Alteration in the susceptibility ofvicia faba toBotrytis fabae by various pretreatments of the leaves

Infection of broad bean leaves byBotrytis fabae was influenced by various pretreatments of the leaves. The number of lesions developing on test leaflets increased after pretreatment of the leaflet for 24 hours with a sucrose, a potassium chloride or a lanthanum chloride solution; pretreatment of leaflets by keeping them in darkness had a similar effect. At least the first phase of the infection process, viz. germination of the conidia on the leaf, was stimulated by these pretreatments. This stimulation may have been caused by increased amounts of leached nutrients present on the pretreated leaflets in comparison with those on untreated ones.