Kaitera, J. and Tillman-Sutela, E. 2015. Fruiting and Sporulation of Inland Spruce Cone Rust (Chrysomyxa pirolata Wint.) on Bells Wintergreen [Orthilia secunda (L. ) House] in Relation to Environmental Factors in Northern Finland. Baltic Forestry. 21(1):

Fruiting and sporulation of Chrysomyxa pirolata Wint. were investigated on Orthilia secunda[ (L.) House] in northern Finland during 2009–2012. Each year of the study, overwintered leaves of O. secunda bearing undifferentiated fruitbodies, uredinia, telia or basidia were collected on 5–7 weekly occasions during the early summer (May–June) and local rainfall and temperature sum were registered. Uredinia developed consistently but telia varied in abundance among years of the study period. Undifferentiated fruitbodies began developing in early May regardless of weather conditions. Uredinia development rate and sporulation increased along rising temperature and rainfall during the latter half of May. Telia and basidia developed between late May and mid-June, and ruptured between mid- and late May. Intense periods of rainfall (i.e., >10 mm per day) in late May coincided with formation of telia and basidia provided that the temperature sum exceeded 100 d.d. Telia did not develop when cumulative rainfall was

Key words: Chrysomyxa pirolata, fruiting, inland spruce cone rust, Picea abies, sporulation, light microscopy