Direct financial cost of weed control in smallholder rubber plantations

A survey was conducted to provide information on weed types, control strategies, and their estimated costs to smallholder rubber outgrowers in Western Ghana. A total of 80 farmers with rubber trees aged 1–4 years were randomly selected for the study. This represents 10.2% of the total number of farmers (783) who fall within this target group in the districts. The results show that smallholder rubber plantation farmers are dealing with diverse weed species, most of which are reported as global weeds. Chromolaena odorata, Scleria boivinii, and Mimosa pudica were the most reported species. Manual weeding and application of herbicides are the major control methods adopted by the farmers in the study area with a small percentage (16%) also using cover cropping. The two major control methods cost farmers an estimated average amount of Ghc 618.24 ± 26.25 (US $140.51 ± 5.91) for one-time weed control per hectare. The average estimated cost of one-time manual weeding per hectare was higher than that of herbicide application per hectare. This estimated amount is only a fraction of the total economic cost of weeds to the farmers. The farmers are likely to spend more if, for example, the costs of yield loss due to weeds are captured. The study thus indicates that the cost of weed management is high for rubber outgrowers and essentially farmers are investing heavily in weed management to keep weed competition on-plantation relatively low. Given that the core objective of rubber growing is to maximize profits, this study recommends the application of herbicides to control weeds in rubber plantations since average estimated cost of herbicide application per hectare was lower than one-time manual weeding per hectare. This recommendation should, however, be weighed against the possible environmental impact of herbicides, which was not assessed in this study.