Transcript Weeds and Weed Control

Weeds
Tuesday 27th April 2010
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Weeds and Weed Control
• What makes a weed
• How weeds work – survival and invasion
techniques
• Weed Prevention
• Mulches for weed control
• Weed control and clearance
• Clearing weed-infested ground
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Weeds and Weed Control
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Simply put a weed is an invasive plant,
growing where you don’t want it
Weeds can divided into three main
categories
1. Ephemeral
2. Annual
3. Perennial
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Plants That Can Become weeds
• Plants that are aggressive colonisers
become weeds tend to be
• wild plants
• some garden plants
• while others have been introduced
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Plants That Can Become weeds
Alcamiller molis
Fallopia japonica
Rhododendron ponticum
Fallopia baldschuanica
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Ephemeral Weeds
• Some weeds can complete their life cycle
within five to six weeks
• Weeds such as hairy bittercress (Cardamine
hirsuta) can be described as ephemeral that
is completing a several of life cycles within
one year
• Where the growing and soil conditions a
favourable weeds such as bittercress can
complete many life cycles in one year
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Ephemeral Weeds
Senecio vulgaris Groundsel
Stellaria media Chickweed
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Cardamine Hirsuta Hairy bittercress
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Annual Weeds
• Annual weeds grow, set seed and die in
the space of one year
• Seed is their mechanism for spread and
survival.
• Can be a problem in disturbed soil
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Perennial Weeds
• Perennial weeds survive from year to year
through a range of mechanisms for longterm survival and spread
• Seed produced in huge quantities
• Runners and stolons which grow along/in
the ground producing buds along them
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Perennial Weeds
• Roots e.g.dandelion (Taraxacum officinale)
and rhizomes can re grow after cutting or
dying back
• Bulbs and bulbils that break off easily
when the plant is dug up in the case of
Lesser celandine Ranunculus ficaria
Taraxacum officinale Dandelion
Ranunculus ficaria Lesser celandine
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Invasion Techniques
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Quick turnaround – seed
Reproduction in adverse conditions
Long-term survival of seed
Huge quantities of seed
Regeneration from roots
Rapid smothering growth
Effective seed distribution
Rapid vegetative spread
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Principles of Weed Control
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Know your weeds
Design out a problem
Take time to prepare the ground
Choose methods of weed control that suit
the time and energy you have
• When clearing ground be realistic
• Never leave the soil bare
• Use mulches
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