Peach fruit flies as well as Oriental fruit flies can infest 230 species of fruits and vegetables, ruining commercial as well as backyard crops. The flies lay their eggs under the skins of soft fruits and vegetables which then hatch into maggots.
Sacramento and Yolo counties are now under quarantine for the Oriental fruit fly, meaning no crops can be transported or moved. Fresno County successfully fought a peach fruit fly outbreak in 2006 with the cooperation of home gardeners who allowed trapping and targeted pesticide application in their yards. Our cooperation is once again essential to the eradication of these pests.
Of course, we’re already fighting one tree fruit pest: the Asian citrus psyllid that carries Huanglongbing or HLB, also called citrus greening disease. HLB has become a serious threat to California’s citrus industry as well as to backyard orchards since it was first detected in Los Angeles in 2012.
The Asian citrus psyllid feeds on new growth on all types of citrus (oranges, lemons, grapefruit and mandarins). Mature citrus trees produce a spring and fall flush of new growth; young citrus trees can produce several flushes of new growth from spring through fall.
Early detection of the psyllid can help limit the spread of the disease which can kill citrus trees within five years. Later signs include branch dieback and oddly shaped sour fruit with a greenish tinge or yellow mottling. Monitor your citrus trees regularly this fall, checking for signs of the psyllids’ presence.
Adult Asian citrus psyllids are tiny, about the size of an aphid, with brownish wings and pointy rear ends. They are the only psyllid to feed in the “bottom up” position. The nymph stage of the psyllid which feeds on tender new leaf tissue is even smaller. You’ll need a hand lens to find them. The nymphs’ feeding causes the new leaves to twist, fold up or become notched. Flatten any twisted, folded leaves and use the hand lens to look for yellow or brownish nymphs or really tiny yellow-beige-orangish eggs. The nymphs produce white. waxy tubes that carry excess sap away from their bodies. The waxy tubes with a bulb at the end are characteristic of only the Asian citrus psyllid and provide a definite identification. The University of California Integrated Pest Management website has good photos of all stages of the psyllid and of infected trees.
Call the CDFA Exotic Pest hotline at 800-491-1899 if you think you might have spotted the Asian citrus psyllid. Or call the Fresno County Master Gardeners hotline at 559-241-7535, Monday-Friday from 9 a.m. -noon. If bringing a sample into the Master Gardeners, please keep it tightly sealed in a plastic bag. The psyllids (as well as fruit flies) are spread by moving infested fruits from one area to another.