APVMA Approval Number: 53015/0700

Effects of Taskforce and Frenock on serrated tussock

Taskforce and Frenock) were applied to mature serrated tussock growing on soil derived from shale 10 km north of Tuena in the southern tablelands of NSW in summer/autumn 2000. Taskforce1 and Frenock were applied on 11 February 2000 and Taskforce2 and Frenock were applied on 10 March 2000. The difference between Taskforce 1 and 2 was that Taskforce 1 had 58.5% flupropanate and Taskforce 2 had 70%. Various rates of each herbicide were applied (Table 1) to compare their respective effectiveness. There were three replications of each treatment arranged in randomised blocks.

 

Table 1. Effect of herbicides on % brown out of serrated tussock measured on 23 May 2000 and % kill measured on 27 April 2001

Time of spraying in 2000

Herbicide

L/ha

kg a. i. /ha

Brown out (%)

Kill

(%)

11 February

Frenock

1.0

0.745

50

99.7

 

(74.5% a. i.)

1.5

1.117

53

100

 

 

 

 

 

 

Taskforce 1

1.0

0.585

47

100

 

(58.5% a. i.)

1.25

0.731

53

100

 

 

1.5

0.877

63

99.7

 

 

1.75

1.024

57

100

 

 

2.0

1.170

60

100

 

 

 

 

 

 

10 March

Frenock

1.0

0.745

57

100

 

(74.5% a.i.)

1.5

1.117

53

100

 

 

 

 

 

 

Taskforce

1.25

0.875

47

100

 

(70% a. i.)

1.5

1.050

47

99.7

 

 

1.75

1.225

53

100

 

 

2.0

1.400

47

100

 

 

3.0

2.100

60

100

 

 

 

 

 

 

 

Nil

0.0

0.0

10

0

 

Observations

There was no difference between the various herbicide treatments as at 23 May 2000 and 27 April 2001. The brown out 3 and 4 months after the sprayings was quite advanced because it generally takes 3 months for the effects of flupropanate herbicides to be readily observable. This was because rainfall had been plentiful after the sprayings. Rainfall (mm/month) in the seven months after spraying on 11 February 2000 was 23, 92, 38, 29, 36, 18 and 35 mm; the respective rainfall after spraying on 10 March 2000 was 93, 44, 50, 70, 56, 112 and 24 mm.

 

All treatments had a high percentage kill of serrated tussock, the only living tussocks were near the edge of the plots which could have resulted from inaccurate spraying. The most remarkable feature of the kill was the high percentage at the low rates of 0.78, 0.98, 1.0, 1.17, 1.18 and 1.37 L/ha.