“The world has a growing population and the consumer demands continuity of supply and value. The bottom line is that we can’t feed the world organically,” he says. “We have to remember that retailer demands are the customer’s demands and they want more food safety and lower residues in the crop. It’s a difficult balance for growers to achieve.”
As a result, many growers of speciality crops are leading innovation and helping develop the use of products in the mainstream which at one time would have been considered a softer ‘alternative’ option, left to the realms of organic farming.
As a grower of 1,400 acres of carrots and parsnips, Mr Poskitt supplies fresh produce to retailers for 48 weeks of the year. Carrots were recently identified as a crop where production is in danger of becoming unsustainable due to the impact of pesticide loss on food production, in a report commissioned by the NFU, AIC and CPA and produced by independent farm business consultants Andersons.
Since 2001 UK farmers have lost more than half of the active pesticide substances approved for use in the EU. The Andersons report suggests that 87 of the remaining 250 pesticides currently approved for use in the UK are threatened by a combination of EU directives.
Reliably identifying the fields where nematodes are likely to cause damage is a big problem, explains Mr Hinds. “Nematodes tend to be clustered in areas within fields, so accurate sampling is unlikely and it is very difficult to predict probable plant damage from sampling results.
Howard Hinds has been involved with the use of NEMguard commercially for the last two years. “NEMguard is recommended to be applied at 20kg/ha and if no rain occurs after drilling, 20mm of irrigation is needed and soil moisture then maintained for the first 4 to 6 weeks of growth to ensure maximum nematicidal activity,” he explains.
The science behind garlic
Dr Chris Hamilton reads Medicinal Chemistry at the University of East Anglia and is at the forefront of research in sulfur chemistry and biochemistry. He explains how garlic extract (the active substance in NEMguard) work to control nematode populations.
This unusual collection of polysulfide molecules contain different length sulfur chains and are one of the few molecules found in nature that contain three or more organic sulfurs in a row within a single molecule. Their biological activity directly correlates with their number of sulfur atoms.” explains Dr Hamilton. “For example, we have shown how the pentasulfides (with 5 sulfurs in a row) are a thousand times more reactive than the trisulfides (with just 3 sulfurs).”
“A key way these garlic-derived polysulfides work is by creating oxidative stress in the target nematodes by reacting with and reducing the levels of important cellular thiols such as glutathione” explains Dr Hamilton. “These thiol biomolecules play an important role as antioxidants in the nematode’s biochemistry so, when they are depleted, cellular damage occurs.”
“Unfortunately for the nematodes, the polysulfides in the garlic extract are very fat soluble. This means they are also able to embed and accumulate in the waxy cuticle of the nematode, which may further exacerbate their effects” comments Dr Hamilton.
“In achieving the official EU pesticide approval, the nematicidal activity of NEMguard has had to be demonstrated to CRD. There are also extensive quality controls in place to make sure NEMguard contains the ‘right’ mix of polysulfides to maintain its efficacy and ensure a long-term release.”
“Nematodes are plant parasites and generally attack the root systems of plants,” says Dr Fleming. “Growers will be familiar with the free-living needle (Longidorus spp.) and stubby-root nematodes (Trichodorus spp.). These are ectoparasites and feed on the root surface.”
“No extensive surveys of nematodes has been carried out in the UK since the 1970’s but a recent survey in Northern Ireland has indicated that numbers of root knot nematodes has increased by 300% in the last 30 years,” comments Dr Fleming.
“We are seeing warmer, wetter weather patterns and these favour nematodes and are encouraging species that prefer warmth, like the root knot, to thrive,” he says. “The reduction in the number of active substances available for use in is also having an effect on populations.”