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Stress from weather conditions is a key factor when evaluating the cause of corn ear drop. Extreme high temperatures during silking (R1 growth stage) can result in a weak ear shank attachment. Ear shanks can be cannibalized for carbohydrates by the ear, leading to shank deterioration. Fungal infections and insect damage may also affect shank strength. Plants can recover after stress at the R1 growth stage and produce normal grain on the upper portion of the ear. This produces a heavier ear tip which the weakened ear shank may not be able to support, resulting in ear drop prior to harvest.1
The incidence of ear drop can vary by planting date, soil type, corn product, and other agronomic factors. Problems with specific corn products will not occur every year and are affected by factors other than genetics alone.
Problem fields should be harvested quickly. Growers should run the corn head as high as possible while adjusting ground and header speed for maximum ear retention. Operating the corn head higher than desired and leaving some lodged plants can result in higher yield than trying to get every plant into the header. Corn fields with ear dropped corn may have significant amounts of plant material remaining even after harvest. Using these fields to graze cattle may seem like the best option to utilize the available nutrients in the field. However, there are many factors to consider prior to cattle turnout.1
In fields with corn ear drop, it is important to first assess how much grain remains in the field prior to grazing. Any field that is grazed by cattle with more than eight to ten bushels per acre of grain can lead to acidosis (digestive problems), lameness and abortions, and in severe cases, death.2 To quantify the amount of corn remaining in the field, count the number of ears on the ground between two rows on 1/1000 of an acre (Table 1). For a more accurate estimate of loss, count multiple areas of the field and average the numbers.3
Count the number of kernel rows and the number of kernels per row on an average ear. Then use Table 2 to determine the amount of yield lost. For example, if an average ear has 14 rows per ear and 37 kernels per row, then 5.8 bushels of corn per acre remain on the field. If there are 5 ears found within 1/1000 of an acre, then roughly 29 bushels of corn per acre would remain on the ground, which is more than the eight to ten bushels maximum allowed for grazing cattle.3 For more information including data for ears with small kernels visit the following web address:
To reduce the risk of feeding too much grain to cattle, it is important to harvest fields with ear drop quickly. Once the field is harvested, there are several management practices that can help prevent cattle from falling ill. The following recommendations may be used:
Continue to monitor cattle for signs of acidosis. Cattle may stop eating and look gaunt or stressed, as well as having loose, grey stools and elongated hooves.4