Dock control project in fields with and without clover 2019

Technical Officer: Sarah Hughes 

Farmer: Richard Roderick

 

Background:

The aim of the demonstration site trial was to monitor dock control and clover retention. It included two field-scale trials of a clover safe product and a standard product, the later having a split spring/autumn half rate application.  The fields were in a block of fields of permanent pasture.  

Field name

Size

Active ingredients used

Rate /ha

Cost of product*

Withdrawal/Harvest period

Bridge Field (no clover)

3.24ha

Triclopyr (150g/l); Fluroxypyr (150g/l) 50% (Doxstar)

1l/ha (apply second dose in September)

£23.75/ha

(£47.50 for 2)

Harvest interval: 7 days

Grazing Period: 7 days

Sycamore Field (clover present)

3.6ha

Amidosulfuron (75% w/w) 100% (Squire Ultra)

0.06kg/ha

£40.00/ha

Harvest Interval: 21 days

*Using the National Association Agricultural Contractors 2018 figures with red diesel at 50ppl spraying costs could be (up to 200l/ha) £12.63/ha on top of spraying costs.

 

Fig 1. Aerial view of the three fields

 

 

                                        

The fields were sprayed in late April/early May at the rosette growth stage when they were actively growing.  It is important to spray them at the correct stage (the label says 20cm rosette width or height).

 

July 2019

Both fields were inspected on 2 July to see the level of control on the docks post spraying. 

 

Bridge Field (no clover present)

The Triclopyr (150g/l); Fluroxypyr (150g/l) mix (Doxstar PRO) in Bridge Field had been applied at half rate (second application will be applied in the autumn). The visual observation showed excellent dock control with more than 85% control above ground and a few around the hedge line.

 

Sycamore Field (clover present) 

The Amidusulfuron (Squire Ultra) showed no clover damage, however there were only partial control of docks and there was some regrowth (more than 50%) and flowering at the base of the stunted docks.


The images show the dock post spraying – blackening of the stalk and re-growth at base.

 

 

 

 

 

 

 

 

 

 

 

 

A second assessment was made in the autumn to decide whether or not to proceed with the follow-up half rate spray of Triclopyr (150g/l); Fluroxypyr (150g/l) (Dockstar PRO) depending on dock weed growth and weed burden.   As there were no significant levels of dock visible it was felt that the farmer/agronomist would look again in spring 2020 to monitor dock levels for further treatment.

Conclusions:

  • Regardless of product type farmers need to spray at correct growth stage according to manufacturer recommendations.
  • In the spring in warm weather, weeds can still grow even after spraying.
  • Awareness of environmental restrictions such as 5m buffer zone when spraying near a watercourse for certain pesticides is essential.
  • Good weed control for over 20% weed burden can be economically viable.

Other information:

  • The white clover safe Amidosulfuron (Squire Ultra) used in Sycamore Field states on the label that it may take longer (up to 2 months) for the weeds to die back fully. The manufacturer recommends 28 days to allow it to work before silage or hay making.  
  • If carrying out a split treatment, it is important to assess the level of control from the first treatment if reducing the dose, as above ground control of leaves can be good but the roots have not been fully controlled, and autumn or following spring re-growth can occur.