Figure 1. Relationship between the severity of chlorosis at the 5-6 trifoliolate stage and seed yield of soybean, North Dakota, 1998-2000.

The rating scale:

1=no chlorosis, plants normal and green

2=a slight yellowing, no differentiation between veinal and interveinal areas on the leaf

3=interveinal chlorosis (leaf veins green but interveinal areas yellow), but no indication of stunting of growth or necrosis (death) of leaf tissue

4=interveinal chlorosis with reduced growth or some necrosis of leaf tissue

5=very severe chlorosis, plants with stunted growth, and youngest leaves and growing point necrotic, or entire plants dead.