Using pesticides in amenity areas such as parks, golf courses and other areas open to the public has to conform to the EU regulations in a similar manner to protecting crops on farms. The main difference is that there are a diverse range of spray targets which frequently have to be treated using manually carried or specialised equipment, rather than by using a tractor sprayer. The equipment can include compression sprayers, motorised knapsacks and Controlled Droplet Application (CDA) equipment, through to specialised high technology spray trains.
Advice in the UK from the Crop Protection Association provides information on why pesticides should be used and the need to comply with the relevant legislation, including the EU Water Framework Directive to protect surface and ground water, but gives relatively little advice on how the pesticides should be applied. As a consequence, in the UK, the sector has established its own voluntary initiative seeking to promote best practice and disseminate guidance – the Amenity Forum
Historically the simplest of sprayers were used to apply relatively large volumes of spray to thoroughly wet the surfaces being treated. Volumes in excess of 1,000 litres per hectare have been recommended. Except for some selected applications, most of the spray drips off target surfaces, once they are wetted, so a high proportion of the chemical can be wasted. An exception exists where current labels for using herbicides on golf greens (recommended at up to 1,000 L/Ha) is designed to get the pesticide to penetrate down into the root zone of plants, especially when uptake by the roots is needed to distribute the pesticide throughout the plants. Whether as much as 1,000 L/Ha is really needed depends on the moisture content of the soil as the pesticide could be well distributed in far less water if the ground is already wet. The emphasis must be on targeted application, applying the chemical at the right levels, at the right time and in the right place.
Certain scheduled weeds such as ragwort, various thistles and docks have to be controlled under The Noxious Weeds Act (1959) to prevent the seeds contaminating neighbouring land. Similarly, control of certain alien plants, such as Giant Hogweed and Japanese Knotweed is required under The Wildlife and Countryside Act (1981). Using herbicides to manage weeds is often significantly less expensive and more costeffective than using mechanical control of weeds.
To reduce the amount of herbicide that needs to be applied, the aim is to target the application as much as possible. This is particularly important where weeds occur on hard surfaces, such as pavements and along the roadside kerb. The Chemical Regulation Directorate (CRD) defines a hard surface as “Any man-made impermeable surface such as concrete or asphalt and ballast along railway tracks that is not intended to bear vegetation”. The target for the spot sprays is thus the weed plants that are actively growing, normally between March and October, so that there is sufficient coverage of the foliage, but no direct spray or ‘run-off ’ of spray. Once the leaves are wetted, the surplus spray will get into nearby drains.
Agricultural sprays are often applied to field crops using wide angle flat fan nozzles (e.g. 80o, 110o) mounted across the spray boom, but weeds on pavements are best treated while young, so a much narrower angle fan, or cone nozzle can be more efficient in placement of spray on specific targets. The volume of spray can be quite low. Some users apply the CDA technique that only uses 7 – 15 litres of Ready To Use (RTU) spray, with droplets in a specific drop size range, to avoid spray drift…
This is an extract of the full article published in International Pest Control – May/June 2016 issue.
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Author: Graham Matthews*
*Emeritus Professor, IPARC, Imperial College, London