Corn seedlings are most vulnerable and susceptible to damage from planting through the V6 growth stage. You must identify early season problems to make important input decisions and save yields.
Travis Belt, Mycogen Seeds customer agronomist, encourages growers to understand the development stages of young corn and to scout fields early and often. He suggests scouting for these six problem areas from planting to V6.
1. Assess emergence and germination.
Uniform, poor emergence patterns can be blamed on various problems, including a jammed planter, excess soil moisture or insect damage. Germination failure can result from a seed's cell tissues rupturing from cold temperatures after planting. Understanding the cause of poor stands is the first step toward corrective action.
2. Identify early season stress.
"Environmental conditions or insect pressure may cause early season stress to plants, Belt says. Black cutworms, corn nematodes and slugs all are culprits that cause early season corn damage. Watch for wilted plants, stunted growth, yellowing and slime trails that indicate the presence of these pests.
3. Check for weeds.
"Weed pressure, especially early in the plant's life cycle, robs stands of valuable moisture and nutrients critical for maximizing yields, Belt says. Early germinating weeds include ragweed, velvetleaf and lambsquarters. Belt recommends applying a postemergence herbicide for hard-to-control weeds.
4. Study visual appearance.
Look for clues to overall plant health in the appearance of young corn. Purpling sometimes occurs during sunny days and cool nights. Yellowing may signal inadequate heat, sunlight or nitrogen (N). Discoloring caused by temperatures will be corrected in adequate weather. N loss should be further investigated.
5. Detect nitrogen loss.
Belt says the best way to determine if the yellowing of corn plants is due to N loss is to take in-season soil samples or leaf tissue samples. If tests show a deficiency, plan for a sidedress application.
6. Weigh alternative options.
If poor field conditions delayed planting or if plants have a poor stand, reevaluate the growing schedule and input decisions. Before considering replanting, Belt says to compare the yield potential of the existing stand with the yield potential of replanted corn.
"Properly identifying problems in early season corn helps growers make well-informed decisions on insect management, herbicide application and replanting to keep plants healthy and save yields at harvest, Belt says.