No matter when your corn was planted, one thing holds true. It needs to be scouted, and perhaps this year more than ever. Warm, moist conditions set crops up for diseases. Widespread planting dates and late-planted corn in an area may impact which insect pests you see where.
Dave Nanda, director of genetics for Seed Genetics-Direct, advises grabbing a scouting book or your cellphone with an app and heading to the field. One quality resource with pictures of things you might see is the Purdue University Corn and Soybean Field Guide.
Nanda says what you will find often falls into these categories:
Normal growth stages. You can stage corn by counting leaves. Nanda prefers the method that counts the uppermost leaf with a collar as the final leaf to count. Knowing growth stage can help you make determinations as to when the growing point is above ground, and in some cases, if it’s still OK to make postemergence herbicide applications. You can also take stand counts at this point. In some cases, you can get a handle on planter performance based on stand counts and plant spacing.
Unusual growth patterns of little consequence. Sometimes a plant shows striping or some other symptom, and it’s the only plant showing that symptom. Occasionally, there’s an important cause, but often it’s just a quirk of nature. Remember, if you’re planting refuge-in-a-bag corn with a second hybrid included because a GMO insect trait is included in the main hybrid, you may see the occasional plant that looks slightly different from other plants.
Signs of nutrient shortages or disease. If you find plants showing classic signs of nutrient shortage, such as purpling, which is usually indicative of a phosphorus deficiency, it may or may not be important. Sometimes these are situational deficiencies, Nanda says, caused by weather conditions. The plant is truly short on phosphorus, but as soon as weather conditions improve, the deficiency will disappear. Purpling doesn’t always mean there is a true deficiency in the soil.
Disease lesions can appear relatively early. The sooner they appear, the more likely the disease could cause economic harm later. Note disease lesions and plan to scout regularly to monitor development.
Nanda’s best advice is to walk fields and pay attention. Try to explain as many potential problems as you can and figure out why you’re seeing what you’re seeing. This may help you make management adjustments for next season, even if it’s something you can’t correct this year.
Check out the slideshow to see photos of these situations.