The mission of the Plant Pest Survey Program is to provide current information on the abundance and distribution of important pests of Minnesota field crops. During the growing season, surveys are conducted in five agronomic crops: corn, soybeans, small grains, alfalfa and sunflowers.

Quick Facts about the Plant Pest Survey:

• Over 5,000 crop fields across Minnesota are sampled each summer.
• Over 50 different insect species are quantified across 5 crops.
• 18 disease symptoms are surveyed in small grains and soybeans.
• Over 100 weed species have been identifed in cropland weed surveys.
• Over 25,000 positive pest observations are made each year.

How the Survey Works:

The Plant Pest Survey collects data on insects, diseases and weeds during the growing season by field staff distributed throughout the state. The majority of surveys are performed June - August. For major crops (corn, soybeans, small grains) approximately five fields of a given crop are sampled in an average sized county. This varies somewhat by geography - for instance, in Polk County generally more fields are sampled overall then in Jackson County due to Polk's larger size. Also, few corn fields and many small grain fields would be sampled in Polk County relative to Jackson County due to the differences in the acreages of the crops. The number of fields needed to make an accurate estimate varies (by geography, the target pest, etc) - but 5 per crop, per county is a compromise between these factors and what is reasonable for staff to accomplish.

Fields to be sampled are selected objectively as field staff use a regular distance (generally 10 miles) to space sampled fields. For instance, a surveyor enters a county and samples a soybean field, then drives 10 miles and samples the first soybean field found after driving the predetermined distance regardless of the condition of the field. This is done to ensure that counts represent the average conditions present in an area and are not biased towards fields with higher or lower pest conditions.

Sampling within individual fields is also done objectively. Surveyors strive to enter a given field without letting field conditions influence their choice of entrance location. Once in a field, a pest is sampled repeatedly along a transect with fixed spacing so as to try to achieve an accurate estimate of the pest conditions in that portion of the field. Sampling is done by sweep netting, inspecting individual plants, inspecting a certain unit of the ground, or by other means depending on the crop and the target pest. Typically a surveyor will employ multiple sampling methods in an individual field and will be estimating numbers of multiple insect species as well as the presence of disease or weeds.

The sampling program is designed to serve as a resource for information on current regional pest conditions. This means that a relatively large number of fields are sampled (lots of data points at a regional level) and therefore less time is spent sampling each individual field. Consequently, estimates are geared towards accuracy at a regional level but not at a field level. In other words, the data generated is a good reference for current regional pest conditions. However, in every region there will be departures from the average and therefore the data are not meant to be used for decision making at the level of an individual field.

Pest Report data should be used as a scouting guide - not a management decision making tool. For instance, the Pest Report can be used to decide when to scout and what to scout for, however it should not be used to decide when or if a treatment should be applied.

Check out the Minnesota Pest Report for the latest on field crop pest conditions in Minnesota.