Quality changes in forage crops following applications of 2,4-D

Very few investigations have been made which report directly on the effect of the plant growth regulator 2, 4-D on a great group of plants, principally grasses and legumes, the forages used by livestock. Under certain conditions such growth regulation substances may effect considerable changes in the chemical composition of higher, plants. The fact that forage value may be deliberately altered by applying sub-herbicidal concentrations of growth regulators seems not to have been carefully studied. An investigation appeared warranted and is the subject of this research. Under field conditions several sub-herbicidal levels of 2,4-D were applied at several stages in the development of red and white clover, perennial ryegrass, Kentucky bluegrass, and timothy growing on Ladner clay and Alderwood loam. Appreciable increases in dry matter and nitrogen yield obtained in certain treatments. Other significant effects were noted in flowering and seed production. Confirmation of the field results was obtained in greenhouse studies on red clover and Olli barley. A search for the source of the increased nitrogen did not reach a definable end but work with the influence of treated plants on soil Rhizobia and Azotobacter suggest that 2,4-D applied to forages may in some instances modify the ecology of the soil flora.Land and Food Systems, Faculty ofGraduat