Effect of plant extracts and emulsifiers on control of anthracnose (Colletotrichum coccodes) in persimmon trees

Abstract

ABSTRACT This study was conducted to determine suppression of the anthracnose fungus (Colletotrichum coccodes), causing disease in persimmon trees (Diospyros kaki Thunb), by (1) extracts from various parts of 45 plant species from 27 families obtained using different extraction methods, and (2) selected plant extracts and emulsifiers. Fermentation extracts of Torilis japonica roots and Portulaca oleracea, all above ground parts, as well as ethanol extracts of Rheum palmatum roots and Cinnamomum cassia barks were found to effectively suppress anthracnose, leading to 83%, or more, suppression by 10% plant extracts in laboratory tests. Additionally, anthracnose was suppressed by 100% by 3% brown rice vinegar, 3% powder soap, 5% loess sulphur, and by 5% natural emulsifier-B in a laboratory test. In the field trial with organically grown persimmon trees, treatments with plant extracts used on their own, resulted a reduction of anthracnose by 63% and 51% by 5% fermentation extract of T. japonica and 5% ethanol extract of R. palmatum, respectively, compared with a control. However, in treatments with combinations of plant extracts and emulsifiers, anthracnose was reduced by 79%, 67%, 63% and 56% when treated with 5% fermentation extract of T. japonica + natural emulsifier-B (1%), 5% fermentation extract of T. japonica + loess sulphur (1%), 5% ethanol extract of R. palmatum + natural emulsifier-B (1%), and 5% ethanol extract of R. palmatum + loess sulphur (1%), respectively, compared with the control. Thus, mixtures of plant extracts and emulsifiers may be used to control anthracnose in organic production systems.