Yield and Nutrient Composition of Orchardgrass Hay as Affected by Dandelion Control

A 7-yr-old orchardgrass stand at the Lethbridge Research Station with 34 dandelion plants/m2 was treated with 2,4-D and 2,4-D + dicamba or picloram to determine the effect of these herbicides on orchardgrass and dandelion yields. Neutral detergent fiber, acid detergent fiber, ether-extractable fraction, P, K, Ca, Mg, and Na content of orchardgrass and dandelions were also measured. The average dandelion yield from all herbicide-treated plots was significantly lower than from untreated plots in years 1 (year herbicides applied) to 4 (last year measured). Applications of 2,4-D at 1.0 kg/ha in spring and fall reduced dandelion yields by 70% and increased orchardgrass yields by 20% (based on average yields for years 2 and 3) compared with the untreated check. Increases in dandelion control with 2,4-D at rates greater than 1.0 kg/ha or with 2,4-D + dicamba mixtures were achieved, especially in year 2. Additional orchardgrass yields were not obtained with these treatments. Total forage yields (orchardgrass + dandelions) were not significantly increased by herbicide treatment and the presence of dandelions did not cause deleterious changes in the nutrient composition of orchardgrass hay or pasture.