Crop protection - Pest control

After particularly challenging conditions for growers in 2012, suppliers are aiming to boost crop protection this year, Gavin McEwan reports.

Slugs: problems worsened by prolonged wet conditions - image: Caplio
Slugs: problems worsened by prolonged wet conditions - image: Caplio

The combination of a gradual loss of conventional crop-protection products, and some of the wettest, coolest, dullest weather for a century made 2012 a particularly challenging one for growers. On the evidence so far, 2013 is shaping up to be little different. Last year was described as "the year of the slug" and the prolonged wet conditions required applications of molluscicides at levels well above normal - a situation that is likely to continue into spring given the extremely wet winter weather to date.

However, the future of the industry's mainstay, molluscicide metaldehyde, is in some doubt due to its alleged impact on watercourses - a particular concern when ground is saturated and runoff correspondingly higher.

Certis marketing and business development manager Robert Lidstone says: "For many, the metaldehyde dose-rate restrictions mean that the allowable maximum application can be used up in just a single application and with slug pressure continuing unabated in many crops there is often a need for a repeat treatment of a molluscicide."

But Certis recently introduced Sluxx, based instead on ferric phosphate, a chemical found naturally in soils. This overcomes these concerns, Lidstone explains, because there are no restrictions on applying it in fields bordering watercourses and no need to allow a buffer zone.

Test year for ferric phosphate

Once ingested, ferric phosphate causes pathological changes to the slug's digestive system, causing it to quickly stop feeding, become less mobile and then die in three-to-six days, often underground and so out of sight. Lidstone adds: "Due to the conditions, 2012 has been a test year for ferric phosphate, but reports from the market strongly support our extensive field trials, which show that it is just as effective as both metaldehyde and methiocarb."

Certis technical officer Alan Horgan points out that in winter, the relative effectiveness of the rainfast pellets is particularly apparent. "Not all slug pellets continue to be as effective as temperatures fall," he says. "At the maximum 7kg per hectare rate you can make four treatments of Sluxx or Derrex respectively, with the flexibility to treat right up to field boundaries."

In common with a number of crop-protection product companies, Certis has expanded into biological controls, with the acquisition of specialist supplier BCP in 2008. Certis has claimed that control of insects, mites and fungi in fruit and vegetables offers the greatest potential in this field due to pressure for reduced or no residues in crops. Due to their natural mode of action, they also avoid the problem of resistance build-up and are less likely to harm beneficial insects, it has said.

DiPel DF from Interfarm UK, part of Sumitomo Chemical, is another example of how large international suppliers are diversifying into specialist biological controls. The caterpillar control has numerous advantages, says Interfarm technical manager Dr David Stormonth.

"The market demands high-quality food with no insect damage, contamination or residues, but this can be difficult to achieve," he adds. "The development of the naturally occurring Bacillus thuringienis var. kurstaki, as in DiPel DF, offers a highly targeted solution that is biodegradable - leaving no detrimental residues on the crop - has no maximum number of applications, no maximum total dose, no harvest interval and no buffer zone requirement."

DiPel DF has label recommendations for a wide range of crops including cabbage, Brussels sprouts, cauliflower, broccoli, strawberries and raspberries as well as protected tomatoes, cucumbers and peppers, adds Stormonth.

Seeking alternative products

Replacing the loss of active chemicals has been the focus of the £2m SCEPTRE project, which has reached the midway point of its four-year run. Project coordinator Tim O'Neill says: "The priority is to fill the gaps that are appearing as conventional products, particularly herbicides, are withdrawn. That can mean looking at other conventional products as well as biological controls. The other priority is to test biological controls for their effectiveness, especially in the disease side, and to work out how they fit into crop-protection programmes. In most cases it's not a straight swap."

The weather has been the main factor in the 30 or so trials under way during 2012, results of which are currently being collated, O'Neill adds. "It has been good in the sense that there has been a tremendous weed burden for candidate treatments to deal with, though it has made other trials more difficult. In my own particular area of protected horticulture, pest control has been going biological-only for some time, and while there is still some use of fungicides, growers are keen to try alternatives on the disease-control side too."

A pest and disease control event hosted by the Horticultural Development Company this month will explain current and emerging threats to tomato growers. British Tomato Growers Association technical officer Phil Morley says: "Growers get better at understanding biological controls and are less likely to see them as something you just spray on - you need a bit of biological understanding too. We are losing actives on the chemical side and at the same time there is a move to less persistent products as retailers want residue-free produce."

Morley and consultant Rob Jacobson have worked together for several years testing and developing biological controls for organic tomato production. "In organic growing there's no second line of defence," says Morley. "We have made huge strides forward but there are always new pests such as Tuta absoluta coming along, which then take more research. You might think it's all sorted, but there is still lots to do."

Exciting times for development

He adds that these are exciting times in the development of alternative controls in the UK. "We pretty much lead the world in the biological approach to pest control and are now looking to control diseases such as Botrytis in a similar way," says Morley. "There are also several projects looking at biological controls in salads. But there is some hold-up with the Chemicals Regulation Directorate, who are not being as generous with their permissions as they might be - though things are changing as more companies look at licensing biological products in the UK."

Meanwhile, herbicides remain one area where conventional products still predominate, and BASF speciality crop manager Rob Storer says the company is determined to defend pendimethalin for vegetable growers. "Although there are some new herbicides for speciality crops under development, none of them have the same weed spectrum or crop safety afforded by pendimethalin" he maintains.

BASF is developing the co-form Wing-P, which contains pendimethalin and dimethenamid-p, and has been granted Extensions of Authorisation for Minor Uses (EAMUs). "The use of Wing-P introduces a new active ingredient for these vegetable crops - dimethenamid-p - which broadens the weed spectrum of pendimethalin, in particular groundsel, which is often difficult to control," says Storer.

The company has also been developing Springbok, which contains metazachlor and dimethenamid-p, in field vegetables and is hoping for approval in brassicas next year, he adds. On disease control, it is also developing several new fungicides for use in vegetable crops, says Storer, adding: "Some will hopefully be available next year and others are a few years off."

Policy delay experienced across Europe

The declining availability of plant-protection products has become a concern across the continent, particularly in light of the European Commission's ongoing delay in setting out a clear policy on the subject, according to COPA-COGECA, the umbrella group for Europe's agricultural cooperatives.

Its phytosanitary group chairman Luc Peeters says: "The lack of proper tools compromises not only the competitiveness of the agri-food chain, including its sustainability and employment, but also the diversity of high-quality food."

The commission was due to present a report to the European Parliament and council on the issue more than a year ago, as foreseen under Regulation (EC) 1107/2009, a delay that COPA-COGECA describes as "not encouraging for European agriculture". In a letter to the commission, it said: "Co-ordination across all 27 member states and support for data generation are both key to ensure the availability of solutions to control pests and diseases. Minor uses and speciality crops should not be seen in isolation from Regulation 1107/2009 and the zonal process for the efficient working of product authorisation.

"We therefore call on the commission to speed up the report and support an ambitious plan aiming at setting up a permanent EU programme for minor uses and speciality crops, accompanied by a coherent funding programme."

The EU's fruit and vegetable output has been valued at EUR45bn, or just over seven per cent of its entire agricultural output.

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