Incidence of Cronartium ribicola in Finnish botanical gardens and five-needle pine plantations in northern Finland

Abstract

Cronartium ribicola causes white-pine blister rust and its main hosts are species of Ribes (telial host) and Pinus (aecial host). Between 2007 and 2010, the distribution and abundance of C. ribicola was surveyed in: (1) Ribes spp. in botanical gardens of southern and northern Finland, and (2) Pinus spp. in five-needle pine plantations and Ribes spp. of northern Finland. The fruit-bearing species Ribes nigrum, Ribes rubrum and Ribes uva-crispa have long been cultivated throughout Finland and Ribes alpinum is a common ornamental. C. ribicola occurred on the leaves of 26 of 36 Ribes species/cultivars. The rust produced spores on all domesticated cultivars of R. nigrum in all botanical gardens each year of the study, whereas some Ribes appeared to be resistant in all locations. Rust infections of Ribes became less common further north and the northernmost infection was found in western Lapland. The rust was not detected on Pinus cembra and Pinus peuce in plantations of northern Finland, although individuals of these and Pinus flexilis were infected in the northern botanical garden.