Main Symptoms

In the nursery Botrytis cinerea attacks in particular the senescent leaves using them as a nutrition source and colonizing them quickly. Subsequently, it spreads on the stem on which it produces more or less extensive cankers. Stem cankers are particularly damaging in nurseries (figures 3 and 4) and in the field after planting (figures 5 and 6). Some plants with a stem surrounded at the collar level (figure 4) eventually wilt (figure 7) and/or may develop axillary buds (figure 8).

In the field it causes beige to brown coulored leaf spots which are sometimes concentric and surrounded by a yellow halo. Foliar disease typically develops close to harvesting (figures 9 to 11). In addition Botrytis cinerea induces stem cankers after having colonised the defoliation wounds (figures 14 to 16). It also grows well on a tobacco during curing. (see the section Curing barn diseases).

When weather conditions are favourable it produces a characteristic grey mould (figures 9, 12, 16) on all the attacked organs, hence the name of the disease.

Some of the information on the worldwide distribution of the disease is obtained from surveys conducted by CORESTA (Cooperation Centre for Scientific Research Relative to Tobacco). The reliability of the information is not confirmed in all countries.