Evaluating winter wheat stand
This year, many areas of Ohio experienced extremely low temperatures for several days. (-20° as I was driving to an Extension meeting in Coshocton County on January 28.) Snowfall was also above average in many areas causing standing water as the snow melted. Where does this leave our winter wheat crop?
Winter wheat is a cold season grass that can tolerate fairly harsh weather conditions. Wheat “hardens” in the fall to acclimate to cold conditions. Cold acclimation is variety-dependent and requires a period of growth when temperatures are between 30° and 60°F followed by slowly declining soil temperatures. After hardening, wheat can tolerate temperatures between 0 and 10°F especially when there is good snow cover. The growing point of wheat is below ground until conditions are warm in the spring, but extremely cold conditions can still cause damage to the plant. However, plants are only killed by low temperatures if the crown (lower stem) is damaged. Although, there were negative air temperatures, soil temperatures remained in the upper 20s to low 30s.
Some fields may have had damaged from areas where melting snow left standing water that later became ice. Standing water and especially ice on plants for several days may lead to “suffocation” of the crowns which may cause weakening of the stand in those areas or complete loss of plants.
Fields should not be evaluated until completely green from warmer temperatures for at least 10 to 14 days. Stand evaluations will be more accurate when made during weather periods that promote growth. Yield potential is reduced if tiller numbers fall below 25 per square foot after green up. Pick about 10 to 15 spots in the field and count the number of plants per foot of row. A stand with an average of about 12 plants per foot of row may still result in a good population of head-bearing tillers per acre. For those fields with tillers, 15 tillers per square foot is considered minimum for an economic crop. The number of tillers per square foot is equal to the number of tillers in 19.2 inches of 7.5-inch wide rows. Our studies have shown that under adequate weather conditions, tillering may compensate for relatively poor initial stand establishment.
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