The ideal swath timing is when 60% of seeds on the main stem are showing some colour change from green to brown. Colour change is considered any amount of yellowing or browning on the seed.
The swath decision becomes more difficult in crops with plants at multiple stages of growth. For example, if some plants are at 60% seed colour change (SCC) on the main stem and other plants are still flowering, growers may want to hold off on swathing. Or if plants are large with many secondary stems, the main stem may be at 60% SCC, but seeds in side branches are still mushy and green. These seeds would wither up and amount to nothing if the crop is swathed at 60% SCC on the main stem.
The decision requires an assessment of the field, and a look at the calendar.
—Check the whole field. If half the plants are ready and half are just beginning seed color change, growers may want to hold off on swathing. By waiting 3 or 4 days, there is minimal risk of frost damage for riper parts of the field and a huge potential benefit for later parts if frost doesn’t occur.
—We’re still in early August. The risk of frost is very low at this time, so multi-stage fields with some plants ready to swath can be left a few days for SCC to begin on side branches.
—If the field has distinct late and early parts, the two parts could be swathed at different times.
—There is no “perfect” time to swath uneven crops. Choose based on the best time for the majority of plants in the field with the least negative impact possible on the rest.