Submitted to: Biological and Cultural Tests for Control of Plant Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/14/2000
Publication Date: N/A
Interpretive Summary: Take-all of wheat, caused by the soilborne fungal pathogen Gaeumannomyces graminis var. tritici, causes major yield losses in wheat in Virginia and other regions of the United States. Biological controls are being developed due to environmental problems associated with chemical control measures. Field trials were performed to screen 132 bacterial seed treatments for suppression of Take-all of wheat under field conditions. Fifty-one of these seed treatments contained bacterial isolates, applied alone or in combination, that were superior to nontreated controls in suppression of Take-all in the 1998 field trial. Additional bacterial strains tested were randomly isolated from wheat roots after the 1998 field trial. Twenty-two bacterial seed treatments provided significantly greater suppression of Take-all than the nontreated controls. In addition, several of these treatments were superior to chemical controls. No phytotoxicity was evident with any of the bacterial treatments. These twenty-two bacterial seed treatments have been included in an ongoing field trial. This information is useful to scientists and extension agents working toward the development of environmentally-safe control measures for Take-all of wheat.
Technical Abstract: The soft red winter wheat cultivar, Madison, was planted at the Eastern Virginia Agricultural Research and Education Center at Warsaw, VA with an Almaco cone planter configured for head row planting. Fifty-one treatments contained bacterial strains, applied alone as seed treatments, or in combination, that were superior to nontreated controls in suppression of Take-all in the 1998 field trial. Additional bacterial strains tested were random isolates selected from apparently healthy wheat roots growing in the region of a field with heavy Take-all symptoms at the end of the 1998 field trial. Treatments were replicated four times. At the end of the growing season, the total above ground biomass from a one meter section of each row was collected and weighed. Several bacterial seed treatments gave better control than the chemical controls. Among isolates retained from the 1998 field trial, applied singly and in pairs, three pairs gave better control of Take-all than the nontreated controls. In addition, several new isolates representing nine different species from seven genera also provided increased biomass over nontreated controls. These isolates were used alone or in combination for the current 1999-2000 field trial.