Peel back the husk and read the pattern. Kernels missing in scattered spots or whole stretches along the cob mean some silks never caught pollen. A bare tip with a well-filled base usually points to stress — drought, heat, crowding or low fertility — around silking and early fill. A tip that's chewed, with crumbly frass and sometimes a caterpillar, is corn earworm damage, not a fill problem. Ears that are short overall can mean the plant was stressed even earlier, during the weeks before silking when it sets how many kernels each ear can hold.
Pollination is the most common cause. Penn State Extension explains that each silk connects to one potential kernel, and pollen from the tassels has to land on that silk for the kernel to form. Corn is wind-pollinated, so in a single long row most pollen blows away from the silks. Plant a block of several short rows side by side — at least 4 rows — so pollen falls wi the patch. Silks keep emerging for 4 to 8 days, with the tip silks last, which is why the tip is often the first part left unfilled.
Drought and heat at silking come next. Mississippi State and Illinois extension guides both note that hot, dry weather during pollination leads to missing kernels, small ears and poorly filled tips. Penn State adds that drought slows silk growth while pollen keeps shedding, so the two can miss each other. Leaves that roll up during the day are the plant's sign it's short on water. Illinois Extension recommends irrigating thoroughly as tassels emerge, through silking and while the ears mature, soaking the root zone rather than sprinkling.
Spacing and feeding matter too. Illinois Extension lists planting too close, poor fertility and lack of potassium among the causes of unfilled tips, and recommends 9 to 12 inches between plants in the row. Mississippi State notes that poorly filled tips can point to low nitrogen, osphorus or potassium. Insects can also clip silks before pollen arrives: Illinois notes that corn rootworm beetles can strip silks heavily enough that cobs devel without a full set of kernels, so check new silks the first few days they emerge.
Ears with gaps are still good to eat. Pick them at the milk stage, about 20 days after the first silks appear, when a kernel punctured with a thumbnail gives milky juice. For the next planting, lay corn out in a block, space plants 9 to 12 inches apart in rows 30 to 36 inches apart, and with nitrogen when plants are knee-high. A soil test through your extension office shows whether phosphorus or potassium also needs attention. Then keep water steady from the time tassels appear until the ears fill.
- Corn Earworm / Tomato FruitwormCaterpillars eating corn kernels from the tip; same species bores into tomato and pepper fruit. Often called 'tomato fruitworm' when found on tomato.
- Blossom End RotDark, sunken, leathery patch on the blossom end of tomato or pepper fruit. The developing fruit is short of calcium, usually because of uneven watering rather than a lack of calcium in the soil.
- MoleRaised surface tunnels and conical soil mounds across garden beds — moles tunnel for earthworms and grubs, not plant roots.
- Bird DamageBerries pecked or missing, seeds scratched from beds, and seedlings dislodged — birds feeding on ripe fruit, seeds, or soil grubs.
- Brown Marmorated Stink BugSunken, corky dimples on fruit and pods caused by a mottled brown shield bug feeding through the skin.
- Why are my corn plants pale green or yellow-green?Pale or yellow-green corn leaves are a classic sign of nitrogen deficiency — corn is a heavy nitrogen feeder and requires more than most garden vegetables.
- What does drought stress actually look like, and how do I know when to water versus when something else is wrong?Drought stress progresses from midday wilting to all-day wilting, leaf curl, and eventually aborted fruit and flowers — the key is catching it before the plant has been dry long enough to abort reproductive structures.
- Why are the edges of my older leaves turning brown and scorched-looking while the centers stay green?Marginal leaf scorch on lower, older leaves — a brown or yellowing burn along the leaf edge — is a characteristic sign of potassium deficiency, which also tends to produce weak stems and poor fruit quality.