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Weeds of National Significance

Weeds of National Significance. National Willows Program WILLOWS WORKSHOP. Supported by the State Government of Victoria. Workshop Game Plan. National, state and regional context Willow identification Willow sawfly in Australia Update regional maps highlighting where willows occur.

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Weeds of National Significance

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  1. Weeds of National Significance National Willows Program WILLOWS WORKSHOP Supported by the State Government of Victoria.

  2. Workshop Game Plan • National, state and regional context • Willow identification • Willow sawfly in Australia • Update regional maps highlighting where willows occur

  3. Willows - a Weed of National Significance • Infest 1000s of km of waterways • Approx. $30 million spent annually • > 32 types of willows • Spread in different ways • Distribution, invasiveness and impacts of specific willows are poorly understood

  4. Did you know? Q: Do willows consume more water than natives? Clue: it depends on where they are in the landscape A: Yes: if growing in the water No: if growing on the bank Can consume approx. 3 megalitres per crown hectare more water than river red gums

  5. Change in vegetation & structure Increased shading of stream Sediment trapping around roots Change in higher trophic orders Erode Riverbanks Terrestrial insects Leaf litter input Obstruct and divert floods Emergent stream insects Aquatic food webs WILLOW IMPACTS? Nutrient transfer Primary production altered (algae)

  6. How do you grow a willow? A: Stick a willow stem in the ground as a fishing rod holder Willows grow easily from stems Q: When sitting along a river, lazily fishing, how might you accidentally grow a new willow tree? Clue: what do you lean your fishing rod on?

  7. How do willows spread? Seed up to 100km Layering Twigs and branches

  8. Spread by seed Salix nigra (black willow) e.g. North East Victoria Salix cinerea (grey sallow) e.g. Sydney catchment

  9. Don’t respect our borders Early detection and eradication of seeding willows in Tasmania

  10. National Willows Taskforce Community SA NSW CMAs Tas Weeds CRC Local gov’t Qld NGIA Community ACT Vic

  11. Did you know? Q: For what religious festivals are willows allowed to still be imported? Clue: they can be imported from Israel and the U.S.A A: Jewish festivals ‘cut flowers and foliage’ ‘only Rabbis may import the cuttings’ One of the Four Kinds taken on Sukkos: “The willow, which is inedible and lacks aroma as well, represents those people lacking both in Torah and good deeds”

  12. National Willows Program • National policy on importation • to prevent future problems • Biological control and other research • protecting our investment for the future • Education / awareness / communications • National Best Practice Management Guide • Nursery and Garden Industry • Increasing broad public awareness • Mapping and weed risk assessment • can’t manage what we don’t know

  13. Developing willow management priorities • Workshops • create/update regional maps • training in mapping, sawfly and ID • Weed risk assessment • risk, impacts, current and potential distribution and feasibility of control • Priority actions for willow management • reports to each state and CMA/NRM region • maps of distribution and potential spread

  14. Find out more... Website: www.weeds.org.au/WoNS/Willows National Willows Network nationalwillowsnetwork@lists.weeds.org.au Willow Strip Newsletter

  15. Weeds of National Significance WILLOW MAPPING Supported by the State Government of Victoria.

  16. Why map willows? Because you can’t manage what you don’t know! Tasmania North East bushfires

  17. E.g. Wingecarribee Swamp

  18. Why map willows? • Eradication of all willows not feasible or desirable • Need to set priorities for management • Factors to consider: • Risk of further spread by seed or branches • Current impacts • Density and location of willows • Accessibility and cost of management • Community support

  19. Did you know? A: Houseboating Industry Nowhere to moor the boats in some sections Q: What industry in South Australia is impacted by willows growing along the River Murray? Clue: they float on water

  20. Weed risk management • Weed risk is based on: • invasiveness (rate of spread) • impacts • current and potential distribution

  21. Weed risk management • One willow may rank more highly than another willow if: • its overall area and / or the number of ecosystems it can invade is greater (invasiveness); • it impacts more on social, environmental and agricultural values (impacts) • it is presently localised - but could spread much further (current:potential distribution)

  22. Feasibility of coordinated control • Total cost is a function of: • total area infested, • annual control cost per unit area and • number of years required to achieve the desired level of control.

  23. Current : potential distribution

  24. Potential Distribution Australian climate match Salix aegyptiaca Sample maps Australian climate match Salix fragilis

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