Diapositive 1

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Grass weed management with IPM Denmark
MODULE C17
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Know your weeds grass weeds
IPM measures for controlling winter annual grass
weeds

• A healthy crop rotation
• Delayed sowing
• Optimal plant density
• Focused soil cultivation, including
• Stale seedbed
• Stubble cultivation
• Ploughing
• Glyphosate before sowing the main crop
• Optimized use of herbicides

IPM means that all plant protection measures have
to be used wisely, otherwise problems like
resistance may develop rapidly
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Importance of the crop rotation
A varied crop rotation will be able prevent grass
weeds
- But remember economic sustainability!
Example of crop rotation suggested by the ENDURE
RA2.6 participants for use under northern
European conditions on a pig producing farm
Alopecurus myosuroides (Black grass)
Apera spica-venti (Loose Silky-bent)
Examples of grass weeds sensitive to a varied
crop rotation
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Importance of the crop rotation
The effect of a varied crop rotation
German experiments
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Sowing date
Early sowing promotes grass weed infestation
Amount of Alopecurus myosuroides in winter wheat
at harvest as a function of the sowing time
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Soil management and grass weed seeds
Combining soil cultivation and herbicides
provides effective control of grass weeds
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Know your weeds important differences
Effective control is achieved through knowledge
of the weed.
Grass weed Flowering(1) Preventive measures
Alopecurus myosuroides Use the general principles, herbicide resistance is developing rapidly
Bromus hordeaceus Avoid stubble cultivation after harvest
Bromus sterilis Harrow light, immediately after harvest
Apera spica-venti Ploughing before sowing will reduce Apera seed bank
Poa trivialis As Apera spica-venti
(1) For climatic conditions similar to the Danish
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Special case Bromus sterilis

• Major reduction of seed bank without using
  herbicides

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Traits of the varieties
Prioritized list for choice of winter cereal
variety

1. Winter hardiness
2. Yield
3. Quality (fodder, grain etc.)
4. Risk of lodging
5. Tolerance towards diseases (varies among species)
6. Competition against weeds

Competition against weeds is not of highest
importance when choosing variety!
Use available information about the yield
potential, disease resistance etc.
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Chemical weed control
Yield increase from chemical weed control
Apera spica-venti
Poa annua Dicot weeds
Lolium sp.
Dicot weeds
Source The Danish National Field Trials 2008
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Chemical weed control

• Choose the right product for the right job!
• Use as little as possible but as much as needed
• Use Decision Support Systems where available,
  e.g. Crop Protection online http//pvo.planteinfo
  .dk/cp/menu/menu.asp?iddemosubjectid1language
  en
• It is a challenge to treat fields individually
  where large scale farming is an important
  parameter, it may e.g. be relevant to think about
  a basic- and advanced treatment
• Divide e.g. the fields in groups according to
  problem
• Consider margin and patch spraying in larger scale

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Prevention of resistance

• Change between products with different modes of
  action
• Avoid using Sulfunylurea-products more than once
  every growing season
• Change between modes of action

This wheat field was in the spring treated with 2
ALS-inhibiting herbicides 110 g Broadway
(florasulampyroxulam) and app. 0.1 l
Iodosulfuron. Lolium perenne is still growing
almost unaffected
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Dispersal of grass weed seeds

• Through machinery
• As the farms grow bigger, the machinery has to
  cover larger areas, and seeds are very likely to
  be spread
• Therefore remember proper hygiene
• This means
• Harvest the infested fields last, whenever
  possible
• Clean machinery when leaving an infested field
• Keep a stable field margin with perennial herbs,
  to avoid weed infestations to spread from here

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Evaluation of the effort

• Before harvest, make a field walk to
• Follow up on the crop protection performed
  through the season
• Plan the strategy for the next season
• Make/update the weed map
• A good result starts with proper planning!
• Weed map