VIEW ARTICLE

Disease Detection and Losses

Forage Yield Losses in Hybrid Pearl Millet Due to Leaf Blight Caused Primarily by Pyricularia grisea. Jeffrey P. Wilson, Research plant pathologist, USDA-ARS Forage and Turf Research Unit, University of Georgia Coastal Plain Experiment Station, Tifton 31793; Roger N. Gates, Research agronomist, USDA-ARS Forage and Turf Research Unit, University of Georgia Coastal Plain Experiment Station, Tifton 31793. Phytopathology 83:739-743. Accepted for publication 9 March 1993. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1993. DOI: 10.1094/Phyto-83-739.

The effects of leaf blight, caused primarily by Pyricularia grisea, on forage yield and digestibility of pearl millet hybrids were evaluated in 1990, 1991, and 1992. A range of disease severities on Pyricularia-susceptible hybrid Tifleaf 1 and on the resistant, near-isogenic hybrid Tifleaf 2 were established by inoculation with P. grisea or by application of chlorothalonil. Even with irrigation, no appreciable leaf blight developed in the dry 1990 season. In 1991 and 1992, disease severities (percentage of foliage with chlorosis and necrosis) in individual plots ranged from 3 to 35%. Leaf blight severity in 1991 and 1992 was negatively correlated (P < 0.01) with green plot yield, dry matter yield, and digestible dry matter yield. In vitro dry matter digestibility was unaffected by disease, and the response of dry matter concentration was inconsistent between years. Within the range of severities obtained, digestible dry matter yield decreased linearly with increases in leaf blight severity. Based on observed leaf blight severities of the Pyricularia-resistant Tifleaf 2, the regression equations estimate that minor pathogens that contribute to the leaf blight complex may reduce digestible dry matter yield of this hybrid by as much as 19%.