California Citrus Thrips Pesticide Efficacy Trial, 1990

Insecticides were evaluated for the control of citrus thrips during spring, 1990 in Field 12 (20-yr-old Atwood navel oranges) located at the University of California’s Lindcove Field Station near Exeter, Calif. Pesticides were applied with a Bean hand-sprayer at 500 psi, outside coverage, approximately 200 gpa. The field was divided into 3 blocks with one replicate of each treatment allocated randomly within each block (except 8 replicates for the untreated control, 3 in two blocks, 2 in the third); each replicate consisted of four trees. Citrus thrips fruit scarring evaluations were taken in Oct 1990 on all fruit on the exterior of the tree from knee to eye level. Typical scarring levels on outside fruit as sampled in this study are approximately twice as high as percent scarring of fruit sampled from the entire tree (inside fruit are less severely scarred). Scarring was rated as: (a) none, (b) slight (any citrus thrips scarring), or (c) severe (complete ring scar or extensive surface scarring at a level that would cause downgrading of fruit in a commercial operation). Economic scarring levels in a normal year are approximately 5% severe scars (approximately 10% severe scarring of outside fruit as sampled in this study).