Late Blight on Tomato
Tom Creswell and Gail Ruhl,
Plant and Pest Diagnostic Lab, Purdue University
We have had several questions pertaining to recent
reports from the
Northeast on Late Blight on tomato.
Tomato plants infected with late blight (causal organism
Phytophthora infestans) were shipped by an Alabama-based
company to large retail stores
throughout the Northeast region of the country, from Ohio to Maine.
the disease has been confirmed this year on tomatoes
in Alabama, Connecticut, Delaware, Georgia, Kentucky, Maine, Maryland,
Massachusetts, New Jersey, New Hampshire, New York, Ohio, Pennsylvania,
Rhode Island, South Carolina, Tennessee, Vermont, Virginia, and
West Virginia (as of August 8th, late blight is
now also confirmed in Indiana).
Late blight is a very contagious disease that infects
members of the
nightshade family (tomatoes, potatoes, sweet peppers, etc.). While
disease is not uncommon in home gardens it is rather unusual for
be infected this early in the growing season.
Since there are many look-alike diseases on tomato leaves identification
requires microscopic examination, not visual determination. Suspect
may be submitted to the Purdue
Plant and Pest Diagnostic Lab for
Two pertinent links:
Blight on Tomato Plants at Local Large Stores in Most States
in the Northeast
Diseases and Disorders (pdf
Click image to enlarge
Late blight symptoms on tomato fruit
Late Blight Sporulating on lesion on the underside of tomato leaves