Weeds and weed management in processing tomato.

The EWRS (European Weed Research Society) Working Group "Weed Management Systems in Vegetables" collected information about weeds and Integrated Weed Management programmes in processing tomatoes. Crops are mostly transplanted and the weed communities are commonly very rich of species (both grasses and broad-leaved weeds) but they are made up by a small group of common species (Echinochloa crus-galli, Amaranthus spp., Chenopodium album, Polygonum spp., Portulaca oleracea and Solanum nigrum) throughout the Mediterranean area. In field-seeded crops and in Northern countries, early-emergence weeds (Alopecurus myosuroides, Avena spp., Lolium spp., and several species of Cruciferae and Compositae) are frequent. S. nigrum (plus S. sarrachoides and S. physalifolium in Spain, and S. eleagnifolium in Israel) is the key weed in all the countries. Paper reports species that are becoming an increasing problem in each country. Among parasitic plants, Orobanche spp. is a problem in Spain, Portugal, Morocco, Italy and Israel while Cuscuta campestris in Spain and Israel. A S. nigrum management system should be based on: 1) chemical control in the previous crops where it is easier; 2) preferring transplanted than direct seeded tomatoes; 3) early soil preparation and chemical control of first emergence fluxes of Solanum before tomato planting; 4) row localisation of residual herbicides at planting integrated by inter-row hoeing and/or by split low-dose treatments with metribuzin+rimsulfuron against S. nigrum at very early growth stage (cotyledons). Some news about chemical weed control and about programmes of integrated control of parasitic weeds are also discussed.