Despite numerous and repeated reassurances by government officials, it seems that a rational debate about the use of pesticides and residue levels is still some way off. Pesticide producers are keen to dispel the myths surrounding their sector and argue that pressures from outside forces have resulted in a number of changes.
The Voluntary Initiative (VI) in particular has been credited with making a significant difference. This five-year programme of measures was launched in 2001 and has been undertaken by the agricultural industry and agreed by government to minimise the environmental impact of pesticides.
VI also means that the issue of a pesticide tax has, for the short-term, taken a back seat. “For the time being, this government is saying it’s better for the industry to collaborate to bring improvements,” says Peter Hingley, general manager for Certis. “The government will review the VI this year to assess its impact and identify further improvements. The options for a tax or other economic measures are still under review.”
According to Certis, two thirds of food monitored in the government surveillance programme is residue free. In the remainder very low residues are recorded. Rather than considering this a problem, Hingley believes that it is important to weigh up the advantages.
“We should be focusing more on the benefits of having safe fruit and vegetables and enjoying them at a good price,” he says. “Without the use of pesticides, it would be a different story.”
Stephen Humphreys, food industry support manager for Bayer CropScience, believes that the pesticide and fresh produce industries enjoy a better working relationship than ever.
He says: “With the pressures from retailers and the supply chain to reduce residue levels, as well as environmental factors, we’re seeing that the pesticide sector and fresh produce industry is working more closely together to meet demands.”
Similarly to his counterparts, he believes communication is a priority. “Bayer has set up its own Business Stewardship department to ensure we have a good dialogue with the fresh produce industry,” Humphreys says. “Today’s pesticides have to meet increasing regulatory standards, but in addition promoting best practises is key.”
There have been a number of changes in pesticide contents in recent years as companies strive to produce newer products that have less impact on the environment. Existing formulations are also being adapted to contain ‘gentler’ solvents which may in some instances work better from a spray operators perspective.
The way in which pesticides are used has also changed. “In many cases pesticides are expensive, not just for the product itself but there’s other costs involved such as labour, transport etc,” Humphreys says. “Farmers will therefore look to justify any pesticide application they make.”
The assumption that pesticides are used indiscriminately is wrong, says Hingley. “In fresh produce, crop pesticides are only used when required,” he says. “Usage has declined in recent years and the number of new products that have been introduced are more target specific. What’s more, their use is based on need, often backed up by sophisticated decision support systems - they aren’t used at random.”
Earlier this year, the Certis-marketed slug pellet treatment Ferramol, gained full approval for all crop use. One of its benefits is very low toxicity to all species other than slugs and snails. This gives Ferramol a key advantage over most alternatives, claims Certis, adding that the pellets have also been formulated to eventually degrade into harmless, naturally occurring plant nutrients.
Certis also markets cropping solutions that do not depend on treating the crop itself, but address the pest and disease issues faced by growers. “A good example is Basamid, a soil sterilant, that’s used to treat the soil profile prior to planting,” says Hingley. “It leaves no residues and is not ozone depleting. It is being widely adopted by salad and soft fruit producers as an effective successor to methyl bromide which is now being phased out.”
Investing heavily in continuing to deliver new and improved cropping solutions, Certis has further projects in the pipeline with new registrations due next year.
More stringent legislation on the use of pesticides have brought changes to the sector and Hingley notes that companies are getting rid of older products as more growers go down the IPM route. “This involves the targeted use of chemistry in combination with biologicals as well as preventative controls such as good hygiene,” Hingley explains.
Certis and its sister company Biological Crop Protection (BCP) are working together to trial programmes which look at integrated chemical and biological programmes that minimise residues while improving grower margins. The companies claim that initial results from recent programmes have shown improvements in grower margin through an integrated approach.
Jennifer Lewis, BCP general manager, notes that Eradicoat and Majestik are two natural products that should assuage consumer concerns over the use of pesticides. She says: “These products work by physical means and provide highly effective control of a range of pests including spider mite, whitefly and thrips as well as suppression of mealy bugs. They are used in a range of crops including protected vegetables, ornamentals, soft fruit and field vegetables.”
“In addition, the new formulation Eradicoat T has been recently developed for improved efficacy and fruit appearance and is used in protected vegetables, in particular tomatoes, in the UK. Further formulation development including mixtures is ongoing.”
Bayer also believes that opportunities exist in the development of new products and improving existing pesticides, while the profile of pesticides could be boosted with the promotion of ICM and IPM programmes.
Bayer has launched a number of new products for the potato industry this year. The first is the insecticide Biscaya, which will be used for aphid control. “We have also launched Infinito, our blight fungicide,” says Humphreys.
“The benefits of Biscaya and Infinito are that there’s no detectable residue and no LERAP (Local Environment Risk Assessment for Pesticides) on the label.”
With the loss of many pesticides in recent years, especially in horticulture and vegetables, Bayer has been looking to support this sector with new product introductions and the expansion of existing product labels. In addition to Biscaya and Infinito, the company hopes to introduce two new herbicide active ingredients for use in vegetables before the end of 2007.
Some consumers opt for organic fresh produce in an attempt to limit pesticide residues, but firms are quick to point out that there are misconceived ideas about organics. “Organically grown fresh produce is still treated with some pesticides albeit usually different ones from conventional produce,” says Hingley, adding that scientific studies have shown that fruit and vegetables grown conventionally are as nutritionally sound as organic.
One key issue facing the sector in the near future is the harmonisation of Maximum Residue Levels (MRLs) in the EU. “Harmonisation will be beneficial in the long-term but short-term there could be teething problems,” Humphreys warns.
“The UK doesn’t currently have a huge number of MRLs but if certain values aren’t set at the EU level during the harmonisation process, or if some slip through the net, that means they’ll default to 0.01 mg/kg - effectively zero,” he explains. “It’s going to be a huge task but the pesticide and fresh produce industries, in conjunction with the Pesticide Safety Directorate (PSD), have all been working to ensure that things go as smoothly as possible.”
GLASS REFLECTS INDUSTRY NEED FOR MORE EFFICIENT SCREENING
Central Science Laboratory (CSL) is developing better methods of screening for pesticides in fresh produce, according to the agency’s Richard Glass.
“We’ve been working with the University of Almería since 1993 to improve the quality of pesticide analysis for a wide range of studies, including monitoring residues in produce for export. CSL has a great deal of expertise in pesticide use in the field for much of the southern European and Latin American countries, where we have been working to improve worker safety, particularly in greenhouses,” he notes.
According to Glass, the levels of pesticide residues have tended to fall in recent years, with supermarkets and governments screening produce for a wide range of pesticides. However there is some evidence that residue analysis, particularly done on produce before in arrives in the UK, is not as stringent as it could be. “This occurs when testing is done on a cost rather than quality basis,” Glass says.
To this end, Glass believes that the Food Analysis Performance Assessment Scheme (FAPAS) is a highly effective tool. It’s claimed that FAPAS is one of the largest and most comprehensive analytical chemistry proficiency testing scheme in the food sector.
Glass explains: “FAPAS regularly sends out samples containing unknown pesticides so that laboratories worldwide can check and evaluate their performance. The by-products of this are reports which indicate (anonymously) the number of laboratories returning satisfactory data for the residue identity and quantity. FAPAS is therefore a very important indicator for monitoring the quality of analyses carried out by laboratories.
In a recent FAPAS test, requested by 103 laboratories, for residues in apple purée, 50 per cent correctly identified the five pesticides added from a possible list of 52. Only 30 per cent both identified and obtained satisfactory scores for all five pesticides.
BELCHIM OUT A BRAND NEW FUNGICIDE
Belchim Crop Protection has launched Contans WG, a new fungicide which it claims is the first product to specifically attack the resting bodies (sclerotia) of Sclerotinia sclerotiorum and Sclerotinia minor.
More than 300 crops are susceptible to Sclerotinia including carrots, lettuce, potatoes and brassicas.
“Contans WG contains a naturally occurring soil fungus called Coniothyrium minitans and is formulated as a wettable granule,” says Belchim’s Simon Leak. “The product is made using a fermentation technique to multiply up the spores which are then filtered and sprayed onto a glucose carrier and dried. Contans attacks the source of the Sclerotinia infection by destroying the sclerotia in the soil before they have the opportunity to produce mycelia or apothecia and then ascospores, which subsequently infect and cause damage and yield loss to a wide range of crops.”
Contans is applied directly to the soil either before planting a susceptible crop or to the crop debris after harvest of an infected crop. “In all cases Contans should be incorporated into the soil immediately after application with the rate of use being dependent on the depth of incorporation,” Leak says. “The aim is to get the C. minitans spores as close to the sclerotia as possible, when they will then germinate and infect the sclerotia. This process of infection and destruction takes two-three months depending on conditions. It is expected that Contans will be used in conjunction with foliar sprays as part of a programmed approach to long term reduction of the source of Sclerotinia infection.”
The approval for Contans allows it to be used before planting or post harvest of any outdoor or protected edible or non edible crop. Furthermore, it can be used in organic crop production.
CONSIDERATE SLUG CONTROL
Where large scale lettuce production meets neighbouring residents a considerate approach needs to be taken with crop inputs. At Merston Farms in West Sussex the environmental characteristics of their slug pellets are as important as efficacy.
David Morris, the farm’s technical assistant responsible for slug control across 300 hectares of iceberg lettuce for supermarket outlets, explains that a network of footpaths across the site is an important consideration. “Little blue pellets littering footpaths where local residents walk their dogs is unacceptable. But, producing in a competitive market, incurring 5-6 per cent crop losses due to slug damage is equally unsustainable,” he says.
Zero tolerance
With supermarkets taking a zero tolerance stance towards slugs, every lettuce head with a hole is unharvestable. The grey field slug is the major culprit and with a capability to breed at any time at temperatures over 6°C, it is much more unpredictable than the black slug that has set breeding cycles.
“The irrigated crop is also the ideal environment for the pests. Moist conditions, the warm haven of a lettuce head and an abundant food source add to the control challenge,” he explains.
Prevention
Prevention and close monitoring are as much a part of the solution as slug pellets. Field boundaries are monitored with traps to stop slugs migrating into crops and a check is kept on soil temperatures to assess when slugs emerge from overwintering deep underground.
Crop rotation and field history are also important for sites with a particular slug problem deliberately not selected for the first crops sown in March and grown under fleece, to avoid removing crop covers so frequently.
Morris says that the growth habit of the lettuce presents its own difficulties. “It is impossible to broadcast pellets after the rosette stage when the lettuce head is approximately the size of your palm due to the risk of pellets becoming wrapped in the leaves. Even though it would not present a health risk by the time it reaches the consumer, it is nonetheless unacceptable.” They therefore switch to inter-row pellet applications from this time through to harvest, but slugs must either emerge in the rows or be sufficiently attracted to the pellets to achieve control.
Slug pellets
Having tried various formulations of conventional slug pellets based on metaldehyde and methiocarb, Merston Farms were constantly wary of the environmental and social impacts of the treatments. “We killed as many beetles as slugs,” he says, noting that the carabid beetle naturally preys on slugs and is otherwise a useful control in itself. Villagers using footpaths, with the risk of dogs eating pellets, was also a significant concern, despite diligent applications.
He adds that their experience of conventional treatments presented additional limitations with only one application of methiocarb allowable and metaldehyde proving less effective in the presence of irrigation. It also has a seven-day harvest interval.
Recognising the value of the new slug pellet Ferramol, launched by Certis last year, with highly targeted control of slugs and snails only and unparalleled environmental characteristics, Morris was keen to trial the new treatment.
Ferramol
Morley Benson of Certis explains that Ferramol is based on ferric phosphate and delivers a different mode of action compared to conventional pellets. “The active ingredient directly affects the calcium metabolism in the gut system of both slugs and snails. Once ingested the damage is irreversible with feeding ceasing immediately and death within three to six days,” he explains. The result is a low toxicity pellet for all species other than molluscs making it suitable for Integrated Pest Management (IPM) programmes. It has also been allowed for use in organic situations by certification organisations.
Delivering both in terms of efficacy and the environment, Morris says: “It gives us the confidence to treat without fear of reproach and with no harvest interval inter-row applications needing to be made up until the day of harvest,” he says.
Some adjustments to application equipment were needed to get optimal performance from Ferramol, including changing the diverter settings of the broadcasting spinner unit from a 4 to a 2, and the flute size of the inter-row applicator was also changed to 6mm to feed the larger Ferramol pellets.
The pellets, which Morris says remain active for 14 days (compared, in his experience, to only 7 days with alternatives) ,eventually break down into their iron and phosphate components. These are naturally occurring anyway and are readily taken up by plants as basic nutrients. Only using 12.5kg/ha of a maximum 50kg/ha dose, the flexibility to increase the rate where necessary provides a useful margin.
Justification
“It will be only a matter of time before supermarket protocols take a less favourable view of older slug pellet chemistry,” anticipates Morris, commenting that Ferramol could be the only option available to lettuce producers in the future. “We have to justify every input and feel that more environmentally friendly treatments are the way forward,” he adds.
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