Mussel scale cultural control

	Mussel scale - cultural control

Mussel scale occurs on a wide range of host plants as well as in the apple orchard itself. Part of fruit infestations in summer originate from wind-blown scale crawlers moving into the orchards from shelter and other host plants. The presence of mussel scale on the bark of these plants (particularly on twigs among the leaf scars) can be checked at any time of the year (it’s easiest in winter when deciduous plants have no foliage) to find those with the highest populations. Once this is known, there are four ways of reducing the problem:

1.	Removal of the shelter or other host plants.
2.	Topping of shelter. This can reduce the numbers of crawlers in the shelter, reduce the distance they are likely to be carried by the wind, and assist with ensuring better spray coverage if the shelter is sprayed.
3.	Spraying of shelter in early spring and/or summer. Selective chemicals are available for use in IFP, and oils can be used by both IFP and organic growers. High volume spraying is vital to obtain good coverage. Shelter should be sprayed from both sides (or if this is not possible, from both directions on one side ).
4.	Replacing shelter with a more scale-resistant tree or variety.

Many orchards are affected by wind-blown crawlers of more than one species of scale. Mussel scale is rarely the main concern and more detailed information on shelter management procedures is provided in the sections on San Jose scale and oystershell scale. Mussel scale does not often reach the high densities of these other pests on shelter and other hosts. When this does occur, the same management procedures should be used as for the other scale pests. Significant risk of mussel scale infestation in pipfruit orchards can come from neglected apple trees or neighbouring stonefruit, particularly if trees are left unsprayed. Apple and stonefruit trees have been sometimes found highly infested with mussel scale. No published information has been found on the differences in resistance to mussel scale of different shelter species or selections.