Season of Application Affects Herbicide Efficacy in Pinus radiata Plantations in the Southern Cape Region of South Africa

Abstract

Three herbicides (glyphosate, hexazinone and metsulfuron methyl) at three rates were tested on indigenous herbaceous shrubs (macchia) in a one-year-old virgin Pinus radiata stand. A mechanical ring weeding of 1 m radius was included as a control treatment. Herbicides were applied over-the-top to uncovered P. radiata. These treatments were tested for each of four seasonal applications. Tree height and diameter growth were measured to determine efficacy of the treatments. Two floristic surveys indicated satisfactory weed suppression.