Leśne Prace Badawcze / Forest Research Papers June 2015, Vol. 76 (2): 191–206 DOI: 10.1515/frp-2015-0019 Available online: www.lesne-prace-badawcze.pl REVIEW ARTICLE Received: 5.12.2013, reviewed: 27.03.2014, accepted: 31.07.2014. © 2015 A. Okorski et al. e-ISSN 2082-8926 Current possibilities and prospects of using fungicides in forestry Adam Okorski 1 *, Agnieszka Pszczółkowska 1 , Tomasz Oszako 2 , Justyna A. Nowakowska 3 1 University of Warmia and Mazury in Olsztyn, Dept. of Diagnostics and Pathophysiology of Plants, Pl. Łódzki 5, 10–727 Olsztyn, Poland; 2 Forest Research Institute, Forest Protection Deptartment, Sękocin Stary, ul. Braci Leśnej 3, 05–090 Raszyn, Poland; 3 Forest Research Institute, Laboratory of Molecular Biology, Sękocin Stary, ul. Braci Leśnej 3, 05–090 Raszyn, Poland *Tel. +48 89 5233511, e-mail: adam.okorski@uwm.edu.pl Abstract. The possibility of using chemicals in European forestry is extremely limited due to the binding legal regulations and specifc conditions concerning the market of plant protection products. This is refected in the limited availability of active fungicides in forestry. Due to this limitation, practitioners using fungicides in forest nurseries and forest cultivation must have substantial knowledge of the biology of pathogens to ensure satisfactorily effective protection. The work presented here provides an overview of the currently recommended fungicides in Polish forestry as well as the mechanisms of interaction between the active substances and the pathogen, the plant and mycorrhizal fungi. The risk of fungi- cide resistance, which has been insuffciently explored in the context of forest pathogens, is also discussed in this paper. Keywords: forest protection, forest nurseries, fungicide resistance, fungicides mode of action 1. Introduction Integrated protection of forest nurseries came into force by way of legal dispositions of the European Commission (Directive No 2009/128/WE dated on October 21, 2009 and the Regulation No 546/2011 dated on June 10, 2011 concer- ning the integrated plant protection against pests). The idea behind it consisted in the complementary usage of nume- rous (or all) possible plant protection methods. Therefore, the Ministry of Agriculture and Rural Development prepa- red a project of a national plan of action for the limitation of risk related to the use of plant protection chemicals for 2013–2017. Unfortunately, due to costly assessment proces- ses concerning the infuence of respective active substances on the environments (amounting to several millions of Euro) some of the producers resigned from taking the effort to re- gister the plant protection chemicals. In result, the supply of the preparations available on the market decreased signif- cantly. The forest practitioners have half the number of plant protection chemicals at their disposal. So what should be done in the event of limited choice of fungicides? This re- view lists preparations currently admitted to use in forestry and shows the mechanisms of their functioning and current and potential effectiveness on different groups of pathogenic organisms, along with the simultaneous analysis of the pos- sibility of fungicide resistance (organisms present in Poland and closely related to them). 2. Current state of chemical protection in forestry The specifcity of forest nursery cultivation causes that the risk of the existence of fungal pathogens menace for the sa- plings is considerably high, and at the same time, due to the minute range of cultivated plant species the accumulation of pathogenic factors may occur, while the limited stock of plant protection chemicals recommended for the use in forest nur- series brings about the situation where the fungicide treatment often proves ineffective. Currently the forest nursery uses a few fungicidally active compounds, (Fig. 1) which constitute an enormous challenge both for the practitioners and resear- ches whose task consists in the optimization of plant protec- tion. This state of affairs is directly related to the policy of chemical companies, for whom high costs of the registration of fungicides in cultivations of small areas (such as nursery production) constitute a barrier blocking the introduction of in- novative fungicides. Therefore nursery production most often