How to Manage Pests

UC Pest Management Guidelines

SYMPTOMS

Cucurbit aphid-borne yellows luteovirus causes a general yellowing of the older leaves, which become thick and leathery. The major veins of these leaves remain green. Growth and yield of infected plants may be reduced.

COMMENTS ON THE DISEASE

This virus is persistent: it is acquired and transmitted in hours and the aphid vector may retain the virus for its entire life. Vector specificity is high; the cotton (melon) aphid, Aphis gossypii, transmits the virus very efficiently while the green peach aphid, Myzus persicae, is a poor vector. The source of the virus is unknown, possibly wild cucurbits.

MANAGEMENT

The occurrence of this virus is erratic and unpredictable; consequently, control of this disease is not attempted. Although not tested specifically on this virus disease, silver reflective plastic mulches applied at planting have been shown to be effective in repelling aphids from plants, thereby reducing or delaying virus infection. These mulches help plants off to a healthy start and are effective until expanding foliage covers the reflective surface. Reflective mulches may need to be removed in the desert areas when summer temperatures are excessive for optimal growth of plants. However, in the Central Valley and cooler areas, these mulches have not caused plant damage in the summer; in fact, they improve soil moisture and nutrient retention, which may further aid plant productivity.

PUBLICATION

UC IPM Pest Management Guidelines: Cucurbits
UC ANR Publication 3445
Diseases
R. M. Davis, Plant Pathology, UC Davis
T. A. Turini, UC Cooperative Extension, Imperial County
B. J. Aegerter, UC Cooperative Extension, San Joaquin County
W. D. Gubler, Plant Pathology, UC Davis
J. J. Stapleton, UC IPM Program, Kearney Agricultural Center, Parlier

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