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Asian Citrus Psyllid (ACP) & Huanglongbing (HLB)

What is ACP & HLB

AsianCitrusPsyllid1 The Asian citrus psyllid (ACP) is a pest that acts as a carrier or vector spreading "huanglongbing" (HLB). Huanglongbing (HLB) is one of the most devastating diseases of citrus in the world. Once infected, there is no cure for disease and infected trees will die within ten years.

ACP has been found in San Joaquin County in Lodi and Manteca.

What can you do to help prevent the spread of ACP & HLB
  • Do not move citrus plants, plant material or fruit in or out of the county (or city
    to city), across state or international borders.
  • Do not take samples of your citrus leaves to the Master Gardeners, Ag Commissioner or local nurseries.
  • Homeowners should inspect trees for the ACP whenever watering, spraying, pruning or tending trees. Slowly walk around each tree and inspect the new growth.
  • If planting new trees, purchase trees from reputable, licensed California nurseries.
  • Use only registered budwood that comes with source documentation.
Invasive Pests in CA

This page contains links to articles, fact sheets, and other information prepared by UC scientists on topics related to exotic and invasive pests that threaten California.

Important Contact Numbers

If you think you have ACP in your yard please contact the CDFA hotline at 1-800-491-1899 or the San Joaquin County Agricultural Commissioner Office at 209-953-6000.

If you have questions or would like more information about ACP please contact the Master Gardeners at 209-953-6112

Frequently Asked Questions
Detecting ACP Video

What does the insect look like?

The Asian citrus psyllid adult is tiny - the size of an aphid (see photo above).  The wings are  brown along the edge, with a clear area. The psyllid feeds with its rear end tilted up at a 45o angle, making the insect appear almost thorn-like on leaves and stems. The tilted body and wing pattern is unique to this pest.

ACP nymph producing curly waxy tubules
ACP nymph producing curly waxy tubules
Juveniles (nymphs) produce white, waxy tubules and are always found on new leaf growth or young stems.  The waxy tubules are unique to this pest.

ACP eggs tucked in tiny leaves
ACP eggs tucked in tiny leaves
The eggs of the Asian citrus psyllid are yellow and are found on the newest leaf growth, nestled among unfolded leaves. They are very tiny and hard to see without a hand lens.





What does the disease look like?

Blotchy yellow HLB-infected leaves
Blotchy yellow HLB-infected leaves
The Agricultural Commissioner has confirmed the ACP but have not documented HLB yet in our county. HLB infected trees are difficult to diagnose because the disease can take more than a year to cause symptoms in a tree and resembles other diseases (such as stubborn disease) and nutritional deficiencies (such as zinc). The first symptom in a Huanglongbing-infected tree, and the most important one to watch for is yellowed leaves. However, citrus trees often have yellow leaves because of nutritional deficiencies so its important to know the difference. Nutrient deficiency causes a similar pattern of yellowing on both sides of the leaf.  HLB causes blotchy yellow mottling and is not the same on both sides of the leaf.


A citrus tree dying from huanglongbing
A citrus tree dying from huanglongbing
Asymmetrical yellow mottling of leaves and odd shape and greening of fruit, symptoms of Huanglongbing (citrus greening)
Asymmetrical yellow mottling of leaves and odd shape and greening of fruit, symptoms of Huanglongbing (citrus greening)
  Later symptoms of HLB-infected trees include lopsided, small fruit, bitter juice and  excessive fruit drop.There is no cure for the infected trees, which decline and die within a few years.







Information and pictures about ACP & HLB from the UC Asian Citrus Psyllid Distribution and Management and the UC IPM sites.