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.
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From the tree breeder’s point of view, an investigation of the chemical compounds in a tree population is worthwhile, if sufficiently high correlations exist between the chemical composition and any economical important characteristics. In Scots pine (Pinus sylvestris L.) populations, such a correlation seems to exist between a high α-pinene and a low Δ3-carene content on the one hand, and the poor resistance to Fomitopsis annosa Fr. (now Heterobasidion annosum (Fr.) Bref.) but a rapid development during the first half of the life cycle on the other hand. Detailed investigation on the terpene contents in pine populations were conducted at 121 locations throughout the Soviet Union. As a result, the range of this species was divided into zones, each of which was characterized by a distinct terpene composition pattern. In continuing selection and breeding work, the terpene contents are being used as indicators when the variation of economically important characteristics of Scots pine populations is studied.
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The purpose of the study was to find out whether Fomes annosus (now Heterobasidion annosum) growing in a Norway spruce (Picea abies (L.) H. Karst.) stump can, with its mycelium, take up the radioactive isotopes 3H, 33P and 125I in the heading, and whether it transfers them via the sporophores in situ to its basidiospores. Wood material in close proximity to active sporophores was injected with radioactive isotopes. All isotopes could be verified from the basidiospores. The production of viable basidiospores by sporophore was reduced by the isotope injections. This latter result may be of importance e.g. in meteorology for observation of the movements of air masses.
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The study was carried out in a Norway spruce (Picea abies (L.) H. Karst.) stand in Southern Finland which was to be clear-cut due to decay. The species composition and incidence of decay fungi were investigated from the cut surfaces of the stumps. In addition, the colour and size of the decayed spot was observed.
About 28% of the total number of trees were decayed. Fomes annosus (Heterobasidion annosum) was the most common decay fungus. It was identified from 75% of the decayed trees, and was the sole agent in 43% of these trees. Armillaria mellea was the second commonest decay fungus. It decayed trees mostly in combination with Fomes annosus. The most common colours of the decay produced by F. annosus were reddish or yellowish brown. The decay caused by A. mellea was blackish brown. The causative agent cannot be reliably identified on the basis of the colour of the decayed part.
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Fomes annosus (Fr.) Cke. (now Heterobasidion annosum (s.str.)) has proved highly adaptable to varying conditions. Thus, the fungus is able to alter the pH as well as in alkalic as acid direction according to the original pH-grade. The fungus spreads mainly by basidiospores or by the sterile mycelium, but maybe also by the conidiospores. The fungus has spread through the temperate zone; in the tropical and sub-tropical zone it is found sporadically. There is a mention in the literature of at least 136 species in which it has been found. It is found in hardwoods but is most disastrous in conifers. The economic losses are considered biggest in England, Germany and Scandinavia.
The research has not been able to find a safe way to protect the trees growing on an infected site. The only way to limit the damage seems to be the use of mixed stands. Stump-protection has proved to be a relatively effective way to prevent the spread of the fungus to uninfected sites. The formerly used creosote has been mainly substituted by new chemicals, such as sodium nitrite. They act by altering the stump in a way that is favourable for antagonists to Fomes annosus, such as Trichoderma viride and Penicillium sp., or the recently presented Peniophora gigantea.
Although the fungus is found in many tree species, there is a difference in the relative resistance of different species. Among the conifers, the Abies-species (with exception of Abies grandis, A. alba and A. sachalienensis) are considered comparatively resistant. The species of Larix and Pseudotsuga are more resistant than those of Picea and Pinus.
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The aim of this investigation was to clarify aerial infection of Fomes annosus (now Heterbasision annosum) in the cross-sections of stumps of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst.) in Southern Finland. In addition, an attempt was made to study possibilities to reduce an eventual aerial infection by means of spreading various protecting substances on the cross-section of the stumps immediately after cutting. The stumps were treated withs creosote, ceruse (lead white) and a product named ”Ventti”, which active constituent is copper. The effect of prescribed burning of the site on the aerial spreading of the fungus was studied.
Five sample plots were located in spruce stands and one in a pine stand. One of the spruce stands was prescribed burned. Samples were taken from the stumps 14–17 and 24–29 months after cutting. To identify the fungi, the samples were cultivated on a nutrient substrate in laboratory conditions. The results show that Heterobasidion annosum had spread by air to cross-sections of stumps of spruce. 11.5% of the samples taken from the spruce stumps 14–17 months and 17% of samples taken 24–29 months after cutting were infected. Burning of the site reduced strongly the aerial infection of stumps by the fungus. The stumps of Scots pine were not infected by Heterobasidion annosum in this study. The infection could be limited by treating the cross-sections with substances that are used to prevent growth of mould.
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The aim of the study was to identify the microbes which reach the cut surface of Norway spruce (Picea abies (L.) Karst.) stumps during the first year after felling by means of air born spores, determine their occurrence frequency and the combinations in which they occur, investigate the colour changes in the wood caused by microbes and identify the microbial species isolated from the sap- and heart-wood.
The material consisted of 360 spruce stumps. 300 of the stumps were innoculated with five different fungi (Phlebia gigantea, Botrytis cinerea, Gliocladium deliquescens, Trichoderma viride, Verticicladiella procera) in order to inhibit air-born attack by Heterobasidion annosum. 60 stumps were left untreated as controls.
The cultural characteristics of the following fungi isolated from the stumps have been described e.g.: Ceraceomerulius serpens, Chondrostereum purpureum, Cylindrobasidium evolvens, Peniophora pithya, Phlebia gigantea (Phlebiopsis gigantea) , P. subserialis, Sistotrema brinhmannii, Bjerkandera adusta, Coriolellus serialis, Trametes zonata, Armillariella mellea, Panellus mitis, Nectria fucheliana (microconidial-stage), Ascocoryne cylichnium (conidial-stage), Leptographium lundbergii, Acremonium butyri, Gliocladium deliquescens, Verticicladiella procera.
The proportion of Basidiomycotina fungi out of the whole material was 53 %, Ascomycotina and Deuteromycotina fungi 37,6 % and bacteria 7,3 %.
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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.
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In 1972, all Norway spruce (Picea abies (L.) H. Karst.) trees of a minimum 7 cm diameter at breast height growing in the sample plots of the Sixth National Forest Inventory were examined on the main island of Aland, Finland. The soundness of standing trees was estimated by means of external characteristics and increment borer chips. The trees were then felled and measured. They were cut into lengths, and the type and extent of decay were studied.
30% of the trees examined was affected by butt rot, ca. 3% by wound decay. A comparison of the results with those of the Sixth National Forest Inventory justifies the estimate that in Aland 23% of spruce trees exceeding 7 cm in diameter at 1.3 m had butt rot.
The proportion of decayed trees in the cubic volume was 31%. Decayed wood material accounted for 5% of the volume including bark. Butt rot increased towards the mature stands. The reduction in the number of timber trees due to decay was 14.5%, in their volume 21.5%, and in the volume of sulphite pulpwood 12%. The share of sulphate pulpwood increased from 1 to 10%. The total reduction in usable wood was 6.3%. The stumpage price of the trees fell by 10.3%. As the degree of decay increased the increment percentage of the trees decreased. The most common cause of butt rot was Fomes annosus (Heterobasidion annosum) found in 46% of the number of decayed trees. Armillaria mellea was found in 16%. Bacteria were found in 50% of the decayed trees.
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Infection of living Norway spruce (Picea abies (L.) H. Karst.) trees by bacteria, and the properties of these bacteria were studied. Bacterial antagonism to three decay fungi was also studied in laboratory conditions.
Bacteria could be found in 26% of all spruce injuries. Bacterial infection was most frequent in injuries made in March–April and June, and least frequent in December–February. Bacteria infected most often sapwood injuries in roots above soil level, 55% of the bacterial colonies were isolated from these injuries. 27% of the colonies were isolated from injuries made by increment borer at breast height, extending to heartwood, 16% from sapwood injuries at breast height, and 2% from injuries at stump height. The main bacterial groups were gram-positive rods (55%) and gram-negative rods (29%).
In 65% of the bacteria the metabolism was fermentative, in 14% slowly fermentative, in 7% oxidative, in 8% slowly oxidative, and in 6% alkalizing. 19% utilized cellulose, 15% in the presence of organic, 3% in the presence of inorganic nitrogen.
One bacterial strain was the only micro-organism growing in the injury a year after the damage, although the injury had been infected with Peniophora gigantea (Phlebiopsis gigantea). In laboratory experiments, this rod bacterium, gram-negative strain proved to be antagonistic to Fomes annosus (Heterobasidion annosum), Stereum sanguinolentum and P. gigantea. It had no capacity for cellulose utilization.
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The study material was collected from 10 localities in South Finland in 1971–72. The material comprised 816 damaged Norway spruce (Picea abies (L.) H. Karst.) trees with a total of 978 injuries.
Decay (discoloration) spread upward from the damaged point was about three times as fast as downward. The mean rate of advance upward was 21 cm/year. The decay spreading at the quickest rate started from above-ground root collar injuries. The size of the damaged area (surface area, width and depth) correlated positively with the rate of increase in decay initiated by the injury. For the first 10 years the decay advanced at the same rate after which the advance became slower though not ceasing. Damage produced in the early summer caused a faster spread of decay than that produced in the late summer or winter. The rate of advance was the greater the larger the stem involved. When decay started from trunk damage its rate of advance was greater the faster the growth of the trees. With a better soil type, the rate of advance in decay increased. Fertilization increased the rate of advance.
The widest stem injuries reduced tree growth by about one-third, and severed roots by nearly half of the growth of trees where the width of the injuries was 0–4 cm. Fomes annosus (Heterobasidion annosum) infected spruce injuries especially in the southern coastal district. The farthest tips of discoloration proved in most cases to be sterile. The most common fungus isolated from these sites was Stereum sanguinolentum.
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The purpose of the present study was to investigate the success of infecting Norway spruce (Picea abies) wounds with a mycelial suspension of Peniophora gigantea (now Phlebiopsis gigantea). In an approximately 100-year old spruce stand on Myrtillus type soil in Southern Finland, two dominant and two suppressed spruce trees were wounded each month during one year, and infected with P. gigantea. Control trees were only wounded. One year after wounding the trees were sawn into discs near the wound. Samples of the discs were cultured to identify the microbes.
In the suppressed trees, the P. Gigantea infection had been successful in 75 % of the wounds extending into heartwood. For dominant trees, the percentage was 50. In sapwood wounds the infection was considerably less successful. In two wounds of the control trees were noted airborne P. gigantea infection, and in four Fomes annosus (now Heterobasidion annosum).
Discoloration starting from the wounds was not a reliable proof that microbes were present. According to the variance analysis, the upward advance of discoloration without microbes showed a greater correlation with the crown class than with the type and site of the wounds. The downward advance depended more on the type of the wounds than the crown class.
A total of 37 fungi were identified by species or family, from the damaged trees. A large number of bacteria were also found. The most common fungi were the Penicillium species, and they had most often advanced farthest above and below the wound. Of the actual decay fungi, Stereum sanguinolentum showed the highest incidence and fastest growth. Coryne cylichnium and Cephalosporium species were also relatively common.
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The incidence of the conidiophores of Fomes annosus (Heterobasision annosum) was investigated in Helsinki in 1967–71 in a Norway spruce (Picea abies (L.) H. Karst.) stand growing on a site of Oxalis-Myrtillus type. The investigation comprised stump surfaces of spruce and pieces of wood, decayed by F. annosus, placed on the ground.
Conidiophores and conidia were seen during a few weeks in May-June on the surfaces of stumps covered by spruce branches. Conidiophores were sometimes seen on the stump surfaces even later in the summer and autumn, but by that time they were only very few. Their occurrence on the stumps that had not been covered was extremely rare, and the conidiophores were always very few in number. Surfaces of trees felled the year before showed no conidiophores. Conidiophores were also found below the pieces of decayed wood lying on the ground.
When spruce trees decayed by F. Annosus were felled in the summer and autumn, the surfaces of stumps covered with spruce branches showed the first conidiophores one week after the felling. The occurrence continued almost uninterruptedly until the winter.
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An attempt was made to restrict the aerial distribution of Fomes annosus (now Heterobasidion annosum) through the cut surfaces of spruce stumps by inoculating the surfaces, immediately after felling, with mycelial suspension, grown in the laboratory on malt agar, of Fomes pinicola, Lenzites sepiaria, Peniophora gigantea (now Phlebiopsis gigantea), Polyporus abietinus and Trichoderma viride. Trees were felled once a month for a year. Samples were taken from the cut surfaces of the stumps approximately one year after the felling and the inoculation.
P. gigantea inhibited the infection of cut stump surfaces by airborne F. annosus. P. gigantea cut down both the total number and the number of the species of fungi infecting the stump through aerial distribution. T. viride had a parallel but less marked effect. F. pinicola, L. sepiaria and P. abietinus proved to be weak colonizers of spruce stumps. When they were used to inoculate the stumps, the number of fungi infecting the cut surfaces was larger than that infecting the stumps treated with P. gigantea and T. Viride. A year after the inoculation some stumps were excavated with their roots. Fungi from the discoloured spots of wood in the stumps were cultured for identification. It was found that many different fungal species from the soil and the points of root grafting had infected the roots of the stump in the course of the year. The majority of the identified microbes were non-Basidiomycetes fungi, and bacteria.
A year after the felling and inoculation, a white mycelial sheet was seen between the wood and bark of many stumps. Several fungi, including Armillaria mellea, Trichoderma viride, Penicillium species, and Peniophora gigantea were isolated from this sheet.
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