Editor’s note: From the early planning stages through the end of the growing season, many factors influence the final yield numbers at harvest time. At right are three “kick-off” tips from the LSU AgCenter to help Louisiana producers realize their corn crop’s maximum yield potential.
Companies offer multiple hybrids for sale to producers for good reasons. Each corn producer has different soil conditions, irrigation practices and crop rotations than neighboring producers. Some hybrids tend to perform better than others based on soil type, planting date, weather conditions and location.
Tip 1: Hybrid Selection
Maturity groups are determined genetically, but the actual maturity date of a given hybrid depends on the daily temperature mean accumulation (growing degree units – GDU) above 50 degrees Fahrenheit for corn because little growth occurs with temperatures below that. Louisiana producers can grow early hybrids (100-108 days), mid-season hybrids (109-119 days) and full-season hybrids (greater than 120 days). Plant height, ear height and stalk strength all are factors that influence corn stands and, ultimately, yield.
Husk coverage is important in wet harvest seasons because loosely shucked hybrids may dry quicker but tend not to withstand the wetter, humid Louisiana harvest season as well as the thicker, tightly shucked ones. Grain quality can be affected along with susceptibility to aflatoxin infection. Some hybrids have tolerance to certain diseases such as leaf blights, rust and viruses. For complete information on participating hybrid characteristics, refer to Extension Publication RS 187, which can be found on the Web at www.lsuagcenter.com/corn.
Tip 2: Planting Rate And Depth
The optimal plant population for corn ranges from 25,000 to 30,000 live plants per acre. Assume 80 percent field emergence if planting early (plant 31,250-37,500 seeds per acre). The lower end of the recommended range should be used when lower yields are expected due to soil type, late planting date, drought-prone area or low fertility. Higher populations should be used on highly productive, deep alluvial soils or irrigated fields where moisture will not be a limiting factor.
Seed size and shape are not critical to a good stand, but be sure to use the correct plate and planter for the size purchased.
Corn should be planted 1.5-2 inches deep. On heavy soils, depth can be increased to two inches. It is vitally important to establish seed contact with moist soil, but planting seeds more than two inches deep can increase the probability of an uneven plant stand, which can affect growth and yield.
Tip 3: Planting Date
Corn should be planted as close as possible to the date of the average last spring freeze. The optimal planting window for south Louisiana is Feb. 25-March 20, and for north Louisiana the optimal planting window generally is from March 10 until April 1. In most years, April 15 is the last date for maximum yield potential. Extending planting to May 1 can result in a yield reduction of 30 percent or more.
Corn younger than V6 (6-leaf stage) usually can withstand a light frost if the temperature does not drop below 30 degrees Fahrenheit. A moderate freeze will burn any existing leaves to the ground, but new leaves can emerge in four to five days with higher temperatures. As the growing point moves upward near the soil surface, however, the possibility of injury increases.
For more information and to view charts, refer to LSU AgCenter Pub 2827, Corn Hybrids for Grain 2013.