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Title: THE EFFECT OF FUNGICIDE SEED PROTECTANTS, SEEDING RATES, AND REDUCED RATES OF HERBICIDES ON NO-TILL SOYBEAN

Author
item BRADLEY, CARL - UNIV OF ILLINOIS
item Wax, Loyd
item EBELHAR, STEPHEN - UNIV OF ILLINOIS
item BOLLERO, GERMAN - UNIV OF ILLINOIS
item PEDERSEN, WAYNE - UNIV OF ILLINOIS

Submitted to: Crop Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/20/2000
Publication Date: N/A
Citation: N/A

Interpretive Summary: No-till soybean production requires the use of effective herbicides combined with rapid soybean canopy closure for optimum weed management. We designed this study to determine if combining fungicide seed treatments, reducing dosages of herbicides, and various soybean seeding rates affected weed management and soybean yield. Three different popular soybean varieties were used, at three different seeding rates, with three levels of herbicide input, with and without fungicide treatment of soybean seed. We found that in one year, fungicide seed treatments improved soybean populations and reduced time to canopy closure, but that in the other year, these treatments had no effect. As seeding rates were increased, the time to canopy closure was decreased, and yields were increased. In most instances, reduced inputs of herbicides provided adequate weed control and maintained high yield levels. These studies show the potential for combining fungicides and high soybean seeding rates to allow effective weed management even though herbicide inputs are reduced. The findings will be beneficial to other scientists conducting weed management studies, and to public and private extension weed scientists providing guidelines to growers and other clientele.

Technical Abstract: No-till soybean [Glycine max (L.) Merr.] requires the use of effective herbicides and rapid canopy closure for weed management. This study was conducted to determine if fungicide seed protectants, reduced rates of a complete preemergence or a complete postemergence herbicide program, and seeding rates affected weed control and yield. `Asgrow 3237', `Pioneer Brand 9273', and `Pioneer Brand 9342' soybeans were planted into corn (Zea mays L.) stubble at Urbana, Illinois in 1995 and 1996. Use of seed protectants increased soybean population density and reduced time to row canopy closure in 1995, but had no effect in 1996. As seeding rates were increased, yields were significantly increased, and the time to row canopy closure was decreased. In general, adequate weed control and soybean yields were maintained using reduced rates of herbicides. In 1996, quality of harvested `Pioneer 9273' and `Asgrow 3237' seed was reduced in the no herbicide, weedy control plots by higher incidence of Cercospora kikuchii [(Matsumoto & Tomoyasu) Gardner].