What to Do About Weeds

1. What to Do About Weeds Developed by: Susan Donaldson University of Nevada Cooperative Extension UNCE, Reno, NV

2. Topics to be covered • What is a weed? • Why worry about weeds in pastures and landscapes? • How weeds are regulated • Weed biology • Factors that lead to plant invasion • Preventing invasion and spread of weeds • Identifying weeds • Control - mechanical, cultural, biological, and chemical • Common weeds in your area

3. What’s a weed?

4. USDA-ARS

5. MSU Extension Service

6. 1900: Arrived from Europe Wow! The wide open continent of North America offers great potential for advancement. 1970 I think I’ll settle down here. This looks like a good place to raise a family. Way to go! 2000 Today: America, The Land of Opportunity UNCE, Reno, NV

7. Invasive Weed Spread UNCE, Reno, NV

8. Weed impacts • Decreased grazing potential • Economic losses from refusals of hay shipments • Decreased crop yields • Cost of control UNCE, Reno, NV

9. Weed impacts • Decreased property values • Loss of wildlife and fish habitat • Impairment of wetland functions • Increased erosion • Toxicity UNCE, Reno, NV

10. Weed impacts • Increased habitat for vermin such as mosquitoes • Impacts to recreation • Altered fire regimes • Lowering of water table depths • Etc…. www.firepix.net

11. How are weeds regulated, and what are your legal responsibilities?

12. The three D’s of noxious weeds • Damaging to the economy or environment • Difficult to control • Tend to Dominate a site

13. How weeds grow

14. Dicot Monocot Broadleaf Grass

15. Classification of plants • Monocots: grasses with one seed leaf, parallel veins and fibrous roots • Dicots: two true leaves; broad leaves have net-like veins; coarse tap root

16. Plant life cycles • Annual • One season for all stages of development • Produce foliage, flower seeds, then die Yellow starthistle tncweeds.ucdavis.edu

17. Plant life cycles • Summer annuals • Live from spring to fall • Examples are foxtail, pigweed • Winter annuals • Germinate in fall and winter • Examples are cheatgrass and mustard

18. Plant life cycles • Biennials • Require two seasons for completion of life cycle • First year: develop roots and low-growing leaves • Second year: flowers, sets seed and matures • Examples are mullein and musk thistle www.arapcsuext.org Musk thistle

19. Plant life cycles • Perennials • Live more than two years • Will produce foliage, seed, and reach maturity year after year • Examples are perennial pepperweed and Canada thistle www.turf.uiuc.edu Dandelion

20. Reproduction • Annuals and biennials • seed • seed bank

21. Reproduction • Perennials • Simple - reproduce by seed and pieces of root, such as dandelions • Bulbous - produce seed, bulblets and bulbs, such as wild onion • Creeping - produce seeds, rhizomes (underground stems), stolons (above ground stems), or creeping roots

22. Creeping roots of perennial pepperweed UNCE, Reno, NV

23. Identifying weeds • Don’t be afraid to ask for help!

24. Plant parts for grass identification NRCS, Bozeman, MT

25. Plant parts for broadleaf identification NRCS, Bozeman, MT

26. How do weeds ensure their success? • They take advantage of the characteristics of sites, including: • exposed or disturbed soil (grading road shoulders) • turfgrass, range, pasture or groundcover that is weakened by disease, pests, or poor management • Places where a desired species is not well-adapted to its environment

27. How do weeds ensure their success? • They are very competitive • grow well in spite of interference from other plants

28. How do weeds ensure their success? • They are persistent • will return year after year • reproduce vigorously • spread seeds effectively

29. How do weeds ensure their success? • They are harmful • can alter the site they grow in by accumulating salts, changing water table depths, increasing erosion, increasing wildfire frequency, etc.

30. How do weeds spread? • Natural means • wind • water • animals nmaa-ryder.si.edu pi.cdfa.ca.gov/weedinfo

31. How do weeds spread? • Mechanical means: • irrigation • roadside shoulder work • construction/fill dirt • vehicles • tillage • contaminated seed or feed • livestock management UNCE, Reno, NV

32. Practice Integrated Weed Management (IWM) USE: • Prevention • Eradication • Mechanical controls • Cultural controls • Biological controls • Chemical controls

33. Building a weed management plan CONSIDER THE: • Identity of the weed • Biology of the weed • Extent of the problem • Environmental conditions of the site • Ultimate objectives for the site • Most economical solution

34. Preventing invasion and spread of weeds • Plant clean, weed-free seed • Avoid spreading weed seeds with manure • Sanitize tillage and harvest equipment prior to them from one field to another • Plant and maintain desirable plant species • Consider crop rotation to slow weed spread

35. Preventing invasion and spread of weeds • Minimize soil disturbance and bare ground • Don’t overgraze pastures • Apply the appropriate amount of water • Avoid driving in weed infested areas

36. Preventing invasion and spread of weeds • Don’t transport flowering plants that you cannot identify • Pull small patches before seed is formed • Carefully remove weeds that have flowered • Report new infestations

37. Reporting • State Weed Specialist, Department of Agriculture • Your local Cooperative Extension office

38. Eradication • Removal of all weeds of a given species from an area so they will not recur unless reintroduced • Must deplete seed bank of viable weed seeds by controlling all seedlings • Only feasible for small, new invasions • Must revegetate the area

39. Mechanical control • Cultivation • Hoeing • Bulldozing • Burning • Hand pulling • Mowing UNCE, Reno, NV CSUCE

40. Mechanical control • Mulching • Solarizing (use clear plastic for maximum affect) • Repeated tillage can help reduce seed populations UNCE, Reno, NV

41. Cultural control • Cultural control involves using land management tools that make it difficult for weeds to be successful • Shading • Water and nutrient management • Correct seeding rates

42. Biological control • Biological control is the use of one organism to suppress another • Can reduce pesticide use • Agents can be free or purchased • Can effectively and economically suppress pests • Does not eradicate a weed USDA-ARS

43. Biological control • Characteristics of successful biocontrol agents: • Prolific • Thrive and become widespread in all habitats and climates that the pest weed occupies. • Good colonizers of new areas. Milfoil weevil (Euhrychiopsis lecontei) on Eurasian watermilfoil

44. Chemical control UNCE, Reno, NV CSUCE

45. What to consider before using chemicals • Have you positively identified the weeds? • Do you know their life cycle? • Have you selected a product that will be effective on your weeds? • Have you read the label carefully? • Is the product labeled for use at the site? • Are you following the label directions? • When is the best time to apply the chemical?

46. What to consider before using chemicals • Are you applying the appropriate amount by the best method? • Do you understand all necessary safety requirements, and have you followed them carefully? (gloves, hat, eye protection, long sleeves, long pants, shoes, etc.) • Have you kept mixing and storage areas away from waterbodies and wells?

47. Chemical control • Nonselective • Will kill or damage any plants it touches ALWAYS READ AND FOLLOW THE LABEL DIRECTIONS!

48. Chemical control • Examples of nonselective herbicides • glyphosate (Roundup ) • imazapyr (Arsenal ; use pre- or post-emergence; long residual in soil) ALWAYS READ AND FOLLOW THE LABEL DIRECTIONS!

49. Chemical control • Selective • Kills only a specific plant or type of plant • Most common types are broadleaf vs. grass NRCS ALWAYS READ AND FOLLOW THE LABEL DIRECTIONS!

50. Chemical control • Examples of selective herbicides • 2,4-D (Weed-b-Gone , Weedar 64 ) • picloram (Tordon , retricted use, persistent) • chlorsulfuron (Telar , Glean ; may be used pre-emergence • triclopyr (Garlon 3A ) ALWAYS READ AND FOLLOW THE LABEL DIRECTIONS!