Published online by Cambridge University Press: 12 June 2017
The interaction of 2,4-D [(2,4-dichlorophenoxy) acetic acid], substrate, and calcium on eurasian watermilfoil (Myriophyllum spicatum L.) was determined. The effectiveness of 2,4-D was twice as great on plants grown on a substrate containing soil as it was on plants grown on a sand substrate. The presence of calcium chloride in sand culture during the period of 2,4-D uptake caused comparable or greater increases than sand culture without calcium in the effectiveness of 2,4-D. Possible differences in effectiveness of field treatments were calculated to be 48% greater at the highest natural concentrations of calcium than at the lowest concentrations in water of the Tennessee Valley. Calcium concentration and substrate altered the effectiveness of 2,4-D on eurasian watermilfoil.