Pesticides available to amateurs

There’s been much press of late of the controversial pesticide Glyphosate with the latest findings being that it does not cause cancer in humans (Nov 9th, 2017) but according to an example Material Data Safety Sheet (of which there are many examples) published for the commercial product it is “Toxic to aquatic organisms; may cause long term adverse effects in the aquatic environment.” (as well as having  “Risk of serious damage to eyes“), so glyphosate washing into drains and polluting the watercourse is a serious problem to some wildlife, which seems to have been underreported in the press due to the focus on potential risk to humans.

I thought it would be useful just to find out the range of pesticides that are available to the amateur gardener to use on their lawn or garden in general.

What is a Pesticide?

A ‘pesticide’ is something that prevents, destroys, or controls a harmful organism (‘pest’) or disease, or protects plants or plant products during production, storage and transport. (Source: European Commission, ‘Pesticides’, accessed 20th December 2017)

Cats-ear weed in lawn

Cats-ear (Hypochaeris radicata) weed in lawn

My biggest concern is not just about the potential amount of pesticide we might be depositing into the environment impacting on wildlife and nature in general, but also the ready availability of such chemicals and why is there the need, and I mean a ‘real need’, for such an amount in practice. So getting a bit of data to reflect on would be helpful.

The range of pesticides available to the amateur in the UK are categorised accordingly:

  • Weed control (all forms): 458 products : 88 approved for use on lawns
  • Insect control: 119 products: None approved for use on lawns
  • Disease control: 21 products: 2 approved approved for use on lawns
  • Combined Insect / Disease control: 11 products: None approved for use on lawns
  • Plant growth regulators (PGR): 9 products: 1 approved approved for use on lawns
  • Unclassified / Miscellaneous: 40 products: 37 approved approved for use on lawns

(Source: HSE Pesticide Safety Directorate – checked 16th December 2017)

Just for reference purposes there are 297 different products available for use with Glyphosate in them.

Clearly weedkillers comprise the largest pesticide group, so I’ll investigate those.

Weedkillers (called herbicides) can be grouped as non-selective, such as glyphosate which will kill green vegetation including your lawn grass, or selective which are the ones you would put on your lawn as these only kill weeds and not the grass plant.

At a first guess I thought maybe a dozen different weedkillers that are selective herbicides that might be available for use on lawns, but clearly this was a bit far of the mark. There are 88 products approved for use on lawns to selectively control weeds, but just 9 unique chemicals (called active ingredients / substances).

The ‘Unclassified / Miscellaneous’ category is interesting in that of the 37 approved products (9 different active substances, 8 of which are included in the weed control list) for use on lawns these are all essentially selective herbicides, so I’m not quite sure why they have been listed under this heading.

The 9 substances which are therefore currently approved (December 2017) for use in Weed control (including moss) are:

  1. Iron sulphate / Ferrous sulphate (mainly moss killer)
  2. 2,4-D
  3. Mecoprop-P
  4. Fatty acids: Pelargonic acid (moss killer only, but primarily for clearing lawns of moss and vegetation rather selective control whilst leaving grasses unharmed, so it’s questionable why this would be listed here)
  5. Dicamba
  6. MCPA
  7. Fluroxypyr
  8. Dichlorprop-P
  9. Clopyralid

The total quantity of pesticide applied by lawn care companies, or similar (not your general gardener though as I haven’t found any figures for these users yet) has been estimated (Defra, ‘PESTICIDE USAGE SURVEY REPORT 254  AMENITY PESTICIDES IN THE UNITED KINGDOM 2012’, V2, published January 2015, p.21) as some 32 tonnes of product (10.4 tonnes of active ingredient) – that’s just for residential properties, not sports surfaces or anything like that.

The RHS has also produced a handy 8 page leaflet ‘Weedkillers for Home Gardeners RHS Gardening Advice’ (March 2017)

So, lots of products, not too large a range of different chemicals, with an unknown total amount being sprayed into the environment, but it will certainly be quite a bit when we consider what the usage is for the contracted residential properties. How much of it is really needed is another matter altogether.

Applying good lawn care practices, especially cultural and physical practices, can certainly help to reduce the need for the application of pesticides, especially herbicides. This is definitely a subject to explore further on another day.

Chris Gray, 20th December 2017