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Pesticides losses bring opportunity for growers

Pesticide loss has become a fact of life. We ask a carrot grower, agronomist and manufacturer their thoughts on how the industry is adapting and what the future may hold.

Pesticide loss has become a fact of life. We ask a carrot grower, agronomist and manufacturer their thoughts on how the industry is adapting and what the future may hold.


Horticulture is changing. Since 2009, the industry has had to adapt to the consequences of major regulatory change and directives encompassing sustainable use of pesticides and improvement in the status of water bodies.


Herbicides have been hardest hit in all sectors but this hasn't been solely due to legislation, says Agrii's horticultural specialist, Chris Wallwork. "Horticulture faces a particular problem because it's a comparatively small market for manufacturers, so the cost of developing new chemistry doesn't stack up," he says. "The adoption of GM cropping on a worldwide scale has also played a part, with very little new development work being done."


But there are signs that this is just beginning to change with new chemistry in the pipeline. "The development of weeds resistant to the herbicides used in GM crops has been a key factor driving the development of new chemistry," he says.


Herbicide resistance is also a risk in UK weeds. One of these problem weeds is groundsel. "Since the loss of propachlor, groundsel has been very difficult to control." explains Chris. "Lettuce production has been kept viable by just two products with Extensions of Authorisation for Minor Use (EAMU's).


"One of the active ingredients (dimethenamid-p) is very widely used in products, Wing-P and Springbok, which have EAMU’s for use in wide range of vegetable crops. That’s a lot of land area depending on a single active ingredient to control groundsel," he says.  


Carrots are another minority crop where growers have been staring into the abyss where loss of pesticides is concerned. As a major supplier of carrots and other vegetables to the retail trade, Guy Poskitt isn't planning on giving up his mainstay crop.


"In a nutshell, we need to keep lobbying as an industry for the retention of some of our pesticides, but they are just one of the tools we have in the toolbox. We also need to look towards innovations which help us produce crops without a heavy reliance on using pesticides to control pests, weeds and diseases."


Creative engineering has become an essential part of carrot production and alternative techniques are something M H Poskitt Ltd is already employing to good effect. "We're reducing our pesticide usage by using high tech systems, like satellite technology to guide mechanical weeding and we’re taking a serious look at the Robocrop Spot Sprayer, which can target tall weeds like volunteer potatoes in crops."


The loss of Dosaflo (metoxuron) left carrot growers without an effective, crop safe option for volunteer potato control. The spot sprayer, developed by Garford as part of a HDC funded project, uses an imaging system which firstly defines the position of the crop and then looks for clumps of weeds growing between or amongst the rows.


It then delivers a jet of herbicide to the target weed through a specially designed nozzle while avoiding any contact with the crop. Garford also have a vision guided system for a mechanical hoe, which can target weeds within the rows of the crop as well as between. 


But husbandry techniques don't need to be high tech to reduce the need for pesticides, Guy points out. "We manage our carrot crops so that the air flow through them is maximised to reduce the risk of disease like sclerotinia developing on the foliage. We also use cultural controls, such as sowing later to avoid the first generation of carrot fly."


Crop covers and insect exclusion meshes are other examples of the integrated approach to pest management that is core to modern production of produce. New techniques usually mean new problems and crop covers are no exception, points out agronomist Chris Wallwork.


"As well as being labour intensive, crop covers create a different environment around the crop and can exacerbate disease," he explains. "Insect exclusion meshes aren't 100% effective. Aphids can land on them and their young are small enough to pass through. Diamond back moth can lay eggs through the mesh and pest populations can build up under the mesh, where predators can't get to them."


Singing from the same hymn sheet, both grower and agronomist agree that agronomy is becoming more complex and requires greater skill targeting problems to get the best out of products. 


"The use of weather stations and prediction systems are already widely employed to help fine- tune pesticide applications," says Chris Wallwork. "Growers have shifted to realising the importance of predators and looking after them. Pests don't read the textbooks, the only way to get a feel for what is going on and for the balance between pests and predators, is by being out in the field and having a regular look."


Asked whether growers are farming better as a result of the changes brought about by the regulatory envelope they’re working within, Guy Poskitt believes the answer is a definite yes.


"We're farming more technically. We have to understand the life-cycles of pests and diseases to target them effectively. It's more complicated now and we have to use a combination of approaches to produce the quality our customers demand."

So how does the manufacturer view the situation facing growers? "The Sustainable Use Directive (SUD) is really about using pesticides as the last option, when you've done everything else you can with as much as necessary, as little as possible the guiding principle," says Robert Lidstone, Certis' marketing and business development manager. "We're moving towards producing food in a more sustainable way, looking after the environment and our small mammals, while producing enough quality produce to feed a growing population.


 "Using products on their own is no longer the solution, the days of fire and forget treatments are a thing of the past," believes Robert Lidstone. "We need to understand how to get the best out of product sequences and mixes in a grower's particular situation, taking account of cultural controls and factoring in variables like soil type, aspect, cropping and microclimate.”


And in the future? An increasing move towards a new era of bio-rational products is likely, believes Robert Lidstone. "Bio-rational products can offer a solution to help preserve the use of traditional chemistry, as we're seeing with metaldehyde stewardship where ferric phosphate (Sluxx) is being used in situations where water quality is at risk," he explains.


 "Stewardship is increasingly becoming an integral part of using the 'hard' chemistry we have left, and under the Water Framework Directive, water quality is an issue we can't ignore."


Solutions are already being found in the growing market for biopesticides. Guy Poskitt has been involved with first trialling and later commercially adopting Certis' biopesticide, Nemguard DE, on some of his carrot crops for the control of nematodes. Containing garlic extracts, the product has appeared to be similar to Vydate (oxamyl) in terms of effectiveness.


"I can't say it's any better," says Guy, pointing out that nematode control isn't an exact science because they occur sporadically and populations are difficult to measure. "Nemguard offers a different way to tackle nematodes and we haven't seen any problems where we've used it."


Earlier this year, Nemguard DE was granted an 120 day emergency approval for use in potatoes to control PCN. With traditional nematicides now under stewardship measures, Nemguard gives growers options, believes Robert. "With a view that nematodes, in particular free living nematodes, are becoming of increasing importance, growers need alternatives." 


What those alternatives may ultimately be is probably in the hands of the regulators and the future will become clearer as products move through the re-registration process, says Agrii's Chris Wallwork, explaining how the process works. 


"Once a product has Annex 1 approval at EU level, every member state is then responsible for reviewing registration every 4 years. We are now seeing a lot of products going through re-registration for the first time and as a result, a number of EAMU's are either going missing or becoming more restricted in their use," he says.


Next year it's likely to become clear how the EU will define an endocrine disruptor, which will lead to further pesticide loss, with the first losses of active ingredients possible from 2017.


"In practice there won't be any changes until actives come up for re-review and we're not sure what will go," explains Chris. "There are already signs that some manufacturers are assuming the worst and not supporting some products at review. One such casualty is Totril (ioxynil), which is being withdrawn from sale in 2015 and means Allium growers will lose a significant contact herbicide."


Part of the solution to the problems posed by pesticide loss may lie in GM crops, believes Guy Poskitt. “We need to get away from the concept of ‘Frankenstein food’ and communicate to our customers the real benefits of selective adoption of this technology.”

Are there positives coming out of this time of change? Yes, if every cloud has a silver lining, this has to be the perfect storm, believes Robert Lidstone. “ If you can show creativity - do things better, challenge the way you do things and do them differently, then there are real opportunities and you don't need to necessarily be a big grower to find opportunity where there is change."