Abstract/Contents: | Describes an experiment to evaluate the effectiveness of imidazolinone as a seedhead suppressor and imidazolinone as a factor in spring green-up. "Experiments were undertaken at the practice football field at Starkville Academy to examine the response of common bermudagrass to treatments with imazaquin (Image) applied alone at 0.38 lbs. ai/A, the combination of AC263, 222 (Cadre) and imazaquin at 0.05 and 0.19 lbs. ai/A, respectively, and a control receiving only water. All treatments were applied with a water carrier using a CO2 backpack sprayer delivering 50 gpa with 30 psi. No surfactant was used with any treatment. Nitrogen was applied at 1# N per 1000 ft2 as 13-13-13 in both May and June, and as 45-0-0 in mid-August. A spring transition study was initiated at Mississippi State Golf Course. This area received approximately 3# N per 1000 ft2 during the growing season of 1989 (1.5#N as 13-13-13 in April and 1.5# N as urea in June) and 2# K2O per 1000 ft2 in September, 1990. No fertilizer applications were made at the golf course prior to initiation of this experiment. No supplemental irrigation was applied to any plat following treatment application. Supplemental irrigation of approximately 0.5 inches of water was applied to turf areas designated for treatment approximately 1 week before treatment during July and August to insure the turf was actively growing before imidazolinone applications were made. The turf area was regularly mowed at a height of 3-cm and all designated treatment areas were clipped to this height 1 week before growth regulator treatment. The spring transition study at Mississippi State Golf Course was initiated on 9 April, 1990. At this time the common bermudagrass was approximately 30% green-up. Ratings of % plot green-up were made weekly from 1 through 4 weeks after treatment (WAT). Experiments were initiated at Starkville Academy on 5 May, 1990 to examine month by month responses of common bermudagrass to imidazolinone applications. Other dates of imidazolinone applications were 5 June, 6 July, 13 August, 17 September, and 15 October. Ratings and measurements made on the bermudagrass plots included grass color (1=brown, 9=green), relative plot quality (1=low, 9=high), seedhead number per ft2, mean seedhead height (cm), and mean plot grass height (cm). All ratings were made weekly from 1 through 4 WAT. Analyses of variance were determined for each experiment and mean separation procedures (Fisher's Protected LSD) were utilized where appropriate." Table 1 gives the percent green-up late for common bermudagrass over a four week period after the treatments with different levels of image and cadre on April 16, 1990. Table 2 shows color, quality, grass height seedhead number and seedhead height of common bermudagrass for each week in a four week period after initial treatment on May 7, 1990. Table 3-6 give the values of the same categories recorded in Table 2 for June 5, July 6, August 14, and September 17, 1990, respectively. Image + Cadre reduced plant height, seedhead height and number reductions appeared to the result of the treatment delaying or retarding seedhead formation of common bermudagrass, and not a complete inhibition of seedhead development. In most cases the color reduction in Image + Cadre-treated bermudagrass plots was sustained for 2 WAT, with few other exceptions (either longer or shorter discoloration periods) being noted. Image applied alone (0.38 lbs ai/Acre) also showed some growth regulator activity on common bermudagrass, but in almost every case the reduction in plant growth was less than that obser4ved for the Image + Cadre combination. |