SELECTIVE HERBICIDE APPLICATIONS FOR CONTROL OF LIANAS IN TROPICAL FORESTS

Abstract

The efficacy of selective herbicide application to control interference from large woody vines (lianas) in managed tropical forests of eastern Bolivia was tested. The efficacy of three chemical formulations (2,4-D, triclopyr and imazapyr) and two methods of herbicide application (cut-surface application and uncut basal stem application) for controlling lianas was compared to the traditional practice of liana cutting with machetes. In addition, costs of herbicide treatments were estimated. For lianas not treated with herbicide, 70% of stems resprouted with a subsequent height growth averaging 140 cm after seven months. Application of 2,4-D to the freshly cut surface of lianas killed 60% of stems after seven months. Basal stem application of triclopyr killed 75% of uncut liana stems and seriously reduced the vigour of another 15% of the stems. Basal stem application of imazapyr killed only 11 % of liana stems. Responses to treatments did not vary significantly among major families of lianas. Application of treatments to free commercial species of lianas cost $1.64 ha^-1 for cutting without herbicide, $1.87 ha^-1 for cut surface application with 2,4-D, $10.76 ha^-1 for basal stem application with triclopyr, and $31.80 ha^-1 for basal application with imazapyr. While this study provides baseline data on efficacy and cost of treatments, operational feasibility of these treatments will largely depend upon local labour costs, availability of chemicals, and the magnitude of liana interference problems.