Effect of tillage and mulch on the emergence and survival of weeds in sweet corn.
Abstract
The effects of tillage and/or rye mulch on the emergence and survival of weeds in maize cv. Jubilee was evaluated in field trials conducted in 1985-87. The 4 most abundant weeds (Amaranthus retroflexus, Chenopodium album, Portulaca oleracea and Digitaria sanguinalis) exhibited significantly lower emergence in tillage than in no-tillage plots, probably because of seed burial and greater seed mortality in the former. Taraxacum officinale, however, did not show this response, probably because of the short time between seed dispersal and germination. Survival of A. retroflexus was significantly greater in no-tillage than in tillage treatments, with the difference most pronounced late in the growing season. The presence of maize ± rye mulch significantly reduced the emergence of all weed species. A procedure for testing for the departure of a survivorship curve from a truncated negative exponential is presented. In the absence of herbicides (1.68 kg/ha glyphosate, 0.56 kg atrazine and 2.24 kg metolachlor), A. retroflexus and C. album mortality rates declined as the plants grew to maturity. In most treatments, late-emerging plants survived to maturity better than earlier emerging plants, possibly because of shorter exposure to mortality factors. In the absence of herbicides, very dense stands of weeds led to greater mortality of later emerging cohorts.