Spring Wheat (Triticum aestivum) Management Can Substitute for Diclofop for Foxtail (Setariaspp.) Control

Abstract

The goal of this research was to determine whether crop management practices could substitute for a herbicide for managing mixed populations of green and yellow foxtail in hard red spring wheat. Crop yield and foxtail growth were measured in two years of field research in North Dakota. Spring wheat yields were as great or greater when early seeding date or 2× seeding rate were substituted for POST diclofop3at 0.75 kg ai ha−1for managing foxtail in spring wheat. Yield of spring wheat competing with foxtails was greater for the high seeding rate (2× = 270 kg ha−1) than both the normal (1× = 130 kg ha−1) and low (0.5× = 70 kg ha−1) seeding rates for early or middle seeding dates, but not for the late seeding date. For both early and middle seeding dates, wheat yield at the 2×seeding rate without diclofop was equal to or greater than that of the 1× seeding rate with diclofop. Late-seeded wheat did not yield well in competition with dense foxtail stands for any treatment combination. Early and middle seeding dates favored the relative increase of green foxtail over yellow foxtail in wheat, whereas late seeding favored yellow foxtail over green foxtail. Economic analysis demonstrated that early seeding date was the most critical factor in determining the stochastic dominance of treatments without diclofop over treatments with diclofop. Seeding rate was much less important than seeding date in determining the ranking of treatments in stochastic dominance analysis.

Limiting Green and Yellow Foxtail (Setaria viridisandS. glauca) Seed Production Following Spring Wheat (Triticum aestivum) Harvest

“…Green and yellow foxtail are two of the most abundant and troublesome annual weeds of the northern Great Plains of the United States (Donald and Nalewaja 1990;Fay 1990; Khan et al 1996) and the Prairie Provinces of Canada (Hunter et al 1990). Green and yellow foxtail can reduce wheat yields (Blackshaw et al 1981;Peterson and Nalewaja 1992), thereby requiring some manage-ment technique, usually herbicide application.…”

“…can lead to early wheat establishment. reduced competition from foxtail, and high grain yields (Khan et al 1996;Rahman and Ashford 1972). Although herbicide application may reduce foxtail competition with wheat during the grow-ing season, it does not prevent seed production following wheat harvest.…”

Effects of Common Wheat (Triticum aestivum) Management Alternatives on Weed Seed Production1

“…Most foxtail seeds were produced by plants growing in mid and late sowings (Table 4), which emphasizes the importance of early sowing of spring wheat for reducing current season (Khan et al 1996) as well as future crop-weed interactions.…”

“…Foxtail seed production increases as densities of plants and panicles increase (Forcella et al 2000) and inflorescence size correlates well with seed production in several grasses (Forcella et al 2000;Norris 1992;Schreiber 1965). Most foxtail seeds were produced by plants growing in mid and late sowings (Table 4), which emphasizes the importance of early sowing of spring wheat for reducing current season (Khan et al 1996) as well as future crop-weed interactions.…”

“…Foxtail effects also can be minimized either by increasing the sowing rate of spring wheat (Blackshaw et al 1981;Khan et al 1996) or by applying herbicides (Ashford et al 1990;O'Sullivan 1990). However, regardless of the approach used, some foxtail plants escape control, complete their life cycle, produce numerous seeds that enter the seedbank, and provide the potential for future infestations.…”