There are three basic methods by which a pest’s sex pheromone can be exploited for control:
- Mating disruption where the pheromone is used alone to interfere with the normal attraction of males to females by providing false trails and/or sensory overload
- Mass trapping where the sex pheromone is used to attract males to a trap where they are captured and killed physically
- Attract and kill where the sex pheromone attracts males to a device or place where they come into contact with an insecticide
The RAK 3+4 mating disruption system
RAK 3+4 is a combined pheromone control system which reduces fruit damage from codling moth (RAK 3) and summer fruit tortrix (RAK 4). Both pheromones disrupt mating behaviour and therefore prevent populations from developing. The pheromones are released from sealed chambers by volatilisation, preventing male and female moths from locating each other and reproducing.
- RAK 3+4 is most effective in orchards with a low pest population density. It should not be used in orchards where more than 1% of fruits (including fallen fruits) were damaged by codling and tortrix moths in the preceding year, unless the first generation of moths is treated with a control product to reduce initial populations.
- Best results are achieved in isolated orchards, i.e. those which are 100 m or more away from other orchards or high trees.
- Optimum results are also achieved in grouped orchards containing trees of similar size and shape.
- RAK 3+4 will not be effective if there is a high density of codling moth and/or tortrix moth in the area adjacent to the orchard being treated. It will not be effective in orchards less than 1 ha in area.
Timing of application and dose rate
- The pest population should be monitored using an appropriate pest forecasting system or monitoring traps and the product should be put in place one week before the forecast arrival of the adult moths.
- The latest time of application is when the first generation of adult moths start to fly. Only one application of product per season is required.
- The product is packaged in airtight bags and protected from the light. The package should therefore only be opened immediately prior to installation to avoid any loss of efficacy.
- RAK 3+4 should be used at a rate of 500 product units per ha. The density should be increased at the orachrd border – see below.
Positioning the dispensers
- The pheromone must be distributed evenly throughout the orchard in a grid system at 500 product units per hectare. One should be placed approximately every 20 square metres, e.g. for a row width of 3.5 m a unit should be placed every 5.7 m.
- It is important to make sure that they are positioned in the shade or in places which will be in the shade by the end of vegeative growth.
- The product must be placed in the upper third of the trees, preferably at alternating heights.
- The manufacturer provides further guidance on using additional pheromone around the orchard borders to prevent moths from encroaching into the treated orchard from adjacent areas.
- Further guidance is provided on the use of additional pheromone monitoring traps to check on the efficacy of the pheromone on a weekly basis.
Pheromone attract and kill:
The sex pheromone is incorporated into a material together with an insecticide (usually a synthetic pyrethroid).
- Blobs of the material are extruded onto the trunk and branches of trees throughout the orchard (typically 1-2 blobs per tree) at the start of moth flight, as indicated by pheromone traps.
- The males attempt to mate with the blobs, picking up a dose of insecticide in the process.
- The technique is effective and uses a fraction of the amount of insecticide used in an insecticide spray treatment.
- However, no product is approved for use in the UK currently.