1. K-State home
  2. »Research and Extension
  3. »News
  4. »News Stories
  5. »Kansas State University continues to lead effort to battle citrus greening

K-State Research and Extension News

Released: May 1, 2017

Kansas State University continues to lead effort to battle citrus greening
Devastating disease has cost billions in lost revenue

Susan Brown, Kansas State University

MANHATTAN, Kan.  – Kansas State University researchers will continue to lead efforts to combat a deadly bacterial disease that’s affected up to 80 percent of Florida’s citrus trees and cost billions in lost revenue.

A $6 million grant from the U.S. Department of Agriculture Specialty Crop Research Initiative supports the continuing efforts of researchers from 10 U.S. academic and national research labs, and the University of Grenada in Spain, who have joined forces to combat citrus greening, a disease that has all but decimated the citrus industry in Florida and is evident in Texas and California groves.

Caused by the proliferation of a bacterial species Candidatus Liberibacter asiaticus (CLas) in citrus trees, the disease is spread by tiny sap-sucking insects called Asian citrus psyllids as they feed. Once introduced into the host trees via the psyllids, the bacteria move through the veins of trees. The disease starves the tree of nutrients and damages its roots. Fruit from the tree are small and misshapen.

“Our goal is to establish a research pipeline to develop and deliver novel therapies designed to kill the insect when it tries to feed on citrus or block its ability to transmit the bacteria,” said Susan Brown, university distinguished professor in the Division of Biology at Kansas State University and principal investigator on the project. “Either way, it can’t spread the disease anymore.”

The new funding will allow researchers to build on work they began two years ago.

Their approach requires detailed knowledge of the interactions between the insect and the bacteria and the effects of any treatment on citrus. Since it is difficult to access information on such diverse systems, an early goal of the project – and one that has been accomplished – was to develop a platform that allows researchers to access information about the genes, proteins and metabolites of the insect, bacterium and citrus to better understand how to combat the disease.

Another major milestone accomplished was the analysis of the psyllid genome, which involved several undergraduate researchers at Kansas State University, Cornell University and Indian River State College. The students identified genes in the insect genome that can be targeted in new therapies.

Jason Ellis, Kansas State University associate professor and interim head of the Department of Communications and Agricultural Education, is a co-principal investigator on the project and leads efforts to interact with industry, academic and consumer groups.

“The continued funding will allow us to move our work from the laboratory to the green house and the grove for efficient deployment to the citrus growers,” Ellis said.

Sometimes referred to as simply “greening,” the disease was first detected in Florida in 2005 and spread rapidly through the state’s citrus groves.

Fruit from infected trees is safe to eat, but production is reduced so much that citrus fruit may be less available and more expensive.

More information can be found at the project website (http://citrusgreening.org).

A survey of citrus growers conducted in 2015 by the University of Florida indicated that as much as 90 percent of their acreage and 80 percent of their trees were infected by the deadly greening disease, which put a huge dent in the state’s $10.7 billion citrus industry. The survey indicated Florida lost about $7.8 billion in revenue, 162,200 citrus acres and 7,513 jobs to citrus greening since 2007. Orange production alone dropped from 242 million boxes to 104 million boxes in 2014. More information about the survey is available at http://edis.ifas.ufl.edu/fe983 and https://www.sciencedaily.com/releases/2016/04/160418092420.htm.

A short video of Susan Brown discussing the citrus greening project is available online.


K‑State Research and Extension is a short name for the Kansas State University Agricultural Experiment Station and Cooperative Extension Service, a program designed to generate and distribute useful knowledge for the well‑being of Kansans. Supported by county, state, federal and private funds, the program has county Extension offices, experiment fields, area Extension offices and regional research centers statewide. Its headquarters is on the K‑State campus in Manhattan.

Story by:
Mary Lou Peter
K-State Research and Extension

For more information:
Susan Brown – 785-532-3935 or sjbrown@ksu.edu
Jason Ellis – 785-532-5804 or jdellis@ksu.edu