Blackgrass plants are growing strongly because of the recent warm weather and growers are being urged to check their sprayers are in tip-top condition to maximise herbicide efficacy in the coming weeks.

There is a real risk that blackgrass plants will soon start to affect yield potential, by diverting vital nutrients and light from cereal crops.

So preparing your sprayer now could be the difference between excellent and poor control of blackgrass this spring, says Paul Miller from NIAB TAG.

Chemical free

Start with a clean machine. When conducting any tests or calibration of the sprayer with water, ensure this water can be safely disposed of, he says.

See also Blackgrass threat looms over late-drilled crops

“If there is any risk that there is pesticide in the water, it should not be put down the drain. And remember, any residue remaining in the tank could antagonise whatever active substance you’re using next.

“Then make sure your machine has been NSTS tested – 12 months is the recommended service interval to achieve a full compliance test.”

Boom test

Prof Miller advises that if a machine has been tested, but was out of action for a few months, a good start would be a static boom test.

“Often overlooked, this involves fully extending the booms and setting them to 0.5m above the ground. Then make a visual inspection to identify any mechanical damage or faults.

Test the boom suspension by pushing down on either end of the boom and releasing it. The boom should bounce only once before returning to its original position. Any overshoot indicates a problem, he says.

“If your boom wobbles, check to see if the dampers need replacing. If the boom is slow to return to the start position, lubrication may be required. Check that pipes running from the machine to the booms are correctly positioned and in good order.

Nozzles

Cleaning all nozzles and filters is crucial. “You want to prevent any build up of chemical behind the nozzles. This will reduce the risk of nozzle blockage resulting in striping and applying uneven chemical loads to the weed canopy,” says Prof Miller.

“Good application technique will help deliver good levels of control,” says Ben Giles, commercial technical manager at Bayer CropScience.

“A forward speed of no more than 12km/h, using 100 litres/ha of water and flat-fan nozzles producing a fine-to-medium spray quality is the most efficient way of covering the most ha/day, which is vital if you’re to make the most from your window,” he says.