Astra Zaluma

Key message After 5–6 decades since inflicting resin tapping wounds, overmature (> 120 years old) Pinus sylvestris stems remain undecayed and vigorous. Abstract Overmature trees of Pinus sylvestris bearing large wounds made by resin tapping decades ago are still present in woodlands of south-eastern Baltic Sea region. The aim of the present study...

Root and butt rots caused by Heterobasidion spp. are destructive diseases of conifer forest stands that may be controlled by spraying freshly cut stumps with chemical or biological treatments, including the effective and widely used biological control agent Phlebiopsis gigantea. In this study, we tested in vitro different Latvian isolates of the fu...

According to several earlier studies, the prevalence of Heterobasidion in peat soils is generally lower compared to mineral soils. However, in some Norway spruce (Picea abies (L.) Karst.) stands on drained peat soils in Latvia, serious damage caused by Heterobasidion root rot has been observed. To determine the spread of Heterobasidion spp. on peat...

Stumps play a pivotal role in the epidemiology of the fungal forest pathogens Heterobasidion spp. because they are the main courts of primary airborne infections. The aims of this study were (i) to determine the susceptibility of seven tree species (i.e., Larix sibirica, Picea abies, Picea sitchensis, Pinus contorta, Pinus strobus, Pinus sylvestris...

This study investigated the efficacy of Rotstop®, a native Latvian Phlebiopsis gigantea strain and 35% urea solution in combination with a stump cover treatment to control against natural spore infection by Heterobasidion spp. upon precommercial thinning of Norway spruce in three stands growing on former agricultural lands. The major findings were...

The induction of defense responses in Pinus sylvestris L. seedlings by methyl jasmonate (MeJA) was investigated in three experiments. Two different MeJA application methods were tested, and induction of defense responses was assayed by seedling inoculation with Heterobasidion annosum (Fr.) Bref. and Lophodermium seditiosum Minter, Staley and Millar...

Stump removal is considered as the most effective method to reduce losses caused by root rot fungi, including Heterobasidion root rot. To evaluate the persistence of Heterobasidion spp. in root fragments left on site after stump removal, and to analyse the ecological impact of stump removal, five permanent sample plots were established in Latvia an...

Because intensive forestry favors the spread of Heterobasidion spp., increasing amounts of decayed Norway spruce (Picea abies) wood in forest stands should be taken into account in the management of commercial forests. Spruce wood colonized by Heterobasidion spp. ensures fruit body formation, which increases the risk of new infections by basidiospo...

Afforestation of former agricultural lands is a common practice in several countries. This is beneficial for avoiding diseases carry-over from previous forest generations and to expand forest areas. However, several biotic and abiotic risks have been reported in such stands, including a higher risk of Heterobasidion root rot after thinning. Therefo...

: Afforestation of former agricultural lands is a well-established practice in several countries. It is beneficial for avoiding previous-generation forest diseases and expanding forest areas. However, several biotic and abiotic risks have been reported for such stands as well as a higher risk of Heterobasidion root rot after thinning. Therefore, th...

Treatment of freshly cut stumps with biological control agents containing Phlebiopsis gigantea spores effectively restricts the spread of new Heterobasidion infections in conifer forests. To test the control efficacy of different P. gigantea strains, conifer stumps or billets cut from tree stems can be artificially infected with asexual Heterobasid...

During 2017, Dutch elm disease was investigated on 67 Ulmus glabra and 29 Ulmus laevis samples from 28 sites in Latvia. The presence of Ophiostoma novo‐ulmi was detected in 61.2% of the samples from U. glabra and in 34.5% of the samples from U. laevis. In 11% of cases, hybrids between subsp. novo‐ulmi and subsp. americana were identified, particula...

Fungi from the genus Heterobasidion are among the most important pathogens of forest trees in Northern Hemisphere causing root rot and wood decay, while Phlebiopsis gigantea is a very common saprotrophic wood decay fungus. Both fungi are primary colonizers of freshly cut conifer stumps (through which Heterobasidion spp. accomplishes primary infecti...

Increasing resistance against biotic and abiotic factors is an important goal of forest tree breeding. The aim of the present study was to develop a root rot resistance index for Scots pine breeding and evaluate its effectiveness. The productivity, branch diameter, branchiness, stem straightness, spike knots, and damage from natural infection of ro...

The literature review focuses on the effect of forest soil properties on infection of coniferous trees and stumps by Heterobasidion spores and further growth of mycelium from tree to tree. Spread of the fungus is greater in alkaline soil. Forest plantations on former agricultural lands have an increased risk of infection, due to lack of antagonisti...

Heterobasidion parviporum and Heterobasidion annosum are widely distributed root‐rot fungi that infect conifers throughout Europe. Infection of conifer stumps by spores of these pathogens can be controlled by treating fresh stumps with a competing non‐pathogenic fungus, Phlebiopsis gigantea. In this study, growth of three Latvian strains of P. giga...

Heterobasidion spp. cause economically important losses in conifer forests in the Northern Hemisphere, especially in Norway spruce stands. Freshly cut stumps are the main route for Heterobasidion spp. infection. Even small stumps of spruce seedlings are known to be susceptible to spore infection, however, very little is currently known about the su...

This study investigated the origins and spread patterns of Heterobasidion root disease in three Pinuscontorta Dougl. ex Loudon plantations established on forest and agricultural land and subjected to three different management scenarios. Trees with decline symptoms and stumps remaining from the previous rotation were sampled for fungal isolations....

The effect of genetics on the level of damage caused by Lophodermium needle cast to Scots pine was assessed in an openpollinated progeny trial (226 families from 12 provenances) and in a control-crossed progeny trial (72 families obtained by diallel crossing of 10 parent trees). Each of the trials was replicated on two test sites. The damage caused...

The aim was to investigate relative susceptibility of stumps of spruce and pine to airborne infections by Heterobasidion following pre-commercial thinnings. The proportions of infected stumps and colonized stump surface areas were analysed in 16 forest stands. In total, 746 spruce and 1063 pine stumps were sampled, and 184 and 105 infected stumps,...

Premature needle cast, affecting the needles on one-year old shoots, thus shrinks the size of green crown of Scots pines, and can cause reduction of increment or even death of trees, especially during first years of their growth. Aim of our study was to evaluate the lasting impact of pathological needle cast to young Scots pines and its implication...

Five-year-old Norway spruce and four-year-old Scots pine seedlings of various origin were inoculated with Heterobasidion annosum s.s. and H. parviporum to estimate whether the susceptibility of seedlings to Heterobasidion was affected by origin of seeds. In total, 520 spruce and 538 pine seedlings from different seed sources and provenance regions...

In the last decade the populations of large game as moose and red deer have increased in Latvia, and the risk of damage to forest stands has increased simultaneously. The aim of this study was to evaluate the extent of bark stripping wounds, decay incidence and associated fungi in 30-year-old Picea abies stems damaged by big game. In total, 90 tree...

The biological control agent Rotstop® composed of a suspension of spores of Phlebiopsis gigantea (Fr.) Jül. is widely used for protecting conifer stumps from aerial infection by Heterobasidion species. The efficacy of Rotstop application on Norway spruce (Picea abies) and Scots pine (Pinus sylvestris) stumps was determined in several locations and...

Growth rates of H. annosum s.s. and H. parviporum were investigated in the functional sapwood of young Pinus sylvestris and Picea abies plants as an indicator of the relative susceptibilities of the hosts to these pathogens. The stems of 520 five-year-old P. abies and 321 four-year-old P. sylvestris plants were inoculated and the extent of infectio...

The aim of this study was to assess the extent of bark stripping wounds, subsequent wood discoloration, and associated fungi in 30-year-old Pinus contorta Douglas ex Loudon stems damaged by large game. In total, 90 trees were evaluated, and 170 bark stripping wounds of different ages (1–20 years) were measured. From each wound, wood samples were co...

We studied morphological parameters and ectomycorrhizal (ECM) fungal colonisation of Norway spruce (Picea abies) seedlings produced from seeds of Western (W1 and W2 provenances), Central (C1 and C2 provenances) and Eastern (E1 provenance) seed regions in Latvia. In total, 50 seedlings of each seed provenance were cultivated in a sphagnum peat subst...

Diversity of saproxylic beetles (Hexapoda: Coleoptera) in clear-cut sites with removed and retained stumps in central Latvia. Acta Biol. Univ. Daugavp., 14 (2): 145 – 157. Saproxylic insects represent an important part of forest biodiversity and have functionally significant role in the forest ecosystems. They are species-rich organisms that depend...