Freedom wheat had the same type of spots. Spots are typically yellow with a dark brown or chocolate center and range in size from 1 to 3 mm. Individual lesions can join to make larger lesions. Symptoms are most noticeable on the flag leaves and lesions are very similar to the brown centers and yellow halo of Septoria. Although Freedom appears to be a good indicator of physiological leaf spot or flecking other varieties may also be displaying these symptoms.
Weather conditions appear to play an important role.
Increased damage is observed when there are extended periods of overcast rainy weather followed by a bright sunny day. Refer to your local weather conditions to see if these conditions occurred in your area. Several studies suggest that physiological leaf spot may be the result of a chloride deficiency that creates an osmotic imbalance in leaf cells which are killed causing leaf spotting. A number of public and private trials have been established this year and we hope to have the results when they are available. Last year was our first significant encounter with physiological leaf spot and some of the lessons we learned was that the number of spots decreased once sunny warm weather arrived and that yield did not seem to be affected.