Investigations on natural durability of important European wood species against wood decay fungi. Part 1: Laboratory tests

The durability of heartwood from European larch, Sessile oak and Scots pine was tested in laboratory against wood decay basidiomycetes and soft rot. The durability test was performed according to CEN/TS 15083-1:2005 with Coniophora puteana, Oligoporus (Poria) placenta and Trametes (Coriolus) versicolor. CEN/TS 15083-2:2005 was applied in order to test the timber with a bioactive soil substrate against soil rotting organisms. For Sessile oak, a very high durability against basidiomycetes (DC 1) was found in contrast to a low durability (DC 4) against soft rot fungi. Furthermore the results indicated that the durability of European larch and Scots pine is slightly deteriorated after leaching according to EN 84:1997. Beside this a minor influence of raw density on mass loss was detected for larch.     

Dealing with heteroconnections and short tree-ring series at different levels of dating in the dendrochronology of the Southwest German pile-dwellings

Within the field of pile-dwelling research in SW Germany, the application of a dendroarchaeological approach to the study of young wood among large timber series has allowed a better understanding of the short-term development of settlement showing high variations of building activity coupled with varying strategies of timber supply and woodland use. This is illustrated by systematic tree-ring investigations at the Neolithic lake-shore site of Hornstaad-Hörnle I, which have demonstrated an occupation of 20 years around 3900 BC. On specific levels of dendrodating and on the basis of heteroconnections, short alternating building phases with specific choice of timber have been found, showing a wave-like development of the settlement. Repeated short-term repairs also give an estimation of the time spans during which the houses were in use. Furthermore, the timber supply seems to have been based principally on coppicing and the defoliation damages caused by the cyclic development of the cockchafer can be detected in the young oak series. Particularly interesting are the alternating building phases with ash (Fraxinus excelsior L.) on one side, and oak (Quercus robur L./Quercus petraea [Matt] Liebl.) and beech (Fagus sylvatica L.) on the other side. After an initial building phase with ash wood gained from the azonal vegetation, the strong development of the village was accompanied by the systematic use of timber from an oak and beech mixed stand located in the mesophile deciduous forest. In our interpretation, this alternance seems to be linked with a shifting cultivation system at the beginning of the Neolithic lake-shore site occupation at Lake Constance. Oak and beech building phases correspond to a short period of greater concentration of occupation, probably with increasing agricultural activities whereas the use of ash wood gained from the hydrophilous vegetation belt behind the village, occurred in the phases of installation or dissolution of the community. In comparison, later settlement development in the whole region shows a greater stability in the building activity as well as in the woodland use.     

Medieval oak chronology from Klaipėda,Lithuania

Klaipėda is a town in western Lithuania on the Baltic Sea coast. Oak timber was actively used to construct buildings in this town until the 17th century. Archaeological investigations began in Klaipėda’s old town in 1979, but it has not been possible to use oak timbers for dating due to the lack of regional chronologies. The goal of this study was to fill this gap by developing a well-replicated oak chronology from timber collected in Klaipėda between 1979 and 1987. The resulting oak chronology from Klaipėda spans 306 years from 1247 to 1552 and includes 62 oak timber cross-sections. The study suggests that the timber was felled in the same local woodland, and that tree-ring widths series from Klaipėda are temperature-sensitive. The negative pointer years mostly coincide with negative anomalies of reconstructed April‒September temperature from elsewhere in Europe. The constructed chronology was compared with local chronologies (Vilquro, Smarhoń, Gdańsk) and with oak chronologies made from imported oak timber of southeast Baltic origin (Baltic 1–3, Dutch). We assessed whether it is possible to determine the origins of the Baltic 1, Baltic 3 and Dutch oak chronologies compiled from imported timber. Based on available chronologies, it could be hypothesised that Baltic 1 and Dutch chronologies are originated from western Lithuania and Baltic 3 from eastern Lithuania.     

Fungal Endophytic Communities in Healthy and Declining Quercus robur L. and Q. cerris L. Trees in Northern Italy

Healthy and declining English oak (Quercus robur) and Turkey oak (Q. cerris) in north‐western Italy, in a plain oak forest showing decline for oak puzzle disease, were tested to assess possible variations in the composition of their fungal endophytic communities and their relation to the health status of trees. Samples collected in spring (buds) and in autumn (leaves, annual shoots and twigs) were surface‐sterilized, cut into fragments and placed on potato dextrose agar for a month; 26 fungal species were isolated, the most frequent being Tubakia dryina, Dendrodochium sp., Eutypella sp. and a sterile mycelium. Correspondence analysis showed significant qualitative differences between assemblages inhabiting twigs and herbaceous tissues that were due to the low frequency of Tubakia dryina in twigs and its higher frequency in buds, leaves and shoots. Tubakia dryina was isolated more frequently from leaves of declining oaks and from buds of healthy oaks; Monochaetia monochaeta showed a preference for healthy trees, especially leaves and buds. According to the Shannon–Wiener index, endophytic fungal communities of leaves, twigs and buds of declining English oak were poorer than those of declining Turkey oak, but there were no significant differences between healthy hosts.     

Characterisation of husk rot in macadamia

The causal agent of husk rot of macadamia is often attributed to Colletotrichum gloeosporioides sensu lato. However, in recent husk rot outbreaks, the characteristic concentric ring of pycnidia of C. gloeosporioides that is associated with the disease was often absent. Due to its sporadic occurrence, the importance of husk rot is often underrated and attributed to environmental and physiological factors. In order to determine the significance, prevalence and factors that influence husk rot in macadamia, this study examined the aetiology of husk rot in Australia. The relative incidence and severity of husk rot was evaluated in several macadamia orchards over eight consecutive years. Pathogenicity assays were developed to confirm the identity of the causal agent. A range of fungi from several genera including: Diaporthe, Lasiodiplodia, Colletotrichum, Pestalotiopsis, Aspergillus, Alternaria, Nigrospora and Epicoccum were isolated from samples of macadamia pericarps with husk rot symptoms from different orchards. Fungi in the genus Diaporthe were most frequently isolated, often from symptomatic fruit. Results from pathogenicity trials showed the characteristic soft or spongy black lesions characteristic of husk rot symptoms in wounded fruits that were incubated with the diseased fruit or inoculated with a conidial suspension of Diaporthe spp. Our results suggest that injury to the macadamia fruit pericarp not only predisposes the pericarp to pathogen infection but it is a prerequisite for infection. Large variations in husk rot severity were observed over years. Husk rot severity was linked to days after anthesis and was associated with mean weekly relative humidity and minimum temperatures. This study confirmed that Diaporthe species cause husk rot in macadamia, hence, a rationale for adopting Phomopsis husk rot as the name of the disease is discussed.     

Reconstructing the oaks’ growth patterns in Greece with the use of historical timber: Case studies from Western Peloponnese

Southern Greece is a region where available oak reference chronologies are still missing, making dendroarchaeology and dating of historical buildings rather challenging, if not impossible. In the current study we performed wood identification and dendroarchaeological analysis on timber from three historical buildings: the castles of Androusa and Koroni and the Church of Agios Dimitrios, in Western Peloponnese. The three monuments represent buildings of different uses covering different periods, but also sharing a common characteristic: oak was the only timber used in their construction, while the number of preserved timber elements is very limited. A dendroarchaeological examination of these three historical buildings, together with radiocarbon and wiggle-matching analysis, provided valuable chronological information for the local archaeologists, historians, and other scientists. Application of dendrochronological techniques has helped place the three buildings under study into the Ottoman period. Our results also show that timber was acquired most probably from local non-managed forests, which suggests that oak forests were present in the broader area at least from the late 15th to the first half of the 18th centuries. The discordance between dendrochronological and radiocarbon dates in one of the three cases highlights the need for further exploration of the study area through a combined implementation of both dendrochronological and radiocarbon dating analyses in order to develop well-replicated local oak chronologies. Our study also shows that dendroarchaeology can contribute significantly to the cultural and landscape history of Western Peloponnese even with an examination of limited number of preserved timber elements from historical buildings.     

Isolation and evaluation of a Bacillus methylotrophicus strain for control of corn stalk rot

Bacteria were isolated from corn plants and efficacy of a selected isolate for control of corn stalk rot caused by Fusarium graminearum was evaluated. The bacterial isolate provided the greatest suppression of F. graminearum in lab studies and reduced corn stalk rot significantly in 2013 and 2014 field experiments.     

Microsatellite markers for northern red oak (Fagaceae: Quercus rubra)

We provide primer sequences for 14 (GA) _n microsatellite loci developed from northern red oak, an important timber species. We screened loci using two sets of samples. A parent–offspring set included DNA from seven acorns collected from one mother tree along with maternal DNA, to determine that all progeny carried a maternal allele at each locus. The other set was comprised of 10 adult trees sampled from Indiana old‐growth forest, providing a measure of diversity revealed by each locus.     

Fungi Associated with Foot Rots on Winter Wheat in Northwest Italy

In a 3-year survey on bread and durum wheat grown in Northwest Italy, brown root rot was the most important disease of the basal part of culm. Year, wheat-growing area, cultivar and their interactions significantly influenced brown root rot incidence. The most important fungal species isolated from lower stems with browning were Microdochium nivale, Drechslera sorokiniana, Fusarium avenaceum, F. graminearum, and F. culmoniliforme, and Pythium spp. were frequently isolated. F., crookwellense was also isolated. Sharp eyespot was a frequent disease; take-all and eyespot occurred only occasionally.     

Botryosphaeria spp. isolated from apple and several deciduous fruit trees are divided into three groups based on the production of warts on twigs, size of conidia, and nucleotide sequences of nuclear ribosomal DNA ITS regions

We examined the phytopathological and biological characters ofBotryosphaeria spp. isolated from apples and other deciduous fruit trees, and determined the nucleotide sequences of their rDNA ITS regions. TheBotryosphaeria isolates from deciduous fruit trees can be divided into three groups based on their production of warts on twigs, size of the conidia, and nucleotide sequences of rDNA ITS 1, ITS 2 and 5.8S rDNA. Isolates ofBotryosphaeria in ITS group A produced conidia of intermediate size and showed warts on infected twigs prior to the development of ring rot on fruit. This group was common on deciduous fruit trees in Japan as a causal agent of ring rot and wart bark diseases of apples and pears; and it appears similar to theB. dothidea from the US that was isolated from apple exhibiting white rot. The ITS group BBotryosphaeria produced small conidia and induced shoot blight without wart development prior to the development of ring rot on fruit. This group was localized on pear, persimmon, and kiwi fruit in restricted areas of Japan. The ITS group CBotryosphaeria consisted ofB. obtusa, the causal agent of apple black rot in the US, which produced large dark brown conidia.     

Root rot disease incidence and severity on some legume species grown in Samsun and the fungi isolated from roots and soils

Abstract

Root rot disease is very common in the bean, soybean, faba bean and pea plants growing areas in Samsun province. Disease incidence and severity were detected the highest at 93.8% and 55.4% in the bean growing area, and the lowest at 64.0% and 24.3% in the faba bean growing area respectively. In this study, a total of 2714 fungal isolates were obtained from some legume plants and soil samples. The most common fungi isolated from root and soil samples were Fusarium spp., multinucleate Rhizoctonia (MNR), binucleate Rhizoctonia (BNR) and Pythium spp. respectively. Fusarium spp. were isolated at high rates from all the examined areas. MN Rhizoctonia and BN Rhizoctonia were isolated both from inner and coastal areas of the province, whereas Pythium spp. were isolated in costal areas, except for the Vezirköprü district which is situated in the inner area. When looking at the interactions among pathogens causing root rot, it was found the great majority of the samples (30.4%) isolated both Fusarium spp. and MNR-BNR group fungi, whereas Fusarium spp. and Pythium spp. were isolated together from 10.9% of the samples and MNR-BNR and Pythium spp. from only 1.5% of the samples.     

<Emphasis Type="Italic">Sporothrix inflata</Emphasis>, a root-inhabiting fungus of <Emphasis Type="Italic">Quercus robur</Emphasis> and <Emphasis Type="Italic">Q. petraea</Emphasis>

The anamorphic fungus Sporothrix inflata, known as a soil-borne fungus with worldwide distribution, was isolated for the first time from the cortex and central cylinder of living and dead roots of healthy and diseased oak trees (Quercus robur and Q. petraea). Isolation frequencies of S. inflata from oak roots varied according to the health status of trees, oak species, study sites, soil depth and root diameter. Colony morphology and growth rate of isolates are influenced by colony age and type of culture medium.     

Sarcodontia pachyodon: a Canker and White‐rot Agent of Plane‐trees

Some lignivorous hymenomycete fungi are capable of causing both cankers and decay in stemwood of adult trees. Recently in Tuscany (Italy), Platanus x acerifolia trees were found colonized by Sarcodontia pachydon (Polyporales, Meruliaceae), a fungus associated with white rot and stem cankers on different host tree species. Because the relationship S. pachyodon‐plane‐tree was only preliminary studied, we decided to investigate whether isolates obtained from this host are distinct from those commonly collected from oaks. For this purpose, isolates obtained from plane‐tree and from holm oak (Quercus ilex) were compared by in vitro test and molecular markers. Results showed that fungal isolates did not differ in growth nor in wood degradation, also molecular tests revealed relative similarity among fungal samples.     

Boxes mimicking tree hollows can help conservation of saproxylic beetles

Old hollow trees have declined in Europe and many saproxylic (i.e. wood-dwelling) invertebrates living on them are threatened. The aim of this study was to investigate to what extent artificial habitats can be exploited by saproxylic beetles. To mimic the conditions in tree hollows, we constructed wooden boxes filled with different combinations of substrates like oak saw dust, oak leaves, a dead hen (Gallus domesticus), chicken dung, lucerne flour or potatoes and placed them on tree trunks. To investigate the importance of distance from dispersal sources, we placed boxes at different distances (0–1,800 m) from three species-rich sites with high densities of hollow oaks. Over 3 years, 3,423 specimens of 105 saproxylic beetle species were caught in 47 boxes. Among beetles found in hollow oaks that were either tree-hollow species, bird nest species, or wood rot species, 70% were also found in the boxes. A dead hen added to the artificial wood mould gave a higher number of beetle specimens. The number of species associated with tree hollows in oak decreased with distance from sites with hollow oaks. In conclusion, the prospects for using artificial environments for boosting substrate availability, or to fill spatial and temporal gaps therein, for saproxylic beetles are good.     

Isolation and Pathogenicity of Rhizosphere Fungi of Cocoyam in Relation to Cocoyam Root Rot Disease

Cocoyam is the second most important staple crop of Cameroon and root rot is a destructive disease of this plant. Pythium myriotylum (Pm), Fusarium solani (Fs), and Rhizoctonia solani (Rs) were isolated from the rhizosphere of root rot affected cocoyams and from the soil of a cocoyam experimental field plot temporarily devoid of same in Mamu, Cameroon. Pm was isolated from the above soil by the cocoyam leaf disc baits. Fs and Rs were also isolated from the same soils by the water dilution method and from the roots of diseased cocoyams but were always associated with mycelial growth of Pm. Pathogenicity of Pm and in combinations with Fs or Rs or Fs + Rs all developed cocoyam root rot disease (CRRD) symptoms on 3– and 7–month old cocoyam plantlets 2–7 days after inoculation. Symptoms included rotted roots and wilting with general chlorosis of inoculated plantlets. No symptoms of CRRD were noted on cocoyam plantlets inoculated with Fs, Rs, Fs + Rs, and distilled water. Results indicated that CRRD is not caused by several pathogens but only by Pm. Pm isolates from the soils and roots of diseased cocoyams and those maintained in the ROTREP laboratory have significantly bigger diameter of mycelial colony growth in 24 h–period at 31 °C on lima bean sucrose agar, V–8 juice sucrose agar, and potato sucrose agar than on potato dextrose agar and 2 % water agar. The cocoyam plantlets were raised axenically from tissue culture of explants in the laboratory.     

Isolation and Phylogenetic Analysis of <Emphasis Type="Italic">Xylella fastidiosa</Emphasis> from Its Invasive Alternative Host,Porcelain Berry

A strain of Xylella fastidiosa was isolated from an invasive alternative host species, porcelain berry. Its genetic relationship with strains isolated from a native alternative host, wild grape; a nonnative alternative host, mulberry; and other economically important hosts including cultivated grape, peach, plum, oak, maple and oleander was determined by using sequence analysis of the 16S–23S rRNA intergenic spacer region. Our phylogenetic analysis revealed that the porcelain berry strain is most closely related to the wild grape strain. These two strains are more closely related to the oak, peach, and plum strains than to the mulberry and oleander strains. They are separated from the maple and cultivated grape strains. Our data suggest that suppression of porcelain berry, wild grape, and mulberry in the vicinity of susceptible economically important hosts such as oak, peach, and plum may provide an important control measure for diseases caused by X. fastidiosa.     

Biological control of postharvest fungal rot of yam (<Emphasis Type="Italic">Dioscorea</Emphasis> spp.) with<Emphasis Type="Italic">Bacillus subtilis</Emphasis>

The potential of isolates of Bacillus subtilis from yam farm soil to control rot of yam in storage barns was investigated. Yam tubers inoculated in vivo with B. subtilis showed no rot while those inoculated with Aspergillus niger, Botryodiploidia theobromae or Penicillium oxalicum showed considerable rot. The set of yams in which B. subtilis and the fungi were simultaneously inoculated produced rot whereas those in which B. subtilis was inoculated a day before the fungi was inoculated were totally reduced or free of rot. Many fewer fungi were isolated from the surface of tubers treated with B. subtilis than from the untreated (control) and there was high recovery of B. subtilis (99–100%) throughout the period of storage. Rot build up was faster in uninoculated control tubers or those inoculated with a spoilage fungus, while those treated with the antagonist were totally reduced or free of rot. The culture filtrate of B. subtilis prevented spore germination in some spoilage fungi. The importance of this study in relation to farmers in developing countries is discussed.     

A new species of <Emphasis Type="Italic">Phellinus</Emphasis> sensu stricto associated with esca on grapevine in South Africa

A new species of Phellinus sensu stricto was isolated from diseased Vitis vinifera in the Northern Cape and Limpopo provinces of South Africa. Phellinus resupinatus is described here based on fruit body morphology, internal transcribed spacer (ITS) and large subunit (LSU) phylogenies. Phellinus resupinatus forms a well-supported clade closely related to Phellinus bicuspidatus, a species associated with white rot in oak trees in the United States. Morphologically, P. resupinatus is characterised by its resupinate fruit body shape, straight, ventricose hymenial setae and broadly ellipsoid hyaline basidiospores. It has been isolated from esca-diseased grapevines in the summer rainfall regions of South Africa and is found on the uppermost trunks of declining vines showing symptoms of white rot.     

Epidemiology of Maize Root Rot in South Africa

Maize roots were rapidly infected by soil inhabiting fungi as soon as they differentiated. The first tissues to develop were the seminal roots and mesocotyls. As their function became superseded by that of the adventitious roots, they rapidly became, completely rotted. Adventitious root rot developed slower and the roots did not become as severely rotted. Numerous fungi were isolated from the roots. The most frequently isolated were Helminthosporium pedicellatum and Fusarium moniliforme. Trichoderma sp. was the next most frequently isolated fungus; it was, however, significantly less frequently isolated than the above. Young and Kucharek (1977) found that the fungi isolated from maize roots occur in communities associated with certain plant growth stages. This was not clearly evident in this study. Numbers of root lesion nematodes (Pratylenchus species) correlated non-significantly with fungus frequencies and root rot.