Estimating Yield and Fruit Numbers of Apple Trees from Branch Samples1

Yield and fruit numbers data were collected from whole trees and sample branches in 4 orchards of 3 cultivars of apple ( Malus domestica Borkh.) over a 4-year period. Coefficients of correlation between yield/tree and (crop load × geometric mean of trunk circumference and trunk cross-sectional area), and between number of fruits/tree and (fruit set × geometric mean of trunk circumference and trunk cross-sectional area), were 0.91 and 0.93, respectively. Using regression analyses, the error of estimate for individual trees was ±11.0% for yield/tree and ±10.4% for number of fruits/tree. The corresponding values for treatment means were ±6.4% and ±5.4%, respectively.