Evaluating the efficacy of different selective herbicides for weed management among six Maksoy Soybean varieties.
Abstract
Weeds are the most economically important biotic stressor in soybean production in Uganda
and Sub-Saharan Africa as a whole. Several selective chemical herbicides provide control
over a wide range of weed species however, there is limited information regarding their
effectiveness in the control of these weeds amongst the Maksoy soybean varieties. Therefore,
a field experimental study was conducted to assess the efficacy of three different post-
emergence selective herbicides in the management of weeds amongst the six Maksoy
soybean varieties at Makerere University Agricultural Research Institute Kabanyolo. The
main objective of the study was to determine the effect of new selective herbicides on weed
management and performance of soybean. The experiment was laid out in a completely
randomized block design in split plot arrangement with two replications. Six Maksoy
varieties were used (Maksoy 1N, 2N, 3N, 4N, 5N and 6N) and the treatments were the three
post-emergence selective herbicides which included; Quizalofop + Fomasafen 16% EC,
Bentazon 15.5% EC and Haloxyfop-R methyl ester 108g/l. Two controls (both hand hoe and
no weeding) were used. Data collected through physical measurement, counting and careful
observation of the parameters of interest was analysed using R analytical tool. The treatments
applied showed significant difference (P<0.05) in several parameters that included plot yield,
number of days to physiological maturity, number of seeds per pods, plant height, number of
branches, number of pods per plant, weed density and weed diversity. Amongst the three
herbicides used during the study, Haloxyfop-R methyl ester 108g/l is the most effective in the
control of weeds of grass family only. The results further indicated that Bentazon 15.5% EC,
exhibited the most effective and excellent control over both grass and broadleaf weed species
and therefore created the most conducive environment for the performances of the six
Maksoy varieties. Therefore, Bentazon can be recommended for the management of both
grasses and broadleaf weed species. There is need to conduct this study in multiple
environments to validate these results obtained in this study. Furthermore, there is need to
identify the most critical stage of herbicide application during the different growth stages of
the weeds.