Netting benefits cause surge in popularity

Insect netting has become a highly effective tool for defending vegetable growers' crops, says Roger Chesher.

Although commercial insect netting was around in Britain in the early 1990s, it was not until Birlane was banned in 2003 that the market started to really evolve. Birlane was a widely-used organophosphate insecticide, the last resort against cabbage root fly for many growers, until they realised how effective an insect net could be.

After just one year, virtually the entire UK swede crop was grown under netting and the science, or art, of growing under nets was truly born.

Anticipating the loss of chlorfenvinphos (Birlane) Allan Fearn claims to be the first commercial grower in the UK to use insect netting for controlling cabbage root fly in swede under the company name of Fearns, a family-run business in Laurencekirk, back in 1999. Swede growers now for more than 30 years, the Fearns started with 30 acres or so under netting and today, as a result of the tremendous success of the technique, they grow 600 acres under mesh.

Perhaps more importantly, the success encouraged them to found Wondermesh in December 2001 to promote and market insect netting as an effective control for cabbage root fly. By 2004 virtually the entire UK swede crop was grown under nets. Today it still remains the most effective method for cabbage root fly control on the market with netting marketed by Wondermesh, Capatex Agro-textiles, Crop Solutions and Agralan (Enviromesh).

Inevitably, insect nets have been tried for other pests and other crops and are now widely used to control cabbage root fly, flea beetle, aphids, carrot root fly and thrips on a range of crops including swede, baby leaf, salads, carrots, cabbages, broccoli, cauliflower, sprouts, soft fruit, herbs and organics.

The principle of netting is, obviously, that it provides a physical barrier that insects cannot penetrate while allowing through 90 per cent sunlight and rain and approximately 70 per cent of natural air flow. This creates a microclimate that, it is claimed, maximises plant health and yield. Other advantages claimed include near normal moisture conditions, slight shading, shelter and a reduced temperature range between day and night. Protection is also given against birds, rabbits and deer.

Set against those distinct advantages must be the cost, perhaps £1,000 per acre but spread over 10 years, and the labour involved. Costs do vary. "From 22p to 26p per square metre," says Ian Campbell, director of Crop Solutions, a company firmly positioned at the quality end of the market. "At 26p - but lasting 10 years - the costs are 2.6p per metre per year. Compare that with, say, 22p but only lasting four years and costs can be as high as 5.5p per square metre per year," he says.

Mike Fearn of Wondermesh tends to agree and cites use of the product for 12 consecutive years. "The biggest threat to netting is mechanical damage," he says. "Proper UV stabilisation and the use of virgin materials lead to high-quality netting."

Indeed, the major players tend to agree on the built-to-last philosophy and in a curious way they may seem at first to have shot themselves in the foot. Following the meteoric uptake of netting for swedes, all the major growers became kitted up for eight to 10 years - leaving that market satisfied until replacements become necessary.

Netting is an essential for swedes. Other crops still have synthetic pyrethroids and approved agrochemicals to control insect pests, so the use of netting for them has to be justified on a raft of other benefits.

But for how long? Agrochemical companies are constantly required to review and register their products and there is never a guarantee that any particular spray will be here for the long term. Amendments to legislation in 2009 mean that decisions on pesticide registration will now be hazardrather than risk-based - and it is always possible that other useful chemicals could disappear. This is not scare-mongering, merely an indication that netting usage is far more likely to grow rather than to decline.

Rather than sit and wait, the major suppliers have diversified into a variety of other crops and uses beyond insect protection, but all of them have a range to suit the core use.

For cabbage root fly and cabbage butterfly the mesh is typically 1.3sq mm, although Mike Fearn notes a trend towards the 0.8mm mesh, now his best seller, to ensure flea beetle control alongside cabbage root fly.

For flea beetle, onion fly, alium leaf miner and leek moth, mesh is 0.85x 0.95mm, aphids require 0.22x0.8mm and for thrip a heavier net of 0.22x 0.35mm.

The trend for net dimensions is upwards in size. Crop Solutions can offer nets from three to 25m in width. Capatex typically keeps 2.1m and 2.4m widths in stock, making custom sizes to order, while for Wondermesh the most popular sizes are 13m wide in 100m or 200m length. They, too, are receiving more and more requests for bespoke sizes.

Flea beetle is on the increase. Fearn's Farm now net carrots and parsnips alongside swedes, using exactly the same class of net - the 0.8mm mesh.

This same gauge mesh is increasingly being used on baby leaf, tender leaf, fruit and flowers with trials underway on "Skywalker" cauliflower. On tender crops, netting is suspended on hoops, removing contact from the leaf and increasing air flow. Cabbage white and flea beetle are the major pests here, so much so that hoops are becoming a major seller.

Even though the majors have products for other areas, development in insect netting does not stand still. Both Ian Campbell and Michael Fearn have product trials under way for 2011 and beyond but, understandably, are reticent to divulge what is on the horizon.

Wondermesh has, however, undertaken field-scale work with coloured netting - black netting showing yield increases over green. But, according to Fearn, the market has yet to capitalise on this.

Capatex director Peter Strauss reports that the company has, alongside insect netting, diversified successfully into windbreaks, shade, anti-hail and crop protection nettings. "These now come in a wide range of wind and shade values," he says. "Fifty per cent porous netting can reduce wind speeds by half for a distance of 12 times the fence height."

But the area that has seen growth by all the netting suppliers is that of bird protection. Pigeon and rook are on the increase, the former encouraged by the planting of increased acreages of oilseed rape.

For Alistair Ewan of East of Scotland Growers, the solution is simply pragmatic. "We move our swede nets onto other Brassicas in March and April and then put them back to care for the root fly."

For others, the problem requires a more dedicated net. This is a growing market for Crop Solutions. "Bird nets are used where growers don't want the microclimate brought about by finer mesh," says Ian Campbell. "The golden rule is to utilise as large a mesh as possible.

"We have just developed a new lightweight bird net to protect crops from birds, rabbits, deer and debris. It has been constructed to the same high standard as our range of insect net using the same four-layer sewn joins and reinforced edges," he reports. The net is for multiple reuse and is expected to last for eight to 10 years. It is available in 13m and 25m widths with other sizes made to order.

While this new 2x8mm mesh size is small enough to prevent most salad leaves growing through, it also allows fertiliser, sprays, and even slug pellets to be applied directly through the net. Crop Solutions bird net has been specifically designed for use on baby leaf, salads, Brassicas and over-wintered vegetables.

Processors & Growers Research Organisation near Peterborough has used the net on a series of unrelated vegetable and salad trials where rook and pigeon were a threat. Senior technical officer Barrie Smith says Crop Solutions' new bird net has been a vital part of these trials, helping to get them established. "It's good on lettuce because of its lightweight construction. You don't need a lot of support underneath it. We wouldn't manage without it," he says.

Capatex also finds 2.5x2.7mm pigeon mesh a growing market. UV stabilised and at 30gm per square metre, it is remarkably light and has resulted in dramatic increases in yield of Brassicas.

"We also find our thermal crop protection netting useful as bird protection," says Strauss. "It's halfway between a fleece and a net but has a five-year life as opposed to the single year of a fleece." This is used on a wide variety of crops including sunflower. The company also has a small mesh knitted net popular among herb producers.

Mike Fearn has a third solution: "As swede growers, we are phasing out 13m-wide netting to use 25m and thus saving on labour cost. The redundant three, four or five-year-old swede netting is now for sale through Wondermesh as a low-price alternative to bird netting." The netting market continues to grow to meet new opportunities.

CONTACTS

- Wondermesh 01561 377946

- Capatex Agro-textiles 0115 9786 111

- Crop Solutions 01738 450437 - Agralan Environmesh 01285 860015


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