Corn Ear Drop Causes and Management

• Corn ears laying on the ground are lost revenue.
• Dropped corn ears can result from agronomic interactions starting in the spring.
• Lost ears and kernels can be problematic for the next crop.

Regardless of cause, seeing corn ears lying on the ground is a hit to the pocketbook and the farm’s potential profitability (Figure 1). Every 3/4-pound ear lost in each 1/100 acre (435.6 sq ft) of field area represents about one bushel of lost yield potential.¹ Quick profitability calculations can make the stomach churn if five, 10, 15, 20, or even more lost ears are found per acre. Combines can’t gather ears that have separated from the stalk. Those on the ground but still attached to a lodged stalk may or may not be pulled into the header. Even if they are harvested, ears that have been on the ground for some time may have diminished grain quality if they’ve suffered from kernel sprouting, molds, or feeding by insects and wildlife. The damaged grain can result in lost revenue when sold directly to an elevator or, if stored, it could incubate storage molds that damage good-quality grain.

Causes of Corn Ear Drop

Usually, no single event causes ear drop. Interactions between compaction, drought, heat stress, moisture, insects, disease, planting date, soil type, wind, genetics, early frost, and other factors can all contribute to seeing those glaring yellow or husk-covered ears lying on the ground. Some example scenarios that can cause corn ear drop include, but are not limited to:

1. Compacted soil can restrict root growth which can reduce nutrient and water uptake, causing plants to prematurely senesce and leading to weakened shanks and ear drop.
2. Plentiful early season moisture and favorable pollination can result in well filled, heavy ears. But later-season drought or disease may cause the heavy ears to droop and eventually release from the shank.
3. Shank tunneling by European corn borers in corn products lacking B.t. protection can weaken the shank and result in ears dropping.
4. Stalk rots can reduce plant nourishment, resulting in weakened shanks and ear loss.
5. Ear rot diseases such as Diplodia can weaken the shank and result in ear drop.
6. A premature hard frost before black layer can pinch and weaken the shank.
7. Wind events that occur after the shanks have been weakened by—for example—the scenarios mentioned above may increase the likelihood of ear drop in affected fields.
8. A few corn products may have a higher tendency for ear drop; however, these products are usually identified during experimental evaluations and not released as commercial products.

To determine the cause of ear drop, the dropped ear and its associated plant should be examined with the following questions in mind:

• Is the ear well filled with good weight, or is it well filled and lightweight?
• Is the husk still attached to the dropped ear?
• Does the shank show signs of insect feeding, disease, or does it have reduced diameter?
• Is the plant prematurely dead?
• Does the plant have insect damage or appear healthy?
• Is the stalk crushable?
• Is the root system restricted from compaction, insect feeding, or diseased?
• Is there a difference between corn products and is the difference represented in other fields with the same agronomic factors, such as planting date, moisture, drought, etc.?

Answering these questions will help growers determine which of the above scenarios, or other situations, may have resulted in the ear drop experienced in their field.

Measuring Potential Corn Yield and Economic Loss from Dropped Corn Ears Preharvest

Measurements and calculations can be made to help estimate potential yield loss and economic impact from preharvest ear drop. When going to the affected field, take a measuring tape to mark an area for evaluation. Walk into the standing corn and measure row length equal to 1/100^th acre based on header size (Table 1). For example, the 1/100^th acre area for an 8-row, 30-inch head would be 21 feet, 10 inches long by 20 feet wide.

Within that area, count the number of ears by relative size (full-size or small) within the measured area and record that information. Full-size ears (about 3/4 lb each) represent about one bu/acre loss in potential yield and three small ears (about 1/2 lb each) represents about two bu/acre of lost yield potential. For example, 15 full-size (3/4 lb) ears found in the 1/100-acre area would represent about 15 bu/acre potential yield loss. At $4.00 per bushel, that would be a potential economic loss of $60.00 per acre.

Table 1. Row measurement for 1/100th acre for three row widths.

Additional economic loss may be attributed to corn kernels shelling at the head or passing through the combine and being spread on the ground (Figure 2). This loss can be estimated by measuring an area behind the combine and counting the kernels lying on the ground or still attached to cobs within that area. Two kernels per square foot equals about one bu/acre loss in yield potential.¹ The amount of shelling at the head can be estimated by itself by backing up the length of the combine and looking for kernels on the ground between the head and standing corn. Safety note—to avoid entanglement in the header, the combine must be shut down before doing this estimation.

Minimizing Corn Ear Drop

As plants mature, fields should be scouted thoroughly for any ear drop and for potential ear shank weakness. Problem fields should be harvested as soon as possible with a well-adjusted combine, especially after a dry growing season. When excessive ear drop is observed, growers should run the corn head as high as possible while adjusting ground and header speed for maximum ear retention to help keep ears from flying out of the head during harvest.¹

Reclaiming Value from Dropped Corn Ears

Methods do exist for reclaiming lost value from dropped ears. For example, some growers have enlisted the help of willing charitable organizations to pick up and sell dropped ear grain to help support their causes. However, this method can take a lot of people and time, neither of which are usually available.

Alternatively, grazing cattle on corn residue after an ear drop issue may be an option—though precautions are needed to help reduce the risk of overconsumption of grain leading to acidosis in the cattle. Management options to reduce the risk of acidosis in cattle include controlling the type of cow allowed to graze, providing supplements, reducing the area of the field available for grazing (fencing off paddocks in the effected field), and providing hay to the cattle prior to grazing.²

Managing Yield Loss From Volunteer Corn

Dropped ears can result in volunteer corn plants in the next crop (Figure 3). Volunteer corn plants can reduce the yield potential of future crops through competition and may become a source for rootworm beetle feeding and egg laying in a soybean crop (Figures 3 and 4). Crop rotation expands the herbicide options for controlling volunteer corn. Also, planting corn with trait protection against certain above-ground insects (especially European corn borer), can help reduce the risk of ear drop by providing protection against shank-boring insects.³ Please see Managing Volunteer Corn in Soybeans, Volunteer Corn Management in Corn, and Selecting Trait Technology for Corn Insect Management for more information.

Sources

¹Hanna, M. 2008. Profitable corn harvesting. Iowa State University. PM 574. https://dr.lib.iastate.edu/server/api/core/bitstreams/262806a1-666a-4c06-9816-f3bc5d8b6951/content
²Stewart, J. 2012. Expert: Exercise proper management when grazing corn fodder. Purdue University. https://www.purdue.edu/newsroom/releases/2012/Q4/expert-exercise-proper-management-when-grazing-corn-fodder.html
³Thomison, P. 2012. Stalk lodging and ear drop impact corn yields. The Ohio State University, Agronomic Crops Network. C.O.R.N. Newsletter 2012-37. https://agcrops.osu.edu/newsletters/2012/37#1
Web sources verified 6/16/26. 1214_153352