Corn pollination can easily be considered one of the most important periods of crop development. For a corn farmer, this time period of crop development and reproduction is what ultimately makes the grain. Any negative impact to a corn plant at this time can have significant consequences to overall grain production.

Unlike other grain crops, corn plants have separate male and female flowering parts; the tassel and ear shoot are the male and female structures, respectively. The flowering stage in corn – which involves pollen shed and silking – is the most critical period in the development of a corn plant for grain yield determination. Drought, high temperature, hail and insect feeding have the greatest impact on yield potential during the reproductive stage.

Pollination, which involves pollen shed from the tassel, usually begins two to three days prior to silk emerging from the ear. This process will continue for five to eight days, with peak shed on the third day. During a typical good weather, mid-summer day, the shedding of pollen is at its peak in the mid-morning. Pollen from the tassel is very light weight and is often carried large distances by wind, however, most of the pollen settles within 50 feet. Pollen shed is not a continuous process; it stops when the tassel is too wet or too dry and begins again when temperature conditions are favourable. Once successful pollen contact with the silk has occurred, the pollen grain immediately starts the growth of the pollen tube down the silk channel; the pollen tube will grow the length of the silk and enter the female flower (ovule) within 28 hours. A well-developed ear shoot can have 750 to 1,000 ovules (potential kernels) with each producing a silk, however, only 500 or so develop into harvestable kernels.

Due to the importance of this short, yet critical stage, any stress from drought, excessive temperatures, hail, or insect feeding will have a significant impact on yield potential. Best management practices will reduce the overall risk exposure from these stresses. They include spreading out your planting dates and developing a hybrid portfolio with your seed specialist that conveys solid genetics with a range of flowering dates to minimize risk during this crucial period.

Planting season is just around the corner, have you talked to your seed specialist yet?

Dave Emery, CCA-ON
Maizex Seeds District Sales Manager, Southwestern Ontario
Twitter: @emeryda

Aldrich, S. R., W. O. Scott, and R. G. Hoeft. 1986. Modern Corn Production. 3rd edition. A&L Publications (Chapter 1 – “How the Corn Plant Grows”). Peter Thomison  – Ohio State University Extension  Department of Horticulture and Crop Science