Broadcast or Banded Atrazine plus Propachlor with Tillage Variables in Corn

Abstract

The herbicide mixture 2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine (atrazine) + 2-chloro-N-isopropylacetanilide (propachlor) was applied preemergence broadcast and in band widths of 18, 36, and 53-cm to corn (Zea maysL.). All herbicide treatments were applied as 1.1 kg of atrazine + 2.7 kg of propachlor per treated hectare. One row-middle cultivation and one rotary hoeing were also imposed on the herbicide treatments as variables. The 18-cm band of atrazine + propachlor with supplementary cultivation was as effective in controlling weed growth and maintaining corn yield as were wider herbicide bands or a broadcast treatment. Broadcast treated corn without row-middle cultivation produced significantly less grain than the handweeded check both years of the experiment. The average ratio of weed dry weight to reduction in corn yield was 0.8 to 1. Cultivation of row middles reduced average end-of-season weed yields 80%. Cultivator effectiveness on an 18-cm herbicide band equalled that measured on wider herbicide bands. Rotary hoeing reduced early season weed yields 82 and 38% in 1970 and 1971, respectively.