Relationship between thrips (Thrips tabaci Lindeman y Frankliniella cestrum Moulton) on lable grapes at bloom and on scarring of berries at harvest. l. Chemical control

Renato Ripa S.1, Fernando Rodríguez A.1 y René Vargas M.1

The effect of thrips duríng bloom on the incidence of russeting of barrías al harvest time was studied on five cultivars of table grapes intwo localities: Los Andes, V Región, and Paine, Región Metropolitana. during two and one season respeetively. The effect of insecticides was tested at different times during bloom period and the population density of thrips determined. The presence of thrips was correlated with the incidence of russeting at harvest time. Two species of thrips were determined, Thrips tabaci and Frankliniella cestrum. In Los Andes T. tabaci exceeded 82% of the individuals, reaching a density of 80 adults and 267 nymphs per cluster in Thompson Seedless. In Paine their densities were much inferior reaching 4 adults and 10 nymphs per cluster. In this variety scarring which could be associated to thrips densities during blossoming was observad only in the absenca of insecticidetreatment. The cultlvars Ribier, Almería and Calmaría did notshow difference among treatments. This suggests that most of russeting is due to factors other than thrips at bloom time.

Keywords: thrips, Thrips tabaci L., Frankliniella cestrum M., russet, pesticides, control.
1 Estación Experimental Control Biológico La Cruz (INIA), Casilla 3, La Cruz, Chile.