In conjuction with BABOG (Bristol & Bath Organic Growers, a regional group of the OGA), the Soil Association’s Duchy Originals Field Labs programme, and via the Organic Research Centre, there was a foam weeding demonstation today at the Somerset Flower Farm in Wrington, south of Bristol. This was part two of the trial; the first demonstration day was back on 19th July, and we took a look at the plots of land that were treated then.
The hot foam weeding system, Foamstream, is currently available to buy direct from the manufacturer (rather out of my price range at circa £24,000); or there are trained operatives who can come and treat your weeds for you, and will charge a day rate according to the size of plot to be covered, weed type, water access, operator and number of days booked – but probably the best starting rate would be £650/day. Our operator was William Iliffe, from Ecological Weeding Techniques; and after checking out the results from the previous application, we also saw a demo of the system in practice.
The ‘foam’ mix is organically approved, and made from plant extracts; however the foam is simply a wetting agent and 0.5% of the total solution, designed to make it easier for the heat from the near-boiling water permeate the cell walls of the weeds and seeds. So it’s the extreme temperature (over 90C) that actually kills the weeds, not the chemicals in the foam. The foam bubbles also helps keep the heat around the plant for longer, acting like a mini blanket.
There was a definite difference between treated and untreated patches, especially where docks were less prevalent; and even aggressive perennials such as docks had been knocked back a couple of weeks after application, compared to untreated areas. However when we saw the patches, 7 weeks after initial application, many weeds that had survived had caught up size-wise to those in the non-treated areas (although on mst holdings any new weeds would have been hoed off very quickly compared to untreated areas, rather than left for trial purposes). It will be interesting to hear whether the stubborn perennial weeds on the treated patch are weaker long-term, such as spring next year; and how long the surface sterilising effect lasts on those patches that showed such a successful marked difference between treatment and control. For the full report on these demos, check out the next issue of the Organic Grower magazine, free to Organic Grower Alliance members.