When ryegrass plants first emerge, the base of the plant is naturally reddish at the base. On bentgrass, a phosphorous deficiency is harder to identify. When the soil is cold, spoon feed with nitrate forms of nitrogen. Ammonium sources will not be as available in the cold weather. N every 10-14 days is usually satisfactory.
Iron deficiencies can readily occur in late fall and winter on tee's and greens.
Generally the turf is light green in color. Iron deficiencies usually effect most areas of the greens. On fairways, the deficiencies appear randomly, due to soil and drainage conditions. Using a small drop spreader, apply a single pass of the fertilizer in question going east to west, and another single pass going north to south. The point where the two fertilizers intersect will get twice the rate.