Mussel scale - monitoring

Mussel scale forms only a very small part of the scale insects which infest apple orchards in New Zealand. Therefore, it is not usually necessary to monitor specifically for mussel scale and it is better to concentrate on the major pest species, such as San Jose scale, oystershell scale, greedy scale, and latania scale. Monitoring and thresholds for fruit infestation in summer and at harvest are used for all scale species (combined) on the fruit at those times. There are three methods of monitoring mussel scale in apple orchards if required.

Monitoring of crawler release (method 1) provides a direct guide to when fruit are at risk from crawler dispersal and when fruit should be monitored to check infestation levels (method 2). Harvest monitoring (method 3) gives a measure of the success of the control programme over the past summer and can be used to determine the need for scale control in the following season. Monitoring in the apple IFP and organic programmes includes the last two methods for use by growers.

Shelter and other host plants around the perimeter or near to the orchard should also be checked for scale infestations as part of a shelter management programme, although this is also less critical for mussel scale than for the major pest species.