(originally published September/October 2016)

Shortly after hiring on as the inaugural executive director of the University of Arizona’s new Yuma Center of Excellence for Desert Agriculture, a public-private partnership devoted to applied agricultural research needed by the desert agriculture industry, Paul Brierley asked his stakeholders what they would like the Center to address first.  The answer was resounding:  Help us mitigate plant diseases!  And not just any plant disease – help us with the seemingly impossible-to-eradicate Fusarium wilt of lettuce.  And thus began the Center’s odyssey against the insidious disease that is wiping out entire fields during warm-season production of iceberg lettuce – costing the industry millions of dollars.

Tomato spotted wilt virus is a thrips-transmitted virus that can infect many crops and weeds. In California’s Central Valley, in an important processing tomato production area, this virus disease may cause substantial economic damage. The most recognizable symptoms include fruit with oval protruding oval deformities or irregular concentric ring color patterns and this virus can kill shoots and plants, so both quality and yield are affected. The host range of this virus includes many common crops and weeds and likely survives the winter on a few weed or crop plants, but quickly amplifies on tomatoes in spring. Therefore, risk increases during the season. The virus is transmitted by thrips; primarily Western Flower Thrips, Frankliniella occidentalis in the Central San Joaquin Valley. The vector must feed on an infected plant as a nymph to be capable of transmitting the virus as an adult. Risk of loss due to TSWV can be reduced but management in high risk situations is going to depend upon several tactics.

By: Larry Bettiga, Viticulture Farm Advisor University of California Cooperative Extension Monterey, San Benito and Santa Cruz Counties

(originally published May/June 2018)

Grapevine leafroll and red blotch disease are two virus-associated diseases that should be on the radar of all grape growers. The following article will hopefully provide you an update on these virus diseases based on our current knowledge. Summer surveying of vineyards for visual leaf symptoms is a great time to assess vineyard blocks for the presence of disease.