Warm soils and heavy dews are providing ideal growing conditions for grassland weeds such as docks, thistles and dandelions, so it is a good time to control them, according to Wynnstay’s Crop Protection Manager Simon Pope.
“Autumn is often overlooked when it comes to spraying weeds in grass fields – but actually there are good reasons for doing it at the end of the season,” he says.
“As day-length shortens and perennial weeds move from reproductive to vegetative growth patterns, they switch their internal transport systems around. Instead of moving nutrients up into their leaves, they start pumping them down into their roots, to build food stores for winter. This means any translocated herbicide applied now is immediately carried deep into the root network to affect a good kill.
Tackle dandelions when they are green
“It is also a great time to tackle dandelions – which ideally should be sprayed before flowering for best results. Once a field has turned yellow with flower heads in late April/early May, it is too late to get great control. Many farmers miss the boat in spring. But in September and October, the dandelions are putting on strong leaf growth again, providing an ideal opportunity to spray with a good translocated product like Pastor.”
Dr. Pope goes on to say: “Spraying now may also help ease workload next spring. The treatment window was unusually long this year with plenty of time before first cut – but most years this can be just a few weeks. Hitting the weeds now may preclude the need to spray next spring and give silage and grazing swards a clean start to the season – whatever the weather throws at us this winter.”
As with spring spraying, it is important to follow basic rules to ensure good results when applying herbicides.
“Essentially farmers need to get a lethal dose into the root,” explains Dr. Pope. “For this to happen there has to be sufficient leaf area and the plant has to be actively growing. Using the best product for the target weed, at the right rate, in the right amount of water is also very important.”