Most corn growers have been patient this spring and avoided planting too early.
Now corn planting is starting and soon we will be evaluating our corn stands.
Timely scouting for corn emergence problems is an essential part of a top corn management program. Early diagnosis of problem fields can lead to timely replanting decisions and management changes that can avoid future problems.
Corn should begin emerging after about 100 to 150 GDDs have accumulated following planting, so plan scouting accordingly.
Here’s a list of a few common problems you might see this year.
• No seed present. This may be due to planter malfunction, bird or rodent damage. Birds have been an increasing problem in some areas.
• Coleoptile unfurled underground. Could be due to premature exposure to light in cloddy soil, planting too deep, compaction, soil crusting, extended exposure to acetanilide herbicides under cool wet conditions, or may be due to extended cool wet conditions alone.
• Seed with poorly developed or twisted radicle or coleoptile. Coleoptile tips may appear brown or yellow. This could be chilling injury or seed with low vigor. It could be an issue on very early planted fields.
• Seed swelled but not sprouted. Often poor seed-to-soil contact or shallow planting where the seed swelled then dried out. This could be a particular problem this year in dry, tilled seedbeds if corn is planted less than 1.5 inches deep.
• Skips associated with discolored and malformed seedlings. This may be caused by herbicide or insect damage. Note depth of planting and herbicides applied compared with injury symptoms such as twisted roots, club roots, or purple plants. Look for wireworm or garden symphylans feeding on roots or seeds.
• Seeds hollowed out. Seed corn maggot or wireworm. Look for evidence of the pest to confirm. Seed corn maggot flies are very prevalent this year and most damage should be controlled with typical seed treatments.
Note the patterns of poor emergence. At times they are associated with a particular row, spray width, hybrid, field or residue that may provide some additional clues to the cause.
Often two or more stress factors interact to reduce emergence where the crop would have emerged fine if only one stress factor was present.
Also, note the population and the variability of the seed spacing. This information is valuable to assess planter performance.