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NFM, Volume 39: 25–34.
Original scientific paper

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Abstract

In Croatia pines are known and valued as pioneer tree species often used for afforestation of degraded habitats and are thus of a great ecological value, especially Austrian pine in Mediterranean karst area and often also the Scots pine in continental parts of the country. At the same time, these tree species are susceptible hosts for various fungal pathogens, one of them being Dothistroma spp., causative agent of red band needle blight. In this research symptomatic needles were collected from Austrian and Scots pine in autumn (September and October) 2015 and spring (May) 2016 in forest plantations at two localities, one maritime (Novaki Pazinski, forest office Pazin area) and one continental (park forest Borik, forest office Đurđevac area). Needles from each pine species, sampling area and sampling period were analysed for the number of present Dothistroma spp. fruiting bodies and their maturity. Occurrence of other fungi was also determined on the same needles. Results revealed statistically significant difference in number of fruiting bodies in all maturity stages (immature, half-developed, mature, empty) on Austrian pine needles in maritime location (Novaki Pazinski) between samples collected in September 2015 and ones collected in May 2016, with a total of 1951 fruiting bodies detected in spring and only 22 in autumn on the sample of 99 and 100 needles, respectively. As for the Scots pine at continental location (Borik), results showed that immature fruiting bodies were statistically more numerous in October 2015, whereas mature and empty ones were statistically more numerous in May 2016, with total numbers of fruiting bodies being similar, that is, without statistically significant difference (541 in autumn, 414 in spring). Given data are in accordance with generally reported pathogen biology from literature and previous research, and the difference between two locations is most probably the result of somewhat later sampling period for Scots pine in Đurđevac forestry office area, but also of different climatic conditions characteristic for each location and difference in susceptibility of researched hosts. This was also confirmed by comparison of acervuli number present on needles of Austrian and Scots pine from the same location (Borik) and collected in the same period (May 2016), which showed that half-developed and mature acervuli containing partially or fully developed infective conidia were statistically more numerous on Austrian pine. Other detected fungi were present on a small number of analysed needles (8 %), Lophodermium pinastri and Cyclaneusma sp. on both pine species, and Sphaeropsis sapinea and Truncatella hartigii only on Austrian pine.

Keywords: Dothistroma, acervuli, fruiting bodies maturity, Austrian pine, Scots pine, forest plantations