Weather raises concerns for corn pollination

Cornfields across the region are entering one of the most important phases of the growing season: pollination. Because each corn plant flowers only once, the success of pollination will determine how many kernels ultimately fill each ear. Poor pollination leads to barren or partially filled ears, making the next several weeks essential for yield potential. Pollination occurs when pollen from the tassels (plant's male flowers) lands on the silks emerging from the ear (plant's female flowers). Each silk corresponds to a potential kernel, and the pollen grain must travel down the silk to fertilize the ovule. A well‑developed ear contains 750 to 1,000 ovules, meaning the plant must successfully pollinate hundreds of silks in a short window. Pollen shed typically begins two to three days before silks emerge and lasts five to eight days, with peak shed occurring mid‑morning once dew has dried. Each tassel produces millions of pollen grains, most of which settle within 20 to 50 feet of their source. Pollen remains viable for only 18 to 24 hours, and shed stops when tassels are too wet or too dry. Silks emerge from the base of the ear first and from the tip last, usually over a three‑ to five‑day period. Silks continue to elongate until pollinated, and long, unpollinated silks often signal timing problems — typically when hot, dry weather causes pollen shed and silk emergence to fall out of sync. Silks turn brown once pollination is complete. By the time pollination begins, the corn plant has reached full height, produced all its leaves, and the number of potential kernels has been determined. The remainder of the season will affect how many kernels will abort at early grain fill, and the final kernel size and weight. Yield ultimately depends on ears per acre, kernels per ear, and kernel weight — each influenced by environmental conditions at different points in the season. Corn transitions to reproductive growth once silks appear, moving through six stages R1 (silking), R2 (blistering), R3 (milk), R4 (dough), R5 (dent) to R6 (physiological maturity). Most hybrids reach maturity about 60 to 65 days after pollination. Farmers in this area aim for pollination to finish by August 1 to ensure the crop reaches maturity before the region's typical first frost around Oct. 10. Weather during pollination can be a deciding factor in yield. Extended heat and drought can shorten pollen viability, dry out silks, or cause silks to emerge after pollen shed has ended. Farmers try minimize the risk of a total pollination failure by planting hybrids of different maturities across their farm operation, so all fields are not pollinating at the same time. In the northern part of the county, the 2025 season offered a stark reminder of how quickly pollination can fail under extreme stress, resulting in barren ears and scattered kernels across many fields. As July progresses, farmers will be watching their fields closely. Pollination is underway or approaching in most early‑planted fields, and the weather during this brief but critical window will play a major role in determining the size of the 2026 corn crop. Ideally, farmers would like to see moderate temperatures and periodic rain over the next several weeks to ensure successful pollination and strong kernel set. Ed Lentz is agriculture and natural resources educator with Ohio State University Extension — Hancock County.