SUMMARYUse of substituted phenoxyacetic acids as yield stimulants for Hevea brasiliensis has been mainly limited to applications below the tapping cut rather than above. Although the above-cut application of these stimulants has exhibited some advantages with respect to yield, its use has been limited due to undesirable bark renewal characteristics. This paper describes studies with a method of above-cut application of stimulant which appears to eliminate the previous disadvantages. Reduced concentrations of growth regulator, applied at frequent intervals in combination with a disease preventive measure, resulted in favourable yield responses, bark renewal characteristics and application economics. Subsequent bark renewal was apparently directly proportional to the concentration of stimulant applied and it was thus possible to control the degree of bark regeneration. The above-cut method shows promise of being particularly effective with systems of reduced intensity tapping on certain clones.

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