We must all respect the ongoing citrus quarantine

QWhat are the current rules about moving citrus to prevent the spread of HLB or citrus greening disease? Where can I find the most up-to-date quarantine maps?

ACitrus greening disease, also known as huanglongbing or HLB, is a bacterial disease that kills citrus trees and has no known cure. The bacteria that cause it is transmitted via the Asian citrus psyllid insect. Since this disease can potentially wipe out California’s citrus industry, we want to do everything possible to slow the spread until an effective treatment can be found.

One of the joys of gardening in Southern California is the ability to grow a variety of citrus trees, and in some areas over 60% of homeowners grow at least one type of citrus. Because of this, we need to be on the lookout for the signs of HLB and know what we can do to slow the spread.

The psyllid is more likely to be found in the spring and early summer when new growth appears on citrus trees. The insect is only about the size of an aphid and likes to hang out near the base of new leaf petioles. It can be identified by its unique habit of sticking its rear end up at a 45-degree angle.

Sometimes you can see curly, waxy-looking tubules that are produced by immature nymphs. You may need a magnifying glass to see the individual insects, but the waxy tubules are usually visible without magnification. If you suspect that your tree has psyllids, determine if your area already has psyllids by consulting the California Department

of Food and Agriculture map at ucanr.edu (search “distribution of HLB”).

Chances are that if you live in Southern California, your area already has psyllids and you will need to treat for them. If you live in Northern California, or in an area that doesn’t have a current psyllid population, contact the Department of Food and Agriculture at 800-491-1899.

The presence of psyllids does not necessarily mean your tree has the disease, but you’ll want to treat to reduce the likelihood of HLB (fewer psyllids means less chance of disease).

Signs of HLB include general tree decline, and bitter-tasting fruit. Overall leaf yellowing can be caused by any number of nutritional deficiencies, but HLB causes irregular, blotchy yellowing. Sometimes only one branch will have yellow leaves. If your tree shows any of these symptoms, especially if psyllids are present, contact the Department of Food and Agriculture immediately. Don’t move citrus trees or unwashed fruit out of a psyllid quarantine zone. This is to prevent the spread of psyllids to new areas. Remember that these insects are really small and can easily hitchhike on plant material.

Don’t purchase (or otherwise acquire) trees or bud wood from random sources! This can spread the disease, which is worse than spreading the psyllids. Get your citrus trees only from reputable nurseries that sell inspected and clean stock. Don’t be tempted to buy a cheap, questionable tree off the back of a truck. You don’t want to be the reason that all of your neighbors have to remove their citrus trees.

Find out more at ipm.ucanr. EDU/PMG/PESTNOTES/PN74155. html

GETTY IMAGES Asymmetrical leaf yellowing can be a sign of citrus greening disease, which has no known cure and so could devastate California’s citrus industry. It is spread by a tiny bug.