Answer: What you describe sounds like the result of incomplete pollination. Maybe the following will help you understand: When the ears of corn begin to develop, each kernal on the cob will have two silks attached to it. When the silks protrude out of the top of each ear, a tassle will have grown on top of the stalk of corn. Pollen develops in the tassle and is shed when it's mature. Corn is wind-pollinated, so it's important that the plants are close enough to their neighbors to receive a good dose of pollen. For this reason, we always recommend you plant so stalks grow in a block, rather than in a long row. When pollen reaches the silks, one grain travels down each tube and reaches the kernal, which begins the process of maturity of that kernal. If pollen doesn't reach a silk, for whatever reason, the kernal it's attached to will not develop. Since the potential is for every kernal on the cob to grow to maturity, poorly pollinated ears will have only some kernals that swell to maturity, and others that never develop. The most common reasons for poor pollination are 1) corn planted in rows rather than blocks, 2) rainfall when the pollen is released (avoid overhead watering, too!), 3) application of oil to the silks (to deter corn earworm) prior to the release of pollen from the tassles. Hope the above information helps you understand the reason behind your partially filled-out ears of corn.
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