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Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 3/28/2002 Publication Date: 8/1/2002 Citation: Wilson, J.P. 2002. Fungi associated with the stalk rot complex of pearl millet. Plant Disease 86:833-839. Interpretive Summary: Current and impending water shortages require that uses in agricultural production be reduced. One method of achieving this goal is the use of drought-tolerant crops. Pearl millet is a new feed grain for the United States which produces high quality grain free of aflatoxins under non- irrigated conditions. Continued advances in crop improvement for economic production requires that production constraints be identified and corrected. One such constraint is stalk rot. This study identifies fungal pathogens that cause stalk rots in pearl millet. Although many fungi can be isolated from diseased stalks, their relative prevalence, distributions within plants, and changes with plant maturation differed greatly. Results indicate that future research efforts for controlling stalk rot can be targeted toward a few particularly important pathogenic fungi. Technical Abstract: Fungi associated with internal colonization and stalk rot were evaluated from a pearl millet population in 1995 and from hybrid HGM100 planted on two dates in 1996 and 1997. In 1995, Bipolaris setariae was most frequently isolated from discolored nodes of rust-infected stalks at the grain fill stage. In 1996 and 1997, plants were randomly sampled at panicle emergence, ,stigma emergence, milk and hard dough stages and all nodes were cultured i the lab. Internal stalk deterioration and fungal colonization increased from the plant base to apex with plant maturation. Thirty fungal genera or species were isolated from nodes of split, surface-sterilized stalks. Fusarium moniliforme was most prevalent at all growth stages (isolated from 24% nodes) and isolation increased with advancing maturity. F. semitectum was predominantly isolated from lower nodes at panicle and stigma emergence but was more uniformly distributed within plants at milk and dough stage. Bipolaris setariae was infrequently isolated during early growth stages bu increased greatly at dough stage. Isolation of Curvularia spp. was not affected by growth stage. Isolation of Alternaria spp. was greatest at the milk stage. F. moniliforme isolation was not correlated with severity of rust infection or node discoloration and was frequently isolated from asymptomatic nodes of less mature stalks. Isolations of F. semitectum, B. setariae and Alternaria spp. were correlated with rust infection and the latter two with internal node discoloration. These 3 fungi were isolated from stalks primarily during the grain filling and maturation stages. |
