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Salix cinerea (tree, shrub)   |
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Management Information
Mechanical: Cremer (1999) gives a brief overview of a variety of mechanical control procedures that can be used in the control of smaller infestations ofS. cinerea and other willow species but for larger invasions chemical methods will yield best results. The author reports that S. cinerea less than 1 metre tall and few in number can be pulled out by hand. Roots that remain do not sucker but buried portions of stems may take root and must also be pulled out. Use of heavy machinery can be effective but is not advisable on wet sites if the accidental incorporation of broken, live branches into the ground cannot be kept to a minimum. S. Cinerea can be felled, but except for some large, old willows the remaining stump usually coppices (produces shoots). The green crowns can be burnt immediately after felling (fire restrictions permitting). Burning may be an option if the tree can be completely girdled by fire at ground level, however young trees tend to sprout from the buried portion of their stem. Grazing can retard young S. Cinerea growth but will rarely kill the plant.Chemical: Cremer (2003) reporst that, "The main method of controlling S. Cinerea is injection of stems with the weedicide Glyphosate. Painting of freshly cut stems with Glyphosate is particularly effective and the spraying of foliage of shorter plants (< 2m tall) is often effective as well." S. Cinerea can sometimes be resistant to this treatment of painting freshly cut stems and may need to be painted several times. Effectiveness is increased if the bark is also sprayed if it is thin or stripped if it is thick (Cremer, 1999). Biological: The introduction of a biological agent has been considered for control of S. Cinerea in New Zealand, but opposition to the intentional introduction of further non native organisms is likely (Syrett, 2002). As other countries explore the possibilities of biological control agents, similar opposition will most likely arise also. Harman (2004) has researched and identified a varying number of possible biological control agents for S. Cinerea. The author gives a brief introduction and background on these species and while many species appear promising, extensive research is needed before any agent is ever released. First, each varying degrees of research must be conducted to determine which species have a narrow host range. This is critical to the success of a biological control program for S. Cinerea in New Zealand. There are many Salix hybrids that are beneficial and are used extensively for riverbank protection and soil stabilization and any introduced agent must be specific enough to not damage desirable hybrids and other species present in New Zealand.  
Location Specific Management InformationAustralia
The Australian Department of the Environment and Heritage's weed management guide suggest the following prevention and control options for the management of invasive Salix spp.
Preventative measures: Early detection and control are essential to prevent the spread of new infestations. Control techniques need to be carefully chosen to minimise unintended impacts. Stem injection of registered herbicide is recommended. Follow-up monitoring and control of regrowth (from stumps, pieces of stems or seeds) may be required for 3-5 years after initial control. Spread of willows that propagate by plant parts, is possible as they are confined to streams and are spread downstream. For seeding willows, prevention of spread is difficult because seed can be dispersed over large areas. A long term plan should be devised which includes replacement of Salix spp. with other desirable species and identification of seed sources so spread can be prevented. Staged removal should be undertaken upstream first and should be worked downstream. In cases where stram flow changes might occur due to removal of constrictions it is advisable to start downstream first. Click here to see Information about chemical control measures New South Wales
In NSW it is at present known only at five locations and probably is still controllable (Cremer, 2003). New Zealand
Seven of 13 Department of Conservation (DOC) in New Zealand conservancies regard it as one of the top 10 environmental weeds in their conservancy (Froude 2002) (Harman, 2004). S. cinerea is included in the First Schedule of the National Pest Plant Accord. All plants on the list are designated as Unwanted Organisms, and are banned from sale, propagation and distribution throughout New
Zealand. Please see National Pest Plant Accord for the complete list. Tasmania
In Tasmania there is a still manageable spread south of Hobart (Cremer, 2003). Waikato Region (North Island)
S. cinerea is classified as a “Nuisance Plant Pest” by Environment Waikato, which means it has been established for a considerable time and is probably widespread. While Region-wide control would be impractical and costly, there is benefit to those who wish to control specific infestations.
Please see definitions for hierarchy of pest designations.
Management Resources/Links
2. Chadderton, W. L. Undated. Management of invasive freshwater fish: striking the right balance!. New Zealand Department of Conservation 3. Champion, P. D., S. M. Beadel, and T. M. Dugdale. 2001. Turf communities of Lake Whangape and some potential management techniques. Department of Conservation: Wellington, New Zealand. Science for Conservation 186. 4. Cremer, K. W. 1999. Willow Management For Australian Rivers. The Australian Association of Natural Resource Management: CSIRO Forestry and Forest Products. 5. Cremer, K. W. 2003. Introduced willows can become invasive pests in Australia. Biodiversity 4(4): 17-24 (Tropical Conservancy). 6. Harman, H. M. 2004. Feasibility of biological control of grey willow Salix cinerea. DOC SCIENCE INTERNAL SERIES 183: New Zealand Department of Conservation. 7. National Pest Plant Accord, 2001. Biosecurity New Zealand.
Summary: The National Pest Plant Accord is a cooperative agreement between regional councils and government departments with biosecurity responsibilities. Under the accord, regional councils will undertake surveillance to prevent the commercial sale and/or distribution of an agreed list of pest plants.
Available from: http://www.biosecurity.govt.nz/pests-diseases/plants/accord.htm [Accessed 11 August 2005] 8. Syrett, P. 2002. Biological control of weeds on conservation land: priorities for the Department of Conservation. New Zealand Department of Conservation: DOC SCIENCE INTERNAL SERIES 82. Results Page: 1
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