Critical time for weed removal in dicamba tolerant soybean as influenced by pre emergence herbicides

Abstract

Field experiment was conducted in 2019 at Haskell Agriculture Laboratory, Concord, NE, USA. Goal of the study was to test the influence of PRE-EM herbicides on the Critical Time for Weed Removal (CTWR) in dicamba-tolerant soybean. The study was arranged in a split-plot design which consisted of four herbicide regimes as main plot treatments and seven weed removal timings as subplot treatments, with four replications. The herbicide regimes included: (1) no PRE and glyphosate, (2) acetochlor and dicamba as PRE and glyphosate as POST, (3) acetochlor and dicamba as PRE and glyphosate and dicamba as POST, and (4) acetochlor and fomesafen as PRE and acetochlor, glyphosate and dicamba as POST. The five weed removal times included the V1, V3, V6, R2 and R5, and there were also weedy and weed-free season long plots. By utilizing herbicide regimes, the CTWR was delayed to 632 GDD (until V4 soybean growth stage, 28 days after emergence) for acetochlor and dicamba as PRE and glyphosate as POST, 861 GDD (until V6 soybean growth stage, 32 days after emergence) for acetochlor and dicamba as PRE and glyphosate and dicamba as POST, and 1060 GDD (until R1 soybean growth stage, 42 days after emergence) for acetochlor and fomesafen as PRE and acetochlor, glyphosate and dicamba as POST.

Ogled je sproveden 2019. godine u Haskell Agricalture Laboratory, Concord, NE, USA. Cilj ogleda bio je da se utvrdi uticaj PRE-EM herbicida na kritičan momenat suzbijanja korova u usevu soje tolerantne na dikambu. Ogled je postavljen kao potpuno slučajan blok sistem sa 28 tretmana (4 herbicidna tretmana sa 7 različitih vremena uklanjanja korova) u 4 ponavljanja. Primenjeni herbicidni tretmani su: (1) glifosat POST-EM, (2) acetohlor i dikamba PRE-EM i glifosat POSTEM, (3) acetohlor i dikamba PRE-EM i glifosat i dikamba POST-EM i (4) acetohlor i fomesafen kao PRE-EM i acetohlor, glifosat i dikamba kao POST-EM. Korovi su uklanjani kada je soja bila u fazama: V1, V3, V6, R2 i R5, a pored njih su postojale kontrole sa korovima i kontrole na kojima su korovi uklanjani tokom čitave vegetacione sezone. Primenom tretmana (2, 3 i 4) kritični momenat suzbijanja korova je bio pomeren za 632, 861 i 1060 SAT (suma aktivnih temperatura vazduha), tj. do V4, V6 i R1 faze razvoja soje, odnosno 28, 32 i 42 dana nakon nicanja. Ključne reči: PRE-EM herbicidi, kritično vreme suzbijanja korova, rezistentnost na glifosat, integralno suzbijanje korova.