Trends in codling moth activity in apple orchards under mating disruption using pheromones in the Elgin area, Western Cape Province, South Africa
The reliability of decisions regarding spray applications for the control of Cydia pomonella (L) using pheromone trapping in orchards under mating disruption and in orchards not under mating disruption was compared. Observations were made on the long-term trends in C. pomonella activity, pesticide use and damage levels in orchards under mating disruption. Decisions regarding spraying in orchards under mating disruption are less reliable than in orchards not under mating disruption (7% and 3% probability of making an incorrect decision respectively). Codling moth trap catches were reduced after the introduction of mating disruption at the two trial sites. This was accompanied by a reduction in the number of codling moth spray applications from eight to 3-5 at the first site. At the second site nine sprays were applied during the season before the use of mating disruption. During the first and second seasons of mating disruption eight and six applications respectively were made to reduce C. pomonella population levels. Thereafter the number of spray applications specifically for codling moth control varied from 3-4. Fruit damage at harvest did not exceed 0.23% on the first site. On the second site there was 30-40% fruit damage prior to mating disruption. This was reduced to 1.02% during the first year after the introduction of mating disruption. Thereafter it did not exceed 0.58%.