Citrus Killing Insect

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This article is to inform home gardeners and others of the danger of the Asian citrus psyllid (ACP), Diaphorina citri, insect that can infest and kill all varieties of citrus.
by Maple Tree · All Zones · Insects · 0 Comments · April 29, 2016 · 6,128 views

Asian Citrus Psyllid and Huanglongbing Disease

The Asian citrus psyllid (ACP), Diaphorina citri, is a tiny mottled brown insect, about the size of an aphid, that poses a serious threat to California’s citrus trees—including those grown in home gardens and on farms. The psyllid feeds on all varieties of citrus (e.g., oranges, grapefruit, lemons, and mandarins) and a few very closely related ornamental plants in the family Rutaceae (e.g., calamondin, box orange, Indian curry leaf, and orange jessamine or orange jasmine).
This psyllid damages citrus directly by feeding on new leaf growth (flush); this feeding twists and curls young leaves and kills or burns back new shoots. More seriously, the insect is a vector of the bacterium Candidatus Liberibacter asiaticus, associated with the fatal citrus disease huanglongbing (HLB), also called citrus greening disease. The psyllid takes the bacteria into its body when it feeds on bacteria-infected plants. The disease spreads when a bacteria-carrying psyllid flies to a healthy plant and injects bacteria into it as it feeds.
HLB can kill a citrus tree in as little as five years, and there is no known cure. The only way to protect trees is to prevent spread of the HLB pathogen in the first place, by controlling psyllid populations and removing and destroying any infected trees.
The Asian citrus psyllid is widely distributed throughout Southern California, and it is likely to continue to spread into the Central Coast and the Central Valley. HLB was found in March 2012 in a tree in a yard in Los Angeles County, which means it is now even more important to keep the psyllid populations low so they don’t find infected trees like this one and spread the disease. HLB is also spreading towards the California border from Mexico.
For up-to-date maps of ACP quarantines, HLB finds, and other important information, see the Asian Citrus Psyllid Distribution and Management web site.

The Asian citrus psyllid and huanglongbing disease originated in Asia or India and then spread to other areas of the world where citrus is grown. The psyllid was first found in the United States in June 1998 in Palm Beach County, Fla., on backyard plantings of orange jessamine, Murraya paniculata. By 2001 the psyllid had spread to 31 counties in Florida, primarily due to the movement of infested nursery plants. Agriculture officials believe HLB was present in Florida in backyard citrus trees, and the psyllid rapidly spread the disease to other backyards and commercial citrus not long after the psyllid arrived in Florida.
In 2001, the psyllid spread to the Rio Grande Valley in Texas on nursery stock (orange jessamine); it also was detected in Louisiana. The insect subsequently spread to other states and is now found in Alabama, Georgia, Mississippi, South Carolina, Arizona, California, and Hawaii as well as Mexico.
In 2008, the Asian citrus psyllid expanded its range from Mexico to Southern California, where it was first detected in San Diego County. Over the next few years the psyllid spread throughout Southern California, particularly in urban and suburban environments, and as of 2013 a handful of detections have occurred in the southern Central Valley.
Because HLB has been found in California, there is major concern that the disease will spread further through the movement of infected plants or infected psyllids. HLB poses a significant threat to both residential citrus trees and commercial citrus production.
To protect the state’s citrus from HLB, it is important to control the psyllid, prevent the accidental introduction of any infected host plant, and detect and remove any infected plants found in California as quickly as possible. The job of detecting infected trees is made difficult by the fact that it takes one to two years for symptoms of HLB to begin to show in the trees.

The adult Asian citrus psyllid is a small, brownish-winged insect about the size of an aphid. Its body is 1/6 to 1/8 inch long with a pointed front end, red eyes, and short antennae. The wings are mottled brown around the outer edge except where a clear stripe breaks up the pattern. The adults may have greenish, yellow, or orange abdomens depending on the time of year and the host plant they have been feeding on.
The adult psyllid feeds with its head down, almost touching the leaf, and the rest of its body is raised from the surface at an almost 45-degree angle with its tail end in the air. No other insect pest of citrus positions its body this way while feeding.
Adults typically live one to two months. Females lay tiny yellow-orange almond-shaped eggs in the folds of the small newly developing feather flush leaves of citrus. Each female can lay several hundred eggs during its life span.
The eggs hatch into nymphs that are wingless, flattened, yellow or orange to brownish, and 1/100 to 1/14 inch long. Nymphs molt four times, increasing in size with each nymphal stage (instar), before maturing into adult psyllids. The nymphs can feed only on soft, young leaf tissue and are found on immature leaves and stems of flush growth on citrus.
The nymphs remove sap from plant tissue when they feed and excrete a large quantity of sugary liquid (honeydew). Each nymph also produces a waxy tubule to help clear the sugary waste product away from its body. The tubule’s shape—a curly tube with a bulb at the end—is unique to the Asian citrus psyllid and can be used to identify the insect.
There are other psyllids such as Eucalyptus psyllids, tomato psyllids, and Eugenia psyllid that can be found in home gardens. The Asian citrus psyllid is easily distinguished from these in its adult stage by the brown band along the edge of its wing with a clear area; its characteristic body tilt; and, in the nymph stage, the shape of the waxy tubules it produces.


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