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vert bar Carpobrotus edulis > Herbicide Trials
Last updated 6 April 2010

As the area affected by Hottentot fig (Carpobrotus edulis) on Howth Head lies within Howth Head SAC 000202 no experimental work or treatments could be carried out during nesting season March - September. The experiment chemical treatment and native species recruitment experiments planned were carried out at an alternative coastal site in Wicklow, the Breaches (ca. 6km South of Greystones, Co Wicklow) (Figure 2). The Breaches comprises a set of lagoons on the inside of the railway track, and the only major break in the long shingle bank between Greystones and Wicklow, that forms the Murroughs. A fence was erected to the west of the railway line during the 1990s, and runs ca. 200m north from the railway bridge.

Tetrads of 1.5m2 (2.25 m2) were treated with each of the three herbicide products trailed (Table 1 and Figure 3), and these were replicated in each of the Hottentot fig (Carpobrotus edulis) patches. The patches were marked using white pebbles, and each patch was separated by 1m from the next treatment. The spray was applied until all leaf surfaces were fully wetted. About litre was used for the two tetrads of each treatment. Each herbicide had a distinctive coloured-bottle, and the code letters apply to these. The sequence of the three treatments was randomised between the 2 patches.

The herbicide treatment was conducted in the evening (5.30pm) of a still dry day. No rain fell in the following 24 hours, and the herbicide was applied according to the manufacturers instructions to prevent contamination of the surrounding habitat, in particular the watercourse to the west. A series of photographs of the terads were taken nine and thirty-seven days after each treatment was applied.

Photographs taken 37 days after treatment
1.5 square metre plots
Treatment Code and commercial name
Active ingredient(s) % mortality

W - B&Q Lawn weedkiller
0.358 g/l mecoprop-P and
0.191 g/l dichlorprop-P soluble

B - Resolva weedkiller 24H Action Westland garden health
3 g/l glyphosate and
0.3g/l diquat

G - Monsanto, Fast action Roundup weedkiller
7.2 g/l glyphosate acid, present as
9.7 g/l isopropylamine salt of glyphosate

If you have information about any other populations of Carpobrotus please notify the following:-
Matthew Jebb
National Botanic Gardens
Dublin 9
matthew.jebb at