Impact of Abiotic Factors on Dialeurodes Citri Ashmead and its Chemical Control

The studies conducted at Punjab Agricultural University, Ludhiana from 1996–1998 revealed that Dialeurodes citri Ashmead revealed that its activity persisted throughout the year except during December-February and it had two critical periods of infestation, one is April-May and another from second fortnight of August to first fortnight of October. Low population recorded during March increased abruptly to its maximum in April - May (45–52 nymphs per 100 leaves). Mean temperature of 26–30°C, sunshine 8–10 hrs/day and wind velocity 3–4 km/hr were having a positive impact on build up of population. Correlation co-efficients between the nymphal population and various abiotic factors showed that only temperature (r = 0.69–0.75) played a significant role. All these factors as a whole contributed about 81–92 per cent (R² = 0.81–0.92) towards population fluctuations. Ethion 0.05 per cent or application of mixture of monocrotophos and diflubenzuron each at 0.05 per cent were significantly effective against D. citri compared to other treatments.