Double-cropping and crop rotation effects on diseases and grain yield of pearl millet

The effects of double-cropping and crop rotation sequences on grain yield a nd diseases of pearl millet [Pennisetum glaucum (L.) R. Br] were evaluated to determine the compatibility of pearl millet in southeastern agricultural cropping systems. Pearl millet hybrid 'HGM 100' (AgraTech Seeds, Inc., Atl anta, GA) was planted with minimum tillage, double-cropped with canola (Bra ssica napus L.) and wheat (Triticum aestivum L.). Soybean [Glycine mar (L.) Merr.] was used as an alternative summer annual to pearl millet in rotatio n sequences. Treatment effects on seedling stand density, panicle number, g rain yield, leaf blight (caused by Exserohilum rostratum), stalk and neck r ot (associated with a number of fungi), and smut (caused by Moesziomyces pe nicillariae) severity were determined. Seedling stands 3 wk after planting were lower following canola than wheat in 1995 and 1997, and panicle number was lower in 1997. No other yield-associated variables were affected by th e previous winter crop. In comparison of crop rotations, inconsistent effec ts were observed in stand density in 1997, and panicle number in 1996 and 1 997. Seedling stand density and panicle number were lower with 2 yr of pear l millet compared with 1 yr, but were highest for the 3 sequential yr of cu ltivation in 1997. A trend toward increased smut severity In plots continuo usly planted to pearl millet was observed in 1997. Within subplots, stand d ensity was highly correlated with panicle number in 1996 and 1997 (r greate r than or equal to 0.51, P < 0.01), with leaf blight severity in 1995 and 1 996 (r greater than or equal to 0.33, P < 0.01) and with stalk and neck rot in 1996 (r = 0.60, P < 0.01). Yield was negatively correlated (r less than or equal to -0.31, P < 0.01) with leaf blight severity in 1995 and 1996, a nd stalk and neck rot in 1996 (r = -0.46, P < 0.01). Stalk and neck rot in 1996 was probably caused by Fusarium graminearum, which was more commonly i solated from pearl millet following canola than wheat. Neither the previous winter annual crop nor the number of sequential years of pearl millet cult ivation had detrimental, limiting effects on pearl millet grain yield or di seases.