Cyanazine: A Potential Preplant Cotton Herbicide

J.P. Chernicky, E.S. Heathman, and B. Barstow


 
ABSTRACT

Field experiments were conducted in 1987 at Cosmo (loam), Goodyear (sandy clay loam), Maricopa (sandy clay loam), and Tolleson (clay loam) Arizona to measure the response of cotton (Gossypium hirsutum DP 90, 77) to preplant applications of cyanazine (0.8 to 3.0 lb/a) and prometryn (1.6, 2.0 lb/a) alone and in combination with either trifluralin or pendimethalin (0.5 to 1.0 lb/a). Cinmethylin was also applied alone (0.5 and 1.0 lb/a) at three of the four locations. Field sites were chosen on the basis that they represented a wide variety of soils and production practices representative of the state of Arizona. All experiments utilized a randomized complete block design with four replications. Depending on location, herbicides were either applied to flat ground (late March, early April) and disced in to 2 - 3 inch depth or applied over-the-top of rounded beds (40 in) and shallowly incorporated prior to planting. In order to measure the influence of irrigation two of the experiments were planted in moisture (Maricopa, Tolleson) and two were planted dry and watered up with an irrigation. Parameters measured included: cotton stand per 10 ft of row, cotton stunt, and a visual estimate of weed control (Goodyear and Maricopa only).

Cotton stand was not significantly reduced at any of the locations as a result of prometryn (up to 2.0 lb/a) or cyanazine (up to 3.0 lb/a) treatments alone or in combination with a dinitroaniline herbicide. Cinmethylin at 1.0 lb/a however did reduce cotton stand by 20 % at three locations. Cotton stunt with the exception of cinmethylin never exceeded 1 0% with prometryn and cyanazine treatments. Cotton injury was most evident at the CDSMO location which had the lightest soil (loam) and required an early post plant irrigation to obtain a stand of cotton. At all four locations cotton injury associated with prometryn or cyanazine treatments were most visible after the first postemergence irrigation and then completely disappeared approximately two weeks after the second postemergence irrigation (mid-late June).

Weed populations were variable at the Tolleson and Cosmo locations, thus weed control ratings were dropped. At Goodyear, cyanazine (at 3.0 lb/a) gave 90% control of palmer amaranth (Amaranthus palmeri). Similar control of this weed was obtained by either prometryn (1.5 lb/a) or trifluralin (0.5 lb/a). A similar trend was evident at the Maricopa location. However at this location cyanazine alone applied preharrow at 1.6 lb/a gave significantly better control of wright groundcherry (Physalis wrightii) than prometryn (1.6 lb/a) alone. If a dinitroaniline herbicide was tank-mixed with prometryn wright groundcherry control was not significantly different from what was obtained by cyanazine.

From the four field trials, cotton appears to be slightly more tolerant of cyanazine than prometryn. Cotton injury was most evident after the first postemergence irrigation with both of these herbicides however neither was severe enough to cause significant stand reductions. Prometryn was more effective on pigweed than cyanazine. The addition of a dinitroaniline herbicide to cyanazine significantly increased pigweed control. The opposite situation existed with wright groundcherry. Further research is required on additional weed species before making any definitive statements relating to efficacy differences between prometryn and cyanazine.



Reprinted from 1988 Proceedings: Beltwide Cotton Production Research Conferences pg. 387
©National Cotton Council, Memphis TN

[Main TOC] | [TOC] | [TOC by Section] | [Search] | [Help]
Previous Page [Previous] [Next] Next Page
 
Document last modified Sunday, Dec 6 1998