Though weather conditions have been perfect, peanut diseases have kept to themselves for most of this year. All the major suspects have been quiet so far ... But there's a lot of season left.
WEATHER SOAKED much of the Deep South peanut crop throughout this season, so far. Diseases should have been thriving in fields, but they haven't, at least not yet.
So far, 2013 has been a perfect weather year for peanut diseases in the Deep South: wet with swampy plus short spurts of hot with swampy.
But that disease pressure just hasn’t hit yet.
“Despite my repeated and dire predictions for severe disease outbreaks this year in our peanut fields, the reports from county agents have been fairly quiet.
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“Although rainfall has been torrential and many farmers have not been able to get into the field to make timely fungicide applications, I know of very few situations where disease has overwhelmed a (peanut) crop,” said Bob Kemerait, plant pathologist with the University of Georgia Cooperative Extension.
Why have peanut diseases not been so bad?
“Fungicides” is the short answer, he said, good fungicide products matched with grower know-how on best ways to use them.
Also, peanut acreage is down in Georgia compared to last year, he said.
“In all likelihood our growers have the opportunity to grow the crop on better rotated land. Better crop rotation means lower risk to disease.”
The new widely planted varieties in use now have much better disease resistance, too, he said. Not perfect resistance, but plenty enough to make a difference this year in disease pressure and early damage.
Wetter weather likely helped stop one disease
Ironically, the stormy weather, and at times torrential weather, likely helped reduce the risk to white mold.
“By keeping soil temperatures cooler and by potentially disrupting the optimal growth of the fungus — and you need to remember much of the white mold fungus is exposed in the canopy to the mechanical action of rainfall — the storms may have kept the incidence of our most important disease (white mold) low,” he said.
Though reports of leaf spot, white mold, Rhizoctonia limb rot and Cylindrocladium black rot are low in many fields, hey, all this can change in August, he said, “especially if rain continues but the temperatures rise to the upper 90s.”
Thriving vine growth matched with moisture and high temps again is the perfect combination for white mold, leaf spot and Rhizoctonia limb rot. Growers need to stick to aggressive fungicide programs, using the best fungicides and staying on time with the applications.
Tomato spotted wilt and CBR will likely show greater in August, too, he said. The cooler and wetter conditions so far this year have not suited white mold, but they do favor CBR.
“As the crop develops and is stressed by an increasing pod load, I believe that plants already infected with CBR and TSWV will become increasingly evident in the field,” he said.
Not much can be done to combat TSWV now. But a strong fungicide program that includes Provost, Abound and maybe Fontelis can reduce the severity of CBR.
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