Monitoring mites in pear orchards

Farmers reported difficulty with the control of pest mites on pears in the Ceres area. To determine when and if insecticides must be applied the development of phytophagous mite populations on different pear cultivars needed to be investigated for the development of an action threshold.

Phytophagous mites and their predators were monitored as described by Pringle & Giliomee (1992). During the first season monitoring was done every second week but thereafter every week. The degree of leaf scorching was also noted on the susceptible pear cultivars.

The number of phytophagous and predatory mites differed between seasons, cultivars and orchards indicating why it is important to use a monitoring system for their management. For the efficient control of mites orchardists have to monitor their mites regularly and only spray when necessary depending on the activity of predatory mites and if high temperatures are expected. Correct irrigation of orchards can minimise the development of scorching and the development of high mite numbers as they develop faster in trees under stress. The management of the cover crop is also important as spraying herbicides at the wrong time can cause high mite numbers early in the season in the pear trees which will lead to the development of early scorching and probably leaf drop. When severe this could have an influence on the crop of the following season.