Cause The beet curly top virus, which is transmitted by the beet leafhopper.
Symptoms Young infected plants die almost immediately without showing characteristic symptoms. On older plants, mature leaves gradually yellow and can eventually die; new growth is dwarfed with shortened internodes. Leaves are dwarfed, puckered, and cupped out, sometimes until the leaves form a globular outline. The runner tip characteristically bends up. Blossoms on diseased shoots usually do not set fruit.
Cultural control
- Use resistant varieties. The varieties, Umatilla Marblehead and Yakima Marblehead show resistance under eastern Oregon conditions.
- In the Hermiston, OR area, plant squash fields away from the borders of irrigated agriculture.
Chemical control Controlling the insect vector has been ineffective at limiting this disease.