The Texas Department of Agriculture (TDA) has issued a second citrus quarantine area in the Texas Rio Grande Valley after a single grapefruit near Mission tested positive last week for Huanglongbing (HLB), or citrus greening disease. The new quarantined area includes a new five-mile radius zone surrounding the grapefruit tree where HLB was detected on Sept. 14.

According to officials with Texas Citrus Mutual (TCM), an industry support organization in the Valley, the tree is located in downtown Mission in a residential yard and was not part of a commercial citrus grove. TCM officials report 1,760 total acres of commercial citrus in the new quarantine area. This represents the second emergency quarantine zone established for the Rio Grande Valley.

The emergency quarantine limits movement of fruit and citrus stock from the grove to packing facilities and also the movement of citrus nursery trees from the quarantine zone.

Huanglongbing is a bacterial plant disease that is not harmful to humans or animals but is fatal for citrus trees. The disease destroys the production, appearance and economic value of citrus trees. Diseased trees produce bitter, hard, misshapen fruit over time and the tree will die within a few years of being infected if not removed immediately. HLB is considered to be one of the most serious plant diseases in the world and currently there is no cure, although promising research over the last year provides potential for new treatments.

 

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HLB is spread by the Asian citrus psyllid, a tiny insect that feeds on the leaves and stems of citrus trees. When an Asian citrus psyllid feeds on an HLB-infected tree, it can pick up bacteria that cause the disease. Once infected, a psyllid carries the disease-causing bacteria for life and can transfer the disease when feeding on other citrus trees.

The United States Department of Agriculture and the Animal Plant Health Inspection Service (APHIS) says detection of HLB can be difficult and citrus growers may not be able to find visual symptoms for up to a year after infection occurs. Generally, the first symptoms are yellowing leaves; however, citrus trees often have yellow leaves because of nutritional deficiencies, making detection that much harder.

Later symptoms of HLB-infected trees include lopsided, small fruit, and premature and excessive fruit drop. Additionally, the disease can cause entire shoots or branches of the tree to become yellow.