Measurement of Faba Bean Diseases
3.5. Scale for Rating Alternaria Spot (Fig. 26)
|
DISEASE
RATING
|
HOST
STATUS
|
DESCRIPTION
|
|
|
1
|
Highly
resistant
|
No lesions or few very small circular flecks (less than 2 mm in diameter) on lower leaves only. | |
|
3
|
Resistant
|
Few small, discrete circular lesions (2-5 mm in diameter) on lower leaves only (0-12.5% leaf area infected). | |
|
5
|
Moderately
resistant
|
Some discrete circular lesions (0.5-1 cm in diameter) on all leaves (12.5-25% leaf area infected), little defoliation. | |
|
7
|
Susceptible
|
Many large, sometimes coalesced lesions (1-1.5 cm in diameter) on all leaves (25-50% leaf area infected), some defoliation. | |
|
9
|
Highly
susceptible
|
Extensive large lesions with more than 50% leaf area infected, extensive defoliation. | |
|
|
Fig. 26. Standard area diagram of faba bean leaves with increasing
alternaria spot severity. 
