What Do Weeds Think?
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The document discusses the nature of weeds, defining them as plants that are unwanted and competitive. It outlines management strategies for various types of weeds including annuals, biennials, and perennials, emphasizing the importance of understanding their life cycles and reasons for their presence. Additionally, it provides control methods such as cultural, mechanical, and chemical approaches, along with an integrated weed management strategy.
What Do Weeds Think?
- 1. RALPH WHITESIDES UTAH STATE UNIVERSITY PROFESSOR AND EXTENSION WEED SPECIALIST ( E M E R I T U S ) What Do Weeds Think?
- 2. What is a Weed? Plant out of place Any plant growing where it is not desired Any plant someone will pay to remove or kill Any plant other than the crop/plant sown Plants that are competitive, persistent, and pernicious. They interfere with human activities and, as a result, are undesirable. (Ross & Lembi)
- 3. Common Approach What is that plant? How do I kill it?
- 4. Thoughtful Approach What is that plant? Why is it there? Why is it there now? How do I keep it from being there in the future?
- 5. Life Cycles and Plant Families “ACEAE” Annual Winter annual Summer annual Biennial Perennial Simple perennial Creeping perennial
- 6. Plant Families Asteraceae (sunflower) Zygophyllaceae (caltrop) Convolvulaceae (morninglory) Brassicaceae (mustard) Poaceae (grass)
- 7. Specimen Weeds Common dandelion Puncturevine Field bindweed Quackgrass Crabgrass Shepherd’s purse Dyer’s woad
- 11. Management Strategy for Annuals Annuals on the list for today Crabgrass Puncturevine Shepherd’s purse
- 12. Management Strategy for Crabgrass Digitaria sanguinalis Poaceae – native to USA, Caribbean Summer Annual = germinate 55 F Single Large plant = 150,000 seeds – seed survive up to 15 years Objective = prevent seeds
- 14. Large Crabgrass
- 15. Large Crabgrass
- 16. Mower Damage to Turf
- 18. Management Strategy for Puncturevine Tribulus terrestris Caltrop Family Summer Annual – native to Mediterranean Region One large plant in California produced 576,000 fruits. Assuming 2 seeds per segment = 1,152,000 seeds/plant Germinates all season – lives in soil at least 4 years Susceptible to glyphosate, 2,4-D, dicamba Mechanical control = sweep seeds, vacuum seeds, roll old pumpkins, or carpet
- 19. Puncturevine
- 22. Mechanical Control of Puncturevine
- 23. Shepherd’s Purse Management Capsella bursa-pastoris Winter annual mustard Member of mustard family Native of Europe Single plant produces several thousand seeds Remain viable for many years Seeds remain dormant in the dark - mulch
- 25. Shepherd’s Purse Seed Pods and Rosette
- 26. Management Strategy for Biennials Biennial on the list for today Dyer’s Woad
- 27. Dyer’s Woad Isatis tinctoria Native to Central and Western Asia Winter annual, biennial, or short-lived perennial Plants produce 350-500 seeds Seed longevity under field conditions unknown – some evidence for 8-10 years
- 28. Dyer’s Woad in Flower
- 30. Management Strategy for Perennials Perennials on the list for today Common dandelion – simple Field Bindweed – creeping Quackgrass – creeping
- 31. Common Dandelion Taraxacum officinale Native to Eurasia Simple perennial with fleshy taproot Spread by seed and new shoots from roots Dent-de-lion
- 33. Dent-de-lion
- 34. Simple Perennial
- 35. Lilac Bush
- 36. Lilac Bush
- 37. Field Bindweed Convolvulus arvensis Creeping Perennial Native of Europe, North Africa, Asia Reproduces by seed and roots Seed longevity > 50 years
- 41. Quackgrass Agropyron repens (Elymus repens) Creeping perennial Native to Europe and Western Asia Reproduces by seed and rootstock (rhizomes and roots) Seed longevity 2-4 years
- 42. Quackgrass Seed and Leaves
- 44. What are Annuals Thinking? Seed production Not necessary to develop huge root reserve, plan to die after they produce seed anyway Seed dispersal
- 45. What are Biennials Thinking? Rosettes Vernalization Seed Production Short-lived perennial
- 46. What are Perennials Thinking? OK to produce seed, but not necessary Establish significant root reserves Develop brittleness as an ecological advantage Send progeny elsewhere and rebuild root reserve
- 48. Brittleness
- 50. Salt Cedar on the Freeway
- 51. Salt Cedar on the Freeway
- 52. Salt cedar
- 53. What Should Humans be Thinking About Weeds? Stop annuals & biennials from seeding Recognize apical dominance in perennials Understand “Source to Sink” in perennials When using herbicides understand “selective” vs “non-selective”
- 54. Apical Dominance
- 58. Herbicide Selectivity Source to Sink Translocation
- 59. Selective Grass Control in the Landscape
- 60. Selective Grass Control in the Landscape
- 61. Selective Grass Control in the Landscape
- 62. Selective Grass Control in the Landscape Sethoxydim – Poast, Segment, others Fluazifop – Fusilade II Clethodim – Clethodim 2EC
- 63. Lawn Violet
- 64. Lawn Violet
- 65. Vinca major – Big Periwinkle
- 66. Lawn Violet (Viola sororia) and Vinca Triclopyr – Garlon 3A (violets are on the label) Carfentrazone – Quicksilver Triclopyr + clopyralid – Confront
- 67. Pillars of Weed Management, Prevention, Physical, Mechanical, Cultural, Biological, Chemical, IWM
- 68. Methods of Weed Control •Prevention •Physical/Mechanical •Cultural •Biological •Chemical •IWM – Integrated Weed Management
- 69. Weed Prevention •Prevent arrival •Prevent establishment •Prevent Spread
- 70. Preventive Weed Control 1. Clean equipment 2. Irrigation water/canals/ditches 3. Soil 4. Organic Matter/Compost 5. Weed seed/seed quality 6. Spot treat/hand pull/herbicide resistance 7. Neighborhood cooperation
- 73. Lack of weed control on canals and ditches.
- 74. 3. Soil
- 76. Virgin River St. George – Dec 21, 2010
- 79. Temperature 140 F or more
- 80. Estimatedhours requiredto kill 90% of seeds (afterDahlquistet.al., 2007) Temperature (°F) 140 122 115 108 time required to kill 90% of seeds (hours) Annual sowthistle <1.0 2.1 13.3 46.5 Barnyardgrass <1.0 5.4 12.6 unaffected London rocket <1.0 4.0 21.4 83.1 Common purslane 1.3 18.8 unaffected unaffected Black nightshade 2.9 62.0 196.6 340.6 Tumble pigweed 1.1 107.0 268.5 unaffected
- 81. 5. Weed Seed/Seed Quality
- 83. 6. Chemical – Spot treatment/selectivity
- 93. Those who say “Work well done never needs redoing” never weeded a garden
- 94. Summary • Weed defined • Plant Life Cycle • Annual (winter or summer) • Biennial • Perennial (simple or creeping) • Methods of Control – prevention, physical/mechanical, cultural, biological, chemical, IWM • What is that Plant? • Why is it There?
Editor's Notes
- #76: Topsoil near Lagoon in Utah contaminated with weeds