SA Graan Februarie 2016

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February 2016
Integrated pest control ON FARM LEVEL
Graph 3: The percentage control of Benghal wandering Jew at the flowering growth stage where
eight different herbicides were applied (means above bars followed by the same letter[s] do not
differ from one another).
Post emergence application
(V4 growth stage)
Application of glyphosate (540 g/l) and 2,4D (480 g/l) at V4 growth
stage gave complete control of 100%, followed by tembotrione
(420 g/l), which gave 80% control. The control of Wandering
Jew varied between 33% and 48% where the following herbicides
were applied: Bendioxide (480 g/l), bromoxynil (225 g/l), glypho-
sate (540 g/l), mesotrione (480 g/l) and topramezone/dicamba
(50/160 g/l) indicating ‘insufficient control’. Glyphosate/mesotrione/
S-metolachlor (250/25/250 g/l) also gave ‘insufficient control’ (less
than 10%) of Benghal wandering Jew (Graph 2).
Benghal wandering Jew showed the highest percentage regrowth
(57%) where bendioxide (480 g/l) was applied, followed by glyp-
hosate/mesotrione/S-metolachlor (250/25/250 g/l) (44%) and top-
ramezone/dicamba (50/160 g/l) (33%). Glyphosate (540 g/l) and 2,4-D
(480 g/l), mesotrione (480 g/l) and tembotrione (420 g/l) showed no
regrowth 36 days after application.
Post-emergence application (flowering)
Poor control of Benghal wandering Jew was recorded where
bendioxide (480 g/l), glyphosate/mesotrione/S-metolachlor (250/25/
250 g/l), mesotrione (480 g/l), tembotrione (420 g/l) and topramezone/
dicamba (50/160 g/l) was applied at flowering.
These herbicides gave control between 10% and 40%, indicating
that they will insufficiently control Benghal wandering Jew at
flowering stage. Application of glyphosate (540 g/l) alone gave
70% control and is classified as ‘reduced or suppressed’ control of
Benghal wandering Jew. Only bromoxynil (225 g/l) and glyphosate
(540 g/l) and 2,4-D (480 g/l) gave complete control of 100% when
applied at the flowering stage (Graph 3).
Benghal wandering Jew can germinate and grow throughout the
growing season of row crops indicating that the broad adaptability
of this weed may require continuous management (Ferreira and
Reinhardt, 1999), which include the use of effective residual
herbicides such as 2,4-D. Producers usually wait too long before
post-emergence herbicides are applied, illustrating the need of
timely and most probably multiple post-emergence herbicide
applications.
When high infestation levels of Benghal wandering Jew are
experienced in fields, pre-emergence herbicides have to be applied
at or before planting of row crops, but before weeds have emerged
to reduce seed numbers in the soil. The most effective herbicide
control strategies for Benghal wandering Jew should therefore
involve combinations of both pre- and post-emergence herbicides
applications (Prostko et al., 2005). Producers should be aware of
herbicide selectivity and make sure that the herbicide(s) applied is
registered to be used on the respective crop(s).
Although this weed is difficult to control, early identification follow-
ed by a proactive management strategy, can greatly reduce the
impact of Benghal wandering Jew on crop yields, as well as reduce
seed numbers in the soil.
For any further information or questions please
contact dr Elbé Hugo at or
018 299 6298.
References
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of germination and seed dormancy inCommelina benghalensis L. Rhodesian
J. Agric. Res 17:151 - 153.
Culpepper, A.S., Flanders, J.T., York, A.C. and Webster, T.M. 2004. Tropical
spiderwort (Commelina benghalensis) control in glyphosate-resistant cotton.
Weed Technol. 18:432 - 436.
Ferreira, M.I. and Reinhardt, C.F. 1999. The role of temperature in the germination
of subterranean and aerial seeds of Commelina benghalensis L. S. African J. Plant
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weeds: distribution and biology. University Press of Hawaii, Honolulu.
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Prostko, E.P., Culpepper, A.S., Webster, T.M., and Flanders, J.T. 2005. Tropical
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of Georgia College of Agriculture and Environmental Science/Coop. Ext. Ser. Bull.,
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Webster, T.M., Grey, T.L., Flanders, J.T. and Culpepper, A.S. 2009. Cotton planting
date affect the critical period of Benghal dayflower (Commelina benghalensis)
control. Weed Sci. 57:81 - 86.
Wilson, A.K. 1981. Commelinacea – review of the distribution, biology and control
of the important weeds belonging to this family. Tropical Pest Management.
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Benghal wandering Jew