Published online by Cambridge University Press: 12 June 2017
Night applications of phenoxy herbicides on plains pricklypear (Opuntia polyacantha Haw.) resulted in more plants being killed than comparable day applications. Night applications gave rapid herbicidal responses that were negated by the second year if chemical concentrations were too high. With low herbicide concentrations (½ and 1 lb aehg) effectiveness increased with proportion of diesel oil in carrier. The ester forms of 2-(2,4,5-trichlorophenoxy)propionic acid (silvex) killed more plants than did the ester or amine forms of (2,4,5-trichlorophenoxy)acetic acid (2,4,5-T) in diesel oil:water (1:4, v/v) carriers.