Following the Christmas rain and snow event, virtually all of the un-sprouted wheat seed in Northeast Texas has begun the germination process and is now coming up to a stand. Much of the earliest planted wheat had come up in early November, so we have the equivalent of two distinct planting dates, approximately two months apart.
What complicates matters is that, in many cases, we have two different crops in the same field. This will present some challenges as we proceed through the growing season. The wheat that emerged in early November is in pretty good condition and has excellent yield potential. It has continued to tiller throughout the fall, even under the dry conditions we experienced.
Up until Christmas Day, the last significant rain we measured at the Cereal Crop Research Incorporated (CCRI) farm in Fairlie was on October 13. This is quite typical of the region, although some areas received slightly more rainfall.
Vernalizationshould be adequate. According to the literature, wheat vernalization can begin when the embryo becomes active in the process of sprouting. It occurs at temperatures between 32 degrees (Fahrenheit) and 50 degrees, with optimum vernalization occurring around 45 degrees. The early emerged wheat has been vernalizing throughout the fall, and following the widespread rain and snow event, we think we know that the vernalization “clock” started on everything by Christmas Day. That means we have already accumulated at least 2 ½ weeks of vernalization on the wheat that is just now emerging.
Most southern-bred varieties require 3 to 4 weeks of chilling, while some of the northern-bred germplasm may require 6 to 7 weeks to fully vernalize. The only varieties that give us any concern at all are the three widely planted later maturing varieties—Pioneer 25R30, Pioneer 25R40, and Terral 8861. Breeders estimate the vernalization requirement of Pioneer 25R30 and Pioneer 25R40 at around 7 weeks, and we suspect Terral 8861 to be in that same range.
Even with those varieties, if the temperature at the soil surface remains at 50 degrees or less, we should achieve 7 weeks of vernalization by mid-February.
Of greater concern with the late emerging wheat is reduced tilleringtime. Tillering is controlled by temperature, moisture, and nutrients. The wheat that emerged in early to mid-Nov. will have at least four months to tiller, while this late emerging wheat will have about half as much time to tiller. We know from our local research, that fall-emerged wheat will tiller and fill in holes the size of a hat with no reduction in yield. The late emerging wheat may not have enough time to fully compensate for the skips in stand.
If field conditions permit, this might be a good year to split nitrogenapplication on the late emerging wheat. The seedling wheat plants will be able to use some additional nitrogen when they are ready to begin tillering.