Timing of spray is key to good weed control

TIMING is everything in getting a good, long-term weed kill in both silage swards and grazing pastures, said weed control specialist Chris Maughan. “The two golden rules of effective weed control are choosing the right product and applying it when weeds are at the right growth stage,” said Chris, who is technical manager with Whelehan Crop Protection.

He said weeds should be actively growing and be at the ‘rosette’ stage in order to ensure the most effective kill with translocated weed-killers such as DoxstarPro, Envy and Forefront T.

“Docks should be eight to 10 inches high or across and before a seed head begins to show. If they have gone beyond this stage, it is best to top them and wait for two to three weeks regrowth when they should be at the correct stage for spraying. In silage swards, it is preferable to harvest the silage and wait to spray the aftergrass,” advised Chris.

SILAGE

The ideal time to spray is about three to four weeks before you plan to cut your silage when the weeds are at the right stage. “Waiting for a minimum of three weeks after the weed-killer is applied before harvesting the silage ensures that the chemical gets fully translocated down to the roots, a vital factor in achieving long-term control.

“Remember the dock taproot can up to a metre deep. This emphasises the importance of using powerful chemicals and giving them enough time to get right into the root system. DoxstarPro would be the product of choice here”

GRAZING

The same rules about the correct growth stage of the weeds apply for grazing as for silage.

“Forefront T, the specialist weed-killer for grazing paddocks has become the product of choice for a growing number of farmers. It contains the most advanced chemistry in weed control technology and is a highly effective all-purpose weed killer. As well as controlling docks, nettles and thistles, it also kills other weeds such as buttercups, dandelions and ragwort.”

CHICKWEED

Where chickweed is a major problem, Envy is the product of choice. Because of its chemical structure, Envy works well in in cooler conditions which make it ideal for early spring applications.

‘Even a three-quarter rate of envy will do an excellent job on chickweed in established grassland’ explains Chris

Envy contains the two potent active ingredients, fluroxypyr and florasulam, and covers a range of other weeds including Docks, dandelions, daisies and plantains. Its an ideal general clean-up product for use on pastures and hay/silage ground.

NEW LEYS

Chris said the risks of chickweed were manifested in fields reseeded in autumn 2018 and chickweed was a major problem in swards, throughout 2019.

A similar situation may occur again this spring, as many reseeds from last Autumn did not get sprayed due to the wet weather throughout the last autumn and winter. Chickweed can smother the new grass, resulting in a very patchy sward. The biggest risk is from common chickweed, but mouse-eared chickweed can also be a problem. Envy is powerful on both.