http://hdl.handle.net/10150/198989 Sun, 17 May 2026 16:23:04 GMT 2026-05-17T16:23:04Z http://hdl.handle.net/10150/208668 Effect of Plant Nitrogen Status on Defoliation of Short-Season Upland Cotton Nelson, J. M.; Hart, Gary Silvertooth, Jeff Field studies have been conducted over a four year period at the Maricopa Agricultural Center to determine the influence of nitrogen (N) fertility level on the effectiveness of chemical defoliants for short- season cotton production. Excessive N resulted in dense foliage and cotton that was difficult to defoliate. When plants were deficient in N from mid-season to termination, defoliants were very effective, but lint yields were reduced. The effectiveness of defoliants decreased as the petiole NO₃-N content increased. The optimum fertility program for short-season cotton is one that provides sufficient N during the season to produce maximum lint yields, but allows the crop to become deficient in N at the end of the season, prior to chemical defoliation. Sat, 01 Feb 1992 00:00:00 GMT http://hdl.handle.net/10150/208668 1992-02-01T00:00:00Z http://hdl.handle.net/10150/208667 Effect of Plant Water Status on Defoliation and Yield of Upland Cotton for Short-Season Production Nelson, J. M.; Bartels, P. G.; Hart, G. Silvertooth, Jeff A field study was conducted at the Maricopa Agricultural Center to determine the influence of plant water status at the time of defoliation on the effectiveness of defoliants and yield of short-season cotton. Irrigation termination dates of 14 and 26 August and 10 September were used to achieve different levels of plant water stress at the time defoliants were applied (19 September). Irrigation termination dates had no effect on seedcotton yield for cotton defoliated in September. As the period between the termination irrigation and the date of chemical defoliation was increased the effectiveness of defoliants was increased. CWSI and plant water potential measurements indicated that the irrigation termination dates resulted in large differences in plant water stress at defoliation time. There was a significant increase in the defoliation percentage as CWSI values increased (from 0.32 to 0.96) and water potential decreased (from -1.5 to -3.5 MPa). Short- season cotton (163 days) produced 4,396 lbs. seedcotton /A as compared to 5,299 lbs./A for a full-season crop (212 days). Sat, 01 Feb 1992 00:00:00 GMT http://hdl.handle.net/10150/208667 1992-02-01T00:00:00Z http://hdl.handle.net/10150/208666 Defoliation of Pima Cotton at 3000 Feet Elevation, Safford Agricultural Center, 1991 Clark, Lee J.; Carpenter, Eddie W.; Odom, Phil; Nelson, John Silvertooth, Jeff A preliminary study of several defoliants and /or combinations was made on the Safford Agricultural Center. Even though conditions were less than ideal because of cool temperatures, acceptable defoliation occurred under several of the treatments. In fact, three of the treatments performed better than sodium chlorate, which is the predominant defoliant used in the area. Sat, 01 Feb 1992 00:00:00 GMT http://hdl.handle.net/10150/208666 1992-02-01T00:00:00Z http://hdl.handle.net/10150/208642 Defoliation Research on Pima and Upland Cotton at the Marana Agricultural Center in 1991 Nelson, J. M.; Silvertooth, J. C. Silvertooth, Jeff A field study was conducted at the Marana Agricultural Center to evaluate the effectiveness of ground rig applied defoliant treatments on Pima and Upland cotton under cool weather conditions. Defoliants were slow acting at this location, however, all chemical treatments tested resulted in good defoliation 14 days after application. Sat, 01 Feb 1992 00:00:00 GMT http://hdl.handle.net/10150/208642 1992-02-01T00:00:00Z