Glycyrrhiza glabra extract protects plants against important phytopathogenic fungi.

In previous investigations an ethanolic plant extract from Glycyrrhiza glabra (2.5% w/v) showed 100% efficacy against late blight (Phytophthora infestans) on detached tomato leaves. Based on these findings, the objective of this work was to investigate the effect of this extract against different important plant pathogenic fungi. Tests were carried out on potted plants. Against P. infestans, efficacies of 75% and 58% were achieved on tomato and potato plants with 5% extract concentration, respectively. Against another Oomycete, Pseudoperonospora cubensis, on cucumber, application of a 2.5% extract led to an efficacy of above 90%. The EC50-value was calculated to be 0.5% In a trial on beans against bean rust (Uromyces appendiculatus), G. glabra extract (5% concentration) showed 92% efficacy. In contrast, against powdery mildew on cucumber (Podosphaera xanthii), no disease reduction was found. Overall, the results indicate a high potential for the extract of G. glabra to control a number of important plant pathogens.