Remember that although a reliable, representative sample is wanted, the object of sampling is to find trouble if it is there.
- Infestations are often patchy so the ground should be covered as well as possible.
- Particular attention should be paid to areas of the orchard with higher disease risk, e.g. for apple scab, dips or sheltered areas in the orchard where the trees are likely to remain wetter for longer.
- Ideally, the 10-20 or more trees will be spread over the whole block of fruit but in practice the sampling route will usually be a compromise between the ideal and the shortest route for covering the ground.
- The most awkward situation is where it is not possible to pass easily through the rows e.g. on hedgerow trees.
- In this situation it is necessary to walk up and down three or four rows.
Suggested routes in example orchards and sampling points are given in the attached diagram. Arrows indicate the route and places for pausing to inspect and sample trees carefully
Normally, the main variety is sampled but where another (pollinator ) variety is present and known to be susceptible to a particular pest, sample that variety instead for that pest (e.g. Worcester Pearmain or Discovery for fruit tree red spider mite, Egremont russet for rosy apple aphid, Gala for scab etc.)