Manipulation of cultural practices to reduce Blissus insularis densities in St. Augustine grass

The southern chinch bug, Blissus insularis (Barber), is a major insect pest of St. Augustinegrass. Feeding damage stunts plant growth and kills entire lawns, often requiring new sod and frequent insecticide applications in Florida. Because of the repeated development of insecticide resistance, cultural practices that maintain quality turfgrass and reduce insect abundance are needed. Thus, we sought to determine the impact of nitrogen fertilization and mowing height on turf health and subsequent B. insularis densities. St. Augustinegrass cultivars ‘Floratam’ and ‘Captiva’ were treated with 100-300 kg nitrogen/ha/yr using soluble and slow release sources in 2011. Significantly more B. insularis were collected from plots that received the highest N rate (300 kg/ha/yr), regardless of the source in both cultivars . In a field study in 2012, N fertilizer rate (100 and 200 kg/ha/yr) and mowing height (5 and 10 cm) did not interact, but plots with taller turf (10 cm) contained more B. insularis than plots with shorter turf (5 cm) consistent with residential lawn sampling. More B. insularis in the taller turf may be because of microclimate differences. Based on the results of this study, we recommend reducing the nitrogen fertilizer inputs and optimizing grass mowing heights in St. Augustinegrass lawns to reduce the requisite of insecticides for B. insularis management.