By Clint Thompson
Georgia strawberry producers may not have had to deal with much of Neopestalotiopsis Fruit Rot this year, but phytophthora root rot is a different story.
“Right now, this year, I’ve seen quite a few samples with phytophthora come in, unfortunately,” said University of Georgia Cooperative Extension Fruit Disease Specialist Phil Brannen.
Brannen discussed some of the possibilities of why the disease has flared up this growing season.
“Phytophthora has been problematic. It’s been real wet. We’ve had a wet season. Unfortunately, I think a lot of our plants are coming with phytophthora,” Brannen said. “We may be seeing some resistance to Ridomil. There does appear to be some possibility that we are seeing a resistance to Ridomil. I’m encouraging people to consider putting out Orondis, which is the new material that just got registered. It’s basically Ridomil plus another material.
“It’s mainly a root and crown issue on strawberries. We are seeing a lot of that this year. It’s a problem when it’s wet, in particular, where you have a lot of rainfall, or you over irrigate. We are seeing it.”
Orondis Gold has two modes of action which is good for resistance management. Growers typically make two applications; one in the fall and one in the spring in March or early April.
According to UGA Extension, phytophthora root rot is caused by Phytophthora cactorum. The source of the inoculum are oospores which persist in the soil or infected plants. Under wet conditions, oospores produce zoospores. These infect wounded plant tissue (root or crown). Wet conditions also encourage the spread of the pathogen from plant to plant.
