Evaluation of plant extracts for tomato late blight control in Cameroon

Abstract

Abstract Late blight caused by Phytophthora infestans is the most important disease of tomato in Cameroon. Three experiments are conducted to assess the fungitoxicity of methylene chloride/methanol leaf extracts of seven plants on P. infestans development . The extracts (3%) are evaluated for sporangial germination inhibition, latent and incubation periods, lesion size and late blight severity on tomato plants. Inoculated leaflets and plants are incubated in the greenhouse at 21°C during the day and 18°C during the night, with a 12 h photoperiod and for 7 days. Sporangial germination is significantly inhibited by Tephrosia vogelli and Entandrophragma angolense extracts, while disease progression is highly limited by Ageratum houstonianum, Tephrosia vogelli, Clausena anisata and Entandrophragma angolense extracts. The fungitoxic effects of some of the extracts is comparable to synthetic fungicides, metalaxyl and maneb, used as positive controls, indicating their potential as components of an integrated pathogen management programme for tomato late blight. Eucalyptus saligna , Deinbollia saligna and Garcinia smeathmannii extracts have low efficiency.