If older leaves on cucumber, melon, or squash are turning yellow and leathery, the plants may be infected with cucurbit aphid-borne yellows.
This viral disease is transmitted by the cucurbit aphid-borne yellows luteovirus (CABYV). Luteoviruses are a genus of viruses that use plants as hosts, and are transmitted by aphids.
Symptoms of aphid borne yellow virus
Early symptoms are chlorotic (yellow) areas on lower leaves. These spots expand to include the entire leaf, leaving the larger veins bright green. The affected areas become leathery and brittle. Stunting and fruit drop are common as the plant struggles. Before genetic testing, this condition was attributed to plant aging (senescence), nutrient deficiencies, or other diseases, such as cucurbit yellow stunting disorder.
How the disease is spread
As the name suggests, this disease is spread by aphids. As aphids pierce plant tissue to feed on sap in the xylem, they infect the plants they eat. Once infected, the aphid will continue to spread the disease as it feeds. This disease can also be spread to lettuces, beets, and several weeds.
Controlling cucurbit aphid borne yellows
There is no way to control the virus, but you can reduce the presence of aphids in your garden with these tips:
Infected plants should be removed and destroyed, to prevent the disease from spreading to nearby plants.
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