Phytotoxicity and longevity of twenty-two preemergent herbicides used on three species of container-grown Palms

Abstract

Twenty-two preemergent herbicides were applied at their maximum labeled rates and twice those rates to determine their safety and effectiveness on areca palm [Dypsis lutescens (H. Wendl.) Beentje and Dransf.], pygmy date palm (Phoenix roebelenii O'Brien), and mexican fan palm (Washingtonia robusta H. Wendl.). Two products, dichlobenil and metolachlor showed consistent phytotoxicity on all three species. Several of the remaining products caused death of the apical meristem in mexican fan palms and reduced growth rates in pygmy date palms, but most caused little damage to areca palms. Herbicides applied as sprays generally remained effective for 2 to 4 months, whereas granular products, especially those containing oxyfluorfen plus another chemical, were effective for up to 8 months.