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Late blight...despite the heat it is still important to remain vigilant

Posted: July 18, 2012

The growing season is not over yet and neither is late blight!
Lesions characteristic of late blight on tomato fruit. Unlike many other diseases, late blight lesions will remain firm unless infected with a secondary soft rot organism. (Photo: Beth K. Gugino)

Lesions characteristic of late blight on tomato fruit. Unlike many other diseases, late blight lesions will remain firm unless infected with a secondary soft rot organism. (Photo: Beth K. Gugino)

In conversations with growers and various ag service providers, I have heard several comments with regard to the weather and our need not to be concerned about late blight any longer this season. This is completely untrue. Although, hot dry weather is not favorable for the spread of the disease, this does not mean that is has gone away. As soon as the nighttime temperatures begin to drop and dew periods lengthen, the disease has the potential to continue where it left off. Today, we confirmed late blight in a tomato field in Lancaster Co. It is suspected that the symptoms first appeared the week of July 8th. There was also a report on tomato from a home garden (the plant was destroyed) in Allegheny Co. This is the first report of late blight west of Blair Co. in Pennsylvania. It is important to continue to scout regularly your crops for late blight.

Remember that late blight is a community disease! If you suspect late blight please contact your local Penn State Cooperative Extension Office, the Penn State Plant Disease Clinic or Beth Gugino at bkgugino@psu.edu or 814-865-7328. Updates will continue to be posted on this Vegetable and Small Fruit Extension Team website and audio-messages posted on the 1-800-PENN-IPM hotline under the tomato/potato. For the most current map of confirmed late blight outbreaks please visit http://usablight.org.