As wheat greenup begins, it will be time to evaluate wheat stands. Just because leaves are brown does not mean the plant is dead; remember, regrowth occurs from the crown tissue below soil level. Early planted wheat with lots of vegetative growth may appear slower to “greenup,” due to the amount of brown leaves from overwintering. After wheat begins to greenup, “purple” wheat is most likely a result of sugar accumulation due to cool/saturated soils (phosphorus deficiency also shows as purple leaves, but that is much less common).
The condition of wheat across the area is more variable than last year- with some fields looking excellent and others damaged from excess and ponding water. Later planted wheat fields (late October/November planted) are at the highest risk of heaving over the next few weeks, as root systems are limited in development.
Each wheat plant includes a main stem (which emerged first) and several tillers, which are additional stems that develop after emergence from nodes on the base of the main stem. Some wheat tillers are established in the fall, and tiller establishment continues in early spring. Fall tillers are usually more productive than spring tillers.
- Optimal stands are 24-35 plants/ft2 with each plant including 2-4 tillers
- 70-100 total tillers/ft2 is desirable in the spring (not all tillers will produce a head)
- 60-80 heads of grain/ft2 is considered optimum to maximize yield
- Acceptable stands can be as low as 15-18 plants/sq. ft., as long as tiller development is expected to compensate (early “greenup” nitrogen application is important to promote more tillers)
- Fields with an average of <15 plants/sq. ft. are not worth salvaging