Last summer my time was spent walking the corn and soybean fields of Southeast Iowa searching for weeds and pests that did not belong in the field. But why was I needed as a crop scout? Farmers’ livelihoods depend on their crops. Weeds and pests can easily overtake the field if not carefully controlled. It was my responsibility as a crop scout to identify the weeds and other possible concerns in the field and inform the farmer.
So what are crop scouts looking for in the field? First they look for any abnormalities in the plant. When plants are off-colored, chewed, stunted or dead, that could indicate issues that the farmer needs to be aware of. The causes could be soil, pest, or nutrient related, but it is important to determine the cause of the problem so it can be solved quickly.
The purpose of scouting is to give a representative assessment of the entire field. While scouting, it is important to look at multiple areas of the field. It depends on the size of the field for how many samples are taken. The rule of thumb is to check a minimum of five locations in fields of less than 100 acres. In fields greater than 100 acres, a minimum of 10 samples should be taken. Taking random samples is imperative to having a representative assessment of the field. Scouts do not just focus on the entrance, edges, waterways, high, and low areas, but rather randomly select various spots in the field to collect samples and stand counts.
A crop scout keeps busy early in the season identifying weeds that are in the field. Scouting for weeds before planting seeds allows the farmer to know what weeds are growing in the field, the growth stage of the weeds, and the weed populations. Controlling weeds before they reach four inches tall can help eliminate yield loss. After the weeds have grown over four inches tall, they are harder to control. Knowing what weeds are in the field allows the farmer to make better management decisions while it is easier to combat the weed issue in the field.
Scouting after the seeds are planting can show farmers seed damage, early pest damage, and many other factors. When plants start emerging, taking stand counts helps the farmer decided if they need to replant. They can also evaluate their management decisions and make changes for next years planting season. When taking a stand count measure 1/1000 of an acre. This measurement can be found by using the table below. Then count the number of plants in the measured area. Take at least six samples throughout the field. Then take the average number of plants and multiply it by 1,000 to calculate the final plant population per acre in the field. Most farmers plant corn at a rate of 29,000 to 38,000 seeds per acre and soybeans at a rate of 130,000 seeds for 21 inch row spacing and 210,000 seeds for 7 inch rows per acre based on 90% germination and 90% emergence rate.
Crop scouts also keep a watchful eye out for insects. The scout must identify the insects present in the field, what ones are harmful, the amount of insects, and assess the damage caused by the pests. Damage can be seen by observing the foliage, seed heads and pods, stems and roots. By swinging a net over the top of the crop canopy, scouts are able to capture insects in the net and get an accurate estimate of how many insects there are per square meter. Inspecting the top individual leaves for insects can also be done in addition to using a sweep net. It is important to observe the stem and roots to look for any signs of damage. Punctures on the stem can indicate insect damage. Signs of chewing can be an indication of insect damage even when you do not see any insects at the time of the scout.
Knowing the symptoms of plant diseases, is another important skill for crop scouting. Plant diseases can be caused by weather, fertilizers, nutrient deficiencies, herbicides, and soil problems. Watch this video for a quick rundown of corn diseases from an Iowa State University Field Pathologist.
Farmers want to make sure they know what is occurring in their fields, so they are sure to scout for weeds, pests, and diseases. Next time you drive by a corn or soybean field, take a look to see if there is someone out scouting a field.
P.S. Did you ever spend time walking fields as a crop scout? Tell us about your experience in the comments below.