curly top
A disease of beets, gourds, and other plants, often caused by the virus Beet curly top virus, which results in stunted or misshapen growth and curled or puckered leaves.
curly top: virus disease that cripples leafy crops
Curly top is a viral disease that attacks beets, squash, melons, beans, tomatoes, and dozens of other crops, causing severe stunting and leaf deformation. The primary culprit is Beet curly top virus (BCTV), a geminivirus transmitted by the beet leafhopper (Circulifer tenellus), a small insect native to western North America. Infected plants develop characteristically thickened, curled, or puckered leaves that roll inward; veins become discolored and brittle. Growth halts, and yield loss can reach 100 percent in severely affected fields.
The beet leafhopper acquires the virus by feeding on infected plants and remains a vector for life, spreading BCTV across fields and between seasons. Infection is most damaging during early crop growth; plants exposed to the virus in seedling stage suffer worse symptoms than those infected later. The virus overwinters in perennial hosts like Russian thistle and other wild plants in arid regions, making it particularly destructive in irrigated western valleys where these plants flourish alongside cultivated land.
Symptoms and detection
Early signs appear two to three weeks after infection: leaf edges curl upward, the blade becomes stiff and brittle, and interveinal yellowing or purpling occurs. On sugar beets, petioles thicken and become abnormally rigid. Affected plants stay dwarfed, and root crops fail to size properly. Diagnosis relies on visual inspection in the field combined with laboratory confirmation using serology or PCR testing, particularly important because other viruses cause similar curling.
Management centers on controlling the leafhopper vector and eliminating overwintering hosts. Planting date adjustment, removal of weeds adjacent to fields, and reflective mulches that confuse the insect can reduce pressure. Some varieties show resistance or tolerance to BCTV, particularly in sugar beet breeding lines developed in western states where the disease is endemic. Insecticidal control of leafhoppers during the critical window after crop emergence provides only partial protection since viruliferous insects may infect plants before being killed.