Suppression of Thielaviopsis basicola by Two Fungicides Applied to Sandy Loam Soils in New Mexico. David C. H. Hsi, Professor of Plant Pathology, New Mexico State University, Middle Rio Grande Branch Station, Los Lunas 87031. Melchor Ortiz, Jr., Assistant Professor of Experimental Statistics, New Mexico State University, Las Cruces 88003. Plant Dis. 64:1011-1012. Copyright 1980 American Phytopathological Society. DOI: 10.1094/PD-64-1011.

Populations of Thielaviopsis basicola in soil were suppressed by adding benomyl (1.7 kg a.i./ha) or thiophanate-methyl (3.2 kg a.i./ha) to alkaline sandy loam soils near Portales, NM. Both fungicides suppressed T. basicola but not Fusarium spp. Recoveries of T. basicola did not differ by month during the growing season. There was also no appreciable seasonal buildup of inoculum in any of the four fields during 1974-1976. Populations of T. basicola were higher in 1975 and 1976 than in 1974, but those of Fusarium spp. did not differ during the 3 yr. The incidence of blackhull (defined as more than 25% of the shell area discolored) was reduced from 55% to 16–31% in 1974 and from 28–44% to 10–25% in 1975 and 1976 by treatment with the fungicides.