USDA/APHIS announcement concerning Cucumber green mottle mosaic virus in California

The United States Department of Agriculture(USDA), in conjunction with the California Department of Food and Agriculture, released a statement concerning new detections of Cucumber Green Mottle Mosaic Virus (CGMMV) in seedless watermelon production fields in San Joaquin, Fresno and Kern counties in California.  This virus infects a number of crops in the cucurbit family, namely watermelon, squash and other melons, and cucumber.  It can be transmitted via seed and is also transmitted mechanically through contaminated farm equipment, workers and irrigation water.

CGMMV is exotic to the U.S. and had not been detected until last year when it was found in a melon seed production field during a routine phytosanitary field inspection for export certification.  Trace forward and trace back investigations located a couple of additional fields that were quickly abated by the CDFA and USDA's Animal Plant Health Inspection Service.  Until this year's detections, the virus was considered eradicated.  

The new detections are all associated with seedless watermelons that were produced from transplants.  It is believed that the source of the problem came from transplants that were likely infected by mechanical means during production in the nurseries then planted in the fields.  

The best course of action continues to be eradication. However, the impacts of CGMMV can be minimized through the use of preventative and management strategies at all levels of agricultural production: seed, transplant and field.  Agricultural producers, especially at this point in time, need to focus on preventive measures including testing of seed prior to sale or planting; sanitation of equipment and workers who may come in contact with host plants; securing transplants from entities that have strong biosecurity programs in place to prevent transmission; becoming familiar with disease symptoms on plants and fruit; and submitting suspect samples to CDFA, APHIS, or county extension agents for official diagnosis.