Individual study: The effect of giant hogweed Heracleum mantegazzianum umbel, leaf and stalk removal on quantity and quality of fruit, Slavkovský les Protected Landscape Area, Bohemia, Czech Republic
Pysek P., Krinke L., Jarosik V., Perglova I., Pergl J. & Moravcova L. (2007) Timing and extent of tissue removal affect reproduction characteristics of an invasive species Heracleum mantegazzianum. Biological Invasions, 9, 335-351
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Control invasive non-native plants on farmland (such as Himalayan Balsam, Japanese knotweed)
A randomized, replicated, controlled study in July 2002 and June 2003 in ten pastureland sites in Slavkovský les Protected Landscape Area, Czech Republic (Pysek et al. 2007) found that giant hogweed Heracleum mantegazzianum seed production was dramatically reduced by removal of flower heads (umbels) and less heavily reduced by removal of leaves. Timing of tissue removal also significantly affected seed production, with 80% of plants that had flower heads removed on 2 July 2003 regenerating and producing some seed compared to 30-60% of plants that were treated on 9-10 July 2002. For treatments that removed the whole plant, cutting the stem above the basal rosette was equally as effective as removing the basal rosette, and cutting 15 cm below the ground was the only treatment that killed the plants. Additionally, they found that 84% of cut flower heads could still produce seed if left on the ground, and 24% of these seeds germinated. The 2002 experiment used 10 different tissue removal treatments, each applied to one randomly selected plant at each of ten sites. The 2003 experiment used 70 plants randomly selected at one site. Two different treatments, cutting 5 cm above the ground and cutting just above the leaf rosette, were applied to ten plants each on 7 June, 20 June and 2 July. Ten plants were also used as a control.