CHANNEL conference, Budapest, 57 April, 2006

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CHANNEL conference, Budapest, 5-7 April, 2006
Current European weed control methods and
strategies against annual and perennial weeds in
organic farming by Bo Melander Danish
Institute of Agricultural Sciences
(DIAS) Department of Integrated Pest Management
Research Centre Flakkebjerg
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Weed categories

• Perennial weeds
• Cirsium arvense
• Elymus repens
• Rumex spp.
• Tussilago farfara
• Sonchus arvensis
• Taraxacum officinale
• Others

• Annual weeds
• Chenopodium album
• Amaranthus spp.
• Stellaria media
• Polygonum spp.
• Tripleurospermum inodorum
• Sinapis arvensis
• Galeopsis spp.
• Avena fatua
• Others

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Annual weeds / Perennial weeds

• Preventive methods
• Crop rotation
• Primary tillage
• Stale seedbed
• Cover crops
• Soil cultivation in darkness

• Cultural methods
• Nutrient placement
• Competitive varieties
• Seed rate
• Row spacing
• Sowing date

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Direct mechanical methods in small grain cereals
and pulse
Weed harrowing mainly effective against annual
weeds
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Weed harrowing against annual weeds in spring
cereals
Post-emer-gence
Pre-emer-gence
Selective
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Interaction between injection of slurry and weed
harrowing - means of 4 experiments
Relative to control-broadcast
From Rasmussen (2002), Weed Research 42(4)
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Direct mechanical methods in cereals and pulse

• Inter-row hoeing in cereals with an automatic
  steering system some effect against perennials
  e.g. C. arvense

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Typical row crops
Intra-row
Inter-row
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Inter-row cultivation with automatic steering
systems
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Hand weeding intra-row weeds
Time consumption for hand weeding
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Examples of current tools for intra-row weeding
Brush weeding

• Low technology
• Poor selectivity
• No effect against perennials

Finger weeding
Flame weeding
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Transplants

• Good results in
• Cabbage
• Leek and onion
• Celery
• (Lettuce)
• Sugar beets
• Provided that
• Well anchored
• Control prior to transplanting
• Early weeding after transplanting, repeated over
  a 3-5 week period

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European research on high technologies for
selective intra-row weeding

• Camera based
• Bontsema et al. (NL) (1998), Proceedings IFAC
  Workshop, 93-97
• Tillet Marschant (UK) (1998), J. Agric. Engi.
  Res. 69, 169-178
• Blasco et al. (ES) (2002), Biosystems
  Engineering 83(2), 149-157
• Bak Jacobsen (DK) (2004), Biosystems
  Engineering 87(2), 125-136
• Søgaard (DK) (2005), Biosystems Engineering
  91(3), 271-281
• Åstrand (SW) (2005), PhD-thesis, Chalmers
  University, Sweden
• Geo-positioning of crop seeds
• Griepentrog et al. (DK) (2005), Precision
  Agriculture 6, 157-165

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Selective intra-row weeding
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Steaming in narrow bands
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• Prototype II in carrot
• 80-90 weeding effectiveness against annual weeds
  at 800C
• tendency for a higher marketable yield
• fuel consumption lt 400 l ha-1

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Perennial weeds direct methods

• Post harvest tillage
• uprooting
• disintegration
• desiccation
• Fallowing
• Inter-row cultivation
• Hand hoeing

• Post harvest tillage
• disintegration
• Fallowing
• Mowing
• Inter-row cultivation
• Hand pulling

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Effect of grass-clover on Cirsium arvense biomass
in subsequent crops

Adapted from Rasmussen et al. (2005), ISOFAR,
first sci. conf., 227-230
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Traditional E. repens control

• Conflicts with the need to retain nutrients,
  especially N, in the system
• Catch-crops
• Perennial crops
• Autumn-sown crops

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Integrated approach
gt 90 effectiveness

Suppressive catch crop
Silage crop
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Conclusions

• Perennial weeds
• No significant technical innovations for several
  years
• Improved strategies especially against Elymus
  repens and Cirsium arvense
• Lack of research, e.g. on the biology of
  Tussilago farfara
• Annual weeds
• Improved strategies combinations of preventive,
  cultural and mechanical methods
• No significant technical innovations for small
  grain cereals
• Interesting development for row crops emerging
  advanced technologies such as GPS and camera
  based systems

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EWRS - working group Physical and Cultural
Weed Control
European Weed Research Society (EWRS)

• Next meeting 12-14 March 2007 in Germany
• (http//www.ewrs.org/pwc/)