Timing Applaud Applications for Control of California Red Scale, 1990

The efficacy of Applaud 50 W (30 g/100 liters) plus Citrex (0.5% narrow range oil with 50% distillation temperature of 22°C) applied at different times relative to crawler emergence was evaluated at two sites in 1988 and 1989/90. Trials were conducted in the eastern Cape Province of South Africa during winter and spring. California red scale population densities were higher in the first season than the second season and had dual and triple cohort population structures respectively. A completely randomized block design was used for each experiment with 17 and 20 single-tree replicates per treatment in 1988 and 1989 respectively. Treatments were applied with handguns at 35.7 kg/cm2 with thorough coverage. The two phenological times used for application were the onset of crawler emergence and mid-way between two peaks of crawler emergence (inter-emergence). Timing of applications was based on pheromone trap counts of males and the use of DD accumulated between 11.7 and 37.8°C. Long term average weather data was used to predict crawler emergence from male flight peaks using an interval of 241 DD. The percentage fruit infested (25 fruit/tree) was recorded.