Efficacy of Selected Plant Extracts against <i>Pyricularia grisea</i>, Causal Agent of Rice Blast Disease

Abstract

Rice blast disease, caused by a seed-borne fungus Pyricularia grisea, is an important and serious disease of rice (Oryza sativa L.) worldwide. The disease has been reported to cause yield losses of up to 40% in Tanzania. Studies were conducted to determine the effect of aqueous extracts of <i>Aloe vera, Allium sativum, Annona muricata, Azadirachta indica, Bidens pilosa, Camellia sinensis, Chrysanthemum coccineum</i>, processed <i>Coffee arabica, Datura stramonium, Nicotiana tabacum</i> and <i>Zingiber officinalis</i> for control of rice blast disease (<i>Pyricularia grisea</i>) <i>in-vitro</i> and <i>in-vivo</i>. The results indicate that processed C. arabica at 10% and 25% (v/v) had the highest (81.12%) and (89.40%) inhibitory effect, respectively, against <i>P. grisea</i>. Aqueous extract from <i>N. tabacum</i> at 10% concentration ranked third (80.35%) in inhibiting <i>P. grisea</i>. These were followed by extracts from 25% <i>A. vera</i> (79.45%) and 25% <i>C. coccineum</i> flower (78.83%). The results also indicate that, extracts from <i>A. indica, A. vera, A. sativum, C. arabica, D. stramonium, C. sinensis, Z. officinalis</i> and <i>N. tabacum</i> did not have any phytotoxic effect on seed germination, shoot height, root length, dry weight, seedling growth and seedling vigour index. These plant extracts can thus be used for rice seed treatment to manage rice blast disease.