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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.
History of HLB in the U.S.
The disease was first detected in the U.S. in June 1998 when a psyllid that carried the strain of citrus greening was found in Florida. Citrus greening is now confirmed in five states including Florida, Georgia, Louisiana, South Carolina and Texas.
As a protection for the citrus industry and as a preventive measure to slow the spread of the disease, mandatory treatments to control Asian citrus psyllid (in accordance with APHIS guidelines for interstate movement of citrus plants) will be required for all citrus nursery stock production in the citrus zone prior to movement within and outside of the affected zone.
Effective May 1, 2012, all citrus nursery stock produced in the citrus zone must be treated with an APHIS-approved systemic insecticide (soil drench) at least 30 days but no more than 90 days before shipment. This must be followed by an APHIS-approved foliar spray no more than 10 days before shipment. Treatment must be conducted with an APHIS and EPA approved product labeled for use on citrus in nurseries. Persons applying treatments must follow the product label, its applicable directions and all restrictions and precautions.
Approved products for treatment of nursery stock are as follows:
- Baythroid XL (cyfluthrin),
- Lorsban 4E (chlorpyrifos),
- Admire 2 Flowable (imidacloprid),
- Brigade 2EC (bifenthrin), and
- Discus (imidacloprid/cyfluthrin).
As of January 18, 2012, TDA placed all citrus and orange jasmine nursery stock in the quarantine area under a seizure order. Effective March 14, 2012, citrus trees from locations outside of or inside of the quarantined area may be moved under special permit to a commercial citrus grove inside the quarantined area for planting. To request a special permit, contact the TDA regional office in San Juan at (956) 787-8866.
Texas Citrus mutual officials report the positive tree in Mission was detected by an ongoing USDA-APHIS sentinel tree survey. The tree has been tested before and citrus greening was not detected in previous samples. The infected grapefruit tree is large according to officials and because of the latency of disease symptoms, it may have had the disease for an extended period of time. USDA inspectors warn that this latency serves as a reminder of the challenges of early detection,which includes knowing what the early symptoms look like and where in the tree to look for them.
Officials warn that early indications are that symptoms are slightly different in Texas compared to other states where infected trees were found. Texas Citrus Mutual is planning upcoming producer meetings in the Valley to share that information with growers to aid in the process of early detection.
In addition, APHIS will be surveying all commercial groves within the new quarantine area beginning with those that are scheduled to be harvested first. If the APHIS inspectors have not finished surveying a producer's grove and grapefruit is ready for harvest, producers will be allowed to proceed with harvest.