Validating NAWF5 as a measure of crop 'cut out' in North Louisiana

Document Type

Conference Proceeding

Publication Date

12-1-1999

Abstract

Validating node above white flower (NAWF)5 as a measure of physiological 'cut out' for selected cotton varieties (NuCOTN 33(B) and Sure-Grow 821) in North Louisiana during 1998 was a primary objective in studies to refine late-season cotton insecticide termination strategies. A two-factor study consisting of NAWF stage (main plot) and method of square removal (subplot) was used to determine when the last harvestable boll population develops on cotton plants. However, numerical trends were similar to that for the main stem/terminal removal treatments. Significant yield differences among NAWF stages in the lower (P = 0.032) and upper (P = 0.005) zones were observed in the control plots. Seedcotton yields harvested in the lower zone at NAWF4 were significantly higher than that in the NAWF6 and NAWF5 plots. Higher yields in the upper zone were harvested in the NAWF6 and NAWF5 plots compared to yields in the NAWF4 plots. Yields in the upper zone (above the main stem tag) represented 18.3%, 11.8%, and 4.8% of the total seedcotton harvested in NAWF6, NAWF5, and NAWF4 non-damaged control plots. In the Sure-Grow 821 test, there were no significant differences in crop maturity based on percent open bolls among the NAWF stages within the non-damaged control (P = 0.912, 74-81% open), and square stripping (P = 0.113, 63-88% open). However, there were significant differences in crop maturity based on percent open bolls in the main stem/terminal removal treatment (P = 0.001, 61-89% open). Plots receiving this treatment at NAWF6 and NAWF5 had fewer open bolls at defoliation compared to that in the NAWF4 and NAWF3 plots. No significant differences in total seedcotton yields (P = 0.063) were observed among NAWF stages for the main stem/terminal removal treatment. However, yields consistently increased as this treatment was delayed from NAWF6 to NAWF3. No significant differences in total seedcotton yield (P = 0.662) were observed among NAWF stages for the square stripping treatment. In the non-damaged control plots, there were no significant yield differences among NAWF stages (P = 0.222) in the lower zone. There were significant differences (P = 0.003) among NAWF stages in seedcotton yields in the upper zone. Yields in the upper zone of NAWF6 and NAWF5 plots were higher than yields in NAWF4 and NAWF3 plots. Yields in the upper zone (above the main stem tag) represented 22.2%, 25.5%, and 7.1% and 2.6% of the total seedcotton harvested in NAWF6, NAWF5, NAWF4, and NAWF3 non-damaged control plots.

Publication Source (Journal or Book title)

Proceedings of the 1999 Beltwide Cotton Conference, January 1999, Orlando, Florida, USA

First Page

1229

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