Benfuresate (2-3-dihydro-3,3 -dimethylbenzofuran-5-yl ethanesulfonate)
is a selective herbicide for the control of purple nutsedge in cotton
. Under outdoor conditions, purple nutsedge was sensitive to benfuresa
te incorporated in soil up to eight days after initiation of shoot spr
outing from the tuber. Older seedlings recovered from the damage. Duri
ng the period of susceptibility to benfuresate, young shoots more sens
itive than the roots. Under controlled environmental conditions, benfu
resate applied directly to apical buds developing from the tuber cause
d severe damage to the treated bud and induced abrupt development of a
xillary buds. Negligible amounts of the applied herbicide were translo
cated from the treated part to the other buds and roots. Application o
f the herbicide to fully developed leaves had no effect, probably beca
use of its rapid metabolism and low basipetal mobility. Its relatively
high volatility may also contribute to its low foliar post-emergence
activity. Tubers also absorbed herbicide vapours. Root uptake of C-14-
benfuresate resulted in a rapid accumulation of C-14 in the shoot, whi
ch had no effect on the purple nutsedge plant, regardless of concentra
tion. The herbicide is rapidly converted, mainly to a non-phytotoxic p
olar product. These results may explain the high sensitivity of the we
ed to benfuresate at early growth stages, and the lack of sensitivity
in mature plants.