ABSTRACT
Brown Bast is the main phenomenon which limits production in Hevea brasiliensis plantations, lying ahead of fungal diseases affecting roots, leaves, or tapping panel tissue. The disease is in effect mainly associated with too intensive exploitation of trees, leading to physiological imbalance and the stopping of latex flow. This physiological imbalance, aggravated by tapping, may also follow poor ecological conditions. The effect of ecological conditions, climate, and soil on the onset of the disease are examined in turn. This mainly concerns experimental or accidental traumatisms and the effect of tapping methods which enable Hevea to modulate outflow of latex and hence yield. Shortly after the establishment of selected populations, it appeared that high sensitivity to Brown Bast was a hereditary feature. In 1969, Milford defined the plugging index, clonal feature linked with production and thus to sensitivity to bark dryness.
