| Summary: | These studies were conducted on several central Texas agricultural producers??
properties, the Stiles Farm Foundation, the Texas Agricultural Experiment Station, and
the Texas A&M University campus. First, an experimental herbicide from Dow
AgroSciences, GF-884, was evaluated for effectiveness in controlling three annual and
three perennial weed species in production pasture lands and hay meadows. Several
rates of GF-884 were examined and evaluated against three registered pasture products
and one non-selective herbicide. Next, GF-884 was assessed for tolerance on two
common bermudagrass hybrids (Cynodon dactylon (L.) Pers.) at three progressive rates
with and without adjuvant. Finally, the herbicides, picloram and fluroxypyr, were
applied to common ragweed (Ambrosia artemisiifolia L.) to characterize their individual
absorption and translocation and assess any influence one might have on the other.
GF-884 applied at rates of 0.91 and 1.14 kg a.e./ha provided >85% and >75%
control of the annual and perennial weed species evaluated, respectively. These same
rates of GF-884 consistently provided control that was equivalent or better than thatachieved with the registered products. No differences were observed among treatments
when shoots from the perennial species were evaluated 12 months following treatment
application. The tolerance experiments utilized GF-884 at rates twice that used to
evaluate weed control efficacy. These elevated rates did not result in discernable
influences on yield or forage quality for either hybrid forage grass when compared to
untreated areas. The efficacy and tolerance observations suggest that GF-884 applied at
the highest recommended weed control rate can effectively control several annual and
perennial weed species without imparting detrimental effects to the hybrid bermudagrass
being produced.
Finally, in the presence of fluroxypyr, 14C picloram absorption was maintained
throughout all sampling intervals. Picloram applied alone, maximized 14C absorption at
6 HAT then declined significantly. At the final sampling, 14C from picloram applied
alone was in greater concentration in the treated leaf and the root.
Picloram significantly decreased absorption of 14C fluroxypyr. Fluroxypyr alone
maintained 14C absorption throughout all samplings, whereas the combination
maximized at 12 HAT. Initially, picloram limited 14C translocation, however at 6, 12,
and 24 HAT this was not evident.
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