How to Manage Pests
UC Pest Management Guidelines
Yellows (Molybdenum Deficiency)
(Reviewed 11/05, updated 11/05)
In this Guideline:
Crown leaves become bright yellow and margins become necrotic. Leaves are stunted and misshapened. Symptoms move out the runners until the entire plant is affected. Fruit set is eliminated and plants may be killed.
COMMENTS ON THE DISEASE
Yellows is the result of a molybdenum deficiency in cucurbit plants. Molybdenum is generally available in high enough quantity for all plant growth. However, under acid soil conditions molybdenum is difficult for melons of some cultivars to absorb. Yellows occurs commonly in the Stanislaus County production areas and has been associated with cut and fill areas along the California aquaduct and the Delta-Mendota Canal.
A single application of sodium molybdate at 200 ppm will result in a complete recovery of affected plants in 2 to 3 days.
UC IPM Pest Management Guidelines:
R. M. Davis, Plant Pathology, UC Davis
Acknowledgment for contributions to Diseases:W. D. Gubler, Plant Pathology, UC Davis