Efficacy of several organic herbicides and glyphosate formulations under simulated rainfall

Abstract

Glasshouse studies were conducted to determine the efficacy and rainfast interval of several organic and glyphosatebased herbicides marketed for use in home gardens The test species used were white clover (Trifolium repens) annual ryegrass (Lolium multiflorum) and couch (Elytrigia repens) After spraying the 6weekold plants some pots were set aside and received no simulated rainfall while others were placed under the rainfall simulator (11 mm rain over 30 minutes) at 2 3 or 6 h after application Plants were visually assessed for herbicide efficacy and after 4 weeks all the new growth was harvested and dry matter measured Rainfall applied 2 or 3 h after application did not reduce the efficacy of organic herbicides In the case of glyphosate rain applied at 2 h after spraying reduced efficacy by 440 while rain 6 h after application reduced it by 020 depending on formulation and plant type