Controlling Pink Bollworms: Effects of Chemical Termination of Cotton Fruiting on Populations of Diapausing Larvae123

Applications of plant growth regulators in late August effectively terminated the fruiting of cotton and significantly reduced populations of diapausing larvae of Pectinophora gossypiella (Saunders) (by 90% or more) in Arizona during 1972–74. As a result, fewer overwintered moths (39%) emerged the following spring from terminated plots. Applications in mid-, or late August were more effective than applications in early September. Yields were not significantly reduced by most treatments. The most effective materials tested were 2.4-D (amine salt of 2,4-dichlorophelloxy) acetic acid + chlorflurenol (methyl 2-chloro-9-hydroxyfluorene-9-carboxylate) and 2, 4-D + chlormequat ((2-chloroethyl) trimethylammonium chloride).