Bacterial wilt was recently detected on butternut squash in Chilton County. Bacterial wilt is a destructive disease of both cucumber and cantaloupe. It can also infect squash and pumpkins. Watermelons are resistant to the disease.
Wilting and drying of individual leaves are the first symptoms of bacterial wilt. Plants usually remain green when wilted instead of turning yellow. Within days, the wilting spreads throughout the vine. Eventually the entire plant collapses.
Bacterial wilt is caused by Erwinia tracheiphila. Cucumber beetles are common carriers of the bacterium. Disease transmission occurs through wounds on leaves created by the feeding beetles. Rapid growth of the bacteria clogs the plant’s vascular tissue, which causes the plant to wilt. Once the plant is infected, there is no way to control the disease.
A simple field test can help growers identify bacterial wilt. Cut a section of the vine from near the crown of the plant. Then cut this piece into two sections. Press the cross sections together and then gently pull them apart. If the plant is infected with bacterial wilt, thread-like strands of bacterial ooze will be visible.
Reducing the potential for cucumber beetles to spread the disease is critical. Physical barriers such as row covers can reduce the spread of bacterium by beetles, but their effectiveness is dependent on beetle numbers. Insecticides, used properly, can be effective in controlling cucumber beetles and spread of the pathogen.
Refer to the 2019 Southeastern Vegetable Crop Handbook for insecticide recommendations.
Send samples for diagnosis to the Auburn University Plant Diagnostic Lab .