TRANSMISSION OF PELARGONIUM FLOWER BREAK VIRUS (PFBV) IN IRRIGATION SYSTEMS AND BY THRIPS

Pelargonium flower break virus (PFBV) has become an important disease in glasshouses in Western Europe. In studies of the spread of PFBV via recirculating nutrient solutions, PFBV was found in nutrient solution s used with PFBV-infected Pelargonium plants 2 wk after starting the c ulture. In previously uninfected plants, PFBV was detected after 6 wk in culture. By 14 wk, 100% of the plants were infected. When the nutri ent solution was decontaminated by means of slow sand filtration, infe ction of the plants was delayed by 6 wk, and the final percentage of i nfected plants was reduced to about one third. PFBV was also transmitt ed by thrips (Frankliniella occidentalis), and 30% of plants became in fected when thrips were caged with PFBV-infected and healthy Pelargoni um plants. When pollen from PFBV-infected plants was dusted onto the l eaves of plants that were then caged with about 15 F. occidentalis per plant, about 40% of the Pelargonium plants became infected. No infect ion occurred with thrips or pollen alone. Pollination and inoculation by rubbing with pollen from PFBV-infected Pelargonium plants also resu lted in virus-infected plants.