Controlling cotoneaster – grub, spray or burn


Old quarry workings on the Isle of Portland have a high conservation value for limestone grassland species but are being overwhelmed by the introduced invasive, small-leaved cotoneaster Cotoneaster integrifolius. Three different approaches to control (mechanical removal, herbicide, and flame gun) were tested on in February 2002. The mechanical treatment and its consequences are outlined below.

On 14 February 2002, mechanical removal of small-leaved cotoneaster was undertaken using a 13-tonne tracked excavator, fitted with a tilting mechanism at the end of the dipper arm. This enabled the bucket to be angled with greater flexibility around lumps of stone and to follow the random contours. Using this method, Cotoneaster was removed with as much root as possible, and burnt on nearby open ground. A trial area of 1,000 m² was cleared.

Anticipated disadvantages were a relatively high cost, the possibility of ripe berries being shed onto the ground (thus giving rise to new plants), safety implications and the fact that this technique could only be used on about 50% of the area due to steepness of the terrain.

The excavator quickly and efficiently removed the Cotoneaster ‘canopy’ but many roots were left in the soil. The process disturbed almost the entire ground surface leaving it open and loose. Any residual limestone flora was also removed with the cotoneaster. The treatment was slowed down by the need to burn the grubbed up material. The estimated cost of treatment was £0.66/m².

Initial monitoring of the treated areas was undertaken four months later in June 2002. The grubbed area looked messy, and vegetative regrowth of Cotoneaster was visible and abundant on remaining root fragments. Recently germinated plants were also visible. Additionally, there were many small bramble Rubus fruticosus, thistle Cirsium spp., ragwort Senecio jacobaea and dock Rumex spp. plants appearing but few desired limestone specialists were apparent.

Eight months after treatment the area had not become much worse but showed little sign of native vegetation recovery. Overall, mechanical removal was not considered a successful method of cotoneaster control at this site.

Note: If using or referring to this published study please read and quote the original paper.

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