Nature Notes – Corn is top crop in United States

By Jim Gilbert

Tassels are the male structures of corn. Last summer the first field corn began tasseling in the Waconia area on July 1. We are now noticing that tasseling is beginning, but much later than last year because of the late spring and late planting. Also, finally the first locally grown sweet corn is just available.
In Minnesota, corn is an annual, usually planted in May. Various varieties of sweet corn are harvested from July into September, with the main harvest time for field corn varieties stretching from late September through November.
Corn is a grass domesticated centuries ago by indigenous people in Mexico and Central America. The Aztec and Mayan people cultivated numerous varieties. Today 350 types are grown in Peru, and in the United States corn is the number one agricultural crop in both volume and value. Minnesota is fourth in the nation in corn production, following Iowa, Illinois, and Nebraska.
An average ear of corn typically has 800 kernels in 16 rows. That’s pretty amazing when you think of one seed being turned into 800, and sometimes more than one ear is produced on a single plant. Just think of the many uses and countless products coming from corn, including plastics, ethanol, cooking oil, corn syrup, and popcorn. But also ponder the pollination biology that makes it all possible. The tassels on top of the plants function to produce ample quantities of pollen to fertilize the female structures – the “ears.” The tassels normally emerge a day or so before the first silks appear.
Silks catch pollen, and there is one silk for each kernel of corn on a cob. Each silk is a long slender tube attached to the potential kernel on the ear, allowing the pollen grain to send its nucleus down to fertilize the egg and begin development of a kernel. It’s a mind-boggling process.

What’s happening outdoors now?
Annual cicadas began calling on July 6 this year; last year it was on June 15. The males sing loudly with a high-pitched buzz from up in trees. Their pulsating buzzing intensifies with warmth.
We have been observing a couple of fall signs already as one season slides slowly into the next. Migrating shorebirds returning from the Arctic, such as least sandpipers and lesser yellowlegs, have been seen in Carver County, as have the first yellow leaflets on butternuts. These trees are the first to show autumn color each year.
It’s time for the Canada geese to begin flying. The adults have been flightless since mid to late June, when they molted their wing feathers. The young geese are testing their new flight feathers, so look for whole families in flight.

On July 25 a year ago
We had a humid, partly sunny day with a low temperature of 75 degrees and a high of 92 degrees F. It was the 24th day of 90 degrees or above in the Twin Cities for 2012. The normal is 13 days each year. The surface temperature of Lake Waconia was 83 degrees. Garden roses looked good. Dahlias of several varieties had begun blooming.