6 November 1999


A clutch of low drift nozzles has won three-star rating for LERAPs. Gilly Johnson weighs up the implications for no-spray buffer zones.

DOES the mention of LERAP make you wince? Is it all just too complicated? Dont give up – persevere with efforts to understand the system, because now theres more flexibility built in to the rules.

The Pesticides Safety Directorate (PSD) has officially recognised certain air induction nozzles as low drift, and therefore less likely to put aquatic life at field margins at risk.

Five nozzles (see panel) are each granted a three-star rating, which is the highest category. So for sprays which are allowed adjustment under LERAP (so-called Category B products), the buffer zone drops to just 1m – and this is for all dose rates and watercourse widths, which makes the calculations easier. Theres also a new system of measuring your buffer zone width (see diagram), which means that a 1m buffer zone may take even less of a chunk out of the sprayed area.

Although there are only five nozzles currently enjoying three-star rating, many more could join this group as soon as information becomes available. PSD needs to assess data from the manufacturers on low drift performance in order to make a verdict. Theres a queue of applications in the system. One of the two lucky companies with nozzles approved is Billericay Farm Services.

"We had all the independent information ready, which is why our nozzles were first to be given their three stars," says Billericays Simon Luxford. "Sales have benefited as a result. As members of the Contractors Association, were keen to keep within the rules and operate LERAP properly."

Lechler, the other manufacturer to have three-star rating, says it has the perfect solution for dealing with the field boundary – a half angle air induction nozzle: "The IS nozzle is probably a far more acceptable solution (than the nozzles with three-star LERAP rating) for LERAP and field boundary compliance because the spray is directed almost vertically," says the companys Bill Sheldon. The PSD is currently investigating its merits.

Libby Powell, agronomist with Morley Research Centre, agrees that many growers seem to be struggling with LERAP. "As new nozzles and spray equipment are given a star rating, it might become more complicated. But its worth making the effort."

Meanwhile, she has some advice for those who are considering using three-star nozzles this season. "Some three-star nozzles may be as effective as conventional flat fan types for soil-acting herbicides, provided the crop canopy is open.

"But if you are targeting blackgrass with contact herbicides such as Topik or Hawk, its better not to choose these air induction types, because this small target needs a smaller droplet. And remember, if youre applying an insecticide with your herbicides, then the insecticide is likely to be a Category A product, which means the whole mix then requires a 5m no-spray buffer zone."

Morley has no information as to whether the three-star nozzles would provide sufficient coverage with pyrethroid insecticides to give the aphid control required.

"Weve tested the Billericay Bubblejet 03 and 04 nozzles for flag leaf fungicide application, and found no difference in efficacy compared to a conventional flat fan nozzle," says Ms Powell.

A point to remember is that where LERAP low drift nozzles are being used to reduce buffer zones, then they should cover a minimum width of 12m from the top of the watercourse bank. The nozzles must also be used within the specified speed and pressure limits given by the manufacturers.

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