Current issue: 54(5)
Under compilation: 55(1)
Ascocalyx abietina (now Gremmeniella abietina Lagerb.) infects Scots pine (Pinus sylvestris L.) by means of ascospores or conidia. Ascospores are dispersed by the wind, while the conidia are splash dispersed. The infection rate is positively correlated with the number of inocula. The aim of this study was to determine the extent to which G. abietina spreads to the trees surrounding the diseased trees and to find the correct time to perform sanitation cutting.
The results were obtained from Ascocalyx-inventory carried out in a Scots pine progeny test at Loppi, Southern Finland. Three Siberian provenances were totally destroyed, while the Finnish progenies remained relatively healthy. The two rows adjacent to the destroyed plots were inventoried separately.
There were 29.7% more diseased or dead trees in the two adjacent rows than in the rest of the same plots. The difference was statistically significant. The trees had probably been infected by conidia, because the effect of the destroyed plot only extended to the adjacent two rows. Furthermore, pycnidia had mainly developed on the dead shoots.
On the basis of the life cycle of the fungus and the results, the correct time to carry out sanitation cutting is the first winter after the disease symptoms have appeared. If it is done later, the disease could be spread and bark beetles (Tomicus spp.) could propagate in dying trees. Susceptible provenances may spread the disease to surrounding resistant trees owing to the increasing number of spores.
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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 aim of the study was to find out if it is possible to use Scots pine (Pinus sylvestris L.) seed from Central-Finnish origin in Northern Finland to supplement supply of local seeds. The principle has been to limit transfer of seeds to 200 km. According to this study, it seems possible to permit 300-400 km transfer of seeds at the same height above the sea level, not including the timber line area.
The author’s observations indicate that the trees originating from seeds of Central Finland at 20-35 years age withstand damage caused by snow and pine blister rust as well as the local provenience. However, the seedlings seem to be more susceptible to snow blight. Spraying of 2-3% sulphurated lime in the autumn before the arrival of snow proved to be most effective way to prevent the damage.
Southern proveniences have been found to grow faster than the local proveniences in Northern Finland. The stands of Tuomarniemi (Central Finland) and Rovaniemi (Northern Finland) provenances had no distinct difference in the summerwood percentage, and the volume weight of the Tuomarniemi provenience was higher than the weight of the provenience of Rovaniemi. The Tuomarniemi stand also gave largest yield, but the difference was probably due to partly at age difference of the sample trees. The naturally regenerated local provenance showed the greatest volume weight.
The article includes a summary in English.