Codling moth granulosis virus: effects of its use on some other orchard arthropods

In four field trials from 1978 to 1980, sprays of codling moth granulosis virus (CpGV) plus 1·0% skimmed milk powder did not significantly affect damage to fruit by leaf rollers (tortrix moths). In laboratory tests, survival of larvae of the leaf roller Archips podana fed on leaves sprayed with CpGV plus milk was unaffected and they grew faster than on unsprayed leaves, because of the milk deposits. This might increase damage by A. podana if CpGV plus milk were applied during the feeding period of this species. In one field trial an unusual infestation of fruit by larvae of pith moth Blastodacna atra was not affected by CpGV. Azinphos-methyl significantly reduced damage by B. atru and, in one field trial where sprays were correctly timed, that by leaf rollers. CpGV had no consistently significant effects on numbers of fruit tree red spider mite Panonychus ulmi or its predators, whereas azinphos-methyl induced outbreaks of P. ulmi by killing its predators.