Department of Entomology, Punjab Agricultural University, Ludhiana-141 004 (India)
The Turbair sprite and the motorized knapsack sprayer gave significantly better performance up to 10 days in causing mortality of psylla, Diaphorina citri Kuwayama on citrus (sweet orange) by the application of dimethoate LVC (250–500 ml a.i./ha). The differences in the percentage reduction in the two sprayers were nonsignificant. However, both of these were better than the Fogair. The mean percentage reduction in the pest population by spraying dimethoate was 78–94 per cent in the recommended dosage (0 51/ha). It was significantly higher than 67–88 per cent in the L2 dosage (0.250 1/ha). The L; dosage (0.375 1/ha), giving a reduction of 72–93 per cent, however, did not differ significantly from the recommended dosage. The persistence of the toxicant for the control of the pest decreased progressively with the decrease in the dosages from the recommended one.
