Posted 12 August 2008. Crop Management.

Cornfield Birds & Bees

University of Illinois at Urbana-Champaign. aces.illinois.edu

Urbana-Champaign, Illinois (July 24, 2008)--2008 is shaping up to be a year for the record books and we are now entering the critical pollination period for corn. Markets have been extremely volatile as farmers, grain traders, and USDA try to determine the potential size of this year's crop. I have had producers who have farmed for over fifty years comment that they have never had such a challenging season and we still have couple months to go! Last Monday's weekly USDA crop condition report had 63% of Illinois' corn in good to excellent condition, 28% fair and 9% poor to very poor. Average corn height was 47 inches compared to an average of 63 inches. We should start to see some tassels emerge this week and our pollination period will cover several weeks as the crop is extremely variable with numerous replanted areas. The recent heavy rain has refilled many of the ponds so much of the replant will be lost.

Inquiring minds have been asking just what exactly happens during the corn pollination period so let's review the cornfield "birds and bees." Special thanks to University of Illinois Extension Crops Specialists Emerson Nafziger and Dennis Bowman plus Purdue University's www.kingcorn.org web site.

• Corn is a monoecious plant with both male and female flowers on the same plant.

• The tassel is the male flower.

• Most central Illinois corn fields will begin pollinating next week through the first week of August due to delayed planting.

• Corn tassels produce between 2 million and 25 million pollen grains.

• Peak pollen shed occurs mid-morning or late in the afternoon.

• Pollen grains are 80% water when shed and die when water content decreases to 40%.

• The silks that emerge from the ear shoots are the stigmas of the female flowers of the corn plant.

• Each silk connects to an individual ovule (potential corn kernel).

• Each silk must be pollinated for the whole ovule to be fertilized and develop into a kernel of corn.

• Up to 1000 ovules form per ear but we normally harvest 400 to 600 kernels per ear.

• As silks emerge, they grown as much as 1.5 inches per day.

• Unusually long silks are a symptom that the ear was not pollinated.

• If rootworm beetles or Japanese beetles have clipped silks below one-half inch before 50% pollination, control measures may be warranted.

• Check pollination by using the "ear shake method." Gently remove husks and gently shake the ear. Silks fall off fertilized ovules and remain attached to unfertilized ovules.

• 85% of grain yield is determined by the number of kernels produced per acre and 15% due to the weight of individual kernels.

Weather over the next 30 days will determine the size of the 2008 crop. We are going into pollination with surplus moisture and seasonal temperatures so stay tuned!