Effects of herbicides on weeds, sugar content and yield of sugarcane (saccharuh officinarum l.' at low and high application volumes
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Date
1990
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Abstract
Results are presented of two field experiments
conducted under rainfed and irrigated conditions to evaluate
the effects herbicides, on weeds, sugarcane (Saccharu»
o-f-ficirtarum L. ) cv NCo 376 yield and quality. The herbicides
were Dimepax (3.0 and 2.0 kg a.i./ha) containing 507. dimethametryn C4-C1,2-di methyl—n-propy1ami no)-2-ethylamino-
6-methylthio-s—triazinel; Gesapax Plus (2.75 and 1.65 kg
a.i./ha) containing 10.3'Z ametryn C2--(ethylamino)-4-
(isopropylamino)-6-methylthio--s-triazine3 and 36. 77. MSMA
(Monosodium methane arsonate); Gesapax H (2.50 and 1.50 kg
a.i./ha) containing 21‘Z ametryn and 29‘Z 2,4—D C(2,4-dichloro
phenoxy) serfi acid3; and Gesapax Combi <4.0 and 2.5 kg a.i./ha) containing 25X ametryn and 257. atrazine C2—chloro— 4- (ethyl ami no) -6- (i sopropylainino) -s—tr i azinel.
Each experiment was laid down as split-plot in a randomised complete block design replicated four times with
main plots assigned to high (213.0 1/ha) and low (26.5 1/ha)
carrier water volumes. Herbicides dosage rates were assigned
to the sub—plots with the lower rate receiving a
supplementary handweeding 6 weeks after spraying.
In the irrigated experiment, where broadleaf weeds were
the main species, Gesapax H at 2.50 and 1.50 kg a.i./ha
provided the best control pf greater than SOX at 6 weeks
after treatment (WAT). Grass weeds, which were dominant at
the rainfed site, were best controlled by Gesapax Plus at2.75 and 1.65 kg a.i./ha which provided a control greater
than 907. during the same period. In both cases,
supplementary handweeding improved duration of weed control.
Reduction of carrier water volume had no biological
advantage but reduced manday requirements for spraying by
69.47..
All herbicides induced recognizable but temporal
phytotoxic symptoms to sugarcane. Most severe symptoms were
shown at the rainfed experiment by Dimepax
(3.00 kg) when
applied in 26.5 1/ha carrier volume.
Best sugarcane yields were obtained where effective
herbicide treatment was supplemented by a handweeding.
In
the irrigated crop the weedfree treatments yielded
significantly <P<0.05> higher than all herbicide treatments
in sugarcane yields but in the rainfed crop it yielded
statistically similar to Dimepax (2.00 kg), Gesapax Plus at
2.75 and 1.65 kg in sugarcane yields. Sugarcane quality was
not significantly (P<0.05) influenced by either herbicide
treatments or application volume.
Economic -analysis showed that Gesapax Plus at 1.65 kg
a.i./ha applied in 26.5 1 /’ha had the highest returns of Sh
49.92 and Sh 12.36 per each shilling invested for rainfed
and irrigated crops respectively.
Description
Dissertation
Keywords
Effects herbicides, Sugarcane, Rainfed, Irrigated condition