UCCE Master Gardeners of San Joaquin County
University of California
UCCE Master Gardeners of San Joaquin County

FAQ

How can the home gardener spot this pest?

The best way to detect the psyllid is by looking at tiny new leaves on citrus trees on a monthly basis. Homeowners should inspect trees for the ACP whenever watering, spraying, pruning or tending trees. Slowly walk around each tree and inspect the new growth. Look for signs of psyllid feeding and damage, including twisted leaves, waxy deposits, honeydew, sooty mold, and adult psyllids. Due to the small size of the psyllid, using a magnifying glass or hand lens will make inspection easier. Nymphs and adults feed on young flush growth. Adults are 1/8 inch in size, about the size of an aphid with brownish mottled wings. They feed with their heads down and “tails” in the air. Nymphs are tiny and yellowish and excrete white waxy tubules. Mature citrus trees typically produce most of their new growth in the spring and fall, but young trees tend to produce flushes of new growth periodically during warm weather. 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.

 

Whom should the homeowner call or contact if they think they have ACP on their citrus trees? If homeowners have questions or would like more information they can call the San Joaquin Master Gardeners at 953-6112. If you think you have ACP you can also call the county ag commissioner at 953-6000. Do not take samples of your citrus leaves to the Master Gardeners, Ag Commissioner or local nurseries.

 

What are signs that a backyard citrus tree may have HLB disease? 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). Early symptoms of HLB include a yellowing of only one limb or sector of the tree canopy. The most characteristic symptom is an asymmetrical blotchy mottling of leaves. Nutritional mottling occurs symmetrically along leaf veins. Chronically infected trees display extensive twig and limb dieback, tend to drop fruit prematurely, and are sparsely foliated with small leaves that point upward.  The fruit produced by infected trees is small, green, underdeveloped, and misshapen, with aborted seeds and bitter in taste. There is no cure for the infected trees, which decline and die within a few years.

 

Is there a home treatment for this pest?
If home gardeners believe they have the ACP they should call the hotline number or the county agricultural commissioner’s office. CDFA has teams in place in Manteca and Lodi that are currently monitoring for ACP.

The Asian citrus psyllid is attacked by many natural enemies, including lady beetles, lacewing larvae, minute pirate bugs, parasitic wasps, spiders, and birds. These natural enemies do not eradicate the psyllid, but they will help reduce psyllid populations, which in turn will help to slow the spread of HLB.

Foliar sprays that are available to home gardeners can be detrimental to the beneficial insects and natural enemies of the ACP and should only be used when the psyllid has been identified and recommended by the CDFA or county Ag Commissioners Office.

The Asian citrus psyllid can fly short distances and be carried by the wind. However, a main way the Asian citrus psyllid spreads throughout the state is by people transporting infested plants or plant material. Homeowners can help fight the spread of the ACP by not moving citrus plants, plant material or fruit in or out of the county, across state or international borders. As tempting as it may be to share the bounty of oranges from your tree this year it will be best to keep them in your yard. If planting new trees, purchase trees from reputable, licensed California nurseries. 

Sanitation is also important in preventing the spread of ACP. Keep the bottom of trees free of rotten fruit and leaves. If you prune your trees, double bag the plant material and throw it away. Do not throw any leaves in the compost pile.

 

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