The Effect of Alachlor-Atrazine Mixture and Diuron on Weed Control, Growth and Yield of Maize and their Residual Effect on Growth, Nodulation and Yield of Cowpea.
Date
1995-03
Authors
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Publisher
University of Ghana
Abstract
Two field experiments were carried out from July 1993
to January 1994 at the University of Ghana farm, Legon.
The first experiment investigated the effects of two preemergent
herbicides alachlor-atrazine mixture and diuron at
the manufacturers' recommended rates and at rates 50% above
those recommended on weed control, growth and yield of
maize variety 'Abeleehi'. The second experiment carried
out on the same plots determined the residual effects of
these herbicides on two varieties of cowpea 'Asontem' and
'Bengpla'.
At the two rates rate of 51/ha (1.8kg + 1.0kg ai/ha)
and 71/ha (2.5kg + 1.4kg ai/ha) for alachlor and atrazine
mixture and 1.12kg/ha (0.9kg ai/ha) and 1.68kg/ha (1.3kg
ai/ha) for diuron investigated both broad-leaved weeds and
grasses were controlled efficiently in maize, although the
effectiveness of the chemical weed control did not differ
significantly from the hand-weeding method.
With regards to their influence on the growth and
development of maize plants, alachlor-atrazine mixture was
tolerated better by the plants than diuron. Highest grain
yield was recorded on plots treated with alachlor-atrazine
mixture at the manufacturer's recommendation of 1.8kg +
1.0kg ai/ha. Increases in the concentration of both
herbicides were toxic to the maize.
Diuron had a significantly adverse carry over effect
on the succeeding cowpea crops, resulting in very low
yields. Alachlor-atrazine mixture at the two rates applied
which may otherwise be toxic to cowpea appeared degraded
from plots by the time of the second cropping,
approximately fourteen weeks after application since there
were no significant adverse effects on cowpea crops.
Although there appeared not to have been a
differential response in the influence of the residual
effect of the herbicides on the growth of cowpeas, varietal
differences were detected for some of the characters
investigated. Overall 'Asontem' emerged a better
succeeding crop with maize in which alachlor-atrazine
mixture at the manufacturer's recommended rate had been
employed for weed control.
Inspite of its relative unsuitability for weed control
in maize in this study, it was suggested that diuron at
rates lower than the manufacturer's recommended could be
tested to ascertain the usefulness of this herbicide for
adequate weed control without injury to maize plants before
ruling it out as one of the choices of herbicides for weed
control in maize
Description
Thesis (MPhil) - University of Ghana, 1995