Excellent conditions for growth over the past six weeks is a likely factor for the increase.

On the Irish Farmers Journal suckler farm in Tullamore, some of the reseeded fields are heavily infested with thistles.

While the field was sprayed with glyphosate prior to reseeding, the thistles were not up at the time, due to poorer growth than normal in April.

The best time to kill a weed is at the seedling stage.

So spraying for weeds in newly sown reseeds is a must.

Why go through all the work and expense of reseeding and then decide not to spray for weeds post-emergence.

Reseeds sown in May should be sprayed by now. When choosing a spray, make sure you use clover-safe sprays if clover was sown with the grass seed.

The problem with thistles is that there are not any clover-safe sprays available that have good thistle control.

In Tullamore, a non-clover safe spray was used to spray the reseeds and kill the thistles. The clover will probably need to be resown at a later date when we know the thistles have been killed.

In established grassland, controlling weeds is more difficult. Thistles, docks and ragwort are the main weeds that farmers have to deal with.

There are two types of thistles.

Creeping thistle has a purple flower and it spreads mainly through creeping roots, so is often found in clusters.

It also spreads in wind-blown seeds after flowering in July and August.

Sprays such as Thistlex, Pastor and Forefront are effective, but it is important to spray at the rosette stage, so topping will be helpful to even up growth stages. Topping by itself will be a useful control mechanism on affected areas.

Topping is less effective for the spear thistle. This thistle is less common than the creeping, but tends to be larger, particularly in the second year. The same sprays will kill both types of thistles. Again, it should be sprayed in the rosette stage and more than one spray may be needed for an effective kill.

On dock control, the best time to spray is when they are at the green leafy rosette stage. Now could be a good time to spray for docks in aftergrass, but it’s too late to spray for them in pastures that have not been cut yet this year or on docks that have gone to seed.

There are lots of sprays on the market.

Pay particular attention to the volume of water used when spraying.

Most of the sprays that control thistles and docks will control ragwort also, but you need to be very careful when grazing cattle in fields that have been sprayed because dying ragwort will become more palatable to livestock.

This is really important, as ragwort is poisonous to stock. Where ragwort is present in relatively small numbers, pulling by hand and safely disposing of the weeds is probably the best control method.

Remember, you must be trained and registered to operate a sprayer.

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