Russeting is characterized by the development of a cork layer among the epidermal cells giving an aspect of rugosity to the fruit surface, reducing its marketability. Fruit thinning is a technique widely used by apple growers. It can be done by hand or by using chemical thinning or by both, chemical and hand thinning. Among the most used chemical for thinning are naphthaleneacetic acid (NAA) and the insecticide carbaryl, commonly known as Sevinâ. In the Brazilian market there are two formulations of carbaryl: wetted powder and flowable solution. None of them are registered as chemical thinning for apple in Brazil. However there is not enough official research data in Brazil in this area that could support the best choice as far as russeting on the fruit is concerned. Some authors say that carbaryl may cause russeting on apples. This trial aimed to evaluate the two carbaryl formulations comparing its effect concerned to russeting. The experiments were carried out in two areas: Fraiburgo and Caçador, Santa Catarina State, Brazil. Two concentrations: 500 ppm and 1.500 ppm of each formulation were tested. One of the formulations was a wetted powder with 85% of a.i., the other was a flowable solution with 48% of a.i. As the incidence of russeting on apple may vary according to cultivar, the experiments were carried out on 'Gala', 'Fuji' and 'Golden Delicious'. It was concluded that: 1) Fraiburgo climactic conditions were much more favorable to russeting than those in Caçador; 2) carbaryl did not cause russeting on 'Gala' and 'Fuji' in both locations; 3) Carbaryl as flowable solution caused more russeting in 'Golden Delicious' at Caçador, so this formulation should not be recommended for this cultivar.
russeting; chemical thinning; carbaryl; naphthaleneacetic acid; apple
