ABSTRACT
Bovey and Davis (1967) found that plant species vary in their rates of paraquat absorption. Washing yaupon (IIex vomitoria) and live oak (Quercus virginana) 1 hr after application of paraquat reduced its effectiveness regardless of air temperature, but washing winter peas (Pisum sativum) 10 min after application had little effect on phytotoxicity. Field-grown mesquite (Prosopis glandulosa) showed extensive leaf necrosis when leaves were washed 20 min after application, but live oak showed no injury. Winged elm (Ulmus alata) response was intermediate. The temperatures of 5 to 6°C delayed leaf necrosis of greenhousegrown oats (Avena sativa), winter peas, husache (Acacia farnesiana, mesquite, live oak, and yaupon for at least 48 hr after paraquat treatment compared to air temperatures of 24 to 28°C. From paraquat absorption and concentration studies Bovey and Miller (1968) found that the phytotoxic differences between white, variegated, and green leaves of hibiscus (Hibiscus rosa sinensis) were not due to the amount or rate of absorption or protoplasmic susceptibility but to the differences in the chlorophyll content of treated leaves. The same reduced activity of paraquat on white leaf tissue was demonstrated for sorghum (Sorghum bicolor) and alpina (Alpina purpurata).
