Transmission of Pelargonium Flower Break Virus (PFBV) in Irrigation Systems and by Thrips. G. KRCZAL, Landesanstalt fur Pflanzenbau und Pflanzenschutz, Mainz, Germany. J. ALBOUY, I. DAMY, C. KUSIAK, and J. M. DEOGRATIAS, Station de Pathologie Vegetale; J. P. MOREAU, Station de Zoologie, INRA (Institut Nationale de la Recherche Agronomique) Versailles, France; and B. BERKELMANN and W. WOHANKA, Forschungsanstalt Geisenheim, Germany. Plant Dis. 79:163-166. Accepted for publication 22 June 1994. Copyright 1995 The American Phytopathological Society. DOI: 10.1094/PD-79-0163.

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 solutions used with PFBV-infected Pelargonium plants 2 wk after starting the culture. In previously uninfected plants, PFBV was detected after 6 wk in culture. By 14 wk, 100% of the plants were infected. When the nutrient solution was decontaminated by means of slow sand filtration, infection of the plants was delayed by 6 wk, and the final percentage of infected plants was reduced to about one third. PFBV was also transmitted by thrips (Frankliniella occidenlalis), and .10% of plants became infected when thrips were caged with PFBV-infected and healthy Pelargonium plants. When pollen from PFBV-infected plants was dusted onto the leaves of plants that were then caged with about 15 F. occidenlalis per plant, about 40% of the Pelargonium plants became infected. No infection occurred with thrips or pollen alone. Pollination and inoculation by rubbing with pollen from PFBV-infected Pelargonium plants also resulted in virus-infected plants.