Procedure for disease assessment
RO = 0%
R1 = 10%
R2 = 35%
R3 = 65%
R4 = 90%
R5 = 100%
Fig. 2. Rating (0 to 5) for powdery mildew on sugarbeet leaves. Both sides of a leaf are examined and an average rating given.
 
For disease assay, examine a leaf which has recently attained full growth.