Establishment of a Model to Estimate Crop Load on Sweet Cherry (Prunus avium L.) before Bloom

Spring frost damage in fruit trees is quite common in Spanish orchards, and when a spring frost event occurs it is necessary for insurance purposes to estimate the yield that could have been obtained under normal conditions. The aim of this work is to establish a model that allows early estimation of potential yield in sweet cherry (Prunus avium L.). During the years 2005 and 2006, in 68 commercial plots of sweet cherry trees there were obtained several measurements related to trunk area, scaffold area, flower bud and spur density. Crop density variables related to the rest of the variables through multiple and simple curvilinear regression models. The model which provided the best fit had scaffold crop density as dependent variable, and spur density per scaffold and scaffold cross sectional area as independent variables (R-2 = 0.67, P<0.001). The model was significant, consistent and appropriate for both years. The obtained regression coefficient is slightly lower than those found in earlier works with apple, pear, and peach, due to a higher variability in fruit set for trees of similar spur density, probably related to factors such as flower quality, nutritional levels or bee activity.