Winter wheat growers ready for spring stand assessments
/by Sonny Murray
At this time of year, Winter wheat producers start to think about their wheat stands and how they’re looking as winter comes to an end. Ideally, the Winter wheat would have been planted early enough last fall so that each plant produced at least three leaves, one tiller, and, just as importantly, a crown.
The presence of a crown signifies that the plant started building up root energy reserves for overwintering. Optimal seeding date and depth are very important for this. Winter wheat will develop a crown when it has accumulated 450 growing degree days. If this does not occur in the fall, the plant will pick up where it left off in the spring. Spring-developed tillers will always produce less yield than fall stems. This is the rationale behind increasing the seeding rate as you move later into the fall – to compensate for the lack of fall tillers by adding more main stems.
When seeding in the fall, it’s crucial to have a goal of growing a wheat field with 60 to 70 heads per square foot. This principle seems to be the sweet spot for maximum yield!
If 60 to 70 heads per square foot seems like a lot, you can calculate the math to help ease your mind. Most seed providers suggest planting 1.5 million seeds per acre during the optimum planting window. Assuming 90 percent germinate, there will be 1.35 million germinated seeds per acre. There are 43,560 square feet in an acre. Therefore, there will be approximately 30 plants per square foot.
When it comes to spring stand assessments, you should ask a number of questions, including: Did I hit the seeding depth target of 1.0-1.5 inch? Is the crown too close to the soil surface, leaving the crop prone to frost heaving? Was fall weed control successful or are there perennials and winter annuals that need to be taken care of in the spring? Am I going to hit the goal of 60 to 70 heads per square foot?
The only way of knowing if you are going to hit the goal of 60 to 70 heads per square foot is to do some quick stand counts. For 7.5-inch row spacing, you should count 35 to 45 heads per foot of row. Grab a measuring tape or a 12-inch clipboard or mark 12 inches on your boot and do some counts. If you are down to half of the heads you require, some early-applied spring nitrogen is needed to encourage the plants to set more tillers early in the spring while the temperatures are cool.
It’s also important to consider the type of nitrogen applied at this time. You want a form of nitrogen that is available while the soils are cool. Not much nitrogen is needed to encourage tillering. Make sure not to overapply because it’s very susceptible to loss this early in the spring.
On the flip side, if you are counting an extreme number of tillers, you may want to delay nitrogen application so that the plants will abort some of the excess tillers. The crop may turn slightly yellow after green-up, but nitrogen should be applied before growth stage 31 to promote yield.
Research performed by Jack van Roestel with funding from the Atlantic Grains Council showed that there was no yield advantage to split applying nitrogen in March and again in April if the wheat was well established (had the correct number of stems per square foot). In this case, most of the required nitrogen should be applied at green-up.
Wheat producers are always itching to get rolling in the spring, but it’s very important to keep your goal in mind and ask yourself how you can manage nitrogen to achieve 60 to 70 heads per square foot.
(Sonny Murray is a field crops specialist with Perennia Food and Agriculture Inc. based in Kentville, N.S.)
