| This profile is part of "Sustainable Agriculture... Continuing to Grow", a publication developed to present some of the excellent sustainable agriculture research and education work done by universities, nonprofit organizations and other institutions in the Western Region over the past twelve years. Additional profiles and abstracts will be posted weekly, with links provided in the Table of Contents. |
Microbe-Induced Resistance in Vegetables: A New Tool for Management of Insect-Transmitted Diseases
Geoffrey W. Zehnder
Co-Authors: J. F. Murphy, E. R. Sikora, and J. W. Kloepper, Auburn University; D. J. Schuster and J. E. Polston, University of Florida
Plant diseases caused by insect-transmitted pathogens are among the most difficult challenges in pest management, particularly in high-value vegetable production where loss of yield can drastically reduce profits. This presentation will provide an overview of the results of experiments conducted in the southeastern U.S. over a five year period that demonstrate the potential of plant growth-promoting rhizobacteria (PGPR) as a crop protection tool. These efforts were directed towards PGPR-mediated induced resistance as an alternative strategy for management of three insect-transmitted diseases that have proven difficult to control with conventional methods. Experiments with cucumber demonstrated that treatment with PGPR significantly reduced the incidence of wilt symptoms, caused by the bacterium Erwinia tracheiphila, and also reduced numbers of the cucumber beetle vectors of the bacteria. Reduced beetle numbers on PGPR-treated plants was associated with significantly lower concentrations of cucurbitacin, a secondary plant metabolite and cucumber beetle feeding stimulant. Subsequent studies with tomato were conducted to identify PGPR strains that could induce resistance against cucumber mosaic virus (CMV), an aphid-transmitted disease pathogen, and whitefly-transmitted tomato mottle virus (ToMoV). Tomatoes treated with PGPR exhibited a reduction in the development of disease symptoms, and often a reduction in the incidence of viral infection and an increase in tomato yield. While preliminary, the results of these experiments demonstrate that PGPR-mediated induced resistance represents a viable and environmentally friendly approach to crop disease management, particularly for insect-transmitted diseases, which are often difficult or impossible to control with pesticides. These studies were supported, in part, by USDA-CREES Southern Region Integrated Pest Management and Alternative Research Programs.
Geoffrey W. Zehnder
Department of Entomology and Plant Pathology
206 Extension Hall,
Auburn University
Auburn, AL 36849-5629
Tel: (334) 844-6388
gzehnder@acesag.auburn.edu
The work to create this publication was sponsored by the Western Sustainable Agriculture Research and Education (Western SARE) program. Western SARE is an effort of the U.S. Department of Agriculture. Since 1988 through federal fiscal 2000, the U.S. Congress has allocated more than $114.6 million to the federal SARE effort; Western SARE has received $26 million. The Western region includes Alaska, Arizona, California, Colorado, Hawaii, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, Washington, Wyoming and the Island Protectorates of American Samoa, Guam, Micronesia and the Northern Mariana Islands.