Weed Control in a Winter Wheat-Corn-Ecofarming Rotation1
- P. B. Vander Vorst,
- G. A. Wicks and
- O. C. Burnside2
Adequate information is not available regarding the influence of row spacing, seeding rate of winter wheat (Triticum aestivum L.), and time of herbicide application on weed control following wheat harvest and in the succeeding corn (Zea Mays L.) crop. Field experiments, conducted during 1977 through 1980 on a Holdrege silt loam (fine-silty, mixed, mesic Typic Argiustoll) at North Platte, Nebr. determined that narrow-row spacing (17 vs. 35 cm) and seeding rates of 67 or 100 kg/ha vs. 33 kg/ha of winter wheat significantly improved weed control in a wheat-corn-fallow rotation. Wheat grain yield did not differ between row spacings. Wheat yielded 15% more grain when seeded at 67 or 100 kg/ha than at 33 kg/ha in 1978. Weed yield and grass weed panicle production in wheat stuhhle increased as atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] + paraquat (l,l'-dimethyl-4,4'-bipyridinium ion) application was delayed from 5 to 25, 45, or 260 days after harvest, but atrazine persistence was not sufficient to maintain better weed control when planted to corn the following year. Atrazine applied 260 days after wheat harvest provided the best weed control in the following corn crop. However, corn yield was reduced 22% in 1978, because weed growth between wheat harvest and herbicide spraying used soil water needed for the corn. Narrow-row spacing and high seeding rate of wheat the year prior to corn reduced weed populations during the fallow period the year following corn. Reduction of weed seed production is essential during the entire rotational sequence in order to prevent the buildup of weed populations.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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