Herbicides Enable the Replanting of Rubber Trees on Small Farms in South Asia

The rubber tree, Hevea brasiliensis, is a major crop for smallholders in Southeast Asia where over 90% of the world’s natural rubber is primarily produced in Indonesia, Thailand and Malaysia. About 70% of rubber production is on small farms; the remaining 30% takes place on large lantations. The smallholder share is gaining in importance since many p plantations are turning to more profitable palm oil crops. The economic life span of the tree is about 30 years. During the first 2 to 3 years after the planting of seedlings, the light intensity at ground level is almost 100%. This is when control of weeds is most important. The success of the crop depends a great deal on effective control of weeds during the critical immaturity phase [1]. As the rubber trees mature and the canopy loses, sunlight and hence the weed population under the rubber trees are y c progressivel reduced. Historically, an abundant supply of cheap labor allowed the use o f hand weeding on rubber tree farms for the first two years after planting. However, rising labor costs have necessitated changes in weed control practices; herbicides are now widely‐used on small farms [2]. Research has demonstrated that the use of chemical herbicides makes a striking reduction n labor required for weeding: from 248 hours/year per acre for hand i weeding to just 8 hours/year per acre with herbicides [3]. Many smallholder farms have low rubber productivity and need to b e replanted. Recognition of the importance of the smallholder sector has resulted in government action to support farmers in the form of credit and technology packages which include seedlings, fertilizers, and herbicides [4].