How pheromone mating disruption works: Oriental fruit moth
Oriental fruit moth (cont from last issue)
For OFM, the response of the male moths to PheroKlip OFM and tube type mating disruption dispensers is a little different from codling moth.
OFM males are overwhelmed by the quantity of pheromone coming from the PheroKlip OFM dispensers. The sensors on their antennae become saturated with pheromone and can no longer detect presence or absence of pheromone—so the signal reaching the brain of the OFM male is, ‘nothing out there; all very boring’.
For this reason, mating disruption of OFM is not highly influenced by moth population density.
Practical considerations
Timing
Mating disruption must be applied before the first flight in spring.
Number per hectare
For codling moth—1000 per hectare
For OFM—500 per hectare
Placement
For codling moth—75% in the top metre of canopy 25% mid canopy
For OFM—upper third of canopy.
Pest population density
More of a consideration with codling moth than OFM.
Supplement with an insecticide program if numbers were high in the previous season.
Orchard hygiene
If there are trees from an old part of the orchard with a significant moth population that were bulldozed in winter, they will still have the larvae under the bark.
Burn the trees or chip them or do something before the moths emerge and fly in spring or they will head straight into your new clean orchard. You can’t afford to wait another season until the dead trees are nice and dry.
Bins that held culled fruit are also a source of infestation. Walnuts are also a host for codling moth.
OFM can breed up in apples, pears (including apparently dormant buds) and the shoots of cherries, plums and apricots and in newly planted peaches.
Take this into account when considering location of mating disruption treatments.
Invasion of mated females
Mated female moths do not respect fence lines.
The comments on orchard hygeine and management of high populations apply if you have an abandoned or poorly managed orchard over the fence.
See this article in Tree Fruit Oct 2018
