Predicting white peach scale phenology on kiwifruit in Sichuan

White peach scale (Pseudaulacaspis pentagona) is a polyphagous pest of perennial horticulture in Asia and many other warm-temperate and tropical regions. In China, it is a serious pest of kiwifruit. The optimal time to control P. pentagona field populations is at the first instar stage of the first, spring generation. Three methods for predicting the hatching of eggs of the first generation from field populations were tested on kiwifruit in Sichuan, based upon the accumulation of heat units (day-degrees) above a developmental threshold, calculated as 10.75 °C. A method developed for P. pentagona control in tea in Japan gave excellent predictions of 50% hatching in 5 of the 6 years under study (2009–2014). The other two methods also gave acceptable predictions of dates of 50% egg hatching (within 5 days of field observed dates). These models may be used as a basis for forecasting spring insecticide application dates targeting the first instar stage (crawlers and settled ‘white caps’).