Control of silverleaf nightshade with glyphosate

Abstract

Glyphosate should have a long-lasting effect against Solanum elaeagnifolium Cav. when its application timing coincides with active translocation of non-structural carbohydrates toward rootstock. A pot experiment was conducted from June 2012 to June 2013 to evaluate glyphosate activity against S. elaeagnifolium at three growth stages: early fruiting, green berries and ripened berries. Herbicide treatments were applied in a water volume equivalent to 200 L.ha-1 at a rate of 5 L.ha-1 (2025 g a.i. ha-1). The experimental design was a randomized complete block design with 10 replications. To assess glyphosate activity, S. elaeagnifolium height and numbers.plant-1 of leaves, flowers, berries and sprouts were measured at 0, 20, 30 and 60 days after treatment (DAT). Therefore, S. elaeagnifolium regeneration was monitored at April, May and June 2013. Glyphosate effect on leaves number.plant-1 was detected since 20 DAT. The reduction reached 90% at 60 DAT for glyphosate timing application at green or ripened berries. However, for early fruiting stage the decrease was not long lasting. Berries number.plant-1 decrease at 30 DAT was more for glyphosate application at green or ripened berries. Sprouts number in June 2013 was maximum for glyphosate application at early fruiting and the least for the green berries stage. Therefore, the most appropriate timing of glyphosate application is green berries growth stage.