2004 Season Review: Vegetable Diseases

Dan Egel, Region Pest Management Specialist, SWPAC, Purdue University

The 2004 season began with a relatively cool spring.  Perhaps for this reason, there were several cases of vegetable transplant damage as a result of faulty heater exhaust.  In a milder spring, these greenhouses will be ventilated from outside more often. 

Compared to the 2003 season, there was a more rainfall spread out over the summer.  More rain resulted in an increase in foliar diseases.  These included early blight and Septoria of tomato, gummy stem blight of watermelon and Alternaria leaf blight of muskmelon.  Another factor in the occurrence of these diseases was the length of the rotation and the history of the disease in that location.  Increased rainfall was also correlated with an increase in certain soil borne diseases.  Examples would be mature watermelon vine decline and Phytophthora diseases.

Other diseases are not as closely related to weather.  A few cases of bacterial fruit blotch of watermelon occurred in southwest Indiana.  This disease can be seed transmitted.  Downy mildew of pumpkins was quite widespread across Indiana.  Some growers reported severe yields losses due to downy mildew.  This disease requires the introduction of the proper spore type from the Gulf States as well as relatively cool, dewy nights.