VARIATION IN CASHEW TREE YIELDS IN SOUTH-EAST TANZANIA AND THE IMPLICATION FOR MANAGEMENT OF CASHEW SMALLHOLDINGS

In 2-ha plots of mature cashew (Anacardium occidentale L.) trees in fa rmers' fields, cashew production showed large variations in relation t o local tree density and canopy ground cover ratio (CGCR). Maximum cas hew production usually occurred between tree densities equivalent to 4 0-80 trees hal but at one site where trees were small it occurred at 1 20 trees hal Below a CGCR of 0.4, cashew production was low and was us ually at a maximum between 0.5 and 0.6. Individual tree yields were hi ghly variable and were poorly correlated with density, canopy ground c over area, trunk cross section area, and yields of surrounding trees. In both on-farm and on-station blocks of trees, individual tree yields were highly correlated with their yields in previous years showing th at, at the same site, tree yields relative to each other were consiste nt from year to year. All on-farm sites contained an appreciable propo rtion of very low-yielding trees. The productivity of smallholder cash ew farms may be improved by a combination of selective thinning of poo r yielding trees and planting available spaces with improved material.