ULTRASTRUCTURAL STUDIES OF THE EFFECTS OF ALLIUM-SATIVUM ON PHYTOPATHOGENIC FUNGI IN-VITRO

A study was made of the effects of garlic on the development of myceli um in the following phytopathogenic fungi: Fusarium solani (Mart.) Sac c., Rhizoctonia solani Kuhn, Pythium ultimum Trow var. ultimum, and Co lletotrichum lindemuthianum (Sacc. and Magnus) Briosi and Cav. A suspe nsion of micronized garlic powder, which has volatile organic compound s mainly consisting of linear chain aldehydes, allyl sulfides and disu lfides, was used for the trials. Mycelial development of the fungi was strongly inhibited at the maximum concentration of the aqueous extrac t tested (100 ml/liter); however only the growth of P. ultimum var. ul timum was entirely blocked. Transmission and scanning electron microsc opy revealed cytomorphological alterations of the hyphae treated with garlic. R. solani and C. lindemuthianum hyphae appeared especially col lapsed, while those of F. solani were less damaged, although thinner t han the control hyphae. A general increase in vacuolization was also o bserved, with consequent reduction in the cytoplasm of the treated fun gal cells. R. solani also revealed a thickening of the cell wall, wher eas C. lindemuthianum revealed a singular accumulation of osmiophil bo dies immediately under the cell membrane.