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High grain protein and low grain yield are indicative of stress on the crop. Late-season stress reduces the duration of grain filling and produces small, pinched or otherwise malformed wheat kernels. Late-season stress is confirmed if the grain test weight is low, and the lower the test weight the more severe the stress conditions. Late-season stress could be caused by high air temperatures and/or moisture stress during grain filling, or late-season disease pressure. Early season stress normally reduces grain yield but not grain test weight. Stress during the crop year reduces yield. This means that the crop likely did not use all of the nutrients available to it. The soil may contain high levels of residual nitrogen, sulfur or other nutrients, which can be confirmed by a soil test and used to adjust fertilizer recommendations in the following year.

Washington State University