Effectiveness and Residues of Simazine in a Coffee Plantation

Abstract

A study on the effectiveness and residues of simazine in coffee plantAtion was conducted ar a two year old coffee plantation in Phrae Province. The trees were planted in 2.5 x 2.5 m with 10-10 m2 plot size. Theherbicide simazine at the rate of 3.375 kg a.j./ha was applied at pre-emergence of the weeds in the coffee plantation soil. The effectiveness of the herbicide was evalually visually and soil samples at three different depths (0-5 , 5-10, and 10-15 cn frin siuk syrface) were cikkected at 21, 45, 90 and 135 days after herbicide application, for siamazine residues analysis. Treatments were arranged in a randomized complete block design with 4 replications.
Simazine could control weeds for appoximately 2 months. The predominant weed species were Brachiaria reptans, Rottboelia exaltata, Amaranthus viridis, and Eupatorium odoratum. The residues of simazine were highest at 0-5 cm soil depth and they decreased as the depth of soil increased (5-10 and 10-15 cm respectively), The breakdown of simazine was very rapid with half life of approximately 3 weeks. there was no phytotoxicity of simazine to coffee tree shown from this experiment.