EFFECT OF THE BIOEXTRACT TO CONTROL THE CURVULARIA LEAF SPOT AND CANKER OF LEMON

Abstract

Effects of the bio-extracts on controlling the Curvularia leaf spot pathogen (Curvularia. sp) and
canker pathogen (Xanthomonas campestris citri) in lemon were assessed under laboratorial procedures at the
Faculty of Agricultural Technology, Rajamangala University of Technology Thanyaburi [RMUTT], Thailand,
during June to July 2015. The bio-extracts were prepared through fermentation of sugar mixed with one part of
water and one part of ground leaves and stems from 4 different species of plants, galangal, chili, basil and alata.
Three categories of ingredients, a bio-based agar, four formulae [1-4] of the bio-extracts and distilled water were
used to formulate testing media for this study. The growth rate and colony sizes of the pathogenic organisms
were determined at 1, 3, 5, 7 and 14 days using a completely randomized design (CRD) experiment with four
replications and five treatments. The results showed that Curvularia sp. growth was inhibited by all bio-extract
formulae at the same degree from 3 days of exposure limiting all colony sizes to be smaller than 1.4 cm. On the
other hand, formulae 1 and 2 bio-extracts showed better inhibition to the growth of the citrus canker bacteria
(Xanthomonas campestris citri) over the rest of treatments. These results suggested that bio-extracts from some
selected plants are capable to control plant diseases.