ARS | Publication request: Affect of crop residue on colonization and survival of Phoma sclerotioides

Submitted to: American Phytopathological Society Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: June 1, 2008
Publication Date: July 26, 2008
Citation: Samac, D.A., Miyamoto, C., Larsen, J.E., Atkinson, L., Hollingsworth, C.R., Motteberg, C.D. 2008. Affect of crop residue on colonization and survival of Phoma sclerotioides [abstract]. Phytopathology. 98:S139.

Technical Abstract: Phoma sclerotioides causes brown root rot (BRR) of alfalfa and root rot of other perennial legumes and some winter hardy grasses. It can survive as a saprophyte on crop debris so crop residues that support the fungus may increase inocula levels. Current management of BRR is based on crop rotation with spring-sown small grains. We grew eight crop species in the greenhouse in infested field soil, overwintered the pots outside at two locations (St. Paul and Crookston, MN), then measured P. sclerotioides density in soil using a quantitative PCR assay. In both years, density of the pathogen was highest in soil from pots with corn, soybean, and canola. Density of the pathogen following alfalfa, winter wheat, spring wheat, and oat was similar to the fallow treatment. In addition, we measured colonization of stems, leaves, and roots of the eight crops plus hairy vetch and winter rye under controlled conditions. The origin of the isolate, whether from alfalfa, perennial rye, or winter wheat, did not affect colonization. Overall, leaf material from spring wheat, winter wheat, winter rye, and corn; or canola roots supported high levels of colonization while soybean roots supported the lowest colonization. Results suggest that rotation to corn, soybean, or canola will not reduce pathogen density on residues for subsequent host plant cultivation. Although colonization of spring wheat leaves was high, results suggest that this does not increase pathogen density in soil.