1. Microstegium vimineum Management and Impacts on Native Plant Communities Caren A. Judge, Joseph C. Neal, Theodore H. Shear, and Jeffrey F. Derr North Carolina State University

2. Microstegium vimineum n Japanese stiltgrass n Summer annual invasive grass (Poaceae) n C 4, shade-tolerant n Wetlands, woodlands, utility easements, lawns, landscapes http://plants.usda.gov

3. Objectives n To use an biological and ecological based research program to make sound management recommendations for Japanese stiltgrass

4. Current management guidelines n Prevent seed production (Tu 2000) n Methods (late-season) –Hand-removal –Mechanical (mow) –Nonselective herbicide (Roundup Pro – glyphosate)

5. Questions and concerns? n Late-season control allows competition to reduce native species n Non-selective methods (Roundup and mowing) kill native species n Management must be timely

6. Photoperiod and flowering (NC) 1 st visible flowers (2002-2004)

7. Photoperiod and flowering (NC) 1 st visible flowers (2002-2004)

8. Photoperiod and flowering (NC) 1 st visible flowers (2002-2004) Approximate floral induction

9. Photoperiod and flowering (NC) 1 st visible flowers (2002-2004) Approximate floral induction

10. Seed development n Harvest inflorescences at various times in the reproductive cycle Oct. 7Oct. 21 Nov. 14Nov. 2

11. Germination of immature seed Collection Date% Germination Oct. 713c Oct. 2157b Nov. 297a Nov. 14100a

12. Stiltgrass PRE Control – 8 WAT LSD=15 P=0.05 * ** *** Percent

13. Stiltgrass & Crabgrass PRE Control Percent

14. Stiltgrass POST Control – 8 WAT LSD=11 P=0.05 * ** *** Percent ***

15. Stiltgrass & Crabgrass POST Control Percent

16. Timing experiment n Herbicides –Acclaim Extra –Vantage –Plateau n Timing –Early season –Mid season –Late season

17. Data collection & analysis n 2 years (2002 & 2003) n 2 locations (NC and VA) n RCBD, 4 replications, ANOVA n Percent control (’02 and ’03) n Percent seedhead reduction (‘03) n Percent stand reduction (May ‘04)

18. Timing: Herbicide effect Herbicide NS Timing NS Herbicide NS Timing NS Herbicide 0.0113 Timing NS a ab b

19. Timing effect – Oct 2003 Nontreated Acclaim Extra: May Acclaim Extra: JuneAcclaim Extra: August

20. Herbicide, rate, and frequency n 2 years (NC) n Herbicides –Acclaim Extra –Vantage n Rates - 1/2X, 1X n # Applications –1 application (mid-season) –2 applications (4 wk interval) Non-treated Vantage 1X-2 apps

21. Herbicide, rate, and frequency ANOVA: Year (NS), Herbicide (NS), Rate (P = 0.0133), Frequency (P < 0.0001), Rate*Frequency (P = 0.133)

22. Herbicide, rate, and frequency Nontreated Vantage 1/2X: 1 appVantage 1/2X: 2 app Vantage 1X: 1 appVantage 1X: 2 app Oct 2003

23. Summary n All three selective herbicides were effective at each application timing n Multiple applications were more effective than single applications (whether 1/2X or 1X)

24. Conventional vs. selective Handweed: AugustRoundup Pro: August Mow: August Acclaim Extra: June x2

25. Data collection & analysis n Percent cover: 2002 to 2004 –Mid-summer –Late-summer n Soil cores: 2002 to 2004 –2 per plot (10 x 5 cm) –Identified species –# of individuals n ANOVA (P ≤ 0.05)

26. Selective vs. nonselective 2002 AugustNovember Acclaim Extra Roundup Pro

27. Selective vs. nonselective 2003 JulySeptember Acclaim Extra Roundup Pro

28. Selective vs. nonselective 2004 JuneSeptember Acclaim Extra Roundup Pro

29. End of 3 rd season comparisons nontreated Acclaim ExtraRoundup Pro

30. Japanese stiltgrass cover: Duke Forest NS c a bc bb

31. Herbaceous dicot cover: Duke Forest a b cccc a ab abc bc c

32. Herbaceous dicot cover: Duke Forest – 2002

33. Herbaceous dicot cover: Duke Forest – 2003

34. Herbaceous dicot cover: Duke Forest – 2004

35. Summary n Japanese stiltgrass –All treatments effective control & seed bank reduction n Herbaceous dicots –Greater diversity in selective treatment

36. The future? n What will happen after we control Japanese stiltgrass? n Will re-established plant communities be less susceptible to invasion? n Can we truly exhaust the seed bank?

37. Questions??