Greenhouse Grown Petunia Infected with a Phytophthora!
Posted: June 8, 2012
ATTN: All who work with greenhouse operators and vegetable growers
The Plant Disease Clinic has received a greenhouse-grown petunia ('Madness', variety which is appropriate in this case and for a Friday afternoon!) infected with a Phytophthora.
It is my understanding that late blight (Phytophthora infestans) affected tomato and potato plants have been detected in PA already this year. Whether this petunia is infected with P. infestans or some other Phytophthora remains to be seen but my penny is on infestans. If not infestans, then maybe it is Phytophthora nicotianae.
Be certain greenhouse operators, particularly those growing petunias and tomatoes, are aware that the weather conditions we have been having (wet...frequently) are ideal for Phytophthora outbreaks. Sporangia may be blowing into the greenhouse.
They MUST be examining their plants carefully and frequently.
Look for collapsing, gray to browning foliage. Plants may look like they are melting away. Get a positive diagnosis as quickly as possible. Contact the PDA plant inspector and Penn State Extension for advice.
Gary W. Moorman, Prof. of Plant Pathology
The Pennsylvania State University, Department of Plant Pathology