ISU Horticulture Publications: 2002 Turfgrass Report

Monsanto 78365 Demonstration for Summer Fastburn Symptomology in Turfgrass

B. R. Bingaman and N. E. Christians

This study was designed to demonstrate at the 2001 Turf Field Day the fastburn symptomology capability of MON 78265 at one, two, three and seven days post treatment and to compare this symptomology to that of Roundup Pro Dry.

This study was conducted at the Horticulture Research Station north of Ames, IA. The plot was in established area of premium Kentucky bluegrass sod mix. The soil was a Nicollet (fine-loamy, mixed, mesic Aquic Hapludoll) with 4.1% organic matter, 93 ppm K, 11 ppm P, and a pH of 6.75. The experimental design was a randomized complete block. Three replications were conducted and individual plot size was 5 x 5 ft.

Experimental MON 78365, Roundup Pro Dry, and Roundup Pro Dry + Scythe 1EC were applied at various intervals before ISU Turfgrass Field Day on August 2 (Table 1). The 14 day before field day treatments were made on July 19, 7 days before on July 26, 3 days before on July 30, 2 days before on July 31, and 1 day before on August 1. All materials were applied using a carbon dioxide backpack sprayer equipped with TeeJet #8006 nozzles at a spray pressure of 30-40 psi. Liquid formulations were mixed with water to a volume equivalent to 3 gal/1000 ft².

Efficacy of the formulations was assessed by estimating the amount of 'brown' (dead and dying) plant material per plot. These percentage data were taken from July 24 through September 26 (Table 1). The Statistical Analysis System (SAS Institute Inc., 1989-1996) and the Analysis of Variance (ANOVA) procedure were used to analyze the data. Treatment effects were examined with Fisher's Least Significant Difference (LSD) means comparison test.

By July 30, turf areas treated with Roundup Pro Dry at 14 days before field day were totally brown and turf treated with MON 78365 on July 26 was 81.7% brown (Table 2). Turf treated with Roundup Pro Dry alone or Roundup Pro Dry plus Scythe on July 26 had 76.7 and 56.7% brown area, respectively.

There were significant differences in brown areas among the treatments on August 3, one day after field day. Dead areas were similar for the treatments applied seven days before field day. The three days before field day treatments also were similar with 78.3% brown area for MON 78365 and 68.3% for Roundup Pro Dry plus Scythe. The symptomology on turf treated two days before field day showed distinct differences. Treatment with MON 78365 resulted in 76.7% brown area and Roundup Pro Dry plus Scythe produced 61.7% brown-out. However, turf treated with Roundup Pro Dry alone had only 16.7% brown area. Percentage brown areas in turf treated with the one day before field day applications were 66.7 and 43.3% for MON 78365 and Roundup Pro Dry plus Scythe, respectively.

From August 9 through August 28, there was 100% brown-out in all treated turf. Regrowth of plant material was noted on September 13 but by September 26, brown areas in treated turf were still greater than 91% for all materials.

Table 1. Timing and rates of application for nonselective herbicides used in the 2001 Monsanto 78365 Demonstration Study.

			Timing of application (days prior to Field Day- Aug 2)
	Material	Rate a.i./A	14 days July 19	7 days July 26	3 days July 30	2 days July 31	1 day Aug 1
1.	Untreated control	NA	NA	NA	NA	NA	NA
2.	MON 78365 66.6%	6 lb		XXXXX
3.	MON 78365 66.6%	6 lb			XXXXX
4.	MON 78365 66.6%	6 lb				XXXXX
5.	MON 78365 66.6%	6 lb					XXXXX
6.	Roundup Pro Dry 64.9%	6 lb	XXXXX
7.	Roundup Pro Dry 64.9%	6 lb		XXXXX
8.	Roundup Pro Dry 64.9%	6 lb				XXXXX
9.	Roundup Pro Dry 64.9% + Scythe 1EC	6 lb 12 qts		XXXXX
10.	Roundup Pro Dry 64.9% + Scythe 1EC	6 lb 12 qts			XXXXX
11.	Roundup Pro Dry 64.9% + Scythe 1EC	6 lb 12 qts				XXXXX
12.	Roundup Pro Dry 64.9% + Scythe 1EC	6 lb 12 qts					XXXXX

Table 2. Percentage dead area¹ in turfgrass treated for the 2001 Monsanto 78365 Demonstration Study.

	Material	Days before Field Day	July 24	July 30	Aug 3	Aug 9	Aug 16	Aug 22	Aug 28	Sept 13	Sept 20	Sept 26	Mean
1.	Untreated control	NA	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
2.	MON 78365 66.6%	7	----	81.7	98.3	100.0	100.0	100.0	100.0	99.3	99.0	97.7	99.3
3.	MON 78365 66.6%	3	----	----	78.3	100.0	100.0	100.0	100.0	99.7	99.3	99.0	97.0
4.	MON 78365 66.6%	2	----	----	76.7	100.0	100.0	100.0	100.0	99.7	99.0	99.0	96.8
5.	MON 78365 66.6%	1	----	----	66.7	100.0	100.0	100.0	100.0	99.3	99.0	97.7	95.3
6.	Roundup Pro Dry 64.9%	14	73.3	100.0	100.0	100.0	100.0	100.0	100.0	96.3	96.3	95.0	98.5
7.	Roundup Pro Dry 64.9%	7	----	76.7	93.3	99.7	100.0	100.0	100.0	97.7	99.0	97.7	98.4
8.	Roundup Pro Dry 64.9%	2	----	----	16.7	98.3	100.0	100.0	100.0	99.7	96.7	99.0	88.9
9.	Roundup Pro Dry 64.9% + Scythe 1EC	7	----	56.7	86.7	98.3	100.0	100.0	100.0	95.0	97.7	91.3	96.1
10.	Roundup Pro Dry 64.9% + Scythe 1EC	3	----	----	68.3	100.0	100.0	100.0	100.0	99.3	99.0	96.3	95.4
11.	Roundup Pro Dry 64.9% + Scythe 1EC	2	----	----	61.7	99.3	100.0	100.0	100.0	99.7	99.0	94.7	94.3
12.	Roundup Pro Dry 64.9% + Scythe 1EC	1	----	----	43.3	98.3	100.0	100.0	100.0	99.7	99.3	99.0	92.5
	LSD_0.05				17.3	2.2	--	--	--	3.1	3.4	4.9	2.3

^{1These data represent the percentage area per plot covered by 'brown' plant material.
Fourteen days before field day applications were made on July 19, 7 days on July 26, 3 days on July 30, 2 days on July 31, and 1 day on August 1, 2001.
Data from August 3 through September 26 are included in calculations for the mean 'brown' area.

ISU Horticulture:Publications:2002 Turfgrass Report
College of Agriculture

106 Horticulture Hall
Ames, Iowa 50011

Phone: (515) 294-2751

Fax: (515) 294-0730

Website or Department-related Questions/Comments: hortdept@iastate.edu

Plant Questions: hortline@iastate.edu

Contents ©1995-2003, ISU Horticulture Department}