments protect yield
• Increase efficacy of soilborne disease control with
  pre-dawn spray, especially at 75 DAP
• Keep soybeans out of peanut rotation, especially
  for CBR
• Proline/Provost and variety selection: The new
  standard for CBR management

New Standard Against CBR
Varieties that offer some level of suppression or resistance are an important component of management for CBR. But that’s just the beginning.

“CBR is the number one control problem if it is in your fields,” Kemerait says. “Root-knot nematode makes it worse, so management of nematodes is important.

“The varieties Georgia 02C, Carver and Tifguard offer some suppression of the disease,” he says. “You can rotate away from it, but it takes five years or more because the disease sits there and waits.”

Rotation crop selection is an important factor.

“Keep the beans out of the rotation once you get into the peanut business, but don’t let a history of soybeans keep you from getting started with peanuts,” Chapin says. “We have made some excellent yields in well-drained fields with soybean history.”

For Virginia-types, Perry is a variety that offers some suppression of CBR, and the variety Bailey, which is in seed increase, will offer producers another option.

As for the chemical component, the standard system has been to fumigate with Vapam or metam sodium.

“Vapam still works,” Chapin says. “But, strip tillage, the necessity to fumigate and bed two weeks ahead of planting, and the convenience factor work against grower acceptance.”

Kemerait recognizes that producers in Georgia have been reluctant to fumigate. “In addition to fumigating now, there is a product from Bayer CropScience called Proline that should be applied in-furrow at 5.7 ounces and followed by Provost.”

“A combination of Proline in-furrow, plus foliar Provost, which also has activity against CBR, white mold and leaf spot, plus variety resistance is what producers need to use on fields with a history of CBR,” Chapin says. “One approach alone isn’t going to solve the problem, and with all three we’re talking suppression, not complete control of severe CBR.”

Editor’s Note: Management of leaf spot will be featured in April Peanut Grower.

PG

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