Head scab fungus, Fusarium graminearum , the bane of wheat crops, can be genetically disarmed. ARS scientists identified and deleted the genetic codes for an enzyme that the fungus needs to produce the toxins trichothecene. The fungus uses this toxin to infect cereal crops. Head scab steals the plant's energy, cutting its yield, and produces toxins which contaminate the grain. Head scab, which causes billions of dollars in losses each year, gets its name because it looks like scabs on the infected plant.
Infections are cyclical, appearing for several years and then disappearing.
However, the Midwest is currently experiencing a sustained infestation of head scab. The fungus mutates frequently, thwarting plant breeders' attempts to build resistance into host plants. Scientists say learning how to disarm the disease opens the door to finding new ways to defeat head scab and other plant diseases. ARS scientists say Kochia scoparia, a member of the tumbleweed family, has already been found as far east as eastern Indiana, possibly spread by seed hitching rides on eastbound trains. Researchers say the best time to battle this weed is early spring, when the newly germinated plant is vulnerable to herbicides in the dicamba and glyphosate chemical families.