A comparison of infection of resistant and susceptible lines of field bean (Vicia faba) by Ascochyta fabae

In a series of growth room experiments, a determinate line of Vicia faba was shown to be more susceptible to infection by Ascochyta fabae than a conventional indeterminate line. On the determinate line, lesions developed more quickly on younger leaves. No evidence of systemic infection was found and disease transfer to the emerging seedling was probably by physical contact with the infected seed testa. Successful establishment of the disease required leaf wetness for periods of 4 h at 20–25° C to 12 h at 10 C. The rate of pycnidiospore germination on leaves decreased with temperature over this range, but did not differ between the determinate and indeterminate lines.