PRM/ARM; Electronic Data Exchange files (right mouse click, "Save target/link as..")
Jack S. Bacheler and Daniel W. Mott
Entomology Department
North Carolina State University
BACKGROUND:
Location: Upper Coastal Plain Research Station: Field C-10
Soil Type: Nahunta Loam
Variety: DP 436 RR
Row Spacing: 36 inches
Tillage System: Conventional; disced and chisel-plowed, March; disced, April 17; ripped and bedded, May
Planting Date: May 1, 2001
Fertility: Broadcast- 400 lb. 5-10-10, April 12; layby- 20 gal. 30% urea, June 22
Weed Management: 26 oz. Roundup Ultra Max burndown, April 10; 1.5 pts. Treflan incorporated, April 30; 26 oz. Roundup Ultra Max overtop, June 6
Experimental Design: 4-row plots (middle two rows treated) x 40 ft., replicated 4 times in a RCBD
Data Analysis: All field data were entered into Gylling’s PRM 5.1 software and analyzed via ANOVA, with LSD values shown in the tables.
Late Season Insect Protection: All plots were protected from late season bollworms and other pests with 3.0 oz. Baythroid/acre applied on August 1, 8, 17 and 23.
PROCEDURES:
Application Information: At-planting granular insecticides (various rates of Temik) were applied via a tractor-mounted plywood box with holes to fit inverted Mason jars. The jar lids were calibrated to deliver a precise amount of insecticide when the jars were inverted over the holes at a constant, known tractor speed. The holes in the plywood platform led directly into the furrow via funnels under which flexible tubes had been placed. All foliar insecticides were applied on May 18 with a CO2-powered backpack type sprayer calibrated to deliver 8.0 gpa at 50 psi with one Spraying Systems TX-8 hollow cone nozzle per row. A second application of Orthene was applied to Treatment 12.
Thrips Assessments: Five cotton seedlings per plot (20 per treatment) were carefully cut off with a razor blade, put into Mason jars filled with soapy water, transported back to NCSU, and processed using the washing technique. Thrips were later counted under a dissecting stereo microscope and separated into immatures (larvae) and adults. Thrips collections were made on May 23 and 29, or at approximately 3 and 4 weeks after planting.. Plant heights were taken on June 19 by measuring 10 plants per plot (40 total per treatment), and stand counts were made on July 11 by counting the number of living plants per plot in 7.5 row feet in the middle two rows (60 row feet per treatment).;
Harvest: The center two rows of each plot were harvested with 2-row John Deere
mechanical harvester on October 25.
RESULTS:
All of the insecticides resulted in significant height increases over the untreated check.
At the initial May 23 thrips evaluation, 3 weeks plus 1 day after planting, all treatments showed significantly lower levels of total thrips than the untreated control, except the Gaucho alone treatment. Also, all treatments showed significantly lower levels of both immature and total thrips than the Gaucho alone treatment.
At the May 29 thrips assessment, 4 weeks after planting, Gaucho alone was the again the only treatment that did not significantly lower immature or total thrips levels from that counted in the untreated check.
By July 11, no significant differences in stand counts were found between treatments.
Due to relatively good late season harvest conditions, few significant yield differences were found between treatments. Only the Orthene twice-treated and the Adage seed plus Orthene foliar treatments showed significantly greater yields that the untreated check.
In each case, except for the Adage plus Temik treatment, when a foliar treatment was made to the Gaucho or Temik plots, a positive response was noted in most of the parameters tested. In part, this may be due to relatively poor uptake conditions at this site in 2001.