Occurrence of tomato spotted wilt and cucumber mosaic viruses in field-grown tomato crops and associated weeds in northeastern Spain

The occurrence of cucumber mosaic (CMV) and tomato spotted wilt (TSWV) viruses in the main vegetable producing regions of northeastern Spain was studied during the growing seasons of 1992 and 1993. by sampling in July and September. Both viruses were found widely distributed in field tomato crops and surrounding weeds. Coastal areas were the most affected by both CMV and TSWV, whereas inland TSWV was nearly absent. Higher levels of infection were found in autumn for TSWV in tomato crops and weeds, and for CMV in tomatoes. From the 51 weed species of 19 families collected. 25 species were found infected with CMV and 15 with TSWV. Among them, Convolvulus arvensis. Malva sylvestris , and Sonchus tenerrimus could be of special importance as local reservoirs; commonly associated with tomato crops. they were infected quite frequently with CMV and/or TSWV and being perennial, could maintain the viruses between cropping seasons.