Next Generation Farming

Warm Winter Not a Serious Threat to Wheat...Yet

Unseasonably warm days are balanced by cold nighttime temps.

If I didn't know any better, I would have thought the entire month of January was actually April. With daytime highs reaching into the 70s, it's been warm enough to work outside in shorts and a t-shirt.

The warmest day here in Lane County, Kan., reached an unbelievable 72 degrees F at the end of January. The average daily high for the month was 48 degrees - 10 degrees warmer than in January 2011.

For anyone grazing cattle, this has been a godsend as they have more days to graze and less need to buy feed. This has been especially true in southern Kansas and Oklahoma where wheat pasture has started growing again and where they've also benefited from some moisture.

But if you're in the business of growing wheat for grain, the warm temperatures aren't exactly ideal conditions.

When temperatures rise above freezing and stay there for more than a couple of days, wheat begins breaking dormancy and starts to grow. If done too early, the wheat plant is vulnerable to a freeze later in the season if temperatures cool back off.  

Making matters worse are dry soils. Because dry soil warms and cools about six times faster than saturated soil, the plant could have to endure repeated temperature swings, which exacerbates the loss of winter hardiness and increases the risk of crown root rot and winter injury. The crown, which lies right beneath the soil surface and is the key growing point for the root system, can ultimately freeze and die, taking the rest of the plant with it.

Fortunately, our temperatures at night still have remained below freezing. As long as nighttime temperatures fall below 32 degrees, it's very unusual to lose much winter hardiness, says Bob Klein, extension agronomist in western Nebraska. The warmest nighttime temperature in January on our farm barely peeked over freezing at 32.5F - cold enough to convince the plant it's still winter despite the warm daytime temps.

But all of that could change if the warm/dry trend caused by La Nina continues through March with nighttime temperatures rising above freezing and soils start drying out. At that point, the plant will be fully back in growth mode with the crown susceptible to winter injury from swinging temps. If temperatures swing hard enough, we'll have plenty more to worry about this spring.

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