Submitted to: Crop Protection Journal
Publication Type: Peer reviewed journal
Publication Acceptance Date: 11/22/2002
Publication Date: 11/22/2002
Citation: PROM,L.K., WANISKA,R.D., KOLLO,A.I., ROONEY,W.L., RESPONSE OF EIGHT SORGHUM CULTIVARS INOCULATED WITH FUSARIUM THAPSINUM, CURVULARIA LUNATA, AND A MIXTURE OF THE TWO FUNGI, CROP PROTECTION JOURNAL, 2002. Interpretive Summary: Grain mold or grain weathering is a fungal disease complex that lowers sorghum yield and seed quality. Worldwide, this is the most important sorghum disease, especially in areas with wet conditions late in the growing season. Several fungal organisms can cause grain mold in sorghum; however, two fungi are commonly associated with the disease in the United States. In order to develop cost-effective control methods, it is important to learn how these two fungi affect different sorghum lines in the U. S. We tested eight sorghum lines with each fungus and a mixture of the two fungi. Some lines were more affected by one fungus and not the other; while, other lines had more disease when we used a mixture of the two fungi. We also found that one fungal organism (Curvularia lunata) may not cause much disease in the field, but it will significantly reduce seed germination. This study demonstrated that factors such as the type of fungal organism present, the environment, and the sorghum line planted in an area will influence the levels of grain mold and seed germination rates. In the future these findings will enable us to determine which sorghum lines could perform better in different areas.
Technical Abstract: This study examines the effect of Fusarium thapsinum, Curvularia lunata, and a mixture of the two pathogens on grain mold severity, seed germination, and the relationship of these two traits on eight sorghum cultivars. The test was conducted in 2000 and 2001 in College Station, TX, and both years, main effects of cultivar (Cul), treatment (Trt), and Cul X Trt interactions for grain mold severity and gemination were highly significant. Sureno had the lowest increase in grain mold severity (GMS). RTx2536 had increased GMS levels when inoculated with F. thapsinum alone; while cultuvar 98LB711 was the most vulnerable to C. lunata alone. The mixture of F. thasinum and C. lunata caused more damage on cultivars 98LB650 and 98LB789. Germination was significantly affected by all fungal treatments. Curvularia lunata had the highest negative effect on germination in 2000 while F. thapsinum produced the most significant reduction in germinationin 2001. There was a negative correlation between GMS and germination (r=-0.51 in 2000 and r=-0.63 in 2001). Even when GMS ratings on panicles inoculated with C. lunata alone were low, this pathogen can cause significant reductions in the germination rate. The germination assay also shows that Sureno was highly susceptible to C. lunata even in environments that are unfavorable to mold development. THe results of this study indicate that the fungal species present, the environment, and the sorghum cultivar all influence grain molding and seed deterioration.