Citrus Orange

A Threat to California Citrus

A plant disease that kills citrus trees has been found in California. The disease, called Huanglongbing or citrus greening disease, isn’t harmful to humans, but it is fatal for citrus trees and has no cure. The disease is spread by a pest called the Asian citrus psyllid as it feeds on citrus tree leaves. Until researchers find a solution, California homeowners who enjoy growing fresh citrus fruit in their yards, and California farmers tending to $3.4 billion worth of citrus fruit trees must work together to protect their trees. Learn more about how to detect the pest and disease and protect California’s beloved citrus heritage.

Protect Your Citrus Trees

The Citrus Pest & Disease Prevention Program recommends these tips to protect citrus trees.

  • Inspect trees for the Asian citrus psyllid and Huanglongbing monthly, and whenever watering, spraying, pruning or tending trees. If the disease is spotted, call the CDFA hotline at 800-491-1899 immediately.
  • Do not move citrus plants, leaves, or foliage into or out of the quarantine area or across state or international borders. Keep it local.
  • As part of tree care, visit your local nursery or garden center to get advice on products that can help protect citrus trees from the Asian citrus psyllid.
  • Recommendations on managing the Asian citrus psyllid can be found by visiting the University of California Division of Agriculture and Natural Resources website.
  • Buy citrus trees from licensed, local nurseries and only use registered budwood.
  • Cooperate with agricultural officials placing insect traps, inspecting trees and treating for the pest.
  • Be sure to dry out citrus tree clippings or double bag them before disposing the plant material.
  • If you no longer wish to care for your citrus tree, consider removing it so it does not become a host to the pest or disease.
Citrus Lime
Citrus Lemon
Map of California
Star Marker San Joaquin Valley The majority of California’s fresh citrus fruit is grown in orchards throughout the San Joaquin Valley. This region’s countless trees provide thousands of jobs and the majority of the nation’s fresh citrus fruit. x
Star Marker Los Angeles Can you picture a giant orange grove in the middle of downtown Los Angeles? Once the original site of commercial citrus orchards, Los Angeles is now home to many residential citrus trees. Unfortunately, Huanglongbing has been found in this region putting all these beloved trees at risk. x
Star Marker Riverside California’s first navel orange tree was planted in Riverside in 1873. Nearly all the navel orange trees grown in the state are descendants of the early trees planted in Riverside. x
Star Marker Coastal California The coastal areas of California are especially suitable for growing lemons – just look to Ventura’s rolling hills of lemon trees and you’ll see proof that citrus thrives here. Pixie tangerines are another regional favorite. x
Star Marker Northern California Mountain mandarins are a long-time favorite of residents and citrus tree owners alike in this part of the state. During the winter, the hills of Placer County glow with the distinct orange color of the ripening fruit. x
Star Marker San Bernardino Huanglongbing was detected in San Bernardino County for the first time in late 2019, putting nearby commercial citrus groves at risk for the disease. x

California: Rich in Citrus Heritage

Citrus has been a beloved part of California landscapes and homes for generations. Click the areas of the map below to learn about the history of citrus in different regions of the state. To see if a particular area is at risk for Huanglongbing or the Asian citrus psyllid visit the Pest & Disease page.

Did You Know?

  • It is illegal to bring citrus fruit, leaves or whole plants into California from other states or countries.

  • Specially trained dogs sniff out citrus fruit, plants and other agricultural material in mail facilities and at airports to prevent infected items from harming California crops.

  • California is the nation’s leading provider of fresh citrus fruit, like oranges, mandarins and lemons.

  • It is estimated that 6 out of 10 residences in California have at least one citrus tree.

  • Huanglongbing is considered one of the most devastating plant diseases in existence because it kills citrus trees and has no cure.