It’s now been over 5 weeks since I last received a report of late blight on tomatoes in Louisiana, so I have to assume that our “balmy” late spring/early summer weather is effectively keeping it in check. However, this is not the case in the rest of the eastern U.S., where late blight has subsequently been reported on tomatoes in Maryland, Kentucky, Pennsylvania, Connecticut and New York. Extension plant pathologists continue to monitor the situation and growers in Ohio have been warned to be on the alert for the disease (http://www.plantmanagementnetwork.org/pub/php/news/2010/OhioLateBlight/). In several instances (Louisiana included), the source of the disease could be traced to infected transplants obtained at local garden centers, but in other instances the exact source could not be pinpointed. However, there is some indication that it may have been carried over on blighted potatoes from last year’s crop. In Louisiana, late blight was ultimately reported on tomatoes in Vermilion, Terrebonne, Lafayette, Ascension, East Baton Rouge, Livingston, Tangipahoa and St. Tammany parishes, and I did not receive any reports of the disease being found in commercial tomato fields.
Donald M. Ferrin, Ph.D., Louisiana State University Agricultural Center, Baton Rouge, LA