Last year was an unusual one for gathering information on peanut diseases, says an Oklahoma State University Extension plant pathologist.

“We usually get good information on Sclerotinia blight from our trials,” says John Damicone. “Last year, we got nothing.”

Pod rot, on the other hand, was severe, which offered an opportunity to collect good data. “It was the most uniformly severe pod rot infestation I’ve ever seen,” Damicone said during the recent Oklahoma Peanut Expo at the Quartz Mountain Resort near Lone Wolf.

“Too many growers saw pod rot last year,” Damicone said, “mostly on Virginia-type peanuts.”

He looked at fungicides, calcium fertility, and variety selection as possible management options for pod rot.

Fungicides included Abound, Ridomil and ProPhyt (phosphorous acid). Fungicide applications resulted in a significant yield response. Damicone said in one test Abound treatments made 4,000 pounds per acre versus the check plot with a 3,500 pound per acre yield.

He said calcium rate was not a factor. “The disease outbreak did not occur because of a calcium deficiency. Some pod rot fields tested high in calcium.”

Spanish and runner varieties had less pod rot than Virginias.
“In runner peanut trials we expected Flavor Runner 458 to perform worse than it did,” he said. “Pod rot levels on Tamrun OL02 and Tamrun OL07 was low.”

Virginias were hit harder. “We used to see less pod rot on Jupiter compared to other Virginia varieties, but not in 2010,” Damicone said.

He said weather conditions likely prompted the heavy incidence of pod rot. “We had above normal temperatures in June, rain in July and hot and dry conditions in August and September.”

Fungicide trials indicated that ProPhyt and ProPhyt plus Abound were the only treatments “that significantly reduced pod rot compared to the untreated check.”