First confirmed report on Fusarium sporotrichioides on Pinus ponderosa var. jeffreyi in Slovakia

Abstract

During 2014–2015, samples from ten 20–25 years old pine (Pinus ponderosa var. jeffreyi) trees showing wilt symptoms were collected from the Arborétum Mlyňany park. A disease was observed on 20% of the trees. The first symptoms are wilting, stunting, chlorosis, and discolouration of needles, which turned yellow on affected twigs, then red and finally they fell off. Isolations of the pathogen were done from the discoloured tissues of needles (twenty samples from each tree) on Potato Dextrose Agar. Colonies of the fungus (3–4 Petri dishes from each tree) were initially aerial, white or slightly violet, but with age they became red and red pigments were produced in agar. The observed micromorphological characteristics of the fungus, such as presence of simple and proliferating conidiophores with polyphialides, microconidia, macroconidial shape, and chlamydospore presence matched the description of Fusarium sporotrichioides. The identity of the fungus was confirmed by phylogenetic analysis of internal transcribed spacer (ITS) sequences. Sequence comparisons placed the fungus to the species F. sporotrichioides with similarity of 99.6% at the ITS sequence level.