Nozzle choice helps vegetable growers target pests and diseases

Grower application trials in lettuce suggest using either Syngenta’s Amistar or vegetable nozzles are most effective for insecticide sprays before the crop “hearts” up.

Each season Syngenta does application trials in two vegetable crops with a grower, the firm’s application specialist Tom Robinson told Farmers Weekly. “This year is was in frilly lettuce and spring onions with Red Star Growers in Pershore.”

The trials investigate the deposition of sprays at a range of spray volumes, and with specific nozzles at a standard water volume.

In lettuce, the latest results suggested that, at lower water volumes, more spray hit the outside part of the lettuce, while higher water volumes increased coverage on the inner part of the lettuce. At 200 litres/ha, both the Amistar and vegetable nozzles worked effectively, Mr Robinson said.

“Pre-hearting our recommendation would be for 200 litres/ha, as it is a good compromise, and to use either of those two nozzles. Once the crop hearts over, the vegetable nozzle is the clear winner.”

That was because the 06 or 08 flat fan jet with a narrower 65 degree fan angle produced a spray with “much more welly behind it”, Syngenta’s field tech agronomist and application expert Ben Magri explained.

“It pushes the spray down into the hearts, and helps in other crops, such as carrots, where you want the spray to get through foliage to the crown.”

The vegetable nozzle was also useful for herbicide sprays in onions, because it bounced off the shiny young onion foliage onto the soil where it was targeted.

Mr Robinson added: “We’ve also found in asparagus using a twin cap set with the 06 vegetable and an 02 flat fan helps target foliar disease in the fern with the fine droplets from the 02, and stem diseases at the bottom of the crop with the spray blasting through with the vegetable nozzle.”