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Weed Management Handbook (0)

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Weed   Management  
Handbook
Summarized by:  Student  X
Introduction
• What is a weed?
•  Disadvantages  and advantages
• Seed  bank
•  Different   ways  to deal with weeds
•  Resistance  of herbicides
What is a weed?
• Older definitions:
-a  plant  not valued for its use or  beauty
-a plant  whose  virtues have yet to be 
discovered
• Modern definitions:
-plants that are  considered  undesirable by 
producers
-unwanted plant which in some way hinders or 
interfers with human  activity . (Crops may at 
some point also be weeds)
Weed disadvantages
• Reduces crop  yield  – weeds and 
crops have to  share  resources  such  
as light, water and nutrients
• Reduces crop  quality  and health – 
increases moisture and  disease  
levels
•  Delay  harvesting –  conservation  
of moisture may 
delay ripening
Beneficial  effects of weeds
• Valuable indicators
• Help against erosion
• Many weeds are used as herbs for 
flavouring
• Some weeds are used for their 
medical properties
Seed bank
• The reservoir of viable seeds found in 
the  soil  or at its surface
• Depends on the intensivity, soil type, 
previous cropping, cultivation and 
herbicide use
• 1000 seeds/m2 in pastures or 
intensively  managed  arable fields
• 80000 seeds/m2 in less intensively 
managed fields
Different ways to deal with weeds
• Herbicide
• Non-chemical
• Integrated weed management
•  Biological   control  of weeds
Herbicides
• ‘’Weedkiller’’
• Pesticides used to  kill  unwanted plants
• Selective herbicides kill specific targets 
while leaving the desired crop unharmed
• Non-selective herbicides kill all plant 
material with whichthey  come  in contact 
(used to clean  waste  ground,  industrial   sites
railways)
• In the US, herbicides account for about 70% 
of all agricultural pesticide use
Herbicide-resistant weeds
• The inferited ability of a weed to survive a 
rate  of herbicide, which would normally 
result in effective control
• This happens trough evolutionary  process
whereby a population changes from being 
susceptible to being resistant-
• Happens when the  same  herbicide has been 
used over a period of  years
• Resistance can be  passed  from one 
generation to the next
Prevention of resistance
Cultural  control methods
• Cultivation- incession  tillage  can  bury  
seeds to a depth from which 
seedlings of most weeds are unlikely 
to  emerge  (5cm or deeper)
• Crop  rotation  – many annual weeds 
are strongly associated with specific 
crops
Prevention of resistance
Herbicidal control methods
•  Alternative  herbicides – likely to have 
effect  on resistant populations
• Mixtures and sequences – use two or 
more herbicides which have different 
modes of  actions
• Herbicide rotations – rotation of 
herbicides from different chemical 
groups should  reduce  selection for 
resistance
Herbicide –  tolerant  crops
• Next revolutionary breakthrough in 
weed control
• Has its upsides and downsides
Herbicide-tolerant crops
Advantages
•  Improved  yield through  good  weed 
control
• Improved quality through removal of 
weeds
• Improved unit  cost  of production
• The possibility to use low-tilage 
systems
Herbicide-tolerant crops
Disadvantages
•  Danger  of cross-pollination
• Potential for  developing  herbicide-
resistant weeds
Non-chemical weed 
management
• Crop rotation – creates an unstable 
environment for annual weeds
• Crop establishment – when crops 
emerge first, it gives a competitive 
advantage  over weeds that emerge 
later
•  Mechanical  weed management – 
Removing by  hand  or using  tools  
such as mowers and trimmers
Conclusion
•  There  are many ways to  fight  weeds, 
but the  best  way to get rid of weeds 
is to use herbicides.  Still  they must 
be used smartly, so your weeds don’t 
get resistant to herbicides.
Thank you for  listening !
References
• Robert E.L. Naylon. (2002). Weed 
management handbook. Blackwell 
Science

Document Outline

  • Slide 1
  • Introduction
  • What is a weed?
  • Weed disadvantages
  • Beneficial effects of weeds
  • Seed bank
  • Different ways to deal with weeds
  • Herbicides
  • Herbicide-resistant weeds
  • Prevention of resistance Cultural control methods
  • Prevention of resistance Herbicidal control methods
  • Herbicide – tolerant crops
  • Herbicide-tolerant crops Advantages
  • Herbicide-tolerant crops Disadvantages
  • Non-chemical weed management
  • Conclusion
  • Thank you for listening!
  • References
Vasakule Paremale
Weed Management Handbook #1 Weed Management Handbook #2 Weed Management Handbook #3 Weed Management Handbook #4 Weed Management Handbook #5 Weed Management Handbook #6 Weed Management Handbook #7 Weed Management Handbook #8 Weed Management Handbook #9 Weed Management Handbook #10 Weed Management Handbook #11 Weed Management Handbook #12 Weed Management Handbook #13 Weed Management Handbook #14 Weed Management Handbook #15 Weed Management Handbook #16 Weed Management Handbook #17 Weed Management Handbook #18
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