Plant Risk Assessment & Management Protocol for MN

1. Plant Risk Assessment & Management Protocol for MN MN Noxious Weed Advisory Committee www.mnnoxiousweeds.wikispaces.com Tim Power, Minnesota Nursery and Landscape Association Berberis thunbergii – Japanese Barberry

2. History of the Noxious Weed Advisory Committee • Early on, MN noxious weeds were ag weeds • MNLA became involved after listing of purple loosestrife in the mid-1980’s • Excellent noxious weed plan developed in 2001-2002, then program was de-funded by state budget cuts • MDA convened study group in 2007, including stakeholders like the MNLA

3. History of the Noxious Weed Advisory Committee • In 2009, the MN legislature completed major revisions to MN Noxious Weed Law • Three sections were added • Noxious Weed and Invasive Species Account • Grant Program • Advisory Committee • In 2013, added category definitions to statute, including Specially Regulated

4. Duties of the Noxious Weed Advisory Committee • Advise the Commissioner regarding responsibilities under the noxious weed program • Evaluate species • invasiveness, difficulty of control, cost of control, benefits of a species, injury caused by a species • Develop weed categories for listing noxious weed species and management criteria for each category • Recommend whether and where an evaluated species should be listed • Reevaluate species every 3 years Lythrum salicaria – Purple Loosestrife

5. Noxious Weed Advisory Committee • Committee representation = Stakeholders • Science-based/evidence-based species evaluation process, called a Risk Assessment • Species evaluations DO NOT = listing, nor do they mean a species is “bad”

6. Plant Risk Assessment & Management Protocol for Minnesota • A tool for objective assessment of: • potential risks associated with plant introductions • regulation and management of harmful species already in the state • Balances potential negative impacts with recognized benefits • Decision-tree process

8. Petitioning Noxious Weeds

9. Risk Assessment for Japanese Barberry • Why conduct a risk assessment for Japanese barberry (Berberis thunbergii)? • Japanese barberry was observed naturalizing in forests in MN and was known to be an invasive species in the eastern U.S. • Information about the level of risk posed by Japanese barberry in Minnesota was needed New York, NY Dept. Env. Cons. photo New Jersey, New Jersey Hills photo Eastern US, Natalie Solomonoff photo Southeastern Minnesota, MN DNR photo

10. Risk Assessment for Japanese Barberry Berberis thunbergii Shade Tolerant Deer Resistant • Box 1: Is the plant species or genotype non-native? • Yes, it is native to Japan • Go to Box 3

11. Risk Assessment for Japanese Barberry • Box 3: Is the plant species, or a related species, documented as being a problem elsewhere? • Yes • US Forest Service Eastern Region Category 1 plant (non-native, highly invasive plants which invade native habitats and replace native species) • Prohibited invasive plant in MA, NH • Naturalized in 30 states and 2 Canadian provinces • Go to Box 6

12. Risk Assessment for Japanese Barberry • Box 6: Does the plant species have the capacity to establish and survive in Minnesota? • Yes • Used heavily in landscapes • Hardy in zones 4-9 • Go to Box 7

13. Risk Assessment for Japanese Barberry • Box 7: Does the plant species have the potential to reproduce and spread in Minnesota? • Yes • Known to naturalize in MN • Spreads by: • Animal-transported seed to new sites • Layering branches within a site • No natural controls are documented • Go to Box 8 Japanese barberry distribution www.EDDMaps.org Sept. 2012

14. Afton State Park – June 2011

15. Afton State Park – June 2011

16. Afton State Park – June 2011

17. Afton State Park – June 2011

19. Box 8 Berberis thunbergii ‘Aurea’ • Box 8: Does the plant species pose significant human or livestock concerns or have the potential to significantly harm agricultural production, native ecosystems, or managed landscapes? • If yes, go to Box 9 • If no, the plant species is not currently believed to be a risk

20. Box 8 – Questions to Consider Berberis thunbergii var. atropurpurea ‘Rose Glow’ • 8A: Does the plant have toxic qualities, or other detrimental qualities, that pose a significant risk to livestock, wildlife, or people? • No • Go to Question B

21. Box 8 – Questions to Consider Berberis thunbergii and var. atropurpurea Small size, desirable habit, and unique colors • 8B: Does, or could, the plant cause significant financial losses associated with decreased yields, reduced crop quality or increased production costs? • No • Go to Question C

22. Box 8 – Questions to Consider • 8C: Can the plant aggressively displace native species through competition (including allelopathic effects)? • Forms dense thickets in native areas, according to studies on the Eastern seaboard (Silander and Klepis 1999, Harrington et. al. 2006) and MN DNR observations in MN. • No mention found of allelopathy. • If yes, go to Box 9; if no go to additional questions under Box 8

23. Box 8 – Questions to Consider Berberis thunbergii ‘Golden Nugget’ • 8D: Can the plant hybridize with native species resulting in a modified gene pool and potentially negative impacts on native populations? • No • Go to Question E

24. Box 8 – Questions to Consider • 8E: Does the plant have the potential to change native ecosystems (adds a vegetative layer, affects ground or surface water levels, etc.)? • Soil under Japanese barberry has a higher pH and higher nitrification and mineralization rates (Ehrenfeld et al. 2001). • Japanese barberry leaf litter is higher in nitrogen than native species and decomposes more rapidly (Ehrenfeld et al. 2001). • Soils under Japanese barberry differ in microbial community structure and function (Kourtev et al. 2002). • Timing of nutrient uptake and deposition differs from native species, and altering soil functions could contribute to ecosystem-level changes (Ehrenfeld et al. 2001, Ehrenfeld 2004). • Ehrenfeld et al. (2001) note that while densities of Japanese barberry start out low, over time they alter the soil by increasing nutrient levels; this makes the site more favorable for additional Japanese barberry plants, leading to dense populations and more altered soils over time. Cassidy et al. (2004) found that Japanese barberry does better on sites with higher nitrogen. • If yes, go to Box 9; if no go to additional questions under Box 8

25. Box 8 – Questions to Consider • 8F: Does the plant have the potential to introduce or harbor another pest or serve as an alternate host? • This has not been documented, but there is some concern. • Common barberry (Berberis vulgaris) has been widely eradicated because it is a host of wheat rust. Japanese barberry is not a host of wheat rust. However, Connolly et al. (2013) note that Berberis x ottawensis (B.thunbergii x B.vulgaris) is relatively common in the wild in Mass. and Conn. and may be capable of producing some viable seed and pollen. • Emerging wheat rust Ug99: If this rust strain reaches North America it would cause extensive damage to US crops and cause millions/billions in crop losses. At this time there is no evidence that Japanese barberry can serve as a host to the stem rust fungus Ug99. Because other barberry species are hosts and not all Japanese barberry cultivars have been tested (some may be hybrids), Canada is not allowing additional Japanese barberry cultivars into Canada except those that are already on its approved list. • If yes, go to Box 9; if no the species is not currently believed to be a risk

26. Box 8 Berberis thunbergii var. atropurpurea • Box 8: Does the plant species pose significant human or livestock concerns or have the potential to significantly harm agricultural production, native ecosystems, or managed landscapes? • If yes, then go to box 9 • If no, then the plant species is not currently believed to be a risk

28. Box 9 • Does the plant species have clearly defined benefits that outweigh associated negative impacts? • If yes, go to Box 11 and determine if the species should be designated as a Specially Regulated Plant • If no, go to Box 10 to determine if the species should be designated as a Prohibited or Restricted Noxious Weed

29. Box 9 – Questions to Consider • 9D: Is a non-invasive, alternative plant material commercially available that could serve the same purpose as the plant of concern? • Sterile cultivars of Japanese barberry are under development at the University of Connecticut.  Additionally, there are currently available Japanese barberry cultivars that have relatively low seed production. • Alternatives are suggested on various websites (all of these suggestions may not be appropriate for MN): • MN Department of Natural Resources / Leatherwood (Dirca palustris), Downy Arrowwood (Viburnum rafinesquianum), American Hazel (Corylus americana), Beaked Hazel (Corylus cornuta) • Midwest Invasive Plant Network / Tilia cordata (Littleleaf linden), Buxus spp. (Boxwood 'Glencoe' or 'Green Velvet'), Ribes alpinum 'Green Mound' (Alpine Currant), Fothergilla major (Large Fothergilla), Cotoneaster divaricatus (Spreading Cotoneaster), Ilex verticillata (Winterberry Holly), Rosa rubrifolia (Redleaf Rose), Rosa 'Knockout'(Knockout Roses), Cotinus coggygria (Smoke bush), Physocarpus opulifolius 'Diablo,' 'Summer Wine', Coppertina' and 'Center Glow' (Ninebark), Weigela florida 'Wine and Roses', ('Wine and Roses' Weigela) • National Park Service / Bayberry (Myrica pensylvanica), Ink-berry (Ilex glabra), winterberry (Ilex verticillata), Arrow-wood (Viburnum dentatum), Mountain Laurel (Kalmia latifolia), Ninebark (Physocarpus opulifolius), and hearts-a-burstin' (Euonymus americana)

30. Box 9 – Questions to Consider Berberis thunbergii ‘Cherry Bomb’ • 9D: Is a non-invasive, alternative plant material commercially available that could serve the same purpose as the plant of concern? • Natural resource organizations list alternatives • Survey of horticultural industry indicated that members did not see a viable alternative to Japanese barberry

31. Box 9 – Questions to Consider • 9B: Is the plant an introduced species and can its spread be effectively and easily prevented or controlled, or its negative impacts minimized, through carefully designed and executed management practices? • The spread of Japanese barberry cannot be easily prevented or controlled once it is introduced. • Birds can spread seed. • Offspring of cultivars (such as purple or yellow-leaved forms) can be green making it difficult to tell which cultivar was a parent to a naturalized barberry plant (Lehrer et al. 2006). However, there are cultivars with low seed production which may be less likely to be invasive. The Connecticut Nursery and Landscape Association implemented a voluntary phase-out of 25 heavy-seeding Japanese barberry cultivars in 2010.  • It is difficult to control the spread of woody species once they are widely distributed. Methods for Japanese barberry control are similar to those for buckthorn or other woody invasives – very time and labor intensive. • If yes go to Box 11, if no go to Question 9C

32. Box 9 – Questions to Consider • 9B: Is the plant an introduced species and can its spread be effectively and easily prevented or controlled, or its negative impacts minimized, through carefully designed and executed management practices? • The spread of Japanese barberry cannot be easily prevented or controlled once it is introduced. • Birds can spread seed. • Offspring of cultivars (such as purple or yellow-leaved forms) can be green making it difficult to tell which cultivar was a parent to a naturalized barberry plant (Lehrer et al. 2006). However, there are cultivars with low seed production which may be less likely to be invasive. The Connecticut Nursery and Landscape Association implemented a voluntary phase-out of 25 heavy-seeding Japanese barberry cultivars in 2010.  • It is difficult to control the spread of woody species once they are widely distributed. Methods for Japanese barberry control are similar to those for buckthorn or other woody invasives – very time and labor intensive. • If yes go to Box 11, if no go to Question 9C

33. CT Voluntary Phase-Out Note: New research by Knight et al. (2011) demonstrates that low-fecundity cultivars may still be invasive and that the only “safe” cultivars are sterile cultivars that cannot produce viable seed or reproduce asexually.

34. NWAC Recommendation • Box 11 – Should the plant species be allowed in Minnesota via a species-specific management plan; designate as specially regulated? • Answer – Yes. The Connecticut Nursery and Landscape Association implemented a voluntary phase-out of 25 heavy-seeding Japanese selections in 2010. Wisconsin is proposing a three-year phase-out and eventual ban of the same CT selections. Minnesota should implement a three-year phase-out of the seediest Japanese barberry selections (using the CT list), followed by a ban of those seediest selections. Future selections with >600 seeds/plant should be banned as well. Ongoing sterility and invasiveness research on Japanese barberry should be monitored closely. If and when horticulturally-acceptable seedless cultivars of Japanese barberry are developed and successfully in trade, revisions should be considered in the seediness level of Japanese barberry cultivars considered “acceptable to plant”.

36. Current Status = Step 4

37. Questions?www.mnnoxiousweeds.wikispaces.com Berberis thunbergii – Fruits & Seedling