Category :
Article
article id 5415,
category
Article
Kim von Weissenberg.
(1990).
Host-parasite relationships in forest ecosystems: A review.
Silva Fennica
vol.
24
no.
1
article id 5415.
https://doi.org/10.14214/sf.a15567
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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,
E-mail:
kw@mm.unknown
Category :
Article
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.
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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.
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Tikka,
E-mail:
pt@mm.unknown
article id 7536,
category
Article
Karl Oskar Elfving.
(1915).
White pine blister rust (Cronartium Peridermium Strobi Kleb) (Cronartium ribicola) found on stone pine (P. cembra) in Finland.
Acta Forestalia Fennica
vol.
4
no.
4
article id 7536.
https://doi.org/10.14214/aff.7536
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An occurrence of Cronartium Peridermium Strobi Kleb has been found in a privately owned garden in Tampere. They are found in several types of currant that the fungus uses as alternate host. The fungi have earlier been found on eastern white pine and now seemingly for the first time on stone pine.
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Elfving,
E-mail:
ke@mm.unknown
Category :
Research article
article id 641,
category
Research article
Juha Kaitera.
(2000).
Analysis of Cronartium flaccidum lesion development on pole-stage Scots pines.
Silva Fennica
vol.
34
no.
1
article id 641.
https://doi.org/10.14214/sf.641
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Historical and current lesion development and sporulation of Cronartium flaccidum was investigated in a stand of artificially seeded pole-stage Pinus sylvestris in northern Finland. An average of 6.5 lesions developed per infected tree, most of them occurring on a minority (25%) of the trees. During the monitoring period of five years, fresh aecia appeared mainly in 7–10-year-old shoots, the age of the shoots bearing aecia varying between 3–20 years. Aecia appeared for the first time most frequently in 5–10-year-old shoots. Infection waves occurred, whereas lesions were formed most frequently in shoots formed in various years through the 1980s. After the lesions started to sporulate, sporulation in most lesions that finished sporulating during the monitoring period lasted for 1–2 years. The aecia in between 47% and 59% of the infected shoots developed annually over a longer length in proximal direction than in distal direction next to the previous year’s infection. The aecia-bearing distal part of the shoot was longer in between 19% and 37% of the shoots.
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Kaitera,
Finnish Forest Research Institute, Rovaniemi Research Station, P.O. Box 16, FIN-96301 Rovaniemi, Finland
E-mail:
juha.kaitera@metla.fi