Submitted to: Mexican Journal of Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/25/2008
Publication Date: 12/1/2008
Citation: Montes-Garcia, N., Williams, H., Prom, L.K., Isakeit, T., Odvody, G.N., Narro-Sanchez, J., Rooney, W.L. 2008. Disease severity and susceptibility of sorghum [Sorghum bicolor (L.)] to infection by Claviceps africana Frederickson, Mantle and de Milliano in Mexico and the United States of America. Mexican Journal of Phytopathology. 26(2):121-126. Interpretive Summary: Sorghum ergot, a fungal disease poses a serious threat to sorghum, especially in hybrid seed production fields. In 2002 and 2003, six sorghum hybrids and 3 male-sterile lines (A-lines) were planted in College Station, TX, and in Rio Bravo and Celaya, Mexico. The hybrid NC+8R18 had the lowest level of ergot infection, whereas the 3 male-sterile lines ATx2752, ATx635, and ATx623 had the highest ergot infection. This study showed that there were differences in ergot infection among the male-sterile sorghum lines which suggests that breeding for resistance in A-lines is a possible control option.
Technical Abstract: Experiments were at College Station, USA, and Rio Bravo and Celaya, Mexico, under irrigated conditions during 2002 and 2003. Six sorghum hybrids and three male-sterile lines were planted at each location. Claviceps africana isolates were applied every other morning. Panicles were inoculated using a hand atomizer until runoff with a suspension of 1.6 x 106 conidia mL-1. Ergot severity was measured at milk stage. Bartlett’s test of homogeneity was performed to determine homogeneity of variances among years. The results showed variability in susceptibility to ergot among genotypes at a single planting date, at planting dates within a year, locations and years. Ergot severity was statistically greater in 2002 in both hybrids and A-lines. Celaya had the greatest amount of ergot on hybrids, followed by College Station and Rio Bravo. In general, A-lines had the greatest ergot severity. ATx2752 had the lowest ergot severity (22.8%), while ATx635 and ATx623, had 27.4% and 36.2%, respectively. Sorghum hybrid AP2233 was the most susceptible, NC+8R18 showed the least amount of ergot severity.