By Patti Phillips and Neil Fernbaugh
UCCE Master Gardeners

Most Californians don’t realize there are more citrus trees in people’s backyards than there are in commercial groves. That is why those of us who have trees in our backyard are the most important people in saving California’s citrus. If you have citrus trees in your backyard, it’s time to take a careful look at them for signs of the Asian citrus psyllid (ACP).

You’ve probably seen pamphlets or billboards about the tiny bug called a psyllid that can carry the HLB disease from tree to tree. The disease spreads when the bacteria-carrying psyllid flies to a healthy plant and injects the bacteria as it feeds. It can kill a tree within five to eight years. Because the problem has fallen out of the local news cycle lately, we wanted to remind everybody how they can help, and explain again the importance of fighting this disease which is fatal to citrus trees and for which there is currently no cure. 

HLB, also known as huanglongbing or citrus greening, has decimated hundreds of thousands of acres of oranges in Florida, Texas and Arizona. In 2012, HLB was found on a backyard citrus tree in Los Angeles County. Since 2012, the ACP has been spreading HLB through the urban areas around Riverside, Los Angeles and Orange Counties. The psyllid that can carry the disease has cropped up in numerous areas of our valley, but so far, no HLB-infected trees have been found locally. Unfortunately, only one infected tree in the valley could be the beginning of an invasion, and once it reaches our valley’s commercial citrus, we could see the destruction of one of California’s major industries, and it could easily wipe out all our backyard trees. 

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 it’s 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. Later symptoms of HLB-infected trees include lopsided, small fruit, bitter juice and excessive fruit drop. Eventually the tree will stop producing fruit and die.

What do we need to know and do? What can we look for? 

The most important thing we can look for is evidence of the Asian citrus psyllid. 

The psyllid itself is about the size of a small aphid. As the weather warms this month, you are most likely to find evidence of the psyllid in and under the light green leaves of new growth (the spring flush) that is easily distinguishable from the darker, older leaves. If you have a good magnifying glass, or great eyesight, you can tell the psyllid from any other insect by the way it feeds with its head down, nearly touching the leaf, and the rest of its body sticking up at almost a 45 degree angle. You can also look for red eyes, a pointed head, and mottled brown wings. You might also see its extremely small, orange, almond shaped eggs. 

The most obvious evidence is the insect’s nymph stage. Nymphs are yellowish with red eyes, and produce easily seen waxy white tubules.

If you find any evidence of psyllids, the most important thing you can do is notify and cooperate with agriculture officials who are trapping and treating for the pest in your neighborhood. If you believe that you have found psyllids on your trees, contact the California Department of Food and Agriculture (CDFA) at 1-800-491-1899. For more information: ipm.ucanr.edu/PMG/PESTNOTES/pn74155.html 

For answers to all your home gardening questions, call the Master Gardeners in Tulare County at 559-684-3325, Tuesdays and Thursdays between 9:30 and 11:30 a.m.

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