COMPARISON OF BLUESTAIN FUNGI GROWN IN-VITRO AND IN FRESHLY CUT PINE BILLETS

Both moulds and bluestain fungi cause serious economic losses and much research is aimed at finding environmentally and economically accepta ble methods of control. Despite this, there has been little study of t he growth of these fungi in freshly cut wood unaltered by drying or st erilization and which therefore resembles the substratum normally inva ded under natural field conditions. Thus, the growth of six sapstain f ungi was compared at 20 degrees C in freshly cut pine billets and on t hree types of artificial media (MEA, TWA and Pine Sapwood agar). The f ungi comprised Ceratocystis coerulescens, Leptographium wingfieldii, O phiostoma minus, Ophiostoma piceae, Phacidium coniferarum and Sphaerop sis sapinea. The six species varied markedly in their linear growth ra te on agar media. In pine billets, they extended at different rates in longitudinal, radial and tangential directions, showing different pat hogenic ability and patterns of colonization. Some species appeared to be 'xylem preferring' while others colonized the phloem tissue more r eadily. The growth of C. coerulescens in pine billets was very rapid ( 19.4 mm/day) and on average was more than twice as fast as on MEA, sug gesting it was strongly stimulated by living pine tissue. The fungi al so tended to grow more slowly in logs cut between autumn and spring co mpared with those harvested in mid- to late summer.