Chinch Bug Control in Sorghum with Liquid and Granular Soil Insecticides, 1989

Abstract

Abstract Funks G522 DR' grain sorghum was planted 21 Aug in loessial silt loam (Gigger-Gilbert complex) at the Macon Ridge branch of the LSU Northeast Research Station, adjacent to a recently harvested corn field to take advantage of chinch bugs seeking fresh vegetation on which to feed and produce the final fall generation. Granular insecticides were applied at planting using a 2-row John Deere Model 71 Flexi-Planter, modified to carry 1-pt jars of insecticide. Jars were inverted above funnels connected by flexible delivery tubes to either a 7-inch band or an in-furrow applicator. The diameter of a single central hole in the lid of each jar, in combination with tractor speed, determined the rate of insecticide flow. Banded insecticides were applied in front of the press wheel and further incorporated by a drag chain attached to the rear of the planter. Liquid insecticides were applied using a carbon dioxide pressurized planter-mounted sprayer dispensing insecticide from 2-liter plastic bottles. Application pressure was 50 psi using a Tee Jet #11004 nozzle. Banded sprays were applied as 8-inch bands across the open seed furrow ahead of the press wheel. For in-furrow spray applications, nozzles were rotated 90 degrees and spray directed into the open seed furrow. A drag chain behind the press wheel provided slight additional incorporation after closure of the seed furrow. A randomized complete block design with 4 replications was used, and each treatment consisted of two 40-ft rows spaced 36 inches apart. Efficacy of insecticide treatments against chinch bugs in sorghum were determined by counting the number of chinch bugs/10 randomly selected plants in each insecticide plot (5 plants/row × 2 rows/plot × 4 replications). The number of plants/40 ft of row was also counted in each insecticide plot (2 rows/plot × 4 replications). Data are reported as mean number of chinch bugs/10 plants and mean number of plants/40 ft of row.