Citrange Stunt Virus Associated with Decline of Shamouti on Swingle Citrumelo Rootstock in South Africa. L. J. Marais, Outspan Citrus Centre, Nelspruit 1200, South Africa. R. F. Lee, University of Florida, IFAS, CREC, Lake Alfred 33850. Plant Dis. 70:892. Accepted for publication 16 April 1986 . Copyright 1986 The American Phytopathological Society. DOI: 10.1094/PD-70-892.

Citrange stunt virus (CSV) was found in Shamouti (Citrus sinensis (L.) Osb.) trees that had originated from certain budwood sources in Swaziland and were growing on Swingle citrumelo (Poncirus trifoliata (L.) Raf. × C. paradisi Macf.) rootstock. These trees declined when 2–4 yr old and showed necrosis and creasing at the bud union. Established field plantings showed that healthy Shamouti trees on Swingle commonly have a crease at the bud union, but this did not seem to be the cause of decline. CSV, identified by indexing on citrus and herbaceous indicators, was found in groves containing declining trees but not in registered Shamouti bud sources. Infected Swingle seedlings, which are good indicator plants for CSV, produced twisted, distorted leaves, distinct ring spots, zigzag stems, and stem lesions. This is the first report of trees declining on Swingle rootstock and containing CSV.