Efficacy of glyphosate and fluazifop-P-butyl herbicides with adjuvants at different levels of cutting for the common reed (Phragmites australis)

Field experiments were conducted to evaluate the efficacy of glyphosate (H1) and fluazifop-P-butyl (H2) herbicides with adjuvants on the common reed without cutting and at two different cutting levels (10 and 30 cm). The adjuvants were urea, nitric acid and sulfonic acid. The relative importance value (RIV), leaf chlorophyll content and plant density were determined to assay the efficacy of herbicides. Glyphosate treatment only (H1 a) was more effective than fluazifop-P-butyl (H2 a) on reeds without cutting and at the 10 cm cutting level. However, no significant difference was observed between them at the 30 cm cutting level. A positive effect of plant cutting occurred on the efficacy of all herbicides applied alone or in a tank mix with adjuvants. Furthermore, the 10 cm cutting level was more effective in eradication of reeds than the 30 cm cutting level. The adjuvants significantly improved the efficacy of the recommended (Hb) and half recommended (Hc) herbicide rates in comparison to being used alone on uncut reeds. The reduction percentages were 94.5, 86.99, 76.61 and 69.94 for H1 b, H1 c, H2 b and H2 c treatments, respectively. However, the adjuvants did not improve the glyphosate effect at different levels of cutting. Conversely the reduction percentage of reeds was improved by the recommended rate of fluazifop-P-butyl with adjuvants (H2 b) to 92.77% and 84.62% at 10 and 30 cm cutting levels, respectively.