NEWS for North Dakotans
Agriculture Communication, North Dakota State
University
7 Morrill Hall, Fargo, ND 58105-5665
June 4, 1998
Checking crops from behind the windshield of a vehicle is not how to scout fields. Only through regular in-the-field inspections can producers evaluate how their crops are progressing and identify pest problems early.
"Record insect, weed and disease infestations on a map or drawing when you walk your fields," says Duane Berglund, extension agronomist at North Dakota State University. "Making an illustrated note of where pests are located will reduce pesticide costs. If one part of a field is heavily infested with weeds, for example, you can spot spray instead of treating the entire field."
Producers should cover as much of a field as possible without duplicating their path, Berglund says. Include sections of fields where pest problems are probable. For example, grassy areas at field margins are a likely place for grasshoppers.
Growers should check fields at least twice a week for emerging weed problems starting early in the growing season, Berglund says. They should make written or mental notes of weed stage, species and number, and check underground (1 to 2 inches) for sprouting weed seedlings.
Berglund says mornings are the best part of a day for field checking. Some weed seedlings, especially grasses, curl and wilt in the afternoons and are harder to identify then.
Weeds and insects are generally evaluated for treatment on a plant- or insect-per-square-yard basis. When monitoring for diseases or insects, producers should start with an infected plant and then inspect the next 19 plants for similar problems. Findings should be recorded as a number of infected plants per 20 or number of insects per plant.
"It’s important to know the density of weeds in field areas," Berglund says. "If you have only one or two weeds per square yard, that’s not much to be concerned about, but it becomes serious if you have five to 20 weeds per square yard because economic losses are highly possible."
Make inspection stops in at least five different places in fields up to 80 acres, adding an extra stop in a field for each additional 25 or 30 acres. Generally, each corner quadrant and the middle of a field should be scouted. This can be accomplished by walking a z-shaped pattern. Paths through odd-shaped fields should be laid out to fit the field outline.
"Enter a field at different areas each time you scout so sampling locations are varied from previous stops. After a few weeks much of the field will have been inspected," Berglund says.
Inspect problem areas of fields during subsequent visits or as long as the problem persists. Growers must learn to distinguish between similar weed or insect species when they scout, Berglund says. For example, wild oat has lighter color than wheat in the seedling stage and grows outside seeded crop rows.
"The best way to recognize wild oat is to pull a suspected plant out of the ground. A wild oat kernel will usually still be attached to the plant base," Berglund explains.
Crop consulting services can be a valuable alternative for growers who don’t have a lot of time to adequately scout crops. Hired crop consultants or field scouts are also more beneficial for growers with high-value crops such as potatoes, sunflower, corn, dry edible beans, sugar beets and certain irrigated crops, Berglund says.
###
Source: Duane Berglund (701) 231-8135
Editor: Dean Hulse (701) 231-6136