Aphid Borne Yellow Virus

If older leaves on cucumber, melon, or squash turn yellow and leathery, they may have cucurbit aphid-borne yellows.

The cucurbit aphid-borne yellows luteovirus (CABYV) causes this viral disease. Luteoviruses are a genus of viruses that use plants as hosts. Aphids carry this disease and spread it to plants as they feed.

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 large veins bright green. The affected areas become leathery and brittle. Stunting and fruit drop are common symptoms as the plant struggles. Before genetic testing, gardeners thought this was plant aging (senescence), nutrient deficiencies, or other diseases, like cucurbit yellow stunting disorder.

How the disease spreads

As the name suggests, aphids carry this disease. As aphids pierce plant tissue to feed on sap in the xylem, they spread infection. Once infected, the aphid will continue to spread the disease as it feeds on squash family plants. Lettuces, beets, and many weeds can also become infected.

Controlling 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:

• Install silver reflective mulch at planting time to repel aphids (remove it as temperatures rise).
• Install row covers to exclude aphids.
• Fertilize and irrigate plants properly to keep them healthy.
• Avoid using broad-spectrum pesticides, which kill off beneficial predators that eat aphids.
• Clear aphid-bearing weeds from the immediate area.

Remove and destroy infected plants to prevent the disease from spreading to nearby plants