ECONOMIC EVALUATION BETWEEN CHEMICAL THINNING VS. HAND THINNING IN 'WILLIAMS' PEAR

Fruit thinning programs are vital to obtain high quality fruit that allows the grower to compete in international markets. In some pear growing areas, chemical thinning practices are less used than in apples. Usually some chemicals applied to apples have less effect in pears, like NAA, or do not have any effect, like carbaryl. However, there are studies that show the efficacy of benzyladenine (BA) as a thinning agent for ‘Williams’ pears. The objective of this work was to determine the economic viability of BA use as a substitute for hand thinning through Partial Budget Methodology. Data were taken from thinning trials performed on ‘Williams’ pear trees in two different experimental plots, with a plantation design of 4 m between rows and 1.5 m between plants for the first plot and 4 m between rows and 3 m between plants for the second plot. Trees in full production grafted on seedling rootstock had homogeneous vigor, health, nutritional status, flowering and fruiting. BA was applied at 100 and 150 ppm by spray solutions with a volume of 1500 L/ha in the first plot and 2500 L/ha in the second plot. Volume rates were calculated according to the Tree Row Volume (TRV) methodology. Both plots had an untreated control. In November all the treatments were hand thinned to calculate hand thinning labor cost. At harvest all fruit were classified according to size. Harvest costs and yield per hectare were also determined. Results showed that in the case of the first plot for the 100 ppm treatment, there was a return of 120 U$S due to labor savings in harvesting and hand thinning. Application costs were higher in the second plot than in the first, due to a larger TRV and that implied a negative result.