18 May, 2010

Late Blight Strikes Again

Disease is likely being introduced on infected transplants.................................
Here we go again folks! This time late blight is infecting gardens in the south. And again the culprit is INFECTED PLANTS from the source
from Garden Center News and LA. Agriculture dept:
Scientists at the Louisiana State University AgCenter recently confirmed the presence of late blight on tomatoes in home gardens in Terrebonne, Lafayette, Livingston and Tangipahoa parishes. Symptoms include black lesions on stems and petioles, blackening of the fruit, and dark, dead areas on the foliage.
"The disease is probably being introduced on infected transplants, so be sure to check tomato plants for symptoms before you buy them," said LSU AgCenter plant pathologist Don Ferrin.
Experts across the state are working to remedy this situation as quickly as they can, Ferrin said.
"I recommend that home gardeners remove and destroy any infected plants," he said. "Additionally, as a preventative measure, I suggest they spray their plants on a regular basis with fungicides such as chlorothalonil, mancozeb, copper or a combination of mancozeb plus copper."
When using the mixture of mancozeb and copper, allow it to sit for about 30 minutes before spraying and stir it frequently, he said, noting that chlorothalonil may be used up to and including the day of harvest, whereas mancozeb cannot be used within five days of harvest.
"Because these fungicides are protectants only, thorough spray coverage is essential for control," Ferrin said.
"A number of fungicides are available at garden centers," he said. "Be sure to read the label carefully to be sure the product is intended for use on tomatoes, and apply the material carefully according to label directions.
"Late blight also occurs on Irish potatoes, so home gardeners may also want to spray them as a preventative measure," Ferrin said. "Fungicide use rates for tomatoes may not be the same for Irish potatoes, so be sure to check the label.
"With any luck, the warm weather that we're now experiencing will slow disease development," he added.
Last year, late blight wiped out thousands of tomato plants in the Northeastern U.S. Late blight, Phytophthora infestans, is the fungus-like pathogen that causes lesions and eventual die-off in tomatoes, potatoes and other tomato-family plants. This disease can be highly contagious among susceptible plants, and gardeners need to take steps to identify the disease and prevent it from spreading.