What is in this article?:
- Planting date sets pace for season-long peanut disease pressure
- Many fungicide options available
- Planting dates have an impact on season-long peanut disease pressure.
- Fungicides options are becoming less expensive as brand-name products go off patent.
COOL, WET SPRING weather conditions slowed the 2014 peanut crop in parts of Alabama. The field shown is in east Alabama in late June.
A cooler, rain-soaked spring in parts of the Southeast pushed peanut planting dates later than usual, a factor that can impact the type and incidence of disease growers experience throughout the remainder of the season.
“Planting dates definitely make a difference in peanut diseases, both in the type of disease you have and the pressure,” says Austin Hagan, Auburn University Extension plant pathologist.
If you plant early, you’ll have less leafspot and less rust pressure, says Hagan. But if you have a field with a history of white mold disease, you’ll have more disease pressure when you plant from late April to the first of May. There’s also a higher risk of tomato spotted wilt virus, he adds, but with current varieties, the disease pressure to date is minimal, even in mid-April planted peanuts.
“The later you plant, the more leafspot will intensify. Also, the later you plant, the less white mold you’ll have because the crop is maturing out at the end of September and into October when soil temperatures are a lot cooler,” says Hagan.
This growing season began much like last year in Alabama, with cooler and wetter-than-normal weather conditions. This was followed by plentiful and sometimes excessive rainfall throughout the course of the season.
“Whenever you talk about a growing season with 60 to 80 inches of rain on peanuts, you’d expect some serious disease issues, especially with leafspot, but that really wasn’t the case last year. But there was a lot of thrips damage this spring but not much tomato spotted wilt virus in Alabama peanut fields,” he says.
Every new generation of peanut variety that comes down the pike seems to be better than the previous ones at managing TSWV, says Hagan.
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“A few years ago, we started growing Georgia Green and thought they were the greatest thing on earth. But the newer varieties we have now are much better. There was early and late leafspot because of all the rain in 2013, but it just wasn’t as bad as it could have been.”
Weather plays a major role in both leafspot disease and white mold, notes Hagan. “One thing that may have slowed leafspot and took out white mold in some fields was cool temperatures. It was cooler in 2013 than in 2012, and we had moisture in the soil constantly.
To get white mold going, we need a fluctuation between wet and dry cycles, and we need higher soil temperatures. It needs to get up into the mid- to upper 90s every couple of days, and we need to have nighttime temperatures in the high 70s. Root-knot nematodes also showed up this past year, and having a lot of moisture in well-drained soils is good for their development.”