An Alternative Planting Geometry for Facilitating Chemical Control of Fall Armyworm (Spodoptera frugiperda) in Maize and Its Impact on Growth and Yield

A potential threat from the recent Fall Armyworm (FAW) outbreak was recorded from maize cultivation in Sri Lanka. Though an integrated approach has been suggested for its management, chemical control is needed in a severe infestation. However, the present planting geometry does not facilitate chemical spraying as the plant height and canopy expand. An experiment was conducted during two consecutive seasons at Field Crops Research and Development Institute, Mahailluppallama (08.60° N, 80.27° E, 137 m AMSL) to explore an alternative row arrangement to facilitate pesticide spraying with minimum impacts on growth and yield. Treatments consisted of 3 new planting geometries (strip planting of maize at 45 × 30 cm spacing as 4 or 6 rows leaving 120 cm inter-strip area and strip planting at 45 × 30 cm spacing as 4 or 6 rows leaving 90 cm inter–strip area) combined with 3 inter cropping arrangements where the inter-strip area was kept either cultivated with groundnut (Arachis hypogea (L.) R. Wilczek) or without cultivating in respective treatments. The present plant geometry was the control. Results revealed that the modified planting geometry did not affect on growth and yield compared to the present practice. Thus, maize planted at 45 × 30 cm in 4 rows with 90 cm space between strips cultivated with groundnut was found to be an effective plant geometry to facilitate both chemical application on FAW with no yield disadvantages and at comparatively low cost of seeding.