Bryophyte extracts with activity against plant pathogenic fungi

Abstract

The effects of extracts from 17 different bryophyte species were investigated against economically important plant pathogenic fungi. In vitro experiments showed that ethanol extracts of bryophytes inhibited mycelial growth of Botrytis cinerea and Alternaria solani. Extracts from Bazzania trilobata, Diplophyllum albicans, Sphagnum quinquefarium, Dicranodontium denudatum, and Hylocomium splendens inhibited fungal development by over 50%. Green pepper plants sprayed with the extracts from 17 bryophytes (at 1% mv-1), with the fungicide dichlofluanide (50 ppm), and untreated plants were compared. Treatments were applied 4 hours prior to inoculation with conidial suspension of the grey mould (B. cinerea). Significant variations between treatments were detected. Extract treatments reduced the grey mould severity ranging from 15 to 23%, whereas dichlofluanide showed efficacy up to 92%. Three dose levels of five candidate extracts sprayed at three pre-infectional time intervals were compared under low and high inoculum pressures of the late blight, Phytophthora infestans, of tomatoes and powdery mildew, Blumeria graminis, of wheat. In general, extracts from B. trilobata and D. albicans showed better efficient disease protection than that of S. quinquefarium, D. denudatum, and H. splendens. The direct mode-of-action of treatments on the surface of leaves gave inefficient disease protection, evidenced on treated plants at 4 hours before the inoculation. However, plants treated by the same extracts at least 2 days before inoculation exhibited less than 90%


disease severity. Therefore, products of bryophytes deserved to be reliable sources as biocontrol agents and may play significant roles for future practical applications in a socially and ecologically healthy crop management system.


Key words/phrases: Alternaria solani, Blumeria graminis, Botrytis cinerea, Bryophyte extracts, Phytophthora infestans


SINET: Ethiop. J. Sci Vol.26(1) 2003: 55-62