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Title:

Weed Identification and control

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All annual weeds. Some established perennials may require repeat applications. Species safe: ... A 3-4' layer will smother many weeds ... – PowerPoint PPT presentation

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Title: Weed Identification and control


1
Weed Identification and control
2
Weed identification and control
  • I. History of weed control large scale
    agriculture to the home gardener
  • II. Weed identification
  • A. Grasses
  • B. Broadleaves
  • III. Weed control
  • A. Herbicides
  • B. Other options
  • IV. Specific examples and questions

3
World population
4
Pesticide regulation
  • Clinton
  • -Must reduce pesticide use by 50 by the year
    2002.
  • -Must have 75 of American farmland managed with
    IPM strategies.

5
The search for alternatives
  • Herbicides constitute 70 of all pesticide use.
  • With current pesticides, we still lose 40 of our
    crops to pests.
  • Result must find alternative and integrated weed
    control strategies.

6
Weed identification
7
Weed control
8
Weeds
  • Since the best way of weeding
  • Is to prevent weeds from seeding,
  • The least procrastination
  • Of any operation
  • To prevent the semination
  • Of noxious vegetation
  • Is a source of tribulation.
  • And this, in truth, a fact is
  • Which gardeners ought to practice,
  • And tillers should remember,
  • From April to December.
  • -New England Farmer, 1829

9
Why control weeds?
  • Weeds harbor diseases and insects
  • Take moisture, nutrients, and light from the crop
  • Reduce quality, crop yield and interfere with
    harvest
  • Aesthetics and allergies
  • Weeds always win!

10
Why weeds always win
  • Prolific seeders
  • Dormancy - wait until conditions are favorable
  • Seed dispersal
  • Genetic diversity
  • Long-term seed viability

11
Keys to good weed control
  • Know your weeds!
  • Timing is critical
  • Short term minimize weed-crop competition
  • Long-term prevent weed seed production

12
Chemical control pros and cons
  • Pros
  • Residual control with preemergent herbicides
  • Decreased labor input (limited hoeing!)
  • Less soil disturbance reduced weed germinations
  • Cons
  • Environmental and human toxicity
  • Expensive - specialized equipment required
  • Potential for drift and carryover

13
Roundup
  • Non-selective
  • Contact herbicide - works only postemergence
  • Translocates through the plant - control symptoms
    may not appear for 2-3 weeks
  • Inhibits amino acid synthesis
  • Symptoms include foliar chlorosis, leaf wilting,
    leaf malformation, and necrosis

14
Roundup
  • Species controlled
  • All annual weeds
  • Some established perennials may require repeat
    applications
  • Species safe
  • None!

15
Treflan
  • Selective herbicide kills some species while not
    injuring others.
  • Preemergence, incorporated
  • Requires moisture to activate herbicide
  • Inhibits root growth by preventing cell wall
    formation
  • Symptoms include enlarged roots, clubbed roots,
    and poor seedling vigor.

16
Treflan
  • Species controlled
  • foxtails, barnyardgrass, purslane, lambsquarters,
    chickweed, pigweed, and field bindweed
  • Labeled for multiple vegetable crops
  • see label for use

17
2,4-D
  • Selectively controls broadleaves
  • Postemergence
  • Drift!
  • Translocates from source to sink
  • Action similar to natural hormone IAA
  • Symptoms include epinasty thickening and
    curvature of stems and petiole

18
2,4-D
  • Species controlled lambsquarter, pigweeds,
    ragweed, velvetleaf, and canada thistle
  • Labeled on multiple vegetable crops
  • see label for use

19
Poast
  • Selectively controls grasses
  • Postemergence
  • Drift!
  • Loss of fatty acid synthesis decreases production
    of chloroplasts
  • Grass growth ceases soon after application
  • Symptoms include loss of vigor, pigment changes,
    and necrosis ( 1-3 weeks )

20
Poast
  • Species controlled barnyardgrass, quackgrass,
    and foxtails
  • Labeled on multiple vegetable crops
  • see label for use

21
Alternatives
  • Hoeing and handweeding
  • Stale seedbed
  • Flaming
  • Interseeding
  • Living and dead mulches

22
Mulches
  • A 3-4 layer will smother many weeds
  • Dead mulches compost, leaves, sawdust, grass
    clippings, straw, wood chips, plastic, newspaper,
    etc.
  • Living mulches clovers, vetches, ryegrass,
    alfalfa, buckwheat, oat.

23
Mulches pros vs. cons
  • Pros
  • 1. Prevent weed germination
  • 2. Keeps soil moist and cool
  • 3. Decomposition releases nutrients
  • Cons
  • 1. Harbors disease, insects, rodents, and slugs
  • 2. Keeps soil moist and cool
  • 3. Many mulches are acidic

24
IPM and home gardener
  • Know your garden
  • Scout for weeds, insects, and diseases
  • Maintain detailed journal of garden
  • past problems
  • varieties
  • locations
  • activities
  • Rotation in garden
  • Have Fun!!
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