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Competency Area 1: Integrated Pest Management (IPM)

PO 8. Outline methods for sampling plant and pest material.

Pest sampling should be based on an understanding of the pest biology. You will need to know pest identification, what to sample (specific areas of the plant, % injury, numbers of insects, an assessment of weed population, etc.), when to sample, how frequently to sample and what constitutes a sample (such as 10 sweep net sweeps per sample site). Sampling for specific pests will often require use of special techniques. Information on pests of concern and when to expect them during the growing season (scouting calendar) for common pests of NY grown alfalfa, field corn, soybeans and wheat are presented in the Integrated Pest Management (IPM) Literature/Bulletin section. To obtain the latest information on sampling techniques for a specific field crop pest, consult your local Cooperative Extension educator, current Cornell Field Crop Guide to Integrated Field Crop Management, or the NYSIPM website.

Correct sampling is the key for obtaining useful field information. It is important to randomly select plants for sampling. Do not examine only the "best" and "worst" plants. A random sample is taken by walking to the general area to be sampled, and looking up to the sky, walk forward five paces. Begin the inspection procedure with the plant nearest the toe of your right foot.

Selecting an appropriate subsample method will depend on the mobility of the pest being scouted. Two subsample methods are recommended:

Consecutive plants are examined when the pest will not be disturbed by sampling procedures on adjacent plants. This method is appropriate for scouting pests such as cutworms, stalk-boring insects, weeds, and diseases.

Random plants are examined when mobile insects are being surveyed. In this case, the next plant examined should be some distance away to remove any possibility of recounting insects that may have moved from plants sampled earlier. Random sampling is the preferred sampling method for insects such as corn rootworm adults.

Sampling Patterns
Pests can generally be found in one of three distribution patterns in a field. Scouting efforts for particular pests should be selected accordingly.

Pattern I. Pests are expected to be uniformly spread over the field. In scouting for a pest with this distribution pattern, sample sites are chosen so as to be evenly distributed over the field, obvious influencing factors such as  field borders being excluded. Pests fitting this pattern would include European corn borer, corn rootworm adults, potato leafhopper, and most foliar diseases.

Pattern II. Pests are expected to be concentrated in particular areas of the field. Pests fitting this pattern would include black cutworm, white grubs, Phytopthora root rot, or other diseases that may be associated with wet areas within the field or with areas with different soil texture, drainage, pH, fertility, or cropping history. If pests are detected in one area and not in another, efforts should be made to subsample that region to determine the extent and severity of the pest infestation more accurately.

Pattern III.Pests are expected to appear at field edges first. Pests fitting this pattern would include common stalk borer in conventionally tilled corn, spider mites, armyworm, grass sawfly, grasshoppers, and alfalfa snout beetle. Sample for these pests by walking fence rows, ditch banks, and field borders.