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Weed Management in Vegetables

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Potatoes (NY)- Katahdin is less competitive than Norchip. Tomatoes (NY)- Supersonic gave ... Scout in a random fashion to detect weeds. weeds grow in patches ... – PowerPoint PPT presentation

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Title: Weed Management in Vegetables


1
Weed Management in Vegetables
  • David Monks
  • Dept. of Horticultural Science

2
Weeds cause
  • Reduce yields - yields can go to 0.
  • Reduce quality - nutsedge growing in tubers
  • Contaminants - cocklebur in greens
  • Cover for rodents
  • Interfers with harvest
  • Hosts for diseases (ie maize dwarf mosaic virus)
  • Hosts for insects

3
Broadleaf Weeds
  • Pigweed- Palmer amaranth, smooth pigweed
  • Common lambsquarters
  • Morningglory
  • Cocklebur
  • Smartweed
  • C. Ragweed

4
Grass Weeds
  • Common crabgrass
  • Goosegrass
  • Broadleaf signalgrass
  • Fall panicum
  • Barnyardgrass
  • Annual bluegrass

5
Weeds
  • Summer crops
  • summer annual weeds North Carolina
  • winter annual weeds Mountains and Piedmont North
    Carolina
  • Winter crops
  • winter annual weeds North Carolina
  • summer annual weeds Eastern North Carolina

6
Weed Management in Vegetables
  • Cultural practices
  • Crop competition, weed-free transplants, plastic,
    rotation
  • Cultivation
  • Herbicides

7
Weed Management Strategies
  • Kill all weeds prior to planting
  • non selective chemical
  • tillage
  • Apply available broadleaf and grass herbicides
  • Monitor each field for weeds to detect changes in
    weed spectrums ie sicklepod

8
Weed Management Strategies
  • Implement remedial control measures
  • cultivation
  • herbicide
  • Prevent seed production

9
Cultural Practices
  • Healthy vigorous crop - suppresses weeds
  • Irrigation
  • Full stands
  • Proper fertilizer
  • Crop competition - vegetables are weak
    competitors
  • peppers- 12 cocklebur/40 ft reduced yield 67
  • tomato- 4 redroot/ 40 ft reduced yield 30
  • squash critical weed free period- 3 to 4 weeks

10
Cultural Practices
  • Growth habit of vegetable crops affect
    competition
  • vine crops- cucurbits, sweetpotatoes, pumpkin
    provide shade later in season
  • upright crops solanaceous crops (tomato,
    eggplant), pod crops (okra)- do not shade soil
    and weeds quickly

11
Growth Habit contd
  • Pickling cucumbers require 12 to 36 days of
    weed-free maintenance to prevent yield reductions
  • Transplanted tomatoes and pepper require 4 to 5
    weeks of weed-free maintenance

12
Cultivars and Competition
  • Potatoes (NY)- Katahdin is less competitive than
    Norchip
  • Tomatoes (NY)- Supersonic gave almost complete
    pigweed control compared to New Yorker

13
Cultural Practices
  • Rows vs broadcast
  • broadcast
  • short seasoned leafy crops
  • weeds greatly impact these crops
  • rows
  • longer season
  • crops have time to recover from weed competition

14
Postemergence Weed control
  • Herbicides
  • Tillage
  • average of 2 to 3 cultivations
  • 1 to 2 hand weedings

15
Scout for Weeds
  • At least 1 to 2 times per week
  • Palmer amaranth grows 1 to 2.5 inches per day
  • Scout in a random fashion to detect weeds
  • weeds grow in patches
  • Scout noncrop land for new weeds
  • sicklepod

16
Tillage
  • Preplant tillage- deep vs shallow tillage vs no
    tillage
  • Shallow tillage after planting prior to crop
    emergence
  • Precision cultivation soon after crop emergence

17
Cultivation Timing
  • Cultivation after crop was established
  • dependant on weed and crop size
  • cultivate when weed are small ie prior to tiller
    initiation of tillers (grasses)
  • shallow
  • less than 2 inches deep
  • deeper results in crop root damage and movement
    of weed seeds to near soil surface
  • weather can affect implementation

18
Hand Removal
  • Hand remove when less than 2 inches tall
  • weeds larger than 2 inches have extensive root
    development
  • weeds can be hoed, pulled or clipped depending on
    their stage of development

19
Herbicides
  • Preplant herbicide
  • glyphosate or paraquat- less than 10 of acreage
    receive a preplant herbicide
  • Preemergence herbicide
  • approximately 60 of acreage of most vegetables
    receive a preemergence herbicide
  • must be activated within a few days of
    application
  • grass broadleaf herbicide

20
Herbicides contd
  • Postemergence herbicide
  • less than 25 of acreage receives a postemergence
    herbicide
  • at least 60 to 80 of soybean acreage receives a
    postemergence herbicide
  • herbicide resistant vegetable crops
  • lettuce
  • potatoes
  • sweet corn

21
Herbicide contd
  • Postemergence herbicides must be timely
  • weeds must be small
  • weeds must be actively growing
  • very safe to crop

22
Prevent Weed Seed Production
  • Prevent weeds from producing seeds
  • weeds are heavy seed producers
  • seeds last for many years

23
Weed Seed
  • Duval buried 107 weed species 8, 22 and 42 inches
    deep.
  • 1 year 71 species germinated
  • 6 years 68 species germinated
  • 10 years 68 species germinated
  • 20 years 57 species germinated
  • 30 years 36 species germinated

24
Weed Seed
  • Barnyardgrass 7,160 seeds/plant
  • Curly dock 29,500
  • C. lambsquarters 72,450
  • R. pigweed 117,400
  • C. Purslane 52,300
  • C. ragweed 2,380
  • P. Smartweed 3,140
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