By JOHN O'CONNELL
Early blight has lived up to its name this season, surfacing in Idaho potato fields a few weeks ahead of normal, according to Rupert crop researcher Jeff Miller.
The fungal potato disease was first detected in a sample of Ranger Russets from Hazelton, Idaho, located in Jerome County on June 19. Miller, with Miller Research, said some Treasure Valley fields have also started showing symptoms.
Though early blight affects growers during most seasons, Miller said it usually arrives closer to the second week of July.
Miller advises growers to be ready to apply their fungicides, if they haven't already done so.
"You don't want to be late," Miller said. "The most effective timing for fungicide application for early blight control is just before row closure."
Early blight creates lesions on leaves, destroying foliage and reducing yields. In extreme cases, it can affect tubers of some varieties, Miller said.
"So far mostly showing up on lower leaves. That's not unusual. As potato plants start to senesce and die, the early blight really gets going," Miller said.
Miller's field trials have shown early blight, which likes mild temperatures and can withstand typical conditions of potatoes under irrigation, has developed some resistance to boscalid fungicides, such as Endura. He suggests tank mixing boscalids with chlorothalonil or EBDC fungicides.
"In almost all of our research trials, we almost always show a significant yield reduction when we don't control it," Miller said.