9 th EWRS Workshop on <strong>Physical</strong> <strong>and</strong> <strong>Cultural</strong> <strong>Weed</strong> <strong>Control</strong> 92 Samsun, Turkey, 28 – 30 March 2011 Round table reports
9 th EWRS Workshop on <strong>Physical</strong> <strong>and</strong> <strong>Cultural</strong> <strong>Weed</strong> <strong>Control</strong> 93 Samsun, Turkey, 28 – 30 March 2011 <strong>Weed</strong> control in vegetables – Report from a round table discussion J. Ascard 1 , F. Fogelberg 2 , D. Hansson 3 <strong>and</strong> S.-E. Svensson 3 1 Swedish Board <strong>of</strong> Agriculture, Box 12, SE-230 53 Alnarp, Sweden, johan.ascard@jordbruksverket.se 2 JTI - Swedish Institute <strong>of</strong> Agricultural <strong>and</strong> Environmental Engineering, Box 7033, SE-750 07 Uppsala, Sweden 3 Swedish University <strong>of</strong> 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 <strong>and</strong> extension service to develop competitive physical <strong>and</strong> cultural weed control methods in vegetables in order to reduce the need <strong>of</strong> h<strong>and</strong> weeding in growing systems with no or limited use <strong>of</strong> herbicides. Before the workshop, the participants were invited to initially present some new ideas <strong>and</strong> innovative methods <strong>and</strong> techniques for weed control in vegetables <strong>and</strong> other high value row crops. Introduction – challenges in cultural <strong>and</strong> physical weed control in vegetable crops The major weed problems in organic vegetable production, <strong>and</strong> in production systems with limited or no use <strong>of</strong> herbicides, are weeds growing within the crop rows, especially in direct-sown smallseeded vegetables, such as carrots. The removal <strong>of</strong> in-row weeds in order to maintain crop yield <strong>and</strong> quality is associated with high labour costs. In organic production <strong>of</strong> carrots, labour requirements <strong>of</strong> around 200 man-hours per hectare is common. Inter-row weeds can usually be controlled rather easily by ordinary row crop cultivation. Various cultural <strong>and</strong> physical methods <strong>and</strong> techniques are available to control in-row weeds, but some <strong>of</strong> them are rather expensive compared with herbicides, <strong>and</strong> they typically do not control enough weeds. <strong>Cultural</strong> techniques include repeated stale seedbeds, delayed sowing, mulching, soil cultivation in darkness, <strong>and</strong> transplanting systems. There are also mechanical in-row cultivators e.g. finger weeder, torsion weeder <strong>and</strong> weed harrow, <strong>and</strong> thermal methods such as flame weeding <strong>and</strong> b<strong>and</strong> steaming. Combined methods using for example stale seedbed, flame weeding <strong>and</strong> in-row cultivation <strong>of</strong>fer 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 <strong>and</strong> large seeded crops. The big challenge remains to control in-row weeds in early established direct-sown small-seeded vegetables. Several methods <strong>and</strong> techniques have been developed <strong>and</strong> evaluated in research, but relatively few are widely used in practice. Some techniques are expensive <strong>and</strong> have relatively low capacity, while others have limited use in certain high value crops. Some methods have low selectivity <strong>and</strong> adjustment <strong>and</strong> timing <strong>of</strong> treatment may be difficult. Many farms are relatively small <strong>and</strong> diversified <strong>and</strong> cannot invest in expensive <strong>and</strong> specialised machinery, so they opt for tools that can be used in many different crops. There is a need to develop economical <strong>and</strong> robust methods that can reduce