Seasonal incidence of rice leaf folder Cnaphalocrocis medinalis (Guenee) in rice at Kanpur Uttar Pradesh

Abstract

The first incidence of rice leaf folder was observed in the last week of July (30 MW) with 0.49 percent damage and reached its peak in 3rd week of October (42 MW) recorded 7.93 percent damage during kharif 2017. the first, second and third week of October observed to be the most congenial stage during which maximum damaged leaves was recorded which ranging between 5.38 to 7.93 percent leaves infestation. Maximum temperature and bright sunshine hours found significant positive correlation with r=0.57 and r=0.62 respectively while minimum temperature, rain fall and Relative humidity found significant negative correlation with r=-0.72, r=-0.725 and r=-0.42 (Table 1, 2 & 3) in Kharif 2017. The first incidence of rice leaf folder was observed in the first week of August (31 MW) with 0.29 percent damage which was coincided with tillering stages and incidence reaches its peak in 3rd week of October (42 MW) recorded 7.15 percent damage during the panicle initiation stage. The field data shows that the first, second, third and fourth week of October observed to be the most congenial stage during which maximum damaged leaves was recorded which ranging between 4.47 to 7.15 percent leaves infestation. Maximum temperature and bright sunshine hours found significant positive correlation on seasonal incidence of rice leaf folder with r=0.23 and r=0.84 respectively while minimum temperature, rain fall and Relative humidity found significant negative correlation with r=-0.90, r=-0.835 and r=-0.46 in Kharif 2018.