VIEW ARTICLE

Disease Control and Pest Management

Rice Residue Disposal Influences Overwintering Inoculum Level of Sclerotium oryzae and Stem Rot Severity. W. W. Bockus, Assistant professor, Department of Plant Pathology, Kansas State University, Manhattan 66506; R. K. Webster(2), C. M. Wick(3), and L. F. Jackson(4). (2)Professor, Department of Plant Pathology, University of California, Davis 95616; (3)Farm advisor, Cooperative Extension Service, Butte County, CA 95917; (4)Assistant professor, Department of Plant Pathology, University of Florida, Gainesville 32611. Phytopathology 69:862-865. Accepted for publication 5 March 1979. Copyright 1979 The American Phytopathological Society. DOI: 10.1094/Phyto-69-862.

The influence of rice residue removal, burning, or soil incorporation on inoculum (sclerotia) level of Sclerotium oryzae and stem rot severity was studied over 3 yr. In continuous rice cropping, greatest inoculum level increases and stem rot severities occurred in treatments where residue was incorporated into the soil by chopping and disking or where rice was cut 20–30 cm above the ground at harvest and the straw baled and removed, with the residue incorporated by disking. Treatments where straw was burned in the fall or spring followed by stubble-disking destroyed inoculum and had the lowest inoculum level increases and stem rot severities. Where rice was cut 0–7 cm above the ground (below the site of infection) at harvest and the straw baled and removed, however, inoculum was removed from the field and inoculum increases and stem rot severities were not significantly different from those with the burning treatments. Simulated introduction of rice residue infested with S. oryzae into field soil resulted in continued production of sclerotia in the residue after incorporation. Inoculum level and stem rot severity can be minimized by complete destruction or removal of rice straw infested with S. oryzae.