The Groundsman

February 2014

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TECHNICAL UPDATE 22 the Groundsman February 2014 Visit www.iog.org for more information and digital editions he aim of the 'Development of zero and minimal herbicide regimes for controlling weeds on hard surfaces and determining their emissions' project is to develop a weed control programme for pavements and roads (amenity use) which minimises risk to the environment - in particular, water quality - compared to using herbicides alone, while still controlling weeds to an acceptable standard. The impacts, including the costs and benefits, of three programmes are being measured over five years and new reactive specifications are being developed for municipal weed control. The methods of controlling weeds fall into three categories: • Chemical – herbicide (mainly glyphosate) • Integrated - combining chemical and non-herbicidal methods to minimise herbicide use and risks • Non-herbicidal – thermal (flaming, infra-red, hot water, steam, hot foam) and mechanical (wire brushing, sweeping, hand removal). A multi-partner, five-year project is targeted to develop zero and minimal herbicide regimes for controlling weeds on hard surfaces The project is comparing the categories over a five-year period to allow the different methods to be explored and evolve. Alternatives to herbicide need to be explored in order to: • Minimise risks to surface and groundwaters • Develop sustainable performance specifications for amenity weed control contracts • Find alternative weed control methods to lessen the risk in the future of restrictions being imposed on herbicide use. Weed classification A new weed level classification system has been developed in the trial areas with a set of photographs to help assessors to estimate weed coverage and growth, quickly and accurately, enabling the contractor to decide when and where the treatments should be applied. Herbicide use Initial methods of non-herbicide control were based on a pedestrian operated infra-red heat treatment for pavement T The road to effective weed control By: Colin Hoskins areas. Pavement edges and kerbs and channels were treated with a hand-held flame gun. A weed ripper (a powered steel brush) machine was also utilised. However, none of these treatments were suitable for all areas of the pavements and road gullies due to risks including damage to vehicles, garden borders and operator exposure to vibrating machinery. During 2012, an alternative non- herbicide method of weed control was explored; a hot foam machine. The machine was used twice within the non- herbicide and integrated zones and proved to be effective on annual weeds but less effective on large perennial weeds. The speed of treatment was much improved over that of the weed ripper and could be operated in most weather conditions and used effectively near parked cars, street furniture and garden walls. The machine was further trialled in 2013 and integrated better for tap rooted weeds with spot treatments of herbicide. To date, the amount of herbicide applied in the integrated approach has been kept under 50 per cent of the allowable maximum dose. Weed growth Researchers have analysed the temperatures held by the plants after hot foam applications, which reach over 40oC; the temperature needed to permanently damage most weeds. Weed growth and coverage in 2012 was at least comparable, if not better in the integrated programme compared to the herbicide-alone programme. Growth and coverage of weeds was more difficult to control in the non-herbicide approach. Interestingly, there was a significant difference between the treatments for three of the weed species, with dandelion, procumbent pearlwort and annual meadow grass being less frequent in the integrated treatment. Weeds after foam application

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