SAMPLING NURSERY STOCK

Strategies for individual nursery situations involve subjective on site judgment. The greater the potential loss, the greater the sampling intensity that can be justified. For routine (nonregulatory) monitoring of container-grown plants to maintain plant health and product quality, extraction of nematodes from single pots may not adequately reflect the situation in a whole block. Removing single cores from a series of pots and bulking them into a composite sample provide a sample representing more plants. A convenient sampling rate of 1-gallon and 5-gallon containers is one core per 100 containers. If the plant is particularly susceptible or if nematode problems are suspected, the block of containers should be divided into groups of 2,000, with each group represented by a single sample of 20 cores. For a more routine sampling, cores from the whole block may be composited into a bucket, mixed thoroughly, and a 1-quart sample removed to represent the block. The proportionally larger sample taken from smaller containers by this approach will help detect earlier stages of nematode infestation on young plants. Core sampling is excessively destructive in containers smaller than 1 gallon; however, the same criteria can be applied by destructively sampling one container per hundred as representative of a single core. The number of cores and sampling pattern for nursery plants in raised beds depends on the value of the plants and potential magnitude of the problem. Representing each bed by one sampling of several cores provides information on the occurrence of nematode problems in individual beds and allows individual bed treatments. If a nematode problem is unlikely, a single sample may represent several beds; this, however, may result in a need for subsequent sampling to identify distribution of a population.

From: McKenry, M.V. and P. A. Roberts. 1985. Phytonematology Study Guide. University of California, Division of Agriculture and Natural Resources. Publication 4045.

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