Oklahoma’s cold winter weather has had wheat plants growing in slow motion, resulting in many being behind “normal” for this time of year in terms of reaching first hollow stem stage.

“The earliest varieties, such as TAM 401 and Fannin, have already reached first hollow stem in September-sown plots in Stillwater,” said Jeff Edwards, Oklahoma State University Cooperative Extension small grains specialist.

First hollow stem is a critical stage for dual-purpose agricultural producers. Oklahoma farmers planted an estimated 5 million acres of wheat in fall 2009 as part of the state’s $1 billion-a-year wheat industry. Anywhere from 40 percent to 60 percent of these acres are annually grazed by cattle during the winter.

“Producers wishing to graze wheat and subsequently harvest grain must decide when to remove cattle from wheat pasture,” Edwards said. “Grazing too long will reduce wheat yields, but removing cattle too early will reduce profit potential of the stocker cattle enterprise.”

Wheat development is governed not only by temperature but also by day length.

“The lengthening days we are now experiencing are telling wheat plants to get it in gear,” Edwards said. “Essentially, Mother Nature has dropped the green flag; once temperatures warm up a little, the race to first hollow stem stage will be underway.”

Edwards expects that most varieties in Oklahoma will reach first hollow stem stage in a three-day to seven-day window once daytime temperatures exceed 60 degrees Fahrenheit for a few consecutive days.

As always, some dual-purpose wheat producers will be weighing the pros and cons of grazing past first hollow stem stage, knowing that a mistimed decision potentially could cause a significant hit to their wallets.

Eric DeVuyst, OSU associate professor of farm and production management in the department of agricultural economics, offers the following table to calculate the potential value: daily gain at first hollow stem stage (pound per head of cattle) divided by the stocking rate (head of cattle per acre), multiplied by the calf price (dollars per hundredweight), and divided by 100 to determine the money gained for a day of grazing (dollars per acre).

“Let’s assume that we have 700-pound steers gaining three pounds per day while grazing wheat,” he said. “To compute the benefits of an additional day of grazing, we first need to compute effective market price.”

At 700 pounds, a steer’s market price is $100 per hundredweight, as an example. After grazing for an additional day, a $6 price slide would give the producer a price of $99.82 for a 703-pound steer. The steer’s value increased $1.73 per head, making the effective price for the additional pounds $58 per hundredweight.

“With a stocking rate of two acres per head and a market price net of price slide effects of $58 per hundredweight, we get benefits from a day of grazing equal to $0.87 per acre,” DeVuyst said.

How many bushels of wheat can a producer lose from extended grazing and just breakeven? To determine this, use the following formula: dollars in gain from a day of grazing (dollars per acre) divided by the price of wheat (dollars per bushel) to determine the breakeven yield loss.

“Since the gain from a day of grazing in the example provided is $0.87 per acre, if we divide $0.87 per acre by $4.40 per bushel of wheat, we get 0.2 bushel per day,” DeVuyst said. “In other words, we are losing profits if wheat grain losses are more than a fifth of a bushel per day due to grazing after first hollow stem.”

Additional information is available by consulting OSU Extension Fact Sheet PSS-2147, “First Hollow Stem: A Critical Wheat Growth Stage for Dual-Purpose Producers,” at http://osufacts.okstate.edu on the Internet.