The influence of organic mulches on weeds, diseases and growth of maize (zea maysl.).

Abstract

Effects of three organic mulches with two intra-row weeding, conventional tillage with two hand weeding and an unweeded check on maize (Zea maysL.) growth, weeds and diseases associated with the maize crop were evaluated for two seasons. The experiment was conducted during the long and short rains of 1989 at Kabete Farm, University of Nairobi, Kenya. During the long rains, the organic mulches proved more effective in controlling annual weeds than the conventional tillage with hand-weeding. Better trends in weed control were registered during the short rains, although the conventional tillage with hand weeding showed superiority over the organic mulches. Maize stover mulch was found to be less effective in controlling Bidens pilosa L. and Commelina benghalensis L. compared to bean husks. However, stover was superior to bean husks in controlling Oxalis latifolia H.B.K. and Oxalis corniculata L. Better crop growth was obtained during the short rainy season compared to that in the long rainy season. This corresponded well with the excellent weed control exhibited by the organic mulches except for the stover which had inferior .;J plants during the long rains. Crop stand, at harvest, during the short rains was superior to the long rains. All the treatments, except the unweeded check, had equally good stands during the short rains. During the long rains, conventional tillage with hand-weeding had the best stand, with bean husk and black polythene mulches at par. The unweeded check registered the least cob length, one thousand grain weight and grain yields during both seasons. The maize stover mulch resulted in very low grain yields during the long rains. However, its yield was comparable to that of black polythene during the short rains. The bean husk treatment gave consistently good yields during both seasons and even proved superior to the other two mulches during the short rains. Maize stover mulch proved to have significant influence on incidence of northern leaf blight of maize. Plants in the maize stover plots attained 100% incidence level only six weeks after emergence compared to eight weeks after emergence in the other four treatments. However, the high incidence of this disease seems to have influenced grain yields in the stover mulched plots only.