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Evaluation of fall-applied, preemergence herbicide application on carbon-banded roughstalk bluegrass

M.D. Butler
1997 WSWS Proceedings
The objective of this project was to evaluate eight fall-applied, preemergence herbicides on carbon-banded roughstalk bluegrass in commercial fields near Madras and Culver, Oregon. Commercial equipment was used to place a 1.5 inch-wide band of carbon over the seed row at the rate of 30 lb/treated A or 300 lb/total A. Treatments included diuron at 2 and 4 lb/A, metribuzin at 0.25 and 0.5 lb/A, terbacil at 0.5 and 1 lb/A, diuron at 2 lb/A with metribuzin at 0.25 lb/A, and diruon at 0.5 lb/A with terbacil at 0.5 lb/A. Treatments were applied preemergence with a CO2 pressurized, hand-held, boom sprayer at 40 psi and 20 gpa at the Roff location September 7, at the DuRette location September 8, and at the Grote location October 4. Plots 10 by 30 ft were replicated three times in a randomized complete block design. Treatments were evaluated for crop injury and stand reduction, and percent control of common groundsel, prickly lettuce, common mallow, henbit, downy brome, volunteer wheat, and volunteer barley. Evaluations were conducted January 18 at the DuRette location, and February 16, 1996, at the Roff and Grote locations.

Diruon at 0.5 lb/A plus metribuzin at 0.25 lb/A provided overall weed control of 95%. Terbacil at 1 lb/A provided 96% weed control or better for all weeds except common groundsel at 33%. Diuron at 0.5 lb/A plus terbacil at 0.5 lb/A provided 94% control or better for all weeds except common groundsel at 40%. Diuron at 2 lb/A provided inadequate control of all weed species evaluated, except 87% control of common groundsel and volunteer wheat. The greatest crop injury and stand reduction resulted from terbacil at 1 lb/A, followed by metribuzin at 0.5 lb/A, diuron at 0.5 lb/A with terbacil at 0.5 lb/A, and terbacil at 0.5 lb/A. Diuron at 2 lb/A, followed by diuron at 4 lb/A and metribuzin at 0.25 lb/A caused the least amount of crop injury and stand reduction in roughstalk bluegrass. (Oregon State University, Central Oregon Agricultural Research Center, Madras, OR 97741).