PRM/ARM; Electronic Data Exchange files (right mouse click, "Save target/link as..")
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Jack S. Bacheler and Daniel W. Mott
Entomology Department
North Carolina State University
COOPERATORS: Gary Hardison, Producer
Location: Open Ground Pecan Cotton Fields, Onslow County, approximately 3 miles south of Richlands, NC
Soil Type: Goldsboro fine sandy loam; planted no-till
Variety: Fibermax 958 RR at 3 seed per 16 inches, hill dropped
Row Spacing: 38 inches
Tillage System: No-Till
Planting Date: May 3, 2002
Previous Crop: Cotton
Insecticide: Temik 15G, 5.0 lb. product at planting for thrips control.
Experimental Design: 4-row plots x 40 ft., replicated 4 times in a RCBDData Analysis: All field data were entered into Gylling’s PRM 5.1 software and analyzed via ANOVA, with LSD values shown in the tables.
Application Information: Treatments were applied with a CO2-powered back pack sprayer calibrated to deliver 8.0 gpa @ 50 psi with 1 Spraying Systems TX-8 hollow cone nozzle per row. The initial spray was on July 23 at a threshold of approximately 15 eggs/100 terminals and approximately 3% live 1st and 2nd instar bollworm; a second spray was made on July 29.
Bollworm Assessments: On August 15, following the 2 applications, 25 bolls from each plot were inspected for live bollworms, European corn borers, fall armyworms, and their damage.
Bollworm:Budworm Ratio: Thirty four bollworm/budworm larvae were taken from the outer rows of the untreated check on August 15, and brought back to the lab for identification.
Harvest: The center two rows of each plot were harvested with 2-row John Deere mechanical harvester on October 25.
Bollworms constituted 95% of the Helicoverpa/Heliothis population in the untreated check cotton on August 15. Therefore, tobacco budworms were not a factor in this test.
At the August 14 sampling date, the untreated check showed significantly more overall boll damage and boll damage due to bollworms than all of the other treatments. Bollworm pressure was exceptionally high at this location, as evidenced by the 59% total damage in the untreated check.
Fury, F0570, and Baythroid showed the greatest numerical reduction in overall boll damage, but this reduction was not significantly less that of the other pyrethroids. The LSD (0.05) value of 15.1 (% total damaged bolls) also indicated a high variability between plots in this year's tests, making separations between treatments less likely.
European corn borer and fall armyworm damage to bolls was low at this location in 2002. Beet armyworms were present in scattered areas in the test, but at levels too low to evaluate the effectiveness of the insecticides.
Due to very poor pre-harvest and harvest conditions (significant fall rainfall excessive regrowth, and late harvest due to the wet conditions - November 8), yields were not well correlated with bollworm damage, as is more often the case under more optimum harvest conditions.