Abstract
Ethrel, a mixture of 2-chloroethanephosphonic acid and its ethyl ester, hastens abscission of leaves, debladed petioles, and flower buds of cotton plants (Gossypium hirsutum, L.). Both young and old leaves abscissed while still green. Application of Ethrel stimulated evolution of ethylene, and this response preceded abscission. Air concentrations of ethylene around enclosed, treated-plants were adequate to produce abscission in plants. Non-treated plants defoliated when enclosed with plants sprayed with Ethrel. The stimulation of abscission of explant petioles by Ethrel was reversed by naphthalene acetic acid. The stimulation of abscission by Ethrel was concluded to be mediated by ethylene.