In a landmark step in the fight against citrus greening disease, also known as huanglongbing (HLB), the U.S. Environmental Protection Agency has approved an application from Southern Gardens Citrus of Florida for an Experimental Use Permit under the Federal Insecticide, Fungicide and Rodenticide Act. This allows researchers to move forward in the development of the possible use of a spinach protein to help control this devastating disease.

Ricke Kress, president of Southern Gardens, said this latest development is a milestone in efforts to fight off HLB.

“A final solution to eliminating this disease may still take some years,” Kress said, “but the latest EPA action and continuation of all research projects are major steps in the right direction.”

Research conducted by Dr. Erik Mirkov, a plant pathologist at the Texas A&M AgriLife Research and Extension Center at Weslaco, resulted in the production of proteins that appear to provide effective control of citrus greening disease.

“Citrus greening is a bacterial disease that affects the vascular system of the tree,” Dr. Mirkov said. “It basically shuts off the tree's ability to take up and use water and nutrients, causing the tree to die. We were able to improve the transgenic trees by having the genes express themselves in the vascular system.”

HLB is the most serious citrus disease in the world. It was first identified and confirmed in Florida in 2005. HLB is now found in every Florida county where citrus is grown commercially. There are no successful control programs yet available for this disease. (NOTE – HLB has been detected just once in California, at a residential property in Los Angeles County in 2012)

Consistent with the conditions established by EPA, researchers may now move forward with field tests to evaluate the efficacy of the spinach protein against HLB in citrus plant tissues and continue generating the environmental, health and safety data that are required under federal law to support a fully registered product for commercial use.