ARS Develops Disease-Resistant Sugarcane

A test that helps select disease-resistant sugarcane cultivars more accurately and efficiently has been developed by Agricultural Research Service scientists at the agency’s Sugarcane Field Stationin Canal Point, Fla.

The new test screens sugarcane plants for resistance to ratoon stunting disease (RSD), which causes higher sugarcane losses worldwide than any other disease--up to 30 percent in some areas. In Florida, RSD causes $36 million a year in losses. As the name implies, RSD produces stunting and poor growth of the shoots, or ratoons, that spring up from sugarcane roots.

The new test relies on a serological–or immune-type–response in the plant. When the plant has been infected by the RSD pathogen, Clavibacter xyli subsp. xyli, proteins called antigens in the pathogen bind to antibodies in the test kit, thus giving a positive reading.

To try to eliminate the pathogen from seedcane, growers in many countries resort to heat- treatment programs. This involves immersing seedcane in water at a temperature of 122 degrees Fahrenheit before planting, to kill the bacterium. But heat therapy is expensive and very labor-intensive. It also doesn’t guarantee that RSD-susceptible cultivars won’t become infected in sugarcane fields, because the pathogen is easily transmitted by contaminated harvesting equipment.

After more than 10 years of screening sugarcane cultivars for genetic resistance to RSD and conducting field tests, ARS researchers have found that RSD incidence is significantly lower in cultivars produced by the Canal Point screening program. One cultivar in particular--CP 72-2086--has proven to be an exceptional performer. Surveys indicate that RSD incidence in this cultivar has averaged less than 3 percent per field. In comparison, more than 69 percent of varieties not selected for their RSD resistance but grown under similar conditions were infected with RSD.

More than 17 percent of commercial sugarcane acreage in Florida is planted to this ARS-developed cultivar. It has been RSD-free for more than a decade without ever being heat treated.

ARS is the U.S. Department of Agriculture’s chief scientific research agency.

Scientific contact: Jack C. Comstock, ARS Sugarcane Field Station, Canal Point, Fla., phone (561) 924-5227, fax (561) 924-6109, [email protected].