Rice blast-mycoflora, symptomatology and pathogenicity

Abstract

Rice (Oryza sativa L.) is the second most important cereal crop of the world as well as of Pakistan. Rice blast caused by a Magnaporthe oryzae (syn: Pyricularia oryzae Cav.) is an infectious fungal disease which is distributed worldwide and prevailing in more than 85 countries of the world. Therefore, present studies were carried out to isolated different fungi associated with seeds and leaves of commercially grown rice varieties and to test the pathogenicity of predominantly isolated species. Seven fungi namely Magnaporthe oryzae, Curvularia lunata, Helminthosporium oryzae, Fusarium moniliforme, Alternaria alternata, Nigrospora oryzae and Aspergillus niger were isolated from seeds and affected leaves of five rice varieties viz., IRRI-6, IRRI-8, DR-82, KS-282 and Shua. N. oryzae was isolated only from IRRI-6 and IRRI-8 rice varieties. Among these fungi, M. oryzae was predominantly isolated both from seeds and leaves of the rice varieties studied. Rice variety IRRI-6 followed by KS-282 appeared as most susceptible rice cultivars to rice blast fungus. M. oryzae was detected with highest frequency from leaves and seeds of IRRI-6. All other fungi were isolated either occasionally or with low frequency. Pathogenicity test of M. oryzae conducted on apparently most susceptible variety IRRI-6 has confirmed the pathogenic nature of the fungus. Plant growth was significantly decreased in inoculated plants as compared to un-inoculated plants. Moreover, typical rice blast disease symptoms were also produced in inoculated plants.

Reaction of introduced Korean rice genotypes for resistance to rice blast in Uganda

“…E-mail: zelalemsafe@gmail.com. (Hai et al, 2007;Hajano et al, 2011;Chuwa et al, 2015). It is becoming severe under high temperature, high relative humidity (85 to 89%), presence of dew, drought stress and excessive nitrogen fertilization.…”

Effect of Foliar and Root Application of Silicon Against Rice Blast Fungus in MR219 Rice Variety

“…Rice blast, caused by the fungus Magnaporthe oryzae (Couch and Kohn, 2002) (anamorph, Pyricularia oryzae Cavara), is among the most significant diseases affecting rice cultivation, since it is prevalent in most rice growing regions and causes serious yield losses (Hayasaka et al, 2008). The disease is widely distributed (85 countries) (Hajano et al, 2011) and under favorable environmental conditions it can be very disastrous (Scardaci et al, 1997). Yield and harvest losses estimated from other areas of the world have ranged from 10−30% (Tongen et al, 2006).…”

First Report ofNigrospora oryzae(Berk. &Broome) Petch Causing Stem Blight onBrassica junceainIndia

“…In Pakistan, N. oryzae caused a rice blast disease that initially appeared as whitish or greyish specks along the leaf margins; these specks developed into elliptical spots with pointed ends. On stems, the fungus developed elongated, grey-to black-coloured lesions (Hajano et al 2011). Nigrospora oryzae reportedly causes numerous, minute black pustules on rice leaves, necrotic spots on rice grains and blight on glumes and culms (Prasad et al 1960).…”