Control of Persian Darnel (Lolium persicum) and Other Grasses with Clethodim

Abstract

The response of Persian darnel, green foxtail, wild oat, and volunteer cereals to clethodim applied at two growth stages, and the effect of these treatments on flax yield and quality were determined in a series of field experiments in which each weed species was evaluated separately. Clethodim applied at 45 g/ha provided excellent control of Persian darnel, green foxtail, wild oat, and volunteer wheat and barley. Sethoxydim applied at 150 g/ha provided excellent control of Persian darnel, green foxtail, wild oat, and volunteer barley. Rax was tolerant at five times the recommended rate of application and was unaffected by plant growth stage at time of application. When applied at an early (2- to 3-leaf) stage, control of Persian darnel, green foxtail, wild oat, and volunteer wheat and barley was excellent at 20 g/ha. Except for Persian darnel, weed control as determined by reduction in plant dry weight, was negatively affected by growth stage at time of application. Although visible control and reduction in plant dry weight were somewhat less when clethodim was applied at the 4-to 5-leaf stage, control of each weed species was acceptable. When weight of water in plant tissue (fresh weight – dry weight) was used as a measure of living plant tissue, wild oat and volunteer barley control were unaffected by growth stage at time of application.

Spring Wheat, Canola, and Sunflower Response to Persian Darnel (Lolium persicum) Interference

“…Persian darnel densities of 2,800 plants/m 2 have been quantified in dryland wheat fields, and a density of 30 plants/m 2 reduced spring wheat yield 15% (Hunter 1984). Persian darnel management in small grain with selective grass herbicides costs $30.00/ha or one-sixth the value of the average Montana wheat crop, even though its yield impact has not been quantified (Hunter 1995;USDA 2000). Integrated management systems that rely more on cultural management practices and less on selective herbicides are essential for long-term profitability of Montana wheat production.…”

Persian Darnel (Lolium persicum) Fecundity Response to Spring Wheat, Canola, and Sunflower Interference

“…Persian darnel emerges slightly before or with spring seeded crops from mid-April through early May in Montana (A. J. Bussan et al unpublished data;Hunter 1995;Rardon and Fay 1995). Persian darnel's early emergence, rapid growth (Bussan and Dietz-Holmes 2000), and fibrous rooting structure (Holman 2002;Stone et al 1998) enabled it to be highly competitive with spring-seeded crops.…”