A group from the Innovative Farmers network are now in year three of trials into control of the pernicious weed creeping thistle. At the most recent meeting in June the group found deep surface cultivations between 8” and 10” to be the most effective of 11 trialled techniques.
 
Deeper cultivations are more commonly used to prevent soil compaction in arable or livestock farming but this group of Innovative Farmers have discovered alternative uses for deep surface cultivation.
 
Most tractor mounted cultivation tools will break up and turn surface soil to between 5” and 8” but deeper cultivation appears effective in damaging the roots of the thistle, resulting in significantly less growth than other techniques trialled.
 
Liz Bowles, head of farming at the Soil Association said; “At the moment we do not know exactly why this technique proved so effective.  However, we think it is important that the cultivations are carried out after thistles have stopped growing in the autumn. This then gives time for rhizome degradation to take place over winter when the plant is not actively growing. Treated and untreated thistle rhizomes were dug up and examined in April this year. There was clear evidence of lack of growth and fungal infection in plants from the treated area.
 
“If this technique can be repeated at scale it provides an exciting opportunity for farmers looking for effective non-chemical control of creeping thistle. It was found to be the most effective treatment in the Innovative Farmers field lab and there is already significant interest in furthering investigation into this. It is interesting to find how technology already at our fingertips, can have additional impacts on the farm.”
 
The Innovative Farmers field lab was carried out at the Sandringham Estate in Norfolk where trial plots were set to test the different techniques. The creeping thistle within the area treated by deep surface cultivation showed definite signs of weakening and the growth seemed to have been depressed. The trial is set to continue, further honing this technique for increased efficiency. The group will now focus more closely on timing and type of cultivator used and the effect of combining this technique with the Garford Hoe.
 
In addition ADAS will look into samples to look at the microbiology of what is happening in the rhizome.
 
Other techniques tested included:
    1    Using a clover ley
    2    Undersowing with buckwheat
    3    Electrical weeder
    4    Comb cut
    5    Garford hoe
    6    Application of Mg / Mn
    7    Biodynamic weed (Thistle) pepper spray
    8    Sub-soiling (12”-14”)
    9    Buckwheat green manure
    10    Weed surfer
    11    Parasites on thistles (Fungus)