T. Moykkynen et J. Kontiokari, Spore deposition of Heterobasidion annosum coll. in Picea abies stands of North Karelia, eastern Finland, FOREST PATH, 31(2), 2001, pp. 107-114
Spore deposition of Heterobasidion annosum coll. was measured with the wood
disc method in 20 Norway spruce stands in June, July and September 1999 in
North Karelia, eastern Finland. The study area crossed the presently known
northern boundary of the distribution area of H. annosum (62 degrees 45 'N
). The spore deposition rate decreased northwards and in the northernmost p
arts of the study area, deposition was detected only in September. On avera
ge 71% of the sport deposition consisted of intersterility group P and 29%
oi intersterility group S. The proportion of S-type in the deposition incre
ased northwards. Most of the isolated colonies were homokaryons, bur the pr
oportion of heterokaryons increased with increasing deposition rate.