engleski

Growth stage sensitivity of Echinochloa crus-galli to decreasing rates of topramezone and adjuvants

Integrated Weed Management requires low herbicide input with post-emergence (POST) application as well as environmentally and economically uses of herbicides. For an effective weed control it is fundamental to set proper time for POST herbicide application when weeds are still at more sensitive phenological stage. Although the best efficacy is expected when herbicides are applied at early growth stages, in the field conditions very rarely plants are at the same stage of development. So the aim of this glasshouse experiment was to determine the efficacy of recommended (67.2 g. a. i. ha-1) and reduced dose (44.8, 33.6, 22.4, 16.8 and 8.4 g. a. i. ha-1) of topramezone combined with adjuvants (NIS and MSO) on Echinochloa crus-galli [L.] P. Beauv. (barnyardgrass) at two different growth stages: three true leaves (BBCH 13) and one-two tiller stage (BBCH 21-22). Topramezone and adjuvants were applied using a precision bench sprayer with a boom equipped with three flat-fan (extended range) hydraulic nozzles with dose spray volume of 300 L ha-1, pressure of 215 kPa, speed of 0.75 m s-1 and using TeeJet® nozzles XR11002-VK. The results showed insufficient efficacy of topramezone applied alone in recommended dose on both growth stages (>50%). Applied with adjuvants (MSO or NIS) at BBCH 13 topramezone achieved 100% visually assessed damage and more than 90% biomass reduction, at each applied doses. In contrast, at BBCH 21-22 only double dose of topramezone achieved 73% visual estimated damages. Reduced topramezone doses applied with adjuvants gave insufficient topramezone control at tillering stage (< 40%). Results indicate possibility of reducing dose of topramezone to more than 87% with adding adjuvants (MSO or NIS) but only at early growth stage of barnyardgrass (BBCH 13). Still, at BBCH 21-22 satisfying barnyardgrass control cannot be achieved neither by using topramezone alone nor applied with adjuvants.

reduce dose, bleaching, three leaves, tillering, MSO, NIS

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