Maize pre-em sprays will keep early weeds in check

Article taken from the Farmers Guardian

Pre-emergence herbicide sprays should play a key part in maize growing programmes this season even where soils are dry.

This is the advice of Cheshire-based Agrovista Phil Campion, who says a pre-emergence treatment will keep early weed growth in check and take the pressure off post-emergence herbicide sprays.


He says: “I like to use a pre-emergence residual based on pendimethalin at 1,000g per hectare.  I am not after any weeds in particular, although it is good on meadow-grass, our main grass-weed target in the North West, and it will hold black nightshade, polygonums and fumitory.

“I regard it as a general holding spray to take the pressure off post-emergence products, which you can target more specifically at problem weeds, using lower rates with reduced chance of crop damage, keeping a check on early weed growth is key as small maize plants are very sensitive to competition,” says Mr Campion.

“A lot of growers in my area rely on contractors to spray their maize, so any hold-ups due to poor weather once the crop has emerged can start costing yield straight away,” he adds.

Wing-P (dimethenamid-P + pendimethalin) can be used, but it is more expensive so will be reserved for where cranesbill is a problem, he says.

Mr Campion recommends using a pre-emergence spray with Remix (adjuvant), a paraffinic oil which improves weed control and crop safety by binding active ingredients in the spray to the top layer of soil, even if it does turn wet, ensuring the spray does the best job possible.”

For some growers, the pre-em spray may not be the first.  If weeds are becoming established on stubbles he recommends glyphosate before ploughing and drilling to ensure the cleanest start.

“You only have to wait five days after spraying before cultivating.  Applying glyphosate takes more pressure off key weeds and plenty of chick-weed in some fields going into maize this season.”


On selected fields, Mr Campion adds N-Lock, a nitrogen stabiliser from Dow AgroSciences, to the pre-em spray on light soils with good yield potential.

Applied at 2.5 litres/ha, N-Lock slows the conversion of ammonium into nitrite.  “This reduces losses and ensures more nutrient is available later in the season when maize plants really need it but when spreaders can no longer travel due to crop heigh.

However, it does need rain to wash it in, but the decision to add or not can be taken on the day, he adds.

Maize pre-em top tips

  • Pre-emergence herbicide applications should be made in 200 litres/hectare of water
  • Use flat fan nozzles to improve coverage
  • Seedbeds should not be too cloddy – they need to be deep and loose with a reasonable proportion of smaller clods on top to avoid capping
  • Alternating forward and vertical nozzles across a boom can improve coverage where seedbeds are less than ideal.


24 April 2015

Seeking a solution for rat’s-tail fescue
With increasing reports of rat’s-tail fescue in North East England, growers are encouraged to act now by improving..
Agrovista strengthens north east agronomy provision
Agrovista is delighted to announce the appointment of Durham-based Agronomist, Helen Lax...
TWITTER @AgrovistaUK


Get trials and technical updates straight to your inbox


01945 870 356




Agrovista UK Ltd
T/A Plantsystems
Rutherford House
Nottingham Science and 
Technology Park