Insecticide Phytotoxicity Evaluation on Potato in Louisiana, 1986

Abstract

Abstract A study was conducted at the St. Gabriel Research Station, Louisiana Agricultural Experiment Station, Louisiana State University, St. Gabriel, LA to evaluate the phytotoxicity of several compounds on potato. Seed potatoes of the cultivar ‘Red Lasota’ were planted on 38-inch rows on 15 May with a plant spacing of 12 inches. Plots were arranged on a randomized complete block design with 5 replications of single row plots 10 ft in length. Pesticides were applied with a hand-held CO2 pressurized sprayer delivering 5 gal/acre at 40 psi through a single hollow cone spray nozzle containing a D-3 disc, No. 25 core, and 16 mesh strainer. Treatments were applied on 20 and 26 Jun, 3, 10, and 18 Jul. Evaluations of phytotoxicity were made on 23 Jul. A phytotoxicity scale was used to evaluate foliar damage, as follows: (0) = no damage; (1) = minor yellowing and/or spotting, less than 5% of leaf area affected; (2) = moderate yellowing and spotting, 5-15% of leaf area affected; (3) = serious yellowing and spotting, 15-50% of leaf area affected; (4) = severe yellowing, greater than 50% of leaf area affected; and (5) = dead plant. A stunting scale was used to evaluate plant stunting, where 0 = no stunting and 1 = obvious stunting present. All plants in each replication were rated for stunting and phytotoxicity.