There seems to be more weeds, particularly thistles in grass pastures this summer than normal. Excellent conditions for growth over the past six weeks is a likely factor along with the fact that more damage was done this week due to wet weather, so pastures are a bit more open than normal.

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.

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

Two types of thistles

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.

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

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.

Dock control

On dock control, the best time to spray for docks 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 ragworth also but you need to be very careful when grazing cattle in fields that have been sprayed because dying docks will become more palatable to livestock. This is really important as ragworth is poisonous to stock. Where ragworth 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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