Retrospective Analysis of Lophodermium seditiosum Epidemics in Estonia

Abstract

The needle trace method (NTM), created and developed by the Finnish forest pathologists prof. T. Kurkela, dr. R. Jalkanen and T. Aalto during the last decade of the XX century, has been already used by several researchers of different countries for retrospective analysis of needle diseases (Hypodermella sulcigena, by R. Jalkanen et al. in Finland) or herbivorous insect pests of Scots pine (Diprion pini, by T. Kurkela et al. in Finland; Bupalus piniaria, by H. Armour et al. in Scotland), but as well of pests of Sitka spruce (Gilpinia hercyniae, by D.T. Williams et al. in England). Scots pine in forest nurseries and young plantations of Estonia is often but irregularly suffering from the epidemics of the needle cast fungus Lophodermium seditiosum. Current environmental regulations exclude from the regulatory (control) measures all the others except of well-argued prophylactic systems, built up on reliable prognoses. The last is inconceivable without the availability of a reliable, as well, and longlasting retrospective time-series of L. seditiosum epidemics, which, as it is known from the last half of the XX century, are occupying large forest areas, usually not least than a half of (the small) Estonia. An appropriate time-series would be useful, as well, for the more basic understanding of the accelerated mortality processes during the stand formation in early pole-age Scots pine plantations. Methodological principles of the use of NTM in an appropriate investigation together with the preliminary results of our research work, looking back for more than a century, are introduced and discussed in this investigation.