Integrated weed management (IWM) has been in the news recently and this blog is a follow-up to an earlier one (Is Glyphosate the best solution?) reporting on the recent findings of Cardiff City Council, that using herbicides to manage weeds in amenity spaces is arguably their ‘best environmental option’. Two commercially available alternatives to glyphosate were independently assessed and shown to be, by and large, less effective/efficient and/or more expensive/environmentally costly in terms of labour, transport, energy and water use.

'Big news' and 'not a surprise'

For the Amenity weed control sector this is, at the same time, ‘big news’ and ‘not a surprise’. It has always seemed to those at the coalface of invasive weed management that using glyphosate herbicides is a reliable and predictable and efficient way to manage e.g. Japanese knotweed. But none of the above changes these simple facts:

• 1) that we have a legal duty under the ‘Sustainable Use’ Regulations to assess (give preference to, where feasible) all possible alternatives to herbicide use and, if herbicides are specified, to minimise their use and potential negative impacts, and:
• 2) that there is a broadly-held view within the general public and many publicly-funded or charitable (wildlife/environment) organisations that pesticides are ‘a bad thing’ which cannot be part of a sustainable future. This seems to be especially true for glyphosate!

So let’s address these issues head-on because they aren’t going away any time soon and one way or another (see below) will continue to have an impact on how professionals manage invasive weeds in the future.

PCA professional Standards

The PCA prides itself on setting high standards within various sectors and enabling professionals to demonstrate how they meet them (with the ultimate aim of delivering reliable and effective services to consumers). For some time now we’ve been flagging the Government’s own communications that there should be greater emphasis given to Integrated weed management (The pros and cons of using herbicides), in other words, show that we are systematically evaluating alternatives to herbicide use. Despite this there seems to be some uncertainty amongst invasive weed management professionals about HOW to create IWM plans that are meaningful and legally compliant.

So, what would a template for an IWM plan look like? Lets start by looking at the Sustainable Use Directive (SUD). This largely addresses food safety concerns but is equally applicable to the amenity sector. As the above link says, “IPM is the cornerstone of the Directive” and gives us this list of ‘Principles’ (we are only listing those applicable to non-agricultural situations, with notes added in italics as they relate to Japanese knotweed):

• cultivation techniques (biomass reduction where feasible, cultivation between herbicide treatments to stimulate growth)
• hygiene measures (cleaning footwear and equipment is a standard part of invasive weed management)
• protection and enhancement of important beneficial organisms (ecological appraisals should form a part of any KMP)
• Application of plant protection based on monitoring data (this is an integral part of a KMP as described in our Code of Practice) and using targeted methods (e.g. spot treatments)
• Use of biological, physical and other non-chemical methods must be preferred to chemical methods if they provide satisfactory pest control (see below)
• The professional user should keep the use of pesticides and other forms of intervention to levels that are necessary (application rates and frequency only in-line with ‘best practice’)
• Review the success of plant protection measures (a normal part of a systematic KMP)

Perhaps Integrated Weed Management isn’t that hard after all?

As we see, most of the above principles are already part of best practice as defined in our Code of practice and other documents. An IWM plan (template) can be created to cover most JKW management scenarios (the ‘principles’) then each site/project can be risk assessed (for e.g. ecological impact potential) following the survey, before the KMP is presented/finalised. But the hard bit is weighing-up all the (many) non-herbicidal options available.

Cardiff has demonstrated that we must avoid simplistic assumptions that non-chemical = less (ecological) impact and it is a self-evident truth that e.g. excavating a site to remove JKW (simply as an alternative to herbicide use) has far greater potential for the destruction of insect/plant communities and soil biota than herbicide use (applied once a year in very low doses and only after appropriate risk assessments). Nevertheless, as above, we are under a duty to consider alternatives and this can only really be done on a case-by-case basis. The key questions are:

• is a guarantee required?
• is cost a limiting factor? If so, is the client willing to accept a hybrid approach?
• is the (proposed non-chemical) method feasible/practical e.g. accessibility of the site, water supply, efficacy (when a guarantee is not required) etc.
• does the non-chemical approach considered result in a sufficient level of control to enable the client to comply with the Wildlife & Countryside Act 1981 or other statutes?

A 3-phase process?

So, we propose that (for invasive weed management) IWM could be a 3-phase process:

• Prepare a IWM plan covering the Principles of SUD (annual review)
• For each INNS species evaluate the practical and financial limitations or advantages of all non-chemical approaches available (annual review)
• Ensure that all site surveys/client discussions include an appraisal of the specific opportunities or limitations presented. If a herbicide application is proposed ensure it meets the SUD principle of “levels that are necessary”.

Finally, our second point from the preamble above; if a herbicide is necessary/justified and can be used safely (as instructed on the label), we need to address the specific challenge of selecting the ‘right’ herbicide. To cut to the chase, for invasive weed management this is often a glyphosate-based formulation and this fact presents its own challenge. We’ve recently posted a video (Future of Glyphosate) from our latest conference addressing the ‘image’ of glyphosate; in short recognising that although it is often demonised most claims are rarely supported by credible evidence published in peer-reviewed journals.

A balanced approach from PCA specialists

No need to repeat the arguments here. But we do stress that the responsible way forward is to avoid making glib assumptions about glyphosate safety. That every client has the right to expect a balanced approach and that using herbicides is only the best option when they are used fully in accordance with label conditions.

In the end this is only one of many reasons why they should welcome a proposal for invasive weed management from a PCA specialist rather than a DIY approach based on Google, where the ‘diesel-and-a-box-of-matches’ method still seems very popular but we all know, would fail every single element of SUD and doesn’t work!

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