A New Type of Elongated Virus Isolated from Apple Trees Containing the Stem Pitting Agent. H. Koganezawa, Morioka Branch, Fruit Tree Research Station, Shimokuriyagawa, Morioka 020-01, Japan. H. Yanase, Fruit Tree Research Station, Fujimoto, Tsukuba 305, Japan. Plant Dis. 74:610-614. Accepted for publication 16 December 1989. Copyright 1990 The American Phytopathological Society. DOI: 10.1094/PD-74-0610.

A flexuous, filamentous virus was always transmitted by mechanical inoculation to Nicotiana occidentalis from apple trees infected with the agent, causing apple stem pitting disease. A virus with particles 12–15 nm wide and 800 nm long was purified from infected N. occidentalis leaves. The virus particles readily formed end-to-end aggregates. Prominent peaks in particle length distribution of 800, 1,600, 2,400, and 3,200 nm were observed in leaf dip preparations of diseased N. occidentalis subsp. obliqua. The particles contained a single species of RNA of M_r 3.1 × 10⁶ and a major coat protein of M_r 48,000. The virus particles were found in the cytoplasm of mesophyll cells. These data suggest that the virus does not fall into any recognized group of plant viruses.