Published online by Cambridge University Press: 12 June 2017
Foliar abscission induced by mist blower applications of endothall [7-oxabicyclo(2,2,1)heptane-2,3-dicarboxylic acid] combined with ethephon [(2-chloroethyl)phosphonic acid] occurred within 14 days on six field-grown deciduous species. Refoliation was essentially complete after one dormant season except on pin oak (Quercus palustris Muenchh.), which exhibited shoot damage from May and June treatments. Abscission did not occur on coniferous species. Effective doses ranged from 150 to 2,400 μg/ml endothall with 4,800 μg/ml ethephon. In greenhouse experiments on white ash (Fraxinus americana L.), the most effective levels of surfactant with endothall/ethephon ranged from 0.5 to 1.3%, and a spray volume as low as one-quarter runoff gave adequate coverage.