Cultural and morphological variability in Rhizoctonia solani causing banded leaf and sheath blight of maize

摘要

Maize (Zea mays L.) crop is attacked by number of fungal, bacterial and viral diseases out of which banded leaf and sheath blight (BLSB) caused by Rhizoctonia solani f. sp. sasakii (Thanatephorus cucumeris) is considered as one of the most important diseases and responsible for low yields. In India, the disease was first recorded in the Tarai region of (foothill plain areas) Uttar Pradesh (Payak and Renfro, 1968). In Guangxi province of China, yield losses of 87.5 and 57.8% were recorded under natural conditions in the hybrids Luyu 13 and Guiding planted at Bao Qiao and Chen Xiang (Sharma, 2005). Most of the composites and hybrids, which are being grown on commercial scale found to be more or less susceptible to BSLB. The reasons for lack of substantial durable resistance in the material may be attributed to presence of variability in the population (Zhang et al., 2012). The problem of banded leaf and sheath blight disease of maize is increasing in this region thus characterization of pathogenicityof the newly emerging population is necessary to generate the information about the emergence of new pathotypes having adaptability to new traditional areas. In recent years, in Karnataka state also it was observed that the maize crop succumbed to banded leaf and sheath blight in several areas. This has led to speculation of possible occurrence of variation in the pathogen. Hence, studies were conducted to know the possible existence of variability in the growth and sclerotial formation among the various isolates from different parts of northern Karnataka.