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New Crops News, Spring 1994, vol. 4 no. 1

Weed Control Studies in Pearl Millet

There is increasing interest in growing pearl millet as a crop following wheat in Indiana. Pearl millet is an attractive double crop because of its relatively short growing season and adaptability to 30" rows, with cultural practices similar to those for grain sorghum. Harvesting of pearl millet seed can be accomplished by combining. A major cultural problem that could limit acreage is the lack of adequate tools to control weeds. Presently, no herbicides are registered for use in pearl millet, and limited research has been conducted to explore safe herbicides.

During 1993, two weed control experiments were conducted in Indiana to determine the tolerance of pearl millet to several pre-emergent and post-emergent herbicides. The experiments were initiated on July 23, 1993 at the O'Neall Research Farm in Lafayette, Indiana. Crop injury and weed control were evaluated. The crop did not reach full maturity before the first fall frost; therefore, no yield measurements were taken. However, the plants headed and maturity would have been reached if planted by the first week of July.

The pre-emergent herbicides were applied after planting prior to crop or weed emergence using dosages at the low and high end of recommendations for agricultural crops. Entries included atrazine at 1.0, 2.0, and 3.0 lb./acre; Bladex at 1.0, and 2.0 lb./acre; Lasso and Dual at 1.0, 2.0, and 3.0 lb./acre; and Goal at 0.25 and 0.5 lb./acre).

Pearl millet was very tolerant to atrazine, Bladex, and Alanap. Pearl millet was intolerant to Lasso, Dual, or Goal at any of the rates applied. Stand was reduced by over 50% by each of these herbicides. Atrazine and Bladex provided excellent control of a wide variety of broadleaf weeds and some suppression of grasses. However, Lasso and Dual, two very common and effective grass herbicides, cannot be safely used in pearl millet. There is a need to test other potential grass herbicides in order to obtain acceptable control of a wide spectrum of weeds.

Post-emergent herbicides were applied three weeks after crop emergence. These included Prowl at 0.75, 1.5, and 3.0 lb./acre; CGA 152005 at 0.025, 0.05, 0.075 and 0.1 lb./acre; Accent or Beacon at 0.0312 and 0.0625 lb./acre; 2,4-D at 0.5 and 1.0 lb./acre; Banvel at 0.25 and 0.5 lb./acre; Buctril at 0.125 and 0.25 lb./acre; Basagran at 0.5 and 1.0 lb./acre; Lentagran at 0.45 and 0.9 lb./acre; and Lexone at 0.25 and 0.5 lb./acre. Pearl millet was tolerant to 2,4-D, Banvel, Basagran, Lentagran, Lexone, and CGA 152005. These herbicides provide excellent broadleaf weed control, but do not control emerged grassy weeds. Pearl millet foliage was severely injured by Accent and Beacon, and the plants brace roots were severely stunted by applications of post-directed Prowl.

The post-emergent herbicide results indicated that several broadleaf-controlling herbicides did not injure pearl millet, while grass selective postemergents caused injury (Accent and Beacon).

Future tests should explore the use of pre-emergent herbicides that contain crop safeners and the use of post-emergence directed sprays of grass killing herbicides. Our goal is a safe weed management system that controls problem weeds without crop injury

Steve Weller