MISSOURI — Cucumbers and other members of the plant family Cucurbitaceae are potentially threatened by a devastating disease called downey mildew.

According to the University of Missouri-Integrated Pest Management (IPM), a case was recently confirmed in Morgan County.

Photo: National Garden Bureau

The IPM indicates that the disease is a fungus-like organism that affects each member of the Cucurbitaceae family differently. For cucumbers, symptoms may first appear as water-soaked lesions following a prolonged period of leaf wetness.

Another symptom is irregularly shaped lesions that appear in the veins of the leaves near the surface. A third sign is the presence of small, fuzzy growth that is purple-gray in color.

The lesions may come together to form a single, large lesion across the leaf surface as the disease progresses, ultimately killing the leaf and then the cucumber plant itself.

According to the IPM, downey mildew spores cannot survive colder temperatures and has to have living plant tissue to survive. The spores are blown in by the wind from the southern United States.

Ensuring that cucumber leaves do not stay wet coupled with proper ventilation are an effective method at combating downey mildew. If necessary, using the appropriate fungicide is another possibility to treat cucumbers.

To find out more about the disease and recommended management practices, visit the University of Missouri-Integrated Pest Management’s website.