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We investigated the occurrence and pathogenicity of Beauveria spp. (Hypocreales: Cordycipitaceae) in forest soils in Poland, in outbreak areas of cockchafers (Coleoptera: Scarabaeidae): Melolontha melolontha L. and M. hippocastani F. We also examined the occurrence of Beauveria in relation to soil pH. Beauveria spp. isolates were characterised at species and genotype levels using ITS and microsatellite markers. Beauveria spp., which were detected at over 80% of sites, were sensitive to pH, preferring neutral or alkaline soils. This suggests that the acidity of forest soils in Poland can affect their efficacy as biological control agents (BCAs). B. brongniartii (Sacc.) Petch as a pathogen of cockchafers occurred at 41% of sites, but often at densities below the threshold values for infection, and it infected only 1.3% of cockchafer grubs. Our results suggest that B. brongniartii genotype isolated from cockchafers in forest soils can potentially expand the pool of BCAs in this environment.

Background: Renewable energy sources such as biomass are an important aspect of the energy policy of the European Union. As the use of 'full-value wood' for energy purposes has been restricted, short-rotation forestry may be an alternative source of woody biomass. In Poland, the most promising genus is poplar (Populus spp.). Methods: Ten poplar cultivars from the Aigeiros or Tacamahaca sections of the genus Populus were compared in 5-and 6-year rotations for biomass components and yields. Additional aims were to preliminarily (a) identify a suitable rotation length and (b) evaluate the sprouting capacity of various cultivars in the climate of northern Poland. The following variables were measured: diameter at breast height (DBH), height, survival rate, single-tree dry mass, crop biomass production, and sprouting ability. Results: The cultivars 'NE-42' and 'Fritzi Pauley' showed the best growth characteristics (DBH and height) and highest biomass production (7.6 and 7.7 t ha −1 year −1 , and 5.2 and 6.9 t ha −1 year −1 , respectively, for cultivars in the 5-and 6-year cycles). These cultivars were also distinguished by a large number of coppice shoots and a high shoot length. Eight cultivars did well enough to produce worthwhile data, and five of these gave higher biomass production (t DM ha −1 year −1 ) during the 6-year, as opposed to the 5-year cycle. Of the eight cultivars analysed, 'AF-8' had the poorest growth parameters and produced two thirds less dry biomass than either the 'NE-42' or 'Fritzi Pauley' cultivars. Data for two Italian cultivars ('AF-6' and 'MON') were not analysed because of their cold tenderness and their high mortality. Conclusions: Rotation length is important for biomass production in energy plantations. Most of the tested poplar cultivars gave higher biomass productivity over an initial 6-year cycle than over a 5-year one. Our preliminary results suggest that the 'NE-42' and 'Fritzi Pauley' cultivars performed best among those tested. Both of these have been tested previously in Poland in medium and long rotations. The data indicate the importance of testing cultivars under local climatic conditions before planting on a commercial scale.

& Key message New genotypes of hybrid poplars from the Aigeiros and Tacamahaca sections have great potential for increasing genetic gain from selection. The most promising traits are associated with productivity and resistance to Sphaerulina musiva-induced canker while wood density can be selected for secondarily.

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