Broadleaf Weed Management in Wildflower Plantings. Leon S. Warren Jr. March 5, 2002 North Carolina State University

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1 Broadleaf Weed Management in Wildflower Plantings Leon S. Warren Jr. March 5, 2002 North Carolina State University

2 3500 roadside acres in North Carolina planted in wildflowers

3 Why Bother?

4 Which do you prefer?

5

6 Methyl Bromide Use rate up to 400 lb/acre Bromine ion reacts with ozone resulting in depletion EPA ban on manufacture and use by 2005 FQPA of 1996 may limit availability of replacement herbicides

7 Methyl Bromide Production Schedule % reduction % reduction % reduction 2005 complete ban

8 Soil Fumigant Alternatives to Methyl Bromide Telone II: excellent on nematodes and insects poor weed control used with Chloropicrin or Vapam Chloropicrin: poor weed control used with Methyl Bromide or Telone II J. Bryan Unruh: University of Florida

9 Soil Fumigant Alternatives to Methyl Bromide (Cont d) Vapam / Metam, Basamid Environmental factors such as soil temperature and moisture affect chemical conversion to biocidal ingredients (inconsistent control) J. Bryan Unruh: University of Florida

10 Soil Fumigant Alternatives to Methyl Bromide (Cont d) Iodomethane (Methyl Iodide) Equal to or greater than Methyl Bromide for control of weeds, nematodes, fungi Degrades quickly in presence of light Not currently registered J. Bryan Unruh: University of Florida

11 Why all the fuss about Methyl Bromide? Wildflowers are noncompetitive

12 Methyl Bromide (Unrealistic Expectations) Plant any wildflower species desired Control EVERY weed species that may be present

13 Methyl Bromide (Reality) Does not control all weeds (vetch and clover species and many other hard-coated seeds germinate quite readily in fumigated beds) Does not prevent weeds from reentering treated areas (wind, water, birds, mammals)

14 2001 Weed Survey NCDOT Eastern Divisions Vetch species Curly dock Carolina geranium Horseweed Dogfennel Common ragweed Common lambsquarter Pigweed species White clover Shepherdspurse Virginia pepperweed Hop clover Morningglory species Smartweed species Prickly sida Camphorweed

15 2001 Weed Survey NCDOT Western Divisions Vetch species Curly dock Carolina geranium Horseweed Dogfennel Common ragweed Common lambsquarter Pigweed species Wild lettuce Little barley Johnsongrass Pokeweed Mullein Serecea lespedeza

16 Methyl Bromide Alternatives (Supplements) Various PRE herbicides for seeding or established wildflowers (Bill Johnson, Dec-Jan TCNC article) February Roundup (POST) February Roundup + Treflan tankmix (POST/ PRE) Pennant + Treflan (PPI)

17 NCSU Cooperation 1996 Incorporated various herbicides before fall seedings POST herbicides in spring on seedling or rosette overwintered wildflowers PRE and POST herbicides on established roadside wildflower beds

18 NCSU Cooperation (Cont d) Present : Greenhouse trials on 29 wildflower species for tolerance to 31 PPI, PRE and / or POST herbicides (3 runs) : Field trials similar to greenhouse trials (Established and )

19 NCSU Cooperation (Cont d) Present : POST weed control data on 23 species PPI / PRE weed data on 14 species (greenhouse and / or field trials)

20 Life Before EPA Ruling Before: I ve got zillions of weeds and dozens of wildflower species to choose from No problem: I ll use methyl bromide

21 Life After EPA Ruling After: I ve got zillions of weeds, and dozens of wildflower species, AND DOZENS OF HERBICIDES to choose from PROBLEM???

22 Life After EPA Ruling What weeds do I have? (Are they winter annuals, summer annuals or perennials?) What herbicide will control all my weeds and not injure my wildflowers? Should I apply PPI, PRE or POST to weeds? Should I apply PPI, PRE or POST to flowers?

23 Research Objectives To develop a comprehensive wildflower weed management program without methyl bromide To present information in a practical, userfriendly format that is of value to field personnel

24 End Result (Preliminary) Individual Wildflower Species Tolerant Herbicides (PPI, PRE or POST) Problem weeds controlled

25 Specific Example Black-eyed Susan (Fall seeded: PPI/PRE Options) Eptam Curbit Staple Pennant 3.5 pt 3 pt 0.6 oz 1 qt Morningglory Shepherdspurse Shepherdspurse Geranium Pepperweed Pepperweed White clover Lambsquarter Pigweed Shepherdsp. Pigweed Morningglory Pepperweed Mustard Pigweed

26 Data Collection Guidelines All herbicides displayed wildflower tolerance of 6 or higher (1 to 9 scale) in greenhouse trials and / or were also statistically similar to nontreated field plots while providing 90+% control of the listed troublesome weeds.

27 NCDOT Field Personnel Must be able to identify seedling grass and broadleaf weeds Some treatments slightly injured wildflower foliage but not at unacceptable levels. How much injury is acceptable to you?

28 Bueno pt/acre 45 DAT Pinnacle 0.25 oz/acre 45 DAT

29 Vetch Species, Curly Dock and Carolina Geranium Vetch species listed as a troublesome weed in 12 of 14 NCDOT divisions Curly dock and Carolina geranium listed in 6 and 8 divisions, respectively All germinate in the fall

30 Preemergence Control of Vetch sp., Curly Dock and Carolina Geranium % Control Cotoran 1 qt Sinbar 0.5 lb Surflan 2 qt Velpar 0.66 lb 0 Vetch Curly Dock Carolina Geranium

31 Cotoran Sinbar Surflan Velpar (PRE Applications: Fall seeded) C. Coneflower C. Coneflower C. Coneflower C. Coneflower Blanketflower Blanketflower Blanketflower P. Coneflower P. Coneflower P. Coneflower Bur-marigold Bur-marigold Bur-marigold Nar. Sunflower Nar. Sunflower Nar. Sunflower Scarlet Flax Spur Snapdragon Corn Poppy S. milkweed

32 Postemergence Control of Vetch sp., Curly Dock and Carolina Geranium Sinbar 1.5 lb Velpar 1.33 lb Vetch Curly Dock (Greenhouse) Curly Dock (Fallow) Carolina Geranium % Control

33 Sinbar Velpar (POST Applications: Fall seeded) Ox-eyed Daisy??? Nothing Sinbar negatively affected ox-eyed daisy seedlings in greenhouse and field trials In established roadside trials, ox-eyed daisy displayed acceptable tolerance

34 Ox-eyed Daisy Nontreated April 7, 2000 Ox-eyed Daisy Sinbar 1.5 lb/acre April 7, 2000 (32 DAT)

35 Ox-eyed Daisy Transline + Surf pt % April 7, 2000 (32 DAT) Ox-eyed Daisy Velpar 1.33 lb/acre April 7, 2000 (32 DAT)

36 Common Lambsquarter and Pigweed Species Consistent problems for NCDOT Western Divisions Summer annuals - spring germination

37 Pre Common Lambsquarter and Pigweed Control Curbit, Factor, Pendulum, Plateau (Cosmos and sulphur cosmos) Authority Cotoran Gallery Goal Goal Sinbar Surflan Velpar

38 Pre Weed Control Ratings Lambsquarter % Control: 35 DAT Greenhouse Surflan 100a Sinbar 99a Pendulum 100a Factor 99a Goal XL 100a Curbit 96a Gallery 100a Cotoran 93a Authority 100a Pennant 92a Velpar 99a Check 0d

39 Pre Weed Control Ratings Lambsquarter % Control: 95 DAT Field Surflan 100a Sinbar 100a Pendulum 83ab Factor 68ab Goal XL 53ab Curbit 47ab Gallery 7b Cotoran 100a Authority 100a Pennant 85ab Velpar 97a Check 0b

40 Pre Weed Control Results Factors Affecting Common Lambsquarter Control Lack of rainfall Applied inches rain from to Lamb: Cot - 6 lf and inch tall Indeterminate germination : lambsquarter still germinating

41 Post Common Lambsquarter and Pigweed Control Pinnacle Goal Plateau Authority Peak Cosmos Catchfly Chicory Dames R. Butter. Chicory Snapdrag. Mixed P. G. Daisy G. Daisy Nar. Sun. Lance C. Nar. Sun. Nar. Sun. Bur-Mar. Corn P. C. Cone. Butterfly Bur-Mar. Butterfly Cal. Pop. Scarlet F. Milkweed sp.

42 Post Weed Control Results Lambsquarter % Control: 23 DAT Greenhouse 13 treatments % control (a) Check 0% control (d) Lambsquarter treated at 1-3 inches tall with 6-10 leaves

43 Post Weed Control Results Lambsquarter % Control: 28 DAT Field Velpar Check 94% control (a) 0% control (c) Lambsquarter treated at 1-10 inches tall with leaves on (very dry late mid April through early May)

44 Conclusions Methyl bromide will not be replaced with a single herbicide; but by a comprehensive weed management program More wildflower species options if implementing a PPI/PRE herbicide

45 Conclusions Field personnel must identify weeds for each problem bed to select an effective control program for that bed Environmental factors (rainfall) will greatly influence herbicide efficacy