Codling moth populations less susceptible to CpGV: What about higher concentrations?

Summary

In an organic orchard with a codling moth (CM) population less susceptible to CpGV it was tested, whether an increased dosage of CpGV by factor 10 would result in any increased efficacy.
The applications were set in shorter than weekly intervals with 10 ml/ha Madex (low dosage plot) and 100 ml/ha Madex (high dosage plot). The higher dosage showed also a better efficacy, espe-cially on the “active damage” (live larvae).
The orchard where the experiments were conducted was known to have a less susceptible CM population (2004) although there were no serious CM problems reported by the farmer despite the CM control was done only with CpGV. It was investigated, whether natural antagonists might have been a reason for the absence of serious problems in this orchard. No signs of a strong presence of other antagonists were found but CM the population was increasing very much in the year the ex-periment was conducted (2005). Thus, probably the reason for the absence of CM problems seems to be just a delayed increase of the CM population after the development of a lower susceptibility of CM against CpGV.