Christmas Tree Weed Identification and Control

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Christmas Tree Weed Identification and Control

  1. 1. Ed Peachey and Chal Landgren, OSUCHRISTMAS TREE WEEDIDENTIFICATION ANDCONTROL
  2. 2. Outline for today§  3:45-Weed biology and implications for control§  4:00 Weed ID ú  1st step to successful control§  4:15 Herbicides: site of action and efficacy§  4:45 Sprayer calibration§  5:00 Finding weed control info on the web
  3. 3. Weed Biology and Control
  4. 4. Weed Seedbanks(ie seeds living in the soil) Source: vric.ucdavis.edu/issues/vegnotes-tomato/weedseed.gif
  5. 5. Weed seed predation videos
  6. 6. Weed Seed Lifespan in Soil§  Many seeds are shorter lived if on the soil surface ú  Seed predation ú  Desiccation§  Grass weeds 1-3 yr seed survival§  Broadleaved 3-7 yr seed survival
  7. 7. Depth of Emergence§  Typically ½ to ¾ inch§  Occasionally up to 2 inches for large seeds§  Many seeds may germinate but not emerge=fatal germination
  8. 8. Seed dormancySeasonal periodicity of germination
  9. 9. Factors that influence germinationand weed shifts§  Water§  Temperature§  Oxygen ú  Tillage provides oxygen to seeds§  Light ú  Light flash during tillage may cause germination ú  Weeds sense light quality changes caused by§  Proximity to surface §  Moves seed from deep in the soil where it is preserved§ 
  10. 10. Herbicides and weed seeds§  Herbicides generally do not effect weed seeds§  Only seeds that are germinating§  Exception is fumigant metam
  11. 11. Successful use of PreemergenceHerbicides§  Apply before seeds germinate§  Activate§  Protect the barrier
  12. 12. Preemergence HerbicidesRainfall/tillage ½ to 1 inch thick Too much rain/ water/or tillage
  13. 13. Seedbanks are a black box What goes in, might come out
  14. 14. Plant Characteristics + Selection Pressure = Weed Shifts Plant Characteristics Selection pressure or methods of controlGrowth habit 1.  Prevention ú  Perennial ú  Annual 2.  Cultural ú  Biennial 3.  ChemicalPlant family Grass, broadleaf, sedge 4.  MechanicalSeason of emergence or 5.  Biological growthRoot system: tap root vs surface rootsSeed dispersal: short vs long distance
  15. 15. Weed IdentificationFirst step to effective control
  16. 16. Dirty Dozen Horseweed (marestail) 1 Annual Lettuce, prickly 2 broadleaves Sowthistle, annual 3 Northern willow herb 4 Bindweed, field 5 Perennial Thistle, Canada 6 broadleaves Blackberry Biennials Queen Anne’s lace 7 Barnyardgrass 8 Annual Grasses Witchgrass 9 Bentgrass 10Perennial grasses Fescue, rattail 11

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