HERBOLOGIA - anubih

Influence of the adjuvant Desh on the efficacy and selectivity of imazamox 40 a.i. l -1 (Pulsar)
The block method was used with three replications and harvest plot size of 20
m 2 .
Natural background of weed infestation was used. The predominant
weed species were also main weeds in the old swards of the above-mentioned
crops: Capsella bursa pastoris L., Thlaspi arvense L., Stellaria media L.,
Veronica hederifolia L., Anagalis arvensis.
The treatment was made with 400 l ha -1 working solution in early
growing season. The adjuvant Desh was added immediately before the
treatment. The following characteristics were observed: selectivity (after
EWRS scale); degree of weed infestation (by the quantity and quantityweight
method); herbicidal efficacy, %; dry biomass yield mathematically
processed by the method of variance analysis.
During the three study years the results of the observed characteristics
retained their trend among the variants which allowed their presentation on
average for the experimental period.
Results and discussion
The herbicide Imazamox applied alone or with the adjuvant Desh
possesses high selectivity to lucerne, birdsfoot trefoil and sainfoin. It belongs
to the group of wide-spectrum herbicides with phytotoxic action to the annual
mono- and dicotyledonous weeds. Under the trial conditions Capsella bursa
pastoris L. and Thlapsi arvense L. showed high susceptibility; they are also
the main weeds of the old stands of the studied species. Our observations
showed complete killing of the weeds that were at earlier stages of their
development (seedlings and rosette) at the moment of treatment. The weeds
that were at a more advanced stage remained chlorotic and formed no flowerbearing
stems. In view of the circumstance that in these stands a considerable
part of the weeds wintered successfully, the timely treatment at the first
opportunity in spring was a necessary condition of reaching high herbicidal
efficacy.
The herbicidal efficacy (Table 2) with regard to the weed weight in
the standard and Imazethapyr reached 96-98% in different crops. The values
for Imazamox at the rate of 20 ml a.i.ha -1
with the adjuvant Desh at the rate
of 1000 ml ha -1, being within the range of 93-97 %, were the closest to these.
When comparing this efficacy with that for the application of the herbicide
alone it was evident that owing to the adjuvant Desh it was higher by 17 to
19%. The synergistic action of the activating additives was also reported by
other authors who explained it by an increase of the retention and absorption
of the herbicidal solution by the leaves (Borona et al., 2003; Woznica, 2005).
At the lower dose of the adjuvant of 500 ml ha -1
the herbicidal efficacy
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