San Diego County supports a highly productive and diverse subtropical agriculture sector, driven by commercial avocado and citrus operations and supported by the region’s unique coastal and inland microclimates. UC Cooperative Extension’s Subtropical Crops program partners directly with growers, pest control advisers, and industry stakeholders to address day-to-day production challenges that impact yield, quality, and profitability. Through applied field trials and on-farm research, the program develops practical, cost-effective, and environmentally responsible solutions for weed, pest, water, and nutrient management under real production conditions. This work helps growers adapt to regulatory pressure, resource limitations, and climate variability while maintaining the economic viability and long-term sustainability of San Diego’s subtropical crop industry.
HLB detected in Riverside County:
The Asian citrus psyllid is a tiny, mottled brown insect about the size of an aphid that poses a serious threat to all of California's varieties of citrus (e.g., oranges, grapefruit, lemons, and mandarins).
“For more information on the Asian Citrus Psyllid, please click on “Exotic Pest” above”
The insect is associated with the fatal citrus disease Huanglongbing (HLB), also called citrus greening disease. The psyllid takes the bacteria into its body when it feeds on bacteria-infected plants and spreads when a bacteria-carrying psyllid flies to a healthy plant and injects bacteria into it as it feeds.
HLB can kill a citrus tree in as little as five years, and there is no known cure. All commonly grown citrus varieties are susceptible to the disease.
The only way to protect trees is to prevent spread of the HLB pathogen in the first place, by controlling psyllid populations and removing and destroying any infected trees.
(Diptera: Lonchaeidae: Silba adipata)
Invasive Fig Pest Recently Discovered in Southern California
Watch this video (in Spanish here) on Avocado Fruit Production. California is the biggest avocado producer nationwide; this delicious, versatile fruit arrived in the state in the 1890s. The demand for avocados has increased substantially over the last couple of decades. Nevertheless, avocado production faces many challenges.
In Book 1, Gary S. Bender, Farm Advisor, takes you through the history of the avocado industry in California and teaches you about grove development.
Book 2 focuses on cultural care and includes articles on irrigation, fertilization, disease and insect control, vertebrate pest management, pruning and frost management. The author for most of the articles is Gary S. Bender, Farm Advisor for Subtropical Horticulture in San Diego County.
