Articles containing the keyword 'rust'

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, E-mail: al@mm.unknown
• Kurkela, E-mail: tk@mm.unknown
• Lilja, E-mail: sl@mm.unknown
• Rikala., E-mail: rr@mm.unknown

The effect of three pesticides containing either dimethoate (0.5% a.i.), permitrin (0.5%) or triadimephon (0.5%) on the cone pests and flowering biology of Norway spruce (Picea abies (L.) H. Karst.) was tested in a seed orchard in mid-May or in the beginning of June. The pesticide treatments significantly reduced infestation by Laspeyresia strobiella and Kaltenbachiella strobi only. Variation in the number of cones infested by both insects and cone rusts was high between the spruce clones. Generally, the pesticides did not affect flower viability, seed quality or seed germination, but reduced drastically the germination capacity of pollen in vitro. In practice, sufficient control cannot be achieved with concentrations or methods used in the present study.

The PDF includes an abstract in Finnish.

• Annila, E-mail: ea@mm.unknown
• Heliövaara, E-mail: kh@mm.unknown

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

The safety clothing, rubber safety boots, belt with lifting hooks and personal protectors can weight about 3 kg more than the normal work clothing including rubber boots. In order to evaluate the increase off the physical strain in logging work due to them, laboratory tests performed on tread mill were made. The physical strain increased 3–11% as estimated from heart rate and 4–8% as estimated from oxygen consumption measurements.

The PDF includes a summary in English.

• Klen, E-mail: tk@mm.unknown
• Louhevaara, E-mail: vl@mm.unknown

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, E-mail: sl@mm.unknown

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, E-mail: pt@mm.unknown

The article describes the distribution of the European white elm; its sites and vegetation communes; phenotype (size and form); variations in the leaves; inflorescence and fruiting; germinative capacity of the seeds; regeneration, both vegetative propagation and from seeds; commercial use of the timber; and the history of European white elm.

The PDF contains a summary in Finnish.  

• Linkola, E-mail: kl@mm.unknown

In practical forestry being able to divide the stem into timber assortments in the best possible way is very important.  Defining the decrease in diameter of the stem plays an important role in that. The article aims to define the slenderness as the relation of the tree height to its breast height diameter. The decrease in diameter is taken into account by measurements of diameter above the breast height. The study is based on the measurements conducted in 1924 for the inventory of forest resources of Finland.

The influence of the stand density to the relationship between height of the pine and the breast height diameter is smaller in the more fertile sites than in the less fertile sites. In the more dense stands are pines more slender than in the sparser stand on all forest types.  

• Lappi-Seppälä, E-mail: ml@mm.unknown

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. 

• Elfving, E-mail: ke@mm.unknown

Indirect selection for resistance is superior to direct selection under certain conditions. The phenotypic correlation was studied between resistance to fusiform rust (Cronartium fusiforme) in loblolly pines (Pinus taeda L.), chosen by a newly-developed stability index, and the amount of resin acids, growth-inhibiting substances, and fatty acids extracted from pine tissue. No association was found between rust resistance and the amount of total or individual resin acids in clones or families. The amount of growth-inhibiting substances present in branches from full-sib families was greater in rust-resistant compared to rust-susceptible families. A strong association was found between resistance and the amount of long-chain fatty acids in four clones. A weak association was found between resistance and the amount of the fatty acid 18:2 in five other clones.

The PDF includes a summary in Finnish.

• Weissenberg, E-mail: kw@mm.unknown

Thekopsora areolata (Fr.) Magnus is a serious cone pathogen that reduces seed crop of Picea abies (L.) Karst. and other Picea spp. Natural sporulation of T. areolata was investigated in nine Norway spruce seed orchards suffering from severe successive T. areolata epidemics in Finland. Habitats occupied by Vaccinium myrtillus L., V. vitis-idaea L., Empetrum nigrum L. and Calluna vulgaris (L.) Hull, and a number of other wild species belonging to ground flora were investigated for Thekopsora areolata uredinia 9–10 times in May–September 2018–2019. Occurrence of Thekopsora uredinia was estimated in current-year leaves of the plants in ca. 25 sample plots of 1 m² in each seed orchard. A sample of plant leaves with rust uredinia or necrotic pustules were collected from each plot. No rust fruiting stages of T. areolata were found on any of the test species of ground flora. However, rust uredinia were observed regularly on leaves of V. myrtillus and V. vitis-idaea in all seed orchards between mid-July and the end of September. Rust sporulation started on V. myrtillus in July and on V. vitis-idaea in August. Based on symptoms, uredinia and spore morphology, the rust on both V. myrtillus and V. vitis-idaea was identified as blueberry rust, Naohidemyces vaccinii (Jørst.) S. Sato, Katsuya & Y. Hirats. ex Vanderwegen & Fraiture. The uredinial stage of the rust on Vaccinium spp. were described. No evidence of natural sporulation of T. areolata on wild plant species other than Prunus was observed in Finnish Norway spruce seed orchards.

• Kaitera, Natural Resources Institute Finland (Luke), Natural Resources and Bioproduction, FI-90570 Oulu, Finland E-mail: juha.kaitera@luke.fi
• Aarnio, Natural Resources Institute Finland (Luke), Natural Resources and Bioproduction, FI-00790 Helsinki, Finland E-mail: leena.aarnio@luke.fi
• Ylioja, Natural Resources Institute Finland (Luke), Natural Resources and Bioproduction, FI-00790 Helsinki, Finland E-mail: tiina.ylioja@luke.fi
• Karhu, Natural Resources Institute Finland (Luke), Natural Resources and Bioproduction, FI-90570 Oulu, Finland E-mail: jouni.karhu@luke.fi

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 E-mail: juha.kaitera@luke.fi
• Kauppila, Botanical Gardens, University of Oulu, FI-90014 Oulu, Finland E-mail: tuomas.kauppila@oulu.fi
• Hantula, Natural Resources Institute Finland (Luke), Natural Resources, FI-00790 Helsinki, Finland E-mail: jarkko.hantula@luke.fi

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

• Kaitera, Finnish Forest Research Institute, Northern Finland Regional Unit, FI-91500 Muhos, Finland E-mail: juha.kaitera@metla.fi
• Nuorteva, Finnish Forest Research Institute, Southern Finland Regional Unit, FI-01301 Vantaa, Finland E-mail: hn@nn.fi

• Lilja, Finnish Forest Research Institute, Vantaa, Finland E-mail: arja.lilja@metla.fi
• Poteri, Finnish Forest Research Institute, Suonenjoki, Finland E-mail: mp@nn.fi
• Petäistö, Finnish Forest Research Institute, Suonenjoki, Finland E-mail: rlp@nn.fi
• Rikala, Finnish Forest Research Institute, Suonenjoki, Finland E-mail: rr@nn.fi
• Kurkela, Finnish Forest Research Institute, Vantaa, Finland E-mail: tk@nn.fi
• Kasanen, University of Helsinki, Department of Forest Sciences, Helsinki, Finland E-mail: rk@nn.fi