Diapositive%201

1
Invasive weedsthe case study of ragweed control
in France France
MODULE C18
2
Introduction Background

• Ragweed is an invasive weed
• Yield losses in summer cropslike sunflower
• Capacities to develop into non-agricultural
  environments
• Very allergenic

Photos ACTA
3
Identification

• Seed
• Young plants Beware of confusions !
• Adults

Ambrosia artemisifolia
Drawings and Photos ACTA and INRA
4
Biological cycle
Ragweed in Rhône-Alpes (France)
Drawings INRA
5
Dissemination

• Very low dispersal abilities
• Spread by agricultural tools
• Spread by contaminated soils

Drawings and Photos ACTA and INRA
6
Development

• Spring and summer crops
• Intercropping period Cereal, peas and rapeseed
  stubbles
• Fallows poorly maintained
• Abandoned agricultural land
• Roadsides, construction sites

Photos ACTA and CETIOM
Photos ACTA CETIOM
7
Control in spring crops
Hoeing In inter-row
Weeder
Pre-emergence herbicide
Post-emergence herbicide
Pre-emergence herbicide
Not easyin gravels soils
Post-emergence herbicide
Post-emergence herbicide
Pre-emergence herbicide
Post-emergence herbicide
Photos ACTA and CETIOM
8
Control at harvest and in intercropping period

• AT HARVEST
• Harvest the contaminated fields after all the
  others
• Clean the harvester machines
• DURING INTERCROPS
• One intervention before flowering
• To avoid pollen emission
• One intervention before graining
• To avoid the reconstitution of the seed bank
• Cultivation Stubble ploughing
• Non-selective herbicides at low rate

Photos ACTA
9
Control in non-agricultural environment

• Priority to prevention control
• No seeds introduction with contaminated soils
• Vegetalization of road, railway sides,
• Mulches in greenspaces
• Possibilities of curative control
• If ragweed is non dominant
• Practice a high shearing (15 cm)
• Use selective herbicides
• Favour natural vegetalization
• If ragweed is dominant
• Try to eliminate plants with non-selective
  herbicides ora low mowing
• Repeat until raqweed becomenon dominant and then
  favorize vegetalization

Photos ARVALIS ACTA
10
Conclusion

• Use of IPM General principles
• Preventive measures
• Beware to not import seeds from contaminated
  areas or with contaminated implements
• Rapid vegetalization in non agricultural areas
• Preferring non-chemical methods
• Mechanical control is possible in agricultural
  and non-agricultural areas
• Correct choice of pesticide and limitation of
  rate
• Beware of pesticides transfer
• You can reduce the herbicides rate on young
  plants