Brownheaded leafroller and other leafroller monitoring

The simplest method for monitoring leafrollers is with pheromone traps. These traps can be used (1) to identify the sources of leafroller outside the orchard, and (2) to estimate the activity of leafroller populations within orchards. Moths in traps may come from either external host plants or from the orchard itself. Perimeter traps can be a guide to external leafroller pressure on orchard blocks but are not useful in determining leafroller control requirements within the orchard. Internal orchard traps give good estimates of the leafroller population and the control required. It is therefore essential that pheromone trapping to determine spray decisions is done internally, at least 30 metres from block borders.
In many situations, it is not necessary to monitor all species of leafroller. Lightbrown apple moth is a common species in all the pipfruit regions of New Zealand, and catches of this species alone can be used as an indicator of the need for leafroller control. However, greenheaded and/or brownheaded leafrollers should also be monitored if they are locally important. Where more than one species is being trapped, single traps for the different species should be placed together at each trap site but a minimum of 4 metres apart. The traps should be hung in the orchard at the start of the spring flights of leafrollers and after the removal of bee hives. Traps must be correctly maintained and cleared each week. Poorly maintained traps will catch fewer moths and under-estimate leafroller control requirements. Trap density is important.
The numbers of moths caught in the traps can be used as action thresholds and determine the need for control measures. There are further factors to consider when monitoring in