Forage yield compensation in maize with differential seed rates against insect herbivory of Chilo partellus (Swinhoe.)

Abstract

The non-pesticidal approach in managing maize stem borer by using differential seed rate (through agronomic manipulations) of fodder maize vis-a-vis borer damage and yield compensation study was conducted in 2016 and 2017. The results indicated significant variation in borer inflicted leaf injury (9.84-21.13%), dead heart incidence (6.74-13.25%) and stem tunneling (2.45-6.33 cm) under different sets of plots. The plant damage was, however, significantly low in insecticidal controlled plots. Unlike chemical control, fewer plant losses were recorded in optimally seeded plots (100 kg/ha). The plant losses gradually increased beyond the threshold of optimal limits and could be attributed to modified crop microclimate favouring the C. patrellus population buildup and its related damage to foliage and tender shoots. The green fodder yield (q/ha) obtained across different treatment plots was significantly superior on account of high plants population. However, the net returns (Rs. ha-1) indicated the superiority of maize plots seeded @ 100 kg ha-1. This was substantiated by data of leaf injury (15.08%), dead heart incidence (8.41%), stem tunneling (5.9 cm), green fodder yield (422.50 q ha-1) and net returns (Rs. 26837 ha-1) and loss in plant population as compared to other plots with lower or higher seed rates. It was concluded that enhanced seed rate of fodder maize @ 100 kg/ha with no chemical protection against C. partellus, had numerical edge for stem borer management, with yield compensation ability and no pesticide usage related issues.