Too early to quit scouting corn

Tom J. Bechman mature cornfield
KEEP SCOUTING: If this field had been scouted closely, someone may have caught stalk rot potential and marked it for earlier harvest.
Corn Pest Beat: Pests and lodging could still steal valuable bushels.

Should I continue scouting corn from now until harvest? If so, what should I look for?

This month’s Indiana certified crop adviser panel includes Traci Bultemeier, an agronomist with Pioneer near Fort Wayne; Jesse Grogan, a retired agronomist based in Lafayette; and Bryan Oversteet, an Extension ag educator for Purdue University Extension in Jasper County.

Bultemeier: Absolutely! Any insect, disease or environmental impact that affects the ear leaf or ear will impact yield. Working with your local Extension, seed company or private agronomist is useful in determining if you might need any rescue treatments. Yield can be impacted until physiological maturity. So, yes, there might be an issue in the field. But is it really cost-effective to treat it?

Tar spot is a leaf disease that can set in at any time given the proper weather conditions. Fungicide applications are generally recommended. Consult your agronomist to learn particular hybrids needing treatment, and how far and fast the disease is progressing on plants. Irrigated fields have shown more prevalence to tar spot in my area of northeast Indiana because conditions created in those fields are more conducive to tar spot.

Northern corn leaf blight may come on strong later in the season for susceptible hybrids. Typically, NCLB is an issue midsummer, but I have seen it progress well into fall on late-planted, susceptible hybrids.

For September through harvest, we should look for ear molds — particularly gibberella, which is the pink mold and can cause vomitoxin levels in grain. Gibberella sets in during pollination, so be sure to review your conditions during that time to know if you are more or less at risk.

Western bean cutworm feeding might well be past, but the damage is still there. Estimating how much grain will blow out the back of the combine or how much dockage you might get at the elevator due to damage from disease or insects is useful in marketing grain and planning for storage.

Grogan: Monitoring stalk and grain quality for harvest scheduling is an important reason for continued scouting in corn. Stalk rots begin to show in early senescence. These fields should be scheduled first for harvest, unless lodging is so widespread and severe that lodged fields are harvested instead.

Check for stalk rots with the push test. Push at least 100 randomly selected stalks at a 30-degree angle. Those that snap back are OK; those that break off or lean will eventually lodge. If 10% or more stalks lodge, the field should be harvested as soon as possible.

Ear rots can also sneak up on you. Husks should be pulled back and grain inspected after black layer. Look for the incidence and severity of ear rots such as fusarium, gibberella and diplodia. Fields with ear rots should be managed separately to minimize yield and quality losses, especially mycotoxin build up. Fields with ear rots should be harvested early and grain dried down to 15%. Grain with fusarium or gibberella ear rot would be evaluated for mycotoxin concentration.

Overstreet: Yes, the crop is almost complete. But I feel you should keep scouting for stalk strength and lodging. You may also want to scout for ear droppage. Some hybrids are more prone to this. The scouting at this time of year will help you plan your harvest schedule. You may need to prioritize some fields over others due to harvest issues.

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