Stability, Host Range, and Distribution of Kalanchoe Mosaic Potyvirus in Kalanchoe blossfeldiana. Karen Husted, Senior Scientist, Danish Institute of Plant and Soil Science, DK-2800 Lyngby, Denmark. Karen Bech, Scientist, Department of Plant Pathology and Pest Management, Danish Institute of Plant and Soil Science, DK-2800 Lyngby, Denmark. Plant Dis. 80:211-214. Accepted for publication 20 November 1995. Copyright 1996 The American Phytopathological Society. DOI: 10.1094/PD-80-0211.

The distribution of Kalanchoe mosaic potyvirus (KMV) coat protein in Kalanchoe blossfeldiana was found to be very uneven, both in individual leaves and among leaves from different parts of the plant. Amounts of viral coat protein were highest in well-developed leaves in the middle of the plants and lowest in the older bottom leaves and in the small top leaves just appearing. For routine detection it is recommended to test leaf pairs number 3 to 5 from the top and to include at least two repetitions per plant. There was a high variation among different cultivars of K. blossfeldiana both in expression of symptoms and in coat protein concentration as measured by enzyme-linked immunosorbent assay (ELISA). Expression of symptoms did not correlate with ELISA values either in naturally infected or in mechanically inoculated plants, and many latent infections were noted. Symptoms were most pronounced in spring coinciding with vigorous plant growth. None of 17 other Kalanchoe spp. mechanically inoculated developed symptoms even though half were latently infected. KMV was infective in a 10-5 to 10-6 dilution of plant sap, and remained infectious after heating to 55°C, and after storage in sap at room temperature for 16 days