Winter annual weeds and early spring insects are common pests of alfalfa grown along the Front Range of Colorado. Blue mustard, Chorispora tenella; is a winter annual weed that competes well with newly growing alfalfa. This weed contaminates first-cutting hay, thereby reducing the quality and economic value of the hay. The alfalfa weevil, Hypera postica; is the most frequently encountered insect pest in Northeastern Colorado and can significantly reduce the quality and quantity of first and second cutting alfalfa. A trend towards sustainable agriculture and organic products has encouraged efforts towards identifying effective, economical alternatives to herbicides and insecticides. The purpose of this study is to examine whether propane flaming treatments of alfalfa fields in the early spring can reduce winter annual weeds and/or insect pests and produce quality alfalfa. Alfalfa was flamed using the Red Dragon TD-12 LPS Alfalfa Flamer. Pursuit herbicide and Baythroid 2 insecticide treatments were used as conventional comparison plots. Flaming dormant alfalfa when blue mustard was a quarter to half-dollar size reduced weed density significantly when compared to the untreated check. Early weevil larvae assessments (9 days after insecticide treatment and 60 days after flaming) showed good activity of flaming on weevil larvae populations. This activity was comparable to any treatment containing an insecticide. However, flamed alfalfa treatments revealed a significant decline in alfalfa weevil activity at 23 days after insecticide treatment and 75 days after flaming. Alfalfa yield evaluations revealed the flamed alfalfa treatments had higher yields than the untreated check in both experiments. The weevil larvae had greater impact on alfalfa yield and quality than the weed populations encountered in this study.
The ESA 2001 Annual Meeting - 2001: An Entomological Odyssey of ESA