Grant Stark, policy adviser at the Chemicals Research Directorate (CRD), part of the Health & Safety Executive, said he and colleagues have to be careful not to make any pronouncements and, in any case, they do not have a crystal ball.
But he warned: "The process of leaving the EU won't be brief and won't be straightforward. It's prudent for you as an industry to work on the basis there will continue to be downward pressure on the use of pesticides. I don't think anybody should expect that a vast range of new products are going to become available."
In the meantime, the UK is still subject to EU regulations and will need to wait until the European Chemicals Agency issues its opinion on whether glyphosate is hazardous to know whether the EU's 18-month approval extension of its use is made permanent, in what has become an increasingly politicised environment.
"Glyphosate decisions are subject to public opinion like never before. The lack of support from some member states for the re-approval of glyphosate reflected political rather than scientific misgivings," Stark said at the event, on 13 October, at Perelli Stadium in Burton-on-Trent, Staffordshire. "Next year's likely to see further lobbying on this ahead of the EU decision due at the back end of next year".
This rather nicely tied in with the theme of this year's conference, "Important and Essential", and the marketing campaign launched by the Amenity Forum, "Get Moving", so called because its key message is that the UK would grind to a halt without effective weed, pest and disease control (see box below).
"In 20-odd years I've been working in the sector I can say the importance of the sector hasn't been as high as it is today," said Stark, who was making this third appearance as a forum speaker.
"You're now subject to increased public scrutiny and pressure. You'll have to convince some folks that you're taking reasonable care that you're protecting the environment and people. You're in a privileged position. You're able to demonstrate the effects and the outcomes of your work." The best way to do this is to continue to support the Amenity Forum, he said.
Stark reminded delegates of the looming sprayer kit testing deadline on 26 November. By then any pesticide sprayer that is not handheld or in a knapsack must be tested and approved through the National Sprayer Testing Scheme. However, he admitted that the Government does not know how many machines are out there.
The CRD has diverted money from its agriculture budget to horticulture in order to conduct a survey of the amenity sector, which Stark urged delegates to respond to, despite surveys being "a bit of a pain in the proverbial sometimes", he said. "If we're going to understand the sector we need data to make sensible decisions in the future."
A new study by academics at Swansea University also aims to give the sector more data after conducting the largest knotweed control study ever undertaken. Led by Dr Dan Jones, the study trialled 24 treatments across three sites - two near Swansea and another near Cardiff - comprising 65, 225 sq m field trial plots.
Jones received his PhD in plant sciences on the subject last year and is continuing his research at the university. He has also established a consultancy, Advanced Invasive. His report, currently in the peer-review process prior to publication in a scientific journal, outlines the results of the first year of a three-year study to test control efficacy of both widely-used and novel control methods, investigating both their efficacy and CO2 emissions.
"Given that we have these huge socioeconomic impacts, it's really essential to get good evidence to inform decision making," he said. Referring to non-chemical approaches, he added: "A lot of the control methods are described as being environmentally-friendly but the implementation of those methods uses a lot more energy in the long term. Importantly in terms of these field trials, we've tried to move away from just throwing the chemical on. We've tried to understand the plant as a system."
Knotweed is a robust plant, said Jones, and up to 65 per cent is made up of the rhizome (root system), most of which is in the first 1m underground but can reach as far as 4.5m down and 20m away from the visible plant.
"It's important to consider, are we actually getting enough herbicide onto these plants to have an impact given the amount of biomass under the ground? You've got to get the chemical down to the roots as well." The study trialled spraying, stem injection, cut and fill, turning before herbicide application and cutting before herbicide application, using Tordon 22 per cent followed by Glyfos ProActive 797 DAT and Glyfos ProActive 689 DAT alone.
The first produced good suppression of knotweed growth, followed by regrowth of healthy sward. Using glyphosate alone, however, left a dead area with no regrowth.
The trial also tried physically covering the plants and so depriving them of sun and rain, but knotweed simply grew around the covering, said Jones. In addition: "A lot of time and effort has gone in, 40 hours of labour. To spray takes less than an hour."
Results were poorer with cutting and then spraying, he added. Stem injection gave very good results but took 190 litres of chemicals per hectare, whereas spraying used 10 litres per hectare, a considerable difference with the addition of extensive labour costs. Using Synero and glyphosate gave good suppression but not as good as Tordon while Chikara gave poor results event when followed up with glyphosate. Full details of the first year's study will be revealed on publication.
"We hope that this will help us to understand that chemicals aren't necessarily a negative thing for the environment," said Jones. "Physical methods have their place but if they are not contributing to knotweed control then they are not sustainable. By working out which work better we will cut down on cost and environmental impact. At the moment people I work with are telling me that there aren't any real economic alternatives where clients expect control, not hope for control, but expect it."
Property Care Association chief executive Stephen Hodgson said properties with Japanese knotweed are simply worth less than those without, an effect of market forces as much as anything else. He said Himalayan balsam and bamboo, "stronger in many respects than knotweed", are also concerns. Native species such as rhododendrons and buddleia could be just as damaging to buildings as non-natives. Jones said buddleia is more damaging to buildings than Japanese knotweed.
Speaking at the event were Tony Sangwine (Highways England), Dinah Hillier (Thames Water), Gordon Duncan (GreenThumb), Alan Ferguson (the FA), Andrew Diprose (Ubiqutek), Barrie Hunt (Monsanto) and Ruth Mann (STRI).
Park life - Meeting community needs in an age of pressure
- There are an estimated 27,000 public parks in Britain.
- Local authorities have no statutory duty to fund and maintain public parks.
- A 2014 report by the Heritage Lottery Fund found 86 per cent of parks managers had seen cuts to their budgets since 2010.
- An estimated 2.6 billion visits are made to public parks each year.
Get moving - Improved resources to boost sector profile
The Get Moving campaign comprises a series of marketing resources - edugraphics (educational graphics), animated videos, leaflets and posters - covering the various amenity sectors that Amenity Forum members can use to promote understanding of what they do among the public and organisations with which they work. The first resources are now available on the Amenity Forum website with more in development. Forum chairman John Moverley said: "We've got to be absolutely proud of what we do."