Glyphosate For Weed Control In Cassava

Two herbicide field experiments were conducted in 1980 at the Corozal and Isabela Agricultural Substations to evaluate Glyphosate /N-(phosphonomethyl) glycine^/ at 1.0, 2.0 and 4.0% applied either as pre-plant or preplant plus post-emergence directed spray for weed control in cassava. Both experiments were carried out on small plots (4.9 x 6.1 m) arranged in a randomized complete block design with four replications. Weed control ratings and phytotoxicity evaluations were made periodically. The edible tubers of cassava were harvested and yield data analyzed statistically. Two applications of Glyphosate (pre-plant plus post-emergence) provided better sustained weed control than a single pre-plant application at both substations. However, two applications of Glyphosate had caused greater crop injury than a single application. Consequently, when plots received two applications, they did not outyield plots with only a single one. Among the different concentration of Glyphosate tested, it is indicated that Glyphosate at 1% applied either pre-plant or post-emergence is sufficiently high enough for controlling major weeds encountered in the experimental plots. Tuber yield of cassava was not significantly increased with higher rates of Glyphosate application.