Treatment Options for Managing Citrus Greening are Heating Up

August 8, 2013

citrus greening grapefruit

Citrus greening or HLB causes plants to bear misshapen, green, inedible fruit. This is an infected grapefruit.

Following an article released Monday, Aug. 5, from the USDA, our Helpline has received multiple calls this week from growers across Florida concerned with citrus greening, or HLB, a serious disease threatening Florida’s citrus industry.

HLB is caused by a bacterium that is spread (vectored), in the Asian form, by the Asian citrus psyllid, Diaphorina citru Kuwayama, which is no bigger than the head of a pin. It can also spread through plant grafting and movement of infected plant material. It cannot be spread by humans, animals, equipment, wind or rain.

Citrus greening has now killed millions of citrus plants in the southeastern United States and threatens to spread across the entire country. Once plants are infected, there is no cure. Where the disease is endemic, citrus trees produce green, misshapen, bitter, inedible fruit. Most infected trees die within a few years.

The article titled, “Recipe for HLB-affected Citrus: Apply Heat—Lots of It” reports that USDA scientists working with the Florida Department of Agriculture and Consumer Services (FDACS) at the Agricultural Research Service (ARS) in Fort Pierce, Fla. have discovered that heating potted citrus seedlings in plastic tents can eliminate symptoms of citrus greening.  This process is also known as thermotherapy.

tim-schubert-headshotAccording to Dr. Tim Schubert, biological administrator of the FDACS/DPI Bureau of Entomology, Nematology and Plant Pathology, “Thermotherapy is used in our Citrus Germplasm Indexing Program as one method to rid plant tissue (in this case citrus plant tissue) from cryptic pathogens and can clean up certain viruses, viroids, bacteria, fungi, phytoplasmas, etc.”

Dr. Schubert and his colleagues have been investigating if it might be possible to heat up a whole intact tree in the ground with microwaves or infrared radiation but notes that the infected root system is a problem. “The heat treatment above ground might knock the pathogen, but it probably has little or no effect on the bacteria residing in the roots,” Schubert said.

To find out more about this possible treatment method, read the extended USDA magazine story, Prescription for Curing Citrus Greening: Apply Heat and Wait.



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