Chemical thinning of 'Sensação' peach trees

Peach tree thinning is essential for harvesting quality fruits and maintaining balanced fruit production for several years. Manual thinning of peach trees requires a large workforce, thereby increasing the production costs. Chemical thinning may be an alternative solution, but its efficiency depends on the dose of the chemical and plant species. This study aimed to evaluate the effect of different concentrations of metamitron on the chemical thinning of peach trees in southern Brazil. The experiment was carried out in a commercial orchard of peach cultivar 'Sensaçao' in Morro Redondo, Rio Grande do Sul (RS) state, Brazil. Different metamitron concentrations 100 mg L-1, 200 mg L-1, 300 mg L-1, and 400 mg L-1 were applied, and manual thinning was carried out 40 days after full bloom (DAFB) and to the treatment where the plants had no thinning. Fruit abscission, effective fructification, total number of plants per plant, production per plant, mean mass, and fruit diameter were evaluated. Applications of 300 and 400 mg L-1 metamitron 40 DAFB promoted high fruit abscission, in addition to decreasing the number of fruits and production. In contrast, applications of 100 and 200 mg L-1 of metamitron 40 DAFB was as efficient in thinning as manual thinning practice with respect to fruit production and fruit mass and its diameter.