Subtropical Fruit Crops Research & Education
University of California
Subtropical Fruit Crops Research & Education

We are San Diego & Riverside County Farm Advisors

HLB - Potential Threat Near San Diego County

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).


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.

Learn more about HLB and how to protect your crops from it by following these links. 


News Stories: 

Distribution & Management: 

IPM Blog: 

IPM Pest Notes 

California Citrus Pest & Disease Prevention Committee: 

Topics in Subtropics Blog

  • Nitrogen Management Plans to Meet Water Quality Standards

    Added February 19, 2019
    Nitrogen mamt areas

    We are now just over halfway through the third term of the Conditional Waiver, adopted in April 2016 and set to expire in April 2021.  Each new term builds upon the last, and adds new requirements aimed at improving water quality and...

  • Frosted Flowers? Still Time to Gibb

    Added February 18, 2019
    Lovatt - gibb spray CAC Grower Education Feb 5-7 2019 Handout GA3 to increase yield

    Avocados in some parts of coastal California have been blooming.  Some of them got hit by the cold weather in the first part of February.   In the coldest areas there was a little bit of new leaf damage, but this has been minimal. Some...

  • Learning How to Spray Trees Better

    Added February 15, 2019
    citrus spray blast

    Dr. Peter Ako Larbi is a Cooperative Extension Specialist in agricultural engineering with UC ANR. As part of his research and extension program, his focus is on developing and promoting best practices for safe, economical, and environmentally sound...

  • Snake Oil, Horticultural Myths and Urban Legends from a Horticulturist

    Added February 13, 2019
    planting diagram gravel

    Horticulture is the cultivation of plants as ornamentals or for the production of food.  When things go wrong (plants grow poorly or not at all), horticulturists sometimes turn to products that can “cure”, revitalize, invigorate,...

  • California‚Äôs Top Counties for Agriculture

    Added February 12, 2019
    lemon rootstock trial with cover crop

    California agriculture saw significant gains in 2017, with the state's counties experiencing a 5.1% jump in total production value. The California Department of Food and Agriculture (CDFA) says combined sales, excluding timber, totaled $59.57...

  • Distinguishing Between Drought and Avocado Root Rot

    Added February 11, 2019
    avocado thinning canopy

    We recently had a series of workshops on Avocado Root Rot and how to manage it.  A common question was how to figure out whether the tree was diseased or just stressed from lack of water or from an accumulation of salts that is also a reflection of...

Avocado Production in California Books

Book 1: Background Information

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.

Browse by Chapter

Book 2: Cultural Care

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.

Browse by Chapter

Webmaster Email: