Fig. 3 shows the microsopic structural changes and struc- tural alterations in B. cinerea in response to different treatments. Normal sporangia and mycelia were stained a darker blue by lactophenol-cotton blue because of their thick cytoplasm content than others treated with antifungal agents (Fig. 3a and b). Micro- scopic observations showed coagulation in the fungal cytoplasm characterized by the appearance of small vesicles in mycelium treated by the combination of GSE and chitosan, and they were hard to stain by lactophenol-cotton blue (Fig. 3c and d). In other cases, the mycelium contained little cytoplasm or even had empty cells devoid of cytoplasm. Moreover, sporangium development and formation became abnormal compared with the control. Microscopic photographs of hyphae treated with GSE alone showed a similar phenomenon but stained a lighter blue than those treated with the combination of GSE and chi- tosan (Fig. 3e and f). The antifungal action of GSE might largely rely on its affect on the fungal membranes, probably as a result of the ability of antifungal compounds in GSE to act as surfactants (physical disruption of the membrane). More- over, chitosan had good fungicidal activity and was effective in halting the growth of B. cinerea (El Ghaouth et al., 1992a). Ait Barka et al. (2004) observed that several sections of B. cinerea hyphae displayed various levels of cellular morphologi- cal changes ranging from wall structural alterations to cytoplasm disintegration as a result of chitosan treatment. In brief, the com- bination of GSE and chitosan was effective in restricting the mycelial growth of B. cinerea, which resulted in marked mor- phological changes and severe structural alterations in the fungal hyphae.