Interim profile, incomplete information
Preventative measures: A Risk Assessment of Rumex crispus prepared for Australia resulted in a high score of 16 with a recommendation of "reject the plant for import (Australia) or species likely to be of high risk (Pacific)" (PIER, 2003).
R. crispus appears to be relatively vulnerable at early stages of development; once the taproot has formed it has great advantage over shallower rooted grasses and herbs, and can be very difficult to eradicate (Zaller, 2004). The long-term goal of control measures against Rumex is to reduce build-up of seeds and weaken their regrowth capacity by removing or destroying their above- and below-ground biomass.
Chemical: R. crispus is sensitive to many herbicides, especially synthetic auxins (MCPA, 2,4-D, dicamba, dichlorprop-P, fluroxypyr, etc.) and many sulphonylureas (tribenuron, thifensulfuron, amidosulfuron, etc.) (Jursík et al., 2008). Thifensulfuron can be used for dock management in perennial legume stands, good efficacy is also shown by asulam, which is recommended for local application only, due to lower selectivity (Jursík et al., 2008).
Public concern about pesticides in the environment has led to greater demand for non-chemical control methods and the development of mechanical and cultural measures to control plants (Zaller, 2004).
Mechanical: If herbicides are not used, the best option is control via manual removal or destruction of plants. This can be achieved via hand weeding, although is only suggested for use in small areas as it is labour intensive. It is necessary to remove the tap root to a depth of 20 cm in order to prevent regrowth (Zaller, 2004). Recent developments in mechanical control include a motor-driven dock pulling machine which can pull up about 600 Rumex plants per hour (Pötsch, 2003 in Zaller, 2004).
Well developed R. obtusifolis plants can be difficult to control with cutting or grazing. Because of rapid replenishment of carbohydrate in roots, plants require repeated defoliation over a period of several years, which can be achieved by frequent cutting or grazing (Stilmant et al., 2010). However, increased cutting frequencies may increase disturbance and offer opportunities for new seedlings to germinate and establish (Grossrieder & Keary, 2004).
Grazing: Grazing by sheep has been proposed as an alternative to manual removal, but may not be as effective as hand pulling (Van Middelkoop et al. 2005 in Van Evert et al., 2009). While Rumex species are unpalatable to many livestock, they are a favourite of deer (Cavers & Harper, 1965). More studies should focus on mixed grazing (e.g. cows and goats) to control Rumex (Zaller, 2004).
Cultural: Mechanical removal can be combined with grassland renewal and rotation with a grain crop (Van Middelkoop et al., 2005 in Van Evert et al., 2005). Some authors have suggested combating the problem of regrowth by leaving the ground as a bare fallow following a rotary cultivation in spring, so that the unearthed root fragments are killed by desiccation (in Grossrieder & Keary 2004). As Rumex seedlings require high light, control through shading may be effective (Zaller, 2004).
Biological: Numerous insects and fungi have been proposed as biological control agents for R. obtusifolius. The most thoroughly studied organisms are the beetle Gastrophysa viridula and the rust fungus Uromyces rumicis. Studies with Coleoptera have found reductions in seed production, regeneration, and leaf and shoot growth. Similarly studies with fungi have found similar effects and increased root rotting. Efficacy of biological control tends to be more effective when plants are already stressed by environmental conditions (Reviewed by Zaller, 2004).
2. Holm, Leroy G., Plucknett, D. L., Pancho, J. V., Herberger, J. P. 1977. The world’s worst weeds: distribution and biology. East-West Center/University Press of Hawaii. 609 pp.
3. IUCN/SSC Invasive Species Specialist Group (ISSG)., 2010. A Compilation of Information Sources for Conservation Managers.
Summary: This compilation of information sources can be sorted on keywords for example: Baits & Lures, Non Target Species, Eradication, Monitoring, Risk Assessment, Weeds, Herbicides etc. This compilation is at present in Excel format, this will be web-enabled as a searchable database shortly. This version of the database has been developed by the IUCN SSC ISSG as part of an Overseas Territories Environmental Programme funded project XOT603 in partnership with the Cayman Islands Government - Department of Environment. The compilation is a work under progress, the ISSG will manage, maintain and enhance the database with current and newly published information, reports, journal articles etc.
4. Jursík, M., Holec, J. & Zatoriová, B. 2008. Biology and control of another important weeds of the Czech Republic: Broad-leaved dock (Rumex obtusifolius) and curled dock (Rumex crispus). Listy Cukrovarnicke a Reparske , 124(7-8): 215-219.
5. Otley H, Munro G, Clausen A and Ingham B. 2008. Falkland Islands State of the Environment Report 2008. Falkland Islands Government and Falklands Conservation, Stanley.
8. Stilmant, D., Bodson, B., Vrancken, C. & Losseau, C. 2010. Impact of cutting frequency on the vigour of Rumex obtusifolius. Grass and Forage Science, 65: 147-153.
9. Van Evert, F.K., Polder, G., Van der Heijden, G.W.A.M., Kempenaar, C. & Lotz, L.A.P. 2009. Real-time vision-based detection of Rumex obtusifolius in grassland. Weed Research, 49: 164-174.
10. Whitehead J. 2008. Priorities for Control: A Risk Assessment of Introduced Species on the Falkland Islands. A RSPB Report to the South Atlantic Invasive Species Project. RSPB, Scotland.
11. Zaller, J.G. 2004. Ecology and non-chemical control of Rumex crispus and R. obtusifolius (Polygonaceae): a review. Weed Research, 44: 414-432.
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