Devoloping an Action Threshold for Citrus Thrips on Lemons in the Low Desert Areas of Arizona

Abstract

Commercial and University citrus groves were sampled over a two year period in an attempt to develop mathematical models capable of predicting fruit scarring based on the population of immature citrus thrips on susceptible fruit. Five predictive models were derived. One model correlated used citrus thrips populations from fetal fall to 2.0 in. diameter fruit. While in the other models, thrips populations were divided into four distinct fruit size cohorts. Four of the five models were statistically valid. Based on these models, lemons ½ in. in diameter, should be treated with insecticides when the number of immature CT reaches 1.5 per 10 pieces of fruit. While fruit > ½ should be treated if immature CT reach or exceed 2.0 per 10 fruit.