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Articles containing the keyword 'diseases'.

Category: Research article

article id 10446, category Research article
Juha Kaitera, Tuomas Kauppila, Jarkko Hantula. (2021). Assessment of the potential of Norway-spruce-seed-orchard associated plants to serve as alternate hosts of Thekopsora areolata. Silva Fennica vol. 55 no. 2 article id 10446. https://doi.org/10.14214/sf.10446
Highlights: Prunus is the only alternate host of cherry-spruce rust identified in this study; Cherry-spruce rust does not infect plants that belong to common ground vegetation flora in Finnish Norway spruce seed orchards; Spores from different Finnish cherry-spruce rust populations are similarly pathogenic on Prunus; Disease control should be focused only on Prunus in seed orchards.

The alternate host range of cherry-spruce rust is poorly studied although such information could be important in protecting spruce seed orchards from infections. Pathogenicity of cherry-spruce rust, Thekopsora areolata (Fr.) Magnus, was investigated on potential alternate host species in a greenhouse and in a laboratory in Finland. Five common species of Ericaceae, Vaccinium myrtillus L., V. uliginosum L., V. vitis-idaea L., Empetrum nigrum L. and Arctostaphylos uva-ursi (L.) Spreng, were inoculated in the greenhouse using aeciospores from seven Norway spruce [Picea abies (L.) H. Karst.] seed orchards suffering from T. areolata in 2018. In addition, young detached leaves of Vaccinium spp. and 17 other plant species of ground vegetation from eight Norway spruce seed orchards were inoculated with aeciospores from six seed orchards in the laboratory in 2019. Also, young leaves of Prunus padus L. trees growing within the seed orchards or close to them were inoculated as controls. None of the inoculated leaves of the potential alternate hosts formed uredinia either in the greenhouse or in the laboratory. In contrast, leaves of P. padus from the seed orchards were infected by the six spore sources from six seed orchards and produced uredinia. As T. areolata spores were able to infect only P. padus, but not the other tested species belonging to ground flora, it was concluded that T. areolata disperses only via Prunus spp. in Finnish seed orchards.

  • Kaitera, Natural Resources Institute Finland (Luke), Natural Resources, FI-90570 Oulu, Finland ORCID ID:E-mail: juha.kaitera@luke.fi (email)
  • Kauppila, Botanical Gardens, University of Oulu, FI-90014 Oulu, Finland ORCID ID:E-mail: tuomas.kauppila@oulu.fi
  • Hantula, Natural Resources Institute Finland (Luke), Natural Resources, FI-00790 Helsinki, Finland ORCID ID:E-mail: jarkko.hantula@luke.fi
article id 10422, category Research article
Juha Kaitera, Jouni Karhu. (2021). Temperature range for germination of Thekopsora areolata aeciospores from Finnish Norway spruce seed orchards. Silva Fennica vol. 55 no. 1 article id 10422. https://doi.org/10.14214/sf.10422
Highlights: Cherry-spruce rust was able to germinate at very low temperature (6 °C) close to the temperature when thermal growth starts; Optimum spore germination occurred between 15–24 °C; High temperature of 30 °C drastically reduced germination; Temperature had the most significant effect on germination, while spore source had less significant effect and agar media a non-significant effect on germination in a Fixed Effects model.

Cherry-spruce rust caused by Thekopsora areolata (Fr.) Magnus is a serious cone pathogen of Norway spruce [Picea abies (L.) Karst.]. The rust causes great economical losses in seed orchards specialized in the production of high quality seeds. Germination range of T. areolata aeciospores from rust populations (spore sources) in seven Finnish Norway spruce seed orchards was tested on water agar and malt agar at nine temperatures varying between 6–30 °C. The temperature range of spore germination was high varying between 6 °C and 27 °C, while germination was retarded at 30 °C. The peak in germination rate of all spore sources occurred between 15–24 °C. In a model with fixed effects of agar media, temperature and spore source, temperature had the most significant effect on germination. Spore source had a less significant effect, while agar media had a non-significant effect on germination. The rust was able to germinate at low temperatures corresponding to temperatures when the thermal growing season starts at 5 °C in the spring. As spores from cones from both the spruce canopy and the ground showed very similar germination ranges, it indicated the great capacity of all spores of the rust to germinate early in the spring. Hot temperatures with over 30 °C drastically reduced germination of the rust.

  • Kaitera, Natural Resources Institute Finland (Luke), Natural resources and bioproduction, Paavo Havaksentie 3, FI-90014 University of Oulu, Finland ORCID ID:E-mail: juha.kaitera@luke.fi (email)
  • Karhu, Natural Resources Institute Finland (Luke), Natural resources and bioproduction, Paavo Havaksentie 3, FI-90014 University of Oulu, Finland ORCID ID:E-mail: jouni.karhu@luke.fi

Category: Article

article id 7383, category Article
Esko Kangas. (1946). Kuusikoiden kuivumisesta metsätuho- ja metsänhoidollisena kysymyksenä. Acta Forestalia Fennica vol. 52 no. 5 article id 7383. https://doi.org/10.14214/aff.7383
English title: Drying of Norway spruce stands as forest damage and forest management issues in Finland.

Observatons of drying of Norway spruce (Picea abies (L.) Karst.) stands increased in 1930s in Southern Finland. The aim of the study was to analyse the advance and causes of drying. The work was begun in 1930s before the Second World War, and the damages caused to the forests by the war was used as supplemental observations in the study. A special method, drying analysis, was developed to study the process. It was used both in cases of insect and fungal diseases in the four research areas in Raivola and Ruotsinkylä. In addition, 7 observation areas were studied.

Several causes for drying of the trees were observed in the Norway spruce stands. These included European spruce bark beetle (Dendroctonus micans), root rot (Heterobasidion annosum), pine weevils (Pissodes sp.), bark beetles and honey fungus (Armillaria mellea).

The role of primary and secondary causes for drying, resistance of the trees and the drying process are discussed. Finally, the influence of forest management in drying process is analysed. Forests in natural state can be considered to be in an ideal balance. On the other hand, forest management can be used to maintain the vitality and resistance of the forests. Drying of Norway spruce stands can be taken into consideration when the stands are managed.

The PDF includes a summary in German.

  • Kangas, ORCID ID:E-mail:
article id 7354, category Article
P. S. Tikka. (1940). Puiden vikanaisuuksien merkitys ja huomioon ottaminen Perä-Pohjolan mäntymetsien hoidossa. Acta Forestalia Fennica vol. 50 no. 1 article id 7354. https://doi.org/10.14214/aff.7354
English title: The effect of injuries in trees on forest management of Scots pine stands in Northern Finland.

The aim of the study was to find out what are the causes of damage in Scots pine (Pinus sylvestris L.) stands and the frequency of different kinds of injuries, which are then discussed in relation to the silvicultural state and management of the stands in comparison to ideal forests. Sample plots were studied in over 80-year old Scots pine dominated stands in mineral soil sites of different forest types in Northern Finland in the area of Perä-Pohjola. 10–40 trees were chosen as sample trees in each sample plot. The sample trees were felled, and the diameter, height of crown and injuries outside and inside of the stem were recorded.

Length of knot-free part of the stem was higher in the dominant trees and in older age classes of the trees. The form of the stem becomes broader and rounder with the age. The crowns are, however, longer in Northern Finland compared to Southern Finland. In management of Scots pine stands, all trees diseased by Scots pine blister rust (Cronartium flaccidum) should be removed. The disease is common in Northern Finland, and the number of diseased trees increases as the stands get older. Decay was more common in trees that had fire wounds. In general, injuries decreased the length and diameter growth of the trees. From the dominant trees should only injured and diseased trees removed in the thinnigs. Codominant trees can be left to grow when spare trees are needed to replace missing dominant trees. Detailed instruction of selection of the removed trees are given for each age class.

The PDF includes a summary in German.

  • Tikka, ORCID ID:E-mail:
article id 5611, category Article
Arja Lilja, Timo Kurkela, Sakari Lilja, Risto Rikala.. (1997). Nursery practices and management of fungal diseases in forest nurseries in Finland. A review. Silva Fennica vol. 31 no. 1 article id 5611. https://doi.org/10.14214/sf.a8512

The purpose of this article was to collate the literature on fungal diseases that occur on seedlings in forest nurseries. It describes the symptoms of the diseases, the infection pattern of each fungus and the possibilities of controlling the diseases. As background a short introduction is given on forests and nursery practices in Finland.

  • Lilja, ORCID ID:E-mail:
  • Kurkela, ORCID ID:E-mail:
  • Lilja, ORCID ID:E-mail:
  • Rikala., ORCID ID:E-mail:
article id 5397, category Article
Juha Kaitera, Risto Jalkanen. (1994). Old and fresh Gremmeniella abietina damage on Scots pine in eastern Lapland in 1992. Silva Fennica vol. 28 no. 2 article id 5397. https://doi.org/10.14214/sf.a9166

Damage on Scots pine (Pinus sylvestris L.) caused by Gremmeniella abietina (Lagerb.) Morelet was assessed in the summer of 1992 in 67 stands in eastern Lapland. The area and severity of damage were smaller and lighter than had earlier been estimated and occurred especially in stands in the first-thinning stage or in middle-age. Significant new infection of 1991 occurred in stands previously heavily infected by G. abietina near Kemihaara river, lake Naruska, the Naruska river, the Tuntsa river and lake Vilma. Fresh damage occurred mainly in the lower or middle parts of the Scots pine canopies.

  • Kaitera, ORCID ID:E-mail:
  • Jalkanen, ORCID ID:E-mail:
article id 5415, category Article
Kim von Weissenberg. (1990). Värd-parasitförhållanden i skogliga ekosystem. Silva Fennica vol. 24 no. 1 article id 5415. https://doi.org/10.14214/sf.a15567
English title: Host-parasite relationships in forest ecosystems: A review.

Based on a survey of world literature it is concluded that 1) the better -researched epidemic forest pathosystems are caused by anthropogenic factors, 2) the systems most likely have a polygenic background, and 3) resistance breeding should maintain polygenic resistance with restrictive incorporation of oligogenic resistance. Corresponding objectives are valid in breeding programs of presently balanced pathosystems, which may turn epidemic if man causes changes in the gene pool and alters critical environmental conditions.

The PDF includes an abstract in English.

  • Weissenberg, ORCID ID:E-mail:
article id 5216, category Article
Anna-Maija Hallaksela. (1984). Causal agents of butt-rot in Norway spruce in southern Finland. Silva Fennica vol. 18 no. 3 article id 5216. https://doi.org/10.14214/sf.a15395

A total of 146 Norway spruce-dominated clear-cutting areas and 140 of the sample plots included in the 7th National Forest Inventory in Finland were examined during 1974–78. The micro-organisms causing decay in Norway spruce (Picea abies (L.) H. Karst.) sample trees were identified. The most common causal agent of butt-rot was Heterbasidion annosum (Fr.) Bref. Other fungi causing decay in the spruce trees were Armillaria mellea (Vahl.) Quél, Stereum sanguinolentum (Alb. & Schw. ex Fr.), Resinicum bicolor (Alb. & Schw. ex Fr.) Parm. and Climacocystis borealis (Fr.) Kotl. & Pouz. Species of Ascocoryne were very often present in the decay. The decay caused by H. annosum was considerably more extensive than cases of decay where the fungus was not present.

The PDF includes a summary in Finnish.

  • Hallaksela, ORCID ID:E-mail:
article id 4858, category Article
Tauno Kallio. (1972). Erään 10-vuotiaan hybridihaapametsikön lahovikaisuus. Silva Fennica vol. 6 no. 1 article id 4858. https://doi.org/10.14214/sf.a14661
English title: Decay in a ten-year old stand of hybrid aspen.
Original keywords: hybridihaapa; sienitaudit; laho; bakteerit

A ten-year old stand of hybrid aspen (Populus tremula x Populus tremuloides), growing in Southern Finland on about 1.5 ha of Oxalis-Myrtillus type (OMT) soil and affected by crown blight, was examined in 1971. The study revealed that almost all trees, both those removed by thinning and the remaining growing stock, were decayed. A number of bacteria, Fungi imperfecti species and ascomycetous fungi were isolated from the discoloured heartwood of the affected trees. No fungus of the Bacidiomycetes was found in the discoloured wood material.

The PDF includes a summary in English.

  • Kallio, ORCID ID:E-mail:
article id 4738, category Article
Sakari Lilja. (1967). Tuomen merkityksestä kuusen tuomiruostesienen, Pucciniastrum padi (Kunze & Schm.) Diet., esiintymiselle kuusessa. Silva Fennica vol. 1 no. 1 article id 4738. https://doi.org/10.14214/sf.a14448
English title: Significance of the bird-cherry (Prunus padus L.) for the occurrence of the rust, Puccinastrum padi (Kunze & Schm.) in spruce.

The present study deals with the occurrence of the rust, Pucciniastrum padi (Kunze & Schm.) Diet., in the shoots and cones of Norway spruce (Picea abies (L.) H. Karst.) in the forest area of the training and experimental farm of Helsinki University at Viikki (60’10’ N; 25’ E). The most important task was to clarify the correlation between the occurrences of the disease in spruce and the abundance of the alternative host of the disease, bird-sherry (Prunus padus L.).

Infected shoots were encountered in a 17-year-old planted seedling stand of spruce. In this stand 8.4% of the seedlings were infected. The density of bird-cherry trees was in the stand higher than in the surrounding areas. The number of infected shoots was the greatest in those places where the density of bird-cherries was highest and already at a distance of some ten metres form the bird-cherry stands the degree of infection decreased considerably. The portion of infected cones in the whole material of this study was 19.5%.

The dependence of the frequency of disease on the abundance of bird-cherries at different distances from the spruce stand was studied by means of regression analysis. For this reason, the percentage infected cones were determined by sample plots and the abundance of bird-cherry trees from six zones (0–50, 50–100, 100–150, 150–200, 200–300, and 300–500 m) around each sample plot. The results showed that the dependence between the degree of infection of cones and the abundance of bird-cherry in the surroundings only reached the closest zone. There were also infected cones at greater distance, for instance, 200–300 m from the bird-cherries about 10% of the cones could be infected. Both the infected cones and shoots were longer than the healthy ones.

The PDF includes a summary in English.

  • Lilja, ORCID ID:E-mail:
article id 7583, category Article
Tauno Kallio. (1976). Peniophora gigantea (Fr.) Massee and wounded spruce (Picea abies (L.) Karst. Part 2Peniophora gigantea ja kuusen vauriot. Osa 2. Acta Forestalia Fennica no. 149 article id 7583. https://doi.org/10.14214/aff.7583

The paper is a continuation of an earlier report by the author on the same subject (Acta Forestalia Fennica 133, 1973). Norway spruce (Picea abies (L.) H. Karst.) wounds were inoculated with Peniophora gigantea (Phlebiopsis gigantea) and the discolorations starting from the wounds were investigated three years after the wounding. Fomes annosus (Heterobasidion annosum) had infected 17 % of the total number of wounded trees. If no microbes were growing at the furthest point of the discoloration that had started from the wound, the discoloration advanced upward from wounds made at breast height at a rate of 61 cm/year in the dominant and 36 cm/year in the suppressed trees. In the dominant trees, a year after the wound was inflicted the discoloration had advanced at a rate of 50 cm/year and after three years the rate was 61 cm/year. This difference is not significant. Where microbes were present at the furthest point of discoloration, the discoloration had advanced 27 cm/year in one year and 42 cm/year in three years. Also, this difference is not significant.

A microbe was isolated from the furthest point of discoloration in only 13 out of 42 possible cases. The most common microbe was Stereum sanguinolentum. Bacteria showed the fastest rate of advance.

The PDF includes a summary in Finnish.

  • Kallio, ORCID ID:E-mail:
article id 7541, category Article
Tauno Kallio. (1970). Aerial distribution of the root-rot fungus Fomes annosus (Fr.) Cooke in Finland. Acta Forestalia Fennica no. 107 article id 7541. https://doi.org/10.14214/aff.7541

An investigation into the aerial distribution of Fomes annosus (now Heterbasidion annosum) in Finland was carried out. Prevalence of the fungus in the air was estimated from cultural counts of mycelia produced by diaspores which had fallen onto spruce discs and agar plates. The influence of climate on deposition of diaspores was determined from weather recordings.

For the main study, F. annosus diaspores collected from spruce stands in Helsinki, Anjala and Jokioinen were recorded at weekly or fortnightly intervals throughout 1968. Diaspores fell during the 24-hour periods almost continuously at all three observation sites from April to November, but the deposition was most frequent from late May to the end of October. The amounts of deposition varied greatly with the observation sites, seasons of the year, and time of the day. The fall was heaviest at Anjala and slightest at Jokioinen.

Throughout the season of deposition, more diaspores were trapped on all observation sites at night than during the day. A significant positive correlation was found between the fall of F. annosus diaspores and the air temperature. Diaspores of F. annosus were found in the forest on needles and leaves, and underneath the humus layer in mineral soil. The fall of diaspores decreased as the distance from sporophores increased.

The aerial distribution of two antagonists to F. annosus, viz. Peniophora gigantea and Trichoderma viride, was also studied. It was found that the diaspores of the former fell mainly during the same seasons as those of F. annosus.

  • Kallio, ORCID ID:E-mail:
article id 4458, category Article
Esko Kangas. (1931). Siikakankaan mäntytaimistojen tuhoista. Silva Fennica no. 17 article id 4458. https://doi.org/10.14214/sf.a8999
English title: Siikakankaan mäntytaimistojen tuhoista.

Regeneration of large open areas in dry mineral soil forest sites that usually grow Scots pine (Pinus sylvestris L.) have several problems. For instance, soil frost, snow, ground vegetation and dryness can prevent germination and growth of seedlings. The damages caused by insects and fungi in seedlings of a large burned area in Siikakangas in Southern Finland was studied. A forest fire burned the area nearly completely in 1909, and 310 hectares have been sowed or planted with mostly Scots pine during the following years. Minor areas have been regenerated with Pinus montana Noll, Pinus excelsa Lamb., Pinus murrayana Balf. and Larix sibirica Ledeb.

No completely healthy pine seedling stands could be found in the area. About 41% of the seedlings in the sample plots were damaged. The most common causes for damage were Evetria resinella (now Retinia resinella L.), Luperus pinicola (now Calomicrus pinicola (Duft.)), Pissodes notatus (now Pissodes castaneus Degeer), Evetria turionana Hb. and Hylobious abietis L. The most usual fungal disease was Lophodermium sp. Evetria resinella caused damages in all the area. Evetria turionana, Pissodes notatus and Hylobius abietina were found in the older seedling stands. Other damages were more localized. The slacks in the terrain seemed to have most damages, the original cause being probably soil frost. Some damages, as Lophodermium, were related to the density of the seedlings, especially in the sown areas. Cleaning of seedling stands could decrease these damages. Planting seems to have succeeded better than patch sowing.

The PDF includes a summary in German.

  • Kangas, ORCID ID:E-mail:

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