Scouting Wheat

DR. ANTHONY OHMES

JACKSON, MO.
   February is still in the window to evaluate wheat to make some management decisions. Wheat maturity is driven primarily by variety response to temperature and photoperiod and not specific dates on the calendar. Therefore, it is important to evaluate a crop by growth stage to help make nutrient, pest management decisions and to determine when to stop grazing. For grazing, to protect yield, pull cattle off just prior to jointing when the base of the stem is hollow. A good guide for following wheat development is Purdue University’s guide: Managing Wheat by Growth Stage.
   Initial evaluation of fields should include overall condition of stand and number of tillers present.  Missouri research indicates that, in general, holding off nitrogen applications until pre-jointing (Feekes 4-5) provides available nitrogen just before the time of greatest need, jointing (Feekes 6) which maximizes yield potential. Also, holding off can potentially reduce nitrogen loss and excessive early spring growth which can increase sensitivity to freeze injury. Fields with less than approximately 70 to 80 tillers per square foot, during tiller development stages (Feekes 2-3), may benefit from applying some nitrogen early to promote tiller development, especially on coarse soils. However, the most consistent timing for nitrogen application is pre-jointing, therefore, concentrate the majority of nitrogen at this timing to maximize potential yield. Consider using urease inhibitors containing the active ingredient NBPT when applying urea based fertilizer. Tissue tests at pre-jointing can help determine nitrogen needs at jointing. Low organic matter (<3%), low CEC (<10), coarse soils of southeast Missouri can be prone to low sulfur conditions. Consider applying 10 to 15 pounds of sulfur per acre in the form of sulfate-sulfur.
   Scout fields for aphids. Early control of spring aphids can help limit spring barley yellow dwarf virus vectored by aphids. Consider insecticide applications before aphid populations exceed 6 to 8 aphids per linear foot of row. Dr. Scott Stewart, University of Tennessee, has a guide available on aphid management and barley yellow dwarf virus.
   For more information on wheat management during green-up refer to MU IPM Guide: Management of Soft Winter Wheat. ∆
   DR. ANTHONY OHMES: Agronomy Specialist, University of Missouri Extension