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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 $2.5 billion worth of citrus fruit trees must work together to protect their trees. Learn more about how to detect pest and disease and protect California’s beloved citrus heritage.



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

  • Inspect trees for the Asian citrus psyllid and Huanglongbingmonthly, and whenever watering, spraying, pruning or tending trees. If you spot the pest or disease, call: 800-491-1899. Psyllids are most noticeable when new leaves are growing on the tips of the branches.
  • As part of your tree care, visit your local nursery or garden center to get advice on products that can help protect your citrus tree.
  • Do not move citrus plants, foliage or fruit into or out of your area, and especially across the state or international borders. This could unknowingly contribute to spreading of the pest and disease.
  • When planting a new citrus tree, be sure to get your tree from a reputable, licensed nursery in your local area.
  • When grafting citrus trees, only use registered budwood that comes with source documentation, such as the budwood offered through the Citrus Clonal Protection Program
  • Be sure to dry out citrus tree clippings or double bag them before removing the plant material from the property.

State agriculture crews are not treating in all areas of California, so you may need to take a proactive stance to protect your tree. Inspect citrus foliage regularly for signs of the pest and disease, and consider treating your citrus tree with a product proven to be effective against the Asian citrus psyllid. Visit your local nursery or garden center and ask about products that will control the Asian citrus psyllid. Always follow label instructions for the safest and most effective use of the product. For more tips about how to treat your citrus tree, visit the University of California’s Division of Agriculture and Natural Resources website.

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