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The Disease: Huanglongbing (HLB)

Leaves of a citrus tree with Huanglongbing citrus greening disease

HLB, also known as citrus greening disease, is fatal for citrus trees. Once a tree becomes infected, there is no cure and it will die. The disease is spread by an insect called the Asian citrus psyllid. The disease:

  • Has been found in Southern California
  • Destroys production, appearance and value of citrus trees.
  • Makes trees produce bitter, inedible, misshapen fruit, and will eventually kill the tree.

What is Huanglongbing?

The Disease: Huanglongbing

Huanglongbing (HLB), also known as citrus greening disease, is a bacterial plant disease that – while not harmful to humans or animals – is fatal for citrus trees. The disease destroys the production, appearance and economic value of citrus trees. Diseased trees produce bitter, hard, misshapen fruit and die within a few years of being infected. HLB is considered to be one of the most serious plant diseases in the world and currently there is no cure. Trees infected with HLB will die and need to be removed in order to protect other citrus trees on the property, neighbors’ citrus trees and the community’s citrus.

How is it spread?

HLB is spread by the Asian citrus psyllid, a tiny insect that feeds on the leaves and stems of citrus trees. When an Asian citrus psyllid feeds on an HLB-infected tree, it can pick up the bacteria that causes the disease. Once infected, a psyllid carries the disease-causing bacteria for life and can transfer the disease when feeding on other citrus trees. An important way to control the spread of HLB is to stop the Asian citrus psyllid.

The disease can also be spread by grafting infected plant tissue onto another plant. For this reason, it is important to only use registered budwood with documentation that demonstrates it came from a disease-free tree.

How do I know if my tree is infected?

Detection of HLB can be difficult, as symptoms may not show up for more than a year after the tree has become infected. The first symptoms are yellowed leaves. However, citrus trees often have yellow leaves because of nutritional deficiencies. HLB leaf symptoms are somewhat unique in that the yellow mottling caused by HLB is not the same on both sides of the leaf.

Later symptoms of HLB-infected trees include lopsided, small fruit, and premature and excessive fruit drop. Additionally, the disease can cause entire shoots or branches of the tree to become yellow.

The best way to protect your citrus tree from HLB is prevention. Inspect your tree monthly for the Asian citrus psyllid. If you think you’ve found an Asian citrus psyllid or symptoms of HLB, ACT FAST! Call the California Department of Food and Agriculture hotline at 1-800-491-1899.

What is at risk?

HLB and the Asian citrus psyllid threaten not only local farms and farmers we count on for fresh, healthy, locally produced citrus, but also residents' ability to grow citrus fruits in their backyards. If HLB is not stopped, all citrus in California is at risk of disappearing. The state’s nearly $2 billion citrus industry and the thousands of workers who depend on it for jobs is at stake. We must act now to protect our state’s iconic citrus heritage.

Once a tree is infected with HLB, it will die and must be removed to protect other nearby citrus trees. Diseased trees can become a reservoir and breeding ground for Asian citrus psyllids carrying HLB, allowing the insects to spread the disease. Infected trees must be removed to protect other citrus trees, the community’s citrus and the quality of life for future generations.

©Copyright 2016 Citrus Pest & Disease Prevention Program     www.CaliforniaCitrusThreat.org