During the early spring of 1993, nine post emergence broadleaf herbicides were applied to both 100% stands of London Rocket and perennial ryegrass turf. These two tests were conducted to measure turf tolerance and weed control during the early spring, when London Rocket is present and ryegrass is the dominant turf.

Post emergence applications were made to 100% stands of London Rocket and to 100% stands of turf-type perennial ryegrass on March 3, 1993. London Rocket plants were 4 inches tall, with 15% of the plants beginning to head. The ryegrass turf was maintained at 2.5 inches and irrigated when necessary to avoid moisture stress. The nine treatments were as follows:

1. EXP 31044A (3.25 SL) 1.73 lb/ai/a.

2. CHIPCO WEEDONE AMINE (3.7S) 0.91 lb/ai/a 2,4-D

0.94 lb/ai/a 2,4-DP.

3. TRIMEC CLASSIC (3.32 SL) 1.01 lb 2, 4-D/A plus

4. TURFLON ESTER (4EC) 0.54 lb/ai/a

5. CLOPYRALID (3EC) 0.18 lb/ai/a

6. CONFRONT (3EC) 0.54 lb/ai/a trich.plus

7. TURFLON D (3EC) 0.27 lb/ai/a trich.

0.54 lb 2, 4-D ai/a

8. TURFLON II AMINE (3.85 EC) 0.54 lb/ai/a trich.amine plus

1.40 lb 2, 4-D ai/a amine

9. FLUROXYPYR (1.5 EC) 0.15 lb/ai/a

10. Untreated Check (no treatment)

EXP 31044A, clopyralid and fluroxypyr are not yet commercially available.

Plot sizes were 5x10, and were replicated four times in each experiment. Chemicals were applied at a solution rate of 53 gallons per acre using a three nozzle boom at a 20 inch spacing with 8004 nozzles at 30 PSI.

Weed control and injury to weeds were measured as the degree of herbicide efficiency using a visual scale of 1-6, 1 = no damage, 6 = severe damage and death. Percent weed control was calculated as 1 - (treated/control) x 100 at 20 and 30 DAT. Turf injury, color changes, stunting or discoloration did not occur at any time, so no turf data was recorded.

March 11, 1993 (8 DAT)

Turflon D, EXP 31044A, Turflon II AM, and Turflon Ester had degree of injury scores of 4.8 or greater (Table 1). These treatments caused twisting and cupping and chlorosis to high levels on the London Rocket. Confront, fluroxypyr and Trimec showed those effects less severely at 8 DAT, with scores of 3.3 to 3.8. Clopyralid alone, had no effect on the weed at 8 DAT, and was not distinguishable from the checks.

March 22, 1993 (20 DAT)

Death to the weeds had occurred by 20 DAT. Turflon II Amine and Turflon D had provided full injury scores of 6.0. EXP 31044A had a mean score of 5.8. Chipco Weedone, Trimec and Turflon Ester had mean scores of 5.3, 5.0 and 4.8, respectively (Table 1). Confront, fluroxypyr and clopyralid had minimal, or no effect.

Percent weed control ranged from 0 (clopyralid) to 96-98% for Turflon II Amine and Turflon D. EXP 31044A, Chipco Weedone, Trimec had 82-90% mean control. Turflon Ester was next with 74% of the plot killed. Confront and fluroxypyr had 38% control only (Table 2).

April 2, 1993 (30 DAT)

Both Turflon II Amine and Turflon D had maintained strong injury on the London Rocket (6.0). EXP 31044A was next with a mean injury score of 5.5, followed by Chipco Weedone and Trimec at 5.3 and 5.0, respectively (Table 1). Turflon Ester was not as injurious, with a mean score of 3.5. Confront and fluroxypyr had minimal effect at 30 DAT. Clopyralid still had no effect on the weeds.

Percent weed control ranged from 0-99%. Turflon D, Turflon II Amine and Chipco Weedone had 96-99% control. EXP 31044A and Trimec had 94 and 95% control, respectively. Turflon Ester was intermediate with 74% mean control. Again, Confront and fluroxypyr had low levels of control (28-30%), and clopyralid was totally ineffective (Table 2).

At this time, certain plots were beginning to show regrowth of the flower stalks. Those which exhibited some regrowth included Turflon Ester, fluroxypyr, and Confront. These three herbicides did not exhibit the strongest injury effects on the London Rocket, nor did they develop the highest weed control levels.

Turf Injury:

No treatments caused injury, discoloration, chlorosis, or stunting to the perennial ryegrass.

1. After a single application on March 3, 1993, pure stands of London Rocket were controlled by Turflon D, Turflon II Amine at 20 DAT.

2. By 30 DAT, EXP 31044A and Trimec herbicides had achieved 94% or greater control.

3. Turflon Ester provided quick injury, but did not have prolonged control or effect as other treatments did.

4. Confront herbicide (trichlopyr plus clopyralid) and fluroxypyr did not have severe effect on this weed.

5. Clopyralid alone had no effect on London Rocket.

6. Perennial ryegrass turf mowed at 2.5 inches showed no effect from these herbicides at the use rates tested here.

Table 1. Degree of injury¹ to London Rocket from a single application of select post emergence herbicides on March 3, 1993. University of Arizona.

TREATMENT ( 8 DAT) (20 DAT) (30 DAT)

TURFLON II AM. 5.0 6.0 6.0

TURFLON D. 5.3 6.0 6.0

EXP 31044A 5.0 5.8 5.5

CHIPCO WEEDONE 3.0 5.3 5.3

TRIMEC 3.3 5.0 5.0

TURFLON ESTER 4.8 4.8 3.5

CONFRONT 3.8 2.8 2.3

FLUROXYPYR 3.5 2.8 2.0

CLOPYRALID 1.0 1.0 1.0

CONTROL 1.0 1.0 1.0
 

MEAN/DATE 3.6 4.0 3.8

LSD VALUE² 0.8 0.5 0.6

²LSD value = Least Significant Difference value. Difference between treatment means must be larger that the LSD value for significance among treatments to occur.

Table 2. Percent weed control¹ of London Rocket from a single application of select Post Emergence Herbicides applied on March 3, 1993. University of Arizona.
 

Date and No. of days after treatment

March 22 April 4

TREATMENT (20 DAT) (30 DAT)

TURFLON D 99 98

TURFLON II AM. 97 98

CHIPCO WEEDONE 86 96

EXP 31044A 90 95

TRIMEC 83 94

TURFLON ESTER 74 74

CONFRONT 38 30

FLUROXYPYR 38 28

CLOPYRALID 0 0

CONTROL 0 0

LSD VALUE² 6 11 

²LSD value = Least Significant Difference value. Difference between treatment means must be larger than the LSD value for significance among treatments to occur.