Index of Disease Rate Infection (%) for Visual Field Inspection
Rate (%) Diseased Plants/Plants Counted Diseased Plants per Acre
1.0 100/10,000 180
0.5 50/10,000 90
0.3 30/10,000 54
0.2 20/10,000 36
0.15 15/10,000 27
0.1 10/10,000 18
0.05 5/10,000 9

The number of plants per acre is 18,000. The number of diseased plants/acre is calculated by "Rate times 180".