IPMP3.0, Oregon State Univesity, Copyright 2000

TAKING SAMPLES

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Care of Samples
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 Core Sampler
Use a soil core or a small shovel to take nematode samples

How a field should be sampled depends on the condition of the field at the time. If the field is fallow and being prepared for planting, no living root material will be present, so taking samples with a soil probe is sufficient. After a mint field is established, it is important to take root samples to recover endoparasites which may be in the roots as well as soil samples for ectoparasites and endoparasites in the soil. However, if several years of sampling have not established the presence of endoparasites, taking cores with soil probes to collect soil-only samples is sufficient to sample for ectoparasites. Rechecking the field for endoparasites with root samples every four years or so would be a good precaution, however.

Taking a combined soil and root sample is best accomplished by taking small soil cores with a shovel. A small shovel like a clam shovel works well and a lily bulb planter takes a very good sample but needs to be reinforced to sustain the rigor of repeatedly penetrating mint fields. Sampling to a depth of 6-8 inches is generally sufficient. Konicek (1961) found 81% of mint nematodes in the top 6 in. and Pinkerton (1983) recovered 83% and 91% of root-lesion nematodes in the top 8 in. from healthy and stunted areas, respectively. Neither nematode appeared to migrate vertically during the year. While mint roots from healthy plants often penetrate deeper than 24 in. in healthy stands, they rarely reach beyond 6 in. in nematode damaged areas.

Subsamples/cores should be taken by walking the area in a zigzag fashion while stopping to take a core at predetermined intervals. This is the optimal walking strategy to uniformly represent the area with sufficient samples to obtain an adequate sample. Cores should be placed together in a bucket as they are taken. If the number of cores taken to represent an area accumulates too much soil, only a portion of each core needs to be included.