Current Research Program
Our research group is interested in the biology and control of plant diseases, and the physiology of plant host-pathogen interaction. We discovered (1984) that certain soil fungi contribute strongly to the herbicidal activity of glyphosate in plants. We have since documented that herbicidal activity is enhanced typically by 10- to 30-fold in herbaceous dicots, and that the phenomenon occurs naturally in diverse kinds of agricultural soils. We have established that the phenomenon occurs in diverse plant taxa, and that the use of glyphosate can increase populations of these glyphosate synergistic fungi in both roots and soil in the field. Pythium spp. are the predominant glyphosate synergists in herbaceous dicot species. Many different Pythium spp. are potentially glyphosate synergistic, and there is little 'host' specificity of Pythium isolates as glyphosate synergists. Glypohsate is now an important tool in our efforts to understand more about natural defense mechanisms in plant roots.
Other research projects in my laboratory typically involve the biology and control of particular plant diseases of local importance. Two being studied at present are apple anthracnose canker and onion white rot. Although the immediate objectives of these latter types of projects usually emphasize disease control, the projects invariably contribute to our broader understanding of plant host-pathogen interaction. The total research program that I supervise provides opportunities for independent and collaborative research that will contribute to better understanding of mechanisms of plant resistance to fungi, and ultimately to opportunities for improved management of plant diseases.
Selected Publications
Descalzo, R.C., Z.K. Punja, C.A. Levesque and J.E. Rahe. 1996. Identification and role of Pythium species as glyphosate synergists on bean (Phaseolus vulgaris ) grown in different soils. Mycological Research 100: 971-978.
Liu, L., Z.K. Punja, and J.E. Rahe. 1995. Effect of Pythium spp. and glyphosate on phytoalexin production and exudation by bean (Phaseolus vulgaris L.) roots grown in different media. Physiological and Molecular Plant Pathology 47: 391-405.
Levesque, C.A. and J.E. Rahe. 1992. Herbicide interactions with fungal root pathogens, with special reference to glyphosate. Annual Review of Phytopathology 30: 579-602.
Rahe, J.E., C.A. Levesque, and G.S. Johal. 1990. Synergistic role of soil fungi in the herbicidal efficacy of glyphosate. In Advances in Biological Control of Weeds Using Microbes and Microbial Products. R.E. Hoagland, Ed. A.C.S. Symposium Series 439.
Johal, G.S. and J.E. Rahe. 1984. Effect of soilborne plant pathogenic fungi on the herbicidal action of glyphosate on bean seedlings. Phytopathology 74: 950-955.
Effects of glyphosate on phytoalexin accumulation in compatible
bean anthracnose host-parasite interaction.
This page last updated February 1997.