Chemical control of common reed (Phragmites australis) by foliar herbicides under different spray conditions

The efficacy of glyphosate and glufosinate applied with two sprayers, a mot orised knapsack mistblower and a hydraulic sprayer, were evaluated for the control of common reed. Phragmites australis had been cut in the beginning of September 1994, 30 d before autumn application. The study sites were cle ared of vegetation to within 10 cm of the surface using an hydraulic escava tor equipped with a mowing bucket, in one operation it cuts and removes the weed. Herbicides were sprayed in October 1994 and April 1995 at different spray volumes and at different rates. Glyphosate rates were 0.81, 1.62, 3.2 4, 4.68 and 6.48 kg a.i./ha applied with a mistblower at spray volumes of 3 00; 800; 1100 l/ha and with a sprayer at 800; 1600 l/ha. Glufosinate rates were 0.3, 0.6, 1.2, 1.38, 1.8 and 2.4 kg a.i./ha applied with a mistblower at spray volumes of 800 l/ha and with a sprayer at 800; 1100 and 1600 l/ha. Glyphosate provided control over 2-3 yr for dense P. australis infestation s in drainage channels when applied up to 1.62 kg/ha, independently of the type of sprayer, times of treatment or spray volume. Glufosinate produced r apid phytotoxicity in aerial parts; however the autumn treatment was more e fficacious than the spring one. Regrowth, during 1995, was high and 1 yr af ter the first application the efficacy had become very low.