Pumpkin, Squash Diseases
Pumpkin, Squash Diseases
Angular Leaf Spot
Angular leaf spot begins as light brown, angular spots on the leaves. The center later drops out leaving a ragged hole. On fruit, gray, water soaked spots form. The spots crack and produce a crusty tan to white lesion. An amber colored ooze often seen on the spot. The disease is favored by humid weather, temperatures between 70 and 80 degrees, and by mechanical or insect injury. The bacteria are spread by wind, splashing water and insects. Use sprays of copper(1).
Scab
Scab produces irregular spots on leaves and stems. The spots have yellow margins and brown center. The center drop out leaving a ragged hole which is often confused with angular leaf spot injury. On fruit, watersoaked spots form and an amber colored ooze will come from the spots. The fruit spots become dark gray to black and are sunken. The disease is favored by humid, wet weather and temperatures between 60 and 80 degrees. The disease is spread by tools, wind, splashing water, and insects. Use copper(1) or Chlorothalonil(0).
Anthracnose
Round watersoaked leaf spots form then turn yellow to brown with red margins. The center drops out giving a shothole appearance. Often, some defoliation occurs. On fruit, a circular dark brown to black sunken lesion forms with pinkish-orange spore masses in the center. The disease is favored by humid wet weather and temperatures between 60 to 80 degrees. The disease is spread by tools, wind, splashing water, and insects. Use sprays of Chlorothalonil(0) or copper(1).
Alternaria Leaf Spot
Circular tan spots with concentric circles form on the leaves. Defoliation sometimes occurs. The disease is favored by bright sunshine, frequent dews and showers, and temperatures between 60 and 90 degrees. The disease is spread by tools, wind, splashing water, and insects. Use sprays of sulfur(5).
Bacterial Wilt
Infected leaves turn dull green then leaves, branches, and whole plants wilt and die. When the stem is cut and squeezed, a sticky, stringy ooze comes out. The disease is spread by cucumber beetles. Cucumber beetle migration and feeding is favored by dry weather. The disease is favored by temperatures between 50 and 70 degrees and frequent dews. Keep the cucumber beetles under control.
Powdery Mildew
Powdery mildew causes a white powdery growth on leaves and stems. Infected parts turn yellow, shrivel and plants are defoliated prematurely. The yield is reduced and fruit quality is reduced. The disease is favored by humid weather, frequent dew and temperatures between 70 and 90 degrees. Use sprays of copper(1) Chlorothalonil(0) or sulfur(5).
Cucumber Mosaic
Mosaic causes mottled dark and light green, crinkled leaves, with symptoms most noticeable on young leaves. Old leaves have V shaped dead areas extending from the leaf margins to the middle vein. The fruit are mottled, warty and misshapen. The disease is favored by poor weed control as many weeds act as hosts to the virus. The disease is spread aphids and cucumber beetles. There is no chemical control for this disease.
