| Research was conducted in 1984 and 1985 at Torrington, WY to evaluate irrigated spring wheat (Triticum aestivum L. var. "Oslo") and barley (Hordeum vulgare L. var. "Steptoe") response, and at Chugwater, WY to evaluate dryland winter wheat (Triticum aestivum L. var. "Buckskin") response to ten broadleaf herbicide treatments applied at three stages of growth. Spring wheat height response to herbicides was inconsistent between years. Dicamba 3,6-dichloro-o-anisic acid and dicamba combinations with 2,4-D 2,4-dichlorophenoxyacetic acid or MCPA 2-methyl-4-chlorophenoxyacetic acid at the boot stage of spring wheat reduced yield 28, 21, and 24%, reduced kernels per spike 27, 33, and 21%, and increased seed protein content 8, 13, and 6%, respectively. Several other auxin herbicides increased seed protein content, particularly at the boot stage. Effects of herbicide treatments on proline and lysine content were not significant. Dicamba and dicamba combinations with 2,4-D or MCPA visibly injured spring barley when applied at all growth stages, reduced barley height at the two-to-four-leaf and fully-tillered stages, and reduced kernels per spike and kernel weight at the fully-tillered and boot stages. Differences in barley yield among treatments were not significant. Barley seed protein content was increased by several herbicide treatments in 1985, especially with applications at the boot stage. Proline or lysine content was not significantly affected by herbicide treatments. Several herbicide treatments reduced winter wheat height and yield with applications at the two-to-four-leaf stage; yield reductions were closely related to reductions in the number of spikes per meter of row. Herbicide treatments had no effect on winter wheat kernels per spike, kernel weight, test weight, or germination, however, seed protein content was increased by several herbicide treatments (especially with applications at the boot stage) in 1984, and decreased by several herbicide treatments in 1985. |
