Thistle-free pastures give higher grass yields and keep stock happy

UK - June 12, 2006

Farmers are losing out on grass productivity because thistles are taking over. That's the view of Vaughn Stansfield, Dow AgroSciences grassland agronomist.

"Many fields are now showing heavy patches of thistles and where there are thistles you don't have grass growing.  A five per cent thistle infestation in the sward could result in up to 0.5t/ha DM loss in grass yield, and that's going to affect your grazing and forage needs for the rest of the season," says Mr Stansfield.

If thistles have grown too high and the flowering buds are showing then this is too late to spray and get an effective result - the thistle will be less susceptible to the herbicide's action.  In this case your best action is to top thistles and then go into spray about 14 days later. Try not to wait until the thistle has seeded as this will only make the problem worse in future years.

The thistle's underground root systems become extensive and what you see on the surface is only the tip of the iceberg down below. Once established the root mass is greater below ground than above it.  Thistle roots can withstand drought better than grass.

"It is essential to hit thistles at the right growth stage, otherwise you are wasting your time and money."

To get the best results thistles should be sprayed with an appropriate herbicide like Thistlex when they are at the rosette stage, showing four to 10 leaves and up to 20cm (8ins) high.  This stage ensures that there is enough leaf area and rapid plant growth for effective uptake of the herbicide, which goes right down to the roots.