The use of Ecoplugs for woody weed control

EcoplugsSummary

Ecoplugs are a novel formulation of crystalline glyphosate encapsulated in a plastic plug. Because of their design, they present practically no risk of non target drift or operator contamination, and it is claimed that Ecoplugs can be used in all weathers at any time of year. Although initially only approved for use on cut tree stumps, because of their potential advantages over conventional application of liquid herbicides, our research focused on testing the suitability of Ecoplugs, compared to traditional chemical thinning methods and ring barking, for the killing of standing trees, as well as for the control of rhododendron.

Research objectives

  1. Compare the efficacy of Ecoplugs, conventional herbicide application and manual ring barking, carried out at different times of year and with and without simulated rainfall, for the killing of standing Douglas fir.
  2. Carry out a time and method study of the relative cost and efficiency of the different chemical thinning and ring barking techniques.
  3. Investigate the impact of the different chemical thinning treatments and ring barking on subsequent infection from the wood rotting disease Heterobasidion annosum, and in addition the efficacy of the treatments for killing standing Japanese larch and Scots pine.
  4. Compare the efficacy of Ecoplugs with conventional herbicide application, with different delays after cutting, and with and without simulated rainfall, for preventing regrowth from cut rhododendron stumps.

Results so far

1. Efficacy of Ecoplugs

Our research found that applying one Ecoplug (formulated as Ecoplug Max® (680 g kg-1 glyphosate); or as Ecoplug Max ® (720 g kg-1 glyphosate)) per 3 cm of stem diameter, an equivalent of 0.068 g a.i. glyphosate per cm of stem diameter, can give effective control of around 90% of standing Douglas fir within 18 months of treatment. Ecoplugs appeared to be a more effective method of applying glyphosate to kill standing Douglas fir trees than the traditional method of chemical thinning which involves spraying neat liquid glyphosate into cuts made in the tree stem. Both traditional chemical thinning and the use of non chemical ring barking also gave some control of standing Douglas fir trees in our work, but the speed of kill was slower and overall efficacy lower than when using Ecoplugs. The artificial rainfall applied had no effect on the treatments.

Full details of this research can be found in the scientific paper:-

Willoughby, I.H., Stokes, V.J. and Connolly, T. (2017). Using Ecoplugs containing glyphosate can be an effective method of killing standing trees. Forestry 90 (5), 719 – 727.

2. Cost and efficiency of different control techniques

The application costs of the different methods of killing standing trees, assuming 2,000 treated stems per hectare, including the costs of tools, safety equipment, chemicals etc, were found to be as follows:-

  • £5,700 per hectare for chainsaw felling to recycle. However, if it were practical to extract and sell the timber, for the study site used this figure would change to a potential net revenue of around £15,000 per hectare.
  • £2,860 per hectare for the Ecoplug method.
  • £2,140 per hectare for manual ring barking.
  • £940 per hectare for the traditional cut and spray method.

Full details of this research can be found in the following report:-

Saunders, C. (2014). An Investigation into the Efficiency of Ecoplugs for Chemical Thinning. Technical Development Job Report 121. Internal report. Technical Development, Forest Research, Ae Village.

This is an internal report but is freely available from Technical Development, Forest Research.

3. Impacts on Japanese larch, Scots pine and Heterobasidion annosum infection

The results from this study also suggested that applying one Ecoplug per 3 cm diameter of stem can give effective control of around 100% of standing Japanese larch and 90% of standing Scots pine within 17 months of treatment in the early spring. Ecoplugs appeared to be a more effective method of applying glyphosate to kill standing Japanese larch trees than the traditional method of spraying neat liquid glyphosate into cuts in the stem, but were no more effective in Scots pine, suggesting that final efficacy of the two treatments may turn out to be similar, but that Ecoplugs may provide more rapid control.

Ecoplugs, conventional herbicide application to stem cuts and manual ring barking all allowed infection to some extent of Heterobasidion annosum, a disease that can cause serious and long term damage to current and future conifer crops. However, although it was not possible to make a direct comparison in our work, the Heterobasidion annosum infection that results from using Ecoplugs is unlikely to be significantly higher than the infection that typically occurs after conventional thinning operations due to accidental stem damage. If an entire stand is going to be killed, then felling and treating stumps with the prophylactic fungicides urea or PG Suspension® (0.5% w/v Phlebiopsis gigantea), will present a lower risk of infection from Heterobasidion annosum than any method of chemically killing standing trees.

Full details of this research can be found in the following scientific paper:-

Tubby, K.V., Willoughby, I.H. and Forster, J. (2017). The efficacy of chemical thinning treatments on Pinus sylvestris andLarix kaempferi and subsequent incidence and potential impact ofHeterobasidion annosum infection in standing trees. Forestry 90 (5), 728 – 736. 

4. Efficacy of Ecoplugs on Rhododendron

Our research found that applying one Ecoplug per 3 cm of stump diameter can give around 80-90% control of regrowth from rhododendron stumps. Control is likely to be as good as, but no better than, conventional sprays of liquid glyphosate, and in both cases, repeat visits to control regrowth will almost certainly still be required. Although it is recommended that Ecoplugs should always be applied to stumps within 2 days of cutting, if a delay is unavoidable, our work suggests that they may still be effective if applied up to eight weeks after cutting. The artificial rainfall applied had no effect on the treatments.

Full details of this research are available in the following scientific paper:

Willoughby, I.H., Stokes, V.J. and Edwards, C. (2017). Ecoplugs containing glyphosate can be effective in preventing regrowth from Rhododendron ponticum stumps. Scottish Forestry,71 (3), 33-39. 

Status

This project started in 2013 and is now complete.

Contact

Dr Ian Willoughby

Funders and partners

This research was funded by Forest Enterprise Scotland and Forestry Commission Scotland. In addition, the Forestry Commission funded the production of the scientific papers via the Delivering Resilient Forests research programme of the Forestry Commission Science and Innovation Strategy

Forestry Commission policy

This research will help managers deliver sustainable management and the protection of the forest resource against biotic threats across the UK as outlined in the UK Forest Standard . It will also help deliver Forestry Commission England, Forestry Commission Scotland ,and Welsh Government polices to reduce the impact of invasive pest species.