Three New Fungi May Be Used as Biological Controls

Three new species of fungi could give agriculture new tools to fill gaps in pest control that may arise if methyl bromide is phased out in 2001 as scheduled.

Agricultural Research Service mycologist Gary Samuels identified and described the new fungi, which belong to the genus Hypomyces. They are cousins of Trichoderma fungi known to destroy "bad" fungi including Verticillium and Pythium that cause wilts and other diseases.

Scientists are encouraged about Hypomyces' potential because efforts to understand their biology--now underway--are crucial to exploiting them. Other ARS scientists have preliminary evidence that different Hypomyces species may have biocontrol potential.

The scientists don't yet know what diseases the new fungi might attack, but alternatives to methyl bromide are needed. The chemical is widely used as a soil fumigant and in postharvest and quarantine treatments to control rots and other pests on many crops such as strawberries, stone fruits, grapes and nuts. But it is scheduled to be phased out because it is thought to damage Earth's ozone layer.

ARS researchers discovered one of the new species, H. viridigriseus, in Illinois. A USDA Forest Service scientist found the other two, H. favoli and H. puertoricensis, on rotting wood in Puerto Rico's rain forest.

According to Samuels, a world expert on Trichoderma, one obstacle to using the new fungi as biocontrols is that they primarily reproduce asexually. Thus, they can't be readily improved by sexual reproduction. However, the scientists' discovery of a sexual state of Hypomyces in nature is a sign the sexual state might be produced in lab cultures. Then the fungus could be genetically improved as a disease fighter.

A story about the three fungi appears in the July issue of Agricultural Research magazine. The story is also on the World Wide Web at:

http://www.ars.usda.gov/is/AR/archive/jul98/fung0798.htm

Scientific contact: Amy Y. Rossman, Systematic Botany and Mycology Laboratory, 10400 Baltimore Ave., Bldg. 011A, Rm. 304, Beltsville, phone (301) 504-5364, fax (301)504-5810, e-mail arossman@fungi.ars-grin.gov.