Gall fly (Pachydiplosis oryzae) is very harmful to rice crop. It damages whole crop of rice. Farmers of Tamar block of Ranchi district in Jharkhand use parso or persu (Cleistanthus collinus) leaves for controlling gallfly. In this practice, fresh leaves of parso or persu are collected and spread in the infested field without processing. About 10 kg leaves are required for 100 m2 area. These leaves are spread at the initial stage of infestation. This practice controls 70-80% insects. All farmers of the village use this age-old practice.
Results and discussion
Results obtained during 2003-2004 showed that when the crop was not given any treatment, i.e. in the control plot, the infestation of gall-midge increased from 6% at 30 days after transplanting (DAT) to 9.8% at 60 DAT. In parso leaf application, the intensity of infestation was reduced from 3.2% at 30 DAT to 2.1 % at 45 DAT and finally to 2.0% at 60 DAT. The reduction in gallfly-affected shoots was maximum where parso leaf @ 100 kg/ha was applied.
Experiments conducted both at Ranchi and Nadia revealed that application of parso leaves is effective in reducing the damage caused by gallfly in rice. Application of parso leaves @ 100 kg/ha was more effective at Ranchi. Although parso leaf reduced the number of silver shoots in rice in Nadia, it was not reflected in the grain yield, because the incidence of gallfly was below the economic threshold limit.