Arkansas tomato plants have been hit harder by a destructive fungal disease this season, but the effect on markets, if any, remains unclear.

Late blight has been more pervasive this season than in any year since 2009, said Jackie Lee, horticulture integrated pest management specialist for the Arkansas Cooperative Extension Service.

Typically, the university’s plant diagnostic lab turns up three samples of late blight per year, Lee said. Through June 21, 20 infected plants had already been found in 14 Arkansas counties, some of them major tomato producers.

Arkansas growers typically begin shipping tomatoes in the first half of June and finish in the second half of July.

“It’s fairly localized, but a couple of growers have lost their entire crop,” Lee said. “It can spread from one plant to the whole field quickly.”

As of June 22, it was too soon to tell what effect the late blight, which was caused by excessive rains this spring, would have on overall Arkansas tomato volumes, Lee said.

Gary Margolis, president of Boca Raton, Fla.-based Gem Tomato & Vegetable Sales Inc., which markets Arkansas-grown Triple M tomatoes, said that as of June 23, there had been no effect on markets, but he said the company would know more the week of June 27.

Triple M hasn’t had any cases of late blight this season, Margolis said.

“It takes a lot of money and chemicals, but late blight is controllable. It’s not an issue with Triple M. Their spray programs are right on target.”

Tomatoes, potatoes, peppers and eggplant can’t be planted in fields that test positive for late blight for about three years after detection, Lee said.