Physical and Cultural Weed Control Working Group of - European ...

9 th EWRS Workshop on Physical and Cultural Weed Control 93
Samsun, Turkey, 28 – 30 March 2011
Weed control in vegetables – Report from a round table discussion
J. Ascard 1 , F. Fogelberg 2 , D. Hansson 3 and S.-E. Svensson 3
1 Swedish Board of Agriculture, Box 12, SE-230 53 Alnarp, Sweden,
johan.ascard@jordbruksverket.se
2 JTI - Swedish Institute of Agricultural and Environmental Engineering, Box 7033,
SE-750 07 Uppsala, Sweden
3 Swedish University of Agricultural Sciences, Box 104, SE-230 53 Alnarp, Sweden
In our round table discussion we were 33 participants from nine countries. This session discussed
how to proceed in research and extension service to develop competitive physical and cultural weed
control methods in vegetables in order to reduce the need of hand weeding in growing systems with
no or limited use of herbicides.
Before the workshop, the participants were invited to initially present some new ideas and
innovative methods and techniques for weed control in vegetables and other high value row crops.
Introduction – challenges in cultural and physical weed control in vegetable crops
The major weed problems in organic vegetable production, and in production systems with limited
or no use of herbicides, are weeds growing within the crop rows, especially in direct-sown smallseeded
vegetables, such as carrots. The removal of in-row weeds in order to maintain crop yield and
quality is associated with high labour costs. In organic production of carrots, labour requirements of
around 200 man-hours per hectare is common.
Inter-row weeds can usually be controlled rather easily by ordinary row crop cultivation. Various
cultural and physical methods and techniques are available to control in-row weeds, but some of
them are rather expensive compared with herbicides, and they typically do not control enough
weeds.
Cultural techniques include repeated stale seedbeds, delayed sowing, mulching, soil cultivation in
darkness, and transplanting systems. There are also mechanical in-row cultivators e.g. finger
weeder, torsion weeder and weed harrow, and thermal methods such as flame weeding and band
steaming. Combined methods using for example stale seedbed, flame weeding and in-row
cultivation offer promising results, as do advanced systems for robotic in-row weed control in
certain crops with rather large crop plant distance, above 15 cm.
Typically the methods for in-row weed control are most suitable in transplanted crops and large
seeded crops. The big challenge remains to control in-row weeds in early established direct-sown
small-seeded vegetables.
Several methods and techniques have been developed and evaluated in research, but relatively few
are widely used in practice. Some techniques are expensive and have relatively low capacity, while
others have limited use in certain high value crops. Some methods have low selectivity and
adjustment and timing of treatment may be difficult. Many farms are relatively small and diversified
and cannot invest in expensive and specialised machinery, so they opt for tools that can be used in
many different crops. There is a need to develop economical and robust methods that can reduce