Fomes annosus (Fr.) Cke. und andere Stammfäulepilze in einem Douglasienbestand,Pseudotsuga menziesii (Mirb.) Franco1

Fomes annosus (Fr.) Cke. and other decay fungi in a Douglas fir stand, Pseudotsuga menziesii (Mirb.) Franco. 40% of the trees in a 40 years old Pseudotsuga menziesii stand showed butt rot. 85 trees were analysed for decay fungi. Fomes annosus, the most frequent fungus, also invaded the sap wood. Factors of the soil favourable to the rot and the possibility of transmission of the most frequent decay fungus, Fomes annosus, from (a) neighbouring spruce stands, (b) from the roots of Scots pine from the previous crop arc discussed. Caniophora puteana was isolated from about 10% of the butt rots. The importance of Calocera viscosa which grew out of the central decay of twelve trees as a decay fungus is still under investigation.     

Stamm- und Wurzelfäulen in Douglasien,Pseudotsuga menziesii (Mirb.) Franco1

Stem and root rot of Douglas fir, Pseudotsuga menziesii (Mirb.) Franco. In 20 year old Douglas fir most of the butt rot was caused by Fomes annosus. Stem decay was central as well as eccentric reaching the sap wood in either case. The side roots of 20 year old Douglas fir were compared with those of a 40 year old stand with butt rot. In individual trees with decay there were less roots with Fomes annosus decay in the younger stand. Calocera viscosa was more abundant in the older stand. Soil conditions which might have favoured root rot in the young stand are discussed.     

Stammfaulen in Douglasien-, Kiefern-, Fichten-Mischbestanden1

Butt rot in mixed conifer stands. 70 years old Pseudotsuga menziesii trees on sandy soil, grown together with Pinus syhestris, Picea abies, Fagus sylvatica were analysed for butt rot. 73 % resp. 70 % of the Douglas fir, 13% resp. 28% of the Scotch pine and 82% resp. 84% of the Norway spruce showed decay. The most frequent fungi in Pseudotsuga were Heterobasidion annosum, Calocera viscosa, Sparassis crispa, in Pinus Sparassis crispa and in Picea Heterobasidion annosum. In a neighbouring stand with 85 years old Pseudotsuga menziesii - more often thinned than the 70 years old stand - only 23 % of the trees were with decay.     

Butt rot ofChamaecyparis obtusa (Sieb. et Zucc.) Endlicher trees caused byPerenniporia subacida in Shikoku district, Japan: Pathogen, distribution of damaged trees in the stand, and soil investigation

The rot ofChamaecyparis obtusa (hinoki) trees was studied in the northern part of Kagawa Prefecture, Japan. Among 158 hinoki examined, butt rot was found in 28.6, 58.3, and 100% of trees in the 29, 30, and 34-year-old stands, respectively. All trees with butt rot, and 11 trees without it had rotted roots. Thirteen hinoki were peeled byCervus nippon (sika deer) and all of them were infected with butt rot. The maximum height of rot in deer-damaged trees was 2.6 m from the ground level, but was 1.9 m in undamaged trees. About eighty-two percent of rotted trees showed rotted areas of less than 40 cm² on the cross section of stems at the ground level. White mycelia and black flecks sometimes appeared in the rotted wood. Basidiocarps of polyporaceous fungus were often found on felled logs and rotted stumps of hinoki and identified asPerenniporia subacida. Basidiomycetous fungus was isolated frequently from rotted wood of roots and stems, and determined to beP. subacida by comparative study on cultural characteristics. An inoculation experiment and wood-decay test proved that the fungus was the cause of the rot of hinoki. Few absorbing roots of living trees were found in the clayey subsurface soil of the high dry bulk density and the less soil aeration. Some absorbing roots had root rot and the rot spread from the base of the absorbing root to the central part of the woody root. This is the first report on the rot of hinoki caused byP. subacida in Japan.     

Serpula himantioides,Heterobasidion annosum and Calocera viscosa as butt rot fungi in a Danish Douglas‐fir stand

A scattered wind fall of 50 trees in a 46‐year‐old stand of Douglas‐fir (Pseudotsuga menziesii) revealed Serpula himantioides, Heterobasidion annosum and Calocera viscosa as decay causing fungi. Sixty‐four percent of the stumps had visible rot on the stump surface. Mainly, a central brown rot was seen, caused by either S. himantioides or C. viscosa combined with eccentrically placed spots of incipient H. annosum rot. Subsequently, the appearance of fruitbodies disclosed that in total 76% of the wind thrown trees were associated with one or more of the three decay fungi. S. himantioides was present in a surprisingly large number of trees (54%), and the rot column extended up to 2 m into the stem. This investigation represents the first known incidence of S. himantioides and C. viscosa causing root and butt rot in living conifers in Denmark.     

Lesion formation and host response to infection by Armillaria ostoyae in the roots of western larch and Douglas‐fir

The process of lesion formation and host response to natural infection by Armillaria ostoyae were studied in the roots of western larch (Larix occidentalis) and Douglas‐fir (Pseudotsuga menziesii ssp. glauca) trees in the three age classes, 6–8, 18–19 and 85–95 years. The characteristics of lesions on infected roots were recorded and bark samples were dissected from infection points and lesion margins in the field and stored in liquid nitrogen for macroscopic study in the laboratory. Infection in the roots of 6‐ to 8‐year‐old trees advanced freely, overcoming any host resistance, quickly girdling the root collar and killing the trees. In 18‐ and 19‐year‐old trees, however, 43% of infections on western larch and 27% of the infections on Douglas‐fir roots were confined to lesions bounded by necrophylactic periderms with multiple bands of phellem. Host response was similar in 85‐ to 95‐year‐old trees, but the percentage of confined lesions was higher than in younger trees. The results suggest that larch shows resistance to A. ostoyae at a younger age and with greater frequency than Douglas‐fir.     

Traumatic resin canals as markers of infection events in Douglas‐fir roots infected with Armillaria root disease

In response to an infection, traumatic resin canals (TRCs) are formed in the roots of many conifers, which may be used to determine the timing and sequence of infection events essential for epidemiological studies of root diseases. Juvenile Douglas‐fir (Pseudotsuga menziesii) tree roots at coastal and interior sites in British Columbia were wounded at various times of the year or were inoculated with an isolate of Armillaria ostoyae, and root sections were taken to determine the timing and extent of TRC formation. Naturally infected Douglas‐fir were also examined to determine the extent of the TRCs in infected and uninfected roots on infected trees and in the lower stem. Wounds made in March and October had poor or no TRC formation while the summer wounds responded strongly and were associated with resin soaking. Roots wounded in October did not respond until the following year in all trees except one. Trees produced TRCs and resin soaked tracheids at all times in response to the fungal inoculations. The most striking difference between wounding or fungal inoculation was the multiple bands of TRCs produced in response to the fungus. TRCs at natural A. ostoyae infections were found 92% of time in roots at the stem junction and 74% of the time in the stem at soil line. TRCs were produced in uninfected roots on infected trees but disappeared with increasing distance from the initiating lesion. TRCs can be used to time yearly and seasonal root infections when they can be traced from an identified lesion.     

Polyporus schweinitzii Fr. und Sparassis crispa (Wulf. in Jacq.) ex Fr. als Fäuleerreger in einem Douglasienbestand (Pseudotsuga menziesii (Mirb.) Franco) mit hohem Stammfäuleanteil1

Polyporus (Phaeolus) schweinitzii and Sparassis crispa as frequent decay fungi in Douglas fir. Of fifty, 55 ears old trees in a Pseudotsuga menziesii stand. 90% showed decay of the heart- wood of the butt. The possibility of transmission of the most frequent decay fungi, P. schwei- nitzii and S. crispa, which also are frequent parasites in the roots and butts of pine, from the roots of the Pinus sylvestris trees of the previous crop into the roots of the Douglas fir is discussed. A first identification of the fungi was made possible by storing the stem discs under moist conditions. The mycelia of P. schweinitzii and S. crispa grew out of the decayed wood and possessed a characteristic form and colour.     

Early root development of poplars (Populus spp.) in relation to moist and saturated soil conditions

Poplars (Populus spp.) are among the fastest growing trees raised in temperate regions of the world. Testing of newly developed cultivars informs assessment of potential planting stock for local environments. Initial rooting by nine poplar clones was tested in moist and saturated soil conditions during an 18-day greenhouse experiment. Clones responded differently to soil moisture, particularly in number of roots, root distribution, and root dry mass accumulation. About 73% of cuttings planted in moist soil produced roots from callus tissue, whereas only 1% of cuttings planted in saturated soil developed such roots. This drove root distribution towards the basal section of cuttings in moist soil, while in saturated soil roots were more evenly distributed among all three below-ground sections of cuttings. Roots originating from the basal section of cuttings planted in moist soil were longer than roots originating from apical and middle sections. Conversely, roots from the apical and middle sections of cuttings planted in saturated soil were longer than those originating from the basal section. Initial rooting among poplar clones established under two soil moisture regimes has implications for genotype deployment in the field, but long-term effects in the field are still unknown.     

Tinctoporellus epimiltinus,a causal fungus of butt rot of Japanese cypress

One of the causal fungi of butt rot of Chamaecyparis obtusa in Kyushu Island, Japan, was identified as Tinctoporellus epimiltinus from cultural characters, and by mating and inoculation tests. The cultural characters of the isolates obtained from butt rot of C. obtusa and T. epimiltinus isolated from the basidiocarp tissue and from decayed wood were examined. The morphological characters and chemical reactions of the isolates from butt rot were typical for T. epimiltinus. Di‐mon mating tests were performed between five monospore isolates of T. epimiltinus and five heterokaryotic isolates from the butt rot. All of the monospore isolates examined were heterokaryotized by the isolates from butt rot. Tinctoporellus epimiltinus isolates were inoculated on roots of 24‐year‐old C. obtusa. Butt rot was observed on all inoculated trees 1–2 years after the inoculation, and the inoculated fungus was re‐isolated from the decayed parts of the inoculated trees.     

Controlling and predicting the spread of heterobasidion annosum from infected stumps and trees of picea abies

Two Norway spruce stands with heavy infections of Heterobasidion annosum were clear‐cut in 1957 and 1959 in Sweden. The stumps were extracted, the soil sifted to remove most of the roots, and young Norway spruce were planted. After 25 and 28 years, H. annosum had infected 1 % and 2% of trees on plots where stumps had been removed and 17 % and 12% of the trees on control plots, respectively. Several of the H. annosum clones fruiting on old‐growth stumps were also detected in decayed, standing trees. The same fungal clone was found to be infecting adjacent trees from several old‐growth stumps. In addition to old stumps, stumps from recent thinnings and diseased living trees were traced as infection sources. Their relative importance in spreading disease was estimated. Disease risk predictions based on the distance of a tree from various infection sources correlated well with observed frequencies of rot.     

Root‐colonizing ophiostomatoid fungi associated with dying and dead young Scots pine in Poland

Ophiostomatoid fungi are carried by various bark beetles. However, very little is known about the role of these fungi in conifer roots. We studied ophiostomatoid fungi in roots of dying and dead Pinus sylvestris trees and tested the potential phytotoxicity of some isolates using a sensitive bioassay with Lepidium sativum in Poland. Fungi were identified based on their morphology and DNA sequencing. Three ophiostomatoid fungi, Leptographium procerum, Sporothrix inflata and Ophiostoma pallidulum, were isolated from the roots. The most abundant soil‐borne fungus, S. inflata, and relatively rare O. pallidulum were isolated for the first time from roots of dying and dead pine trees. The frequency of S. inflata and O. pallidulum correlated with tree decline. The fungi were isolated more frequently from roots of dead than dying trees. Sporothrix inflata and O. pallidulum slightly reduced the stem and root growth of L. sativum. Leptographium procerum reduced more significantly root than stem growth. This species reduced root elongation 32–54% after 10–17 days of incubation.     

Signs and symptoms associated with Heterobasidion annosum and Armillaria ostoyae infection in dead and dying mountain pine (Pinus mugo ssp. uncinata)

Symptoms and signs associated with root rot caused by Heterobasidion annosum or Armillaria ostoyae in mountain pines (Pinus mugo ssp. uncinata) were investigated in the Swiss Alps. A sample of dying or recently dead mountain pine trees (≥12 cm d.b.h.) and saplings (<1.3 m height) was assessed for root pathogen infection by taking root samples followed by isolations in the laboratory. From a subsample, an additional core was taken from the butt of each tree and evaluated in the same fashion. A total of 157 dying or recently dead mountain pine trees and 184 saplings with roots infected by either of the two pathogens or which lacked infection were analyzed using logistic regression models. The main objectives were to determine the most prominent symptoms induced by the fungi (resinosis), signs of the fungi (mycelia, fruiting bodies and rhizomorphs), and tree characteristics (d.b.h./height and evidence of wounds) that would allow an easy and reliable determination of H. annosum and/or A. ostoyae infection of mountain pines in the field. Heterobasidion annosum caused both root and butt rot on mountain pine, whereas A. ostoyae was mostly restricted to the root systems of the trees sampled. The most discriminating sign for the presence of A. ostoyae infection was the presence of characteristic mycelial fans, and for H. annosum root rot the presence of H. annosum mycelia (sheets of paper‐thin mycelium and mycelial pustules). In addition, resinosis was a powerful predictor for A. ostoyae in trees. Symptoms and signs indicating A. ostoyae or H. annosum infections were more reliable for saplings than for mature trees. Armillaria rhizomorphs were not useful in detecting A. ostoyae infection and, if present, were often formed by saprophytic Armillaria species. Heterobasidion annosum fruiting bodies were rarely observed and poorly reflected the widespread occurrence of this pathogen in the mountain pine forests.     

Etiology of oak decline in Spain

In different areas of Extremadura, Western Spain, soil samples were taken at the bottom of holm oak (Quercus ilex) trees that were showing decline symptoms. Half of each sample was sterilized, and acorns were sown in both sterilized and nonsterilized soil samples. The resulting seedlings were used as baits for the isolation of fungi. Seedlings growing on the natural, nonsterilized substrate were characterized by having a lower vegetative growth than the ones growing on the sterilized soil samples, and most of them died. Phytophthora dnnamomi was consistently isolated from their roots. Fusarium oxysporum was also isolated as well as different species of Pythium, although to a lesser extent. Pathogenicity tests were performed on holm oak seedlings with five different isolates of P. chinnamomi, with F. oxysporum, Pythium and with a mixture of the three fungi. All the inoculated seedlings with P. chinnamomi developed root rot and grew slowly, and 35.7% of them died up to the end of the experiments. P. chinnamomi was consistently isolated from their roots, indicating that this fungus is the causal agent of holm oak decline. However, F. oxysporum caused similar symptoms on oak seedlings as P. chinnamomi, and was isolated also from the roots, although its frequency was lower than that of. P. cinnamomi.     

Necrophylactic periderm formation in the roots of western larch and Douglas‐fir trees infected with Armillaria ostoyae. I. The response to abiotic wounding in non‐infected roots

The sequence of events leading to necrophylactic periderm formation was studied throughout the year following the abiotic wounding of the non‐infected roots of 10‐ and 27‐year‐old western larch (Larix occidentalis) and 11‐ and 25‐year‐old Douglas‐fir (Pseudotsuga menziesii) trees that were infected with Armillaria ostoyae. The sequence was the same for both ages and species of trees. Wound repair was more rapid in the summer compared with the spring and autumn. Following cell hypertrophy, a zone of lignified impervious tissue was in the initial stages of formation within 10 days of wounding in the summer and 14 days in the spring or autumn. The new phellogen produced a layer of phellem three to four rows of cells thick after 20 days in the summer or 40 days in the spring. Modified cells abutting the inner boundary of the impervious zone frequently developed thick lignified abaxial walls and thin suberized adaxial walls. A typical exophylactic periderm in healthy root bark tissue of both western larch and Douglas‐fir consisted of stone phellem one to four rows of cells thick and a layer of thin‐walled phellem three to six rows of cells thick in western larch and two to three rows thick in Douglas‐fir, a single row of phellogen cells and one to three rows of phelloderm cells. Mature thin‐walled phellem cells had pigmented contents, red in western larch and light brown in Douglas‐fir. In response to wounding, 27‐year‐old western larch and 25‐year‐old Douglas‐fir developed necrophylactic periderms with annual bands of phellem. The bands included a layer of phellem that was six to 12 and nine to 15 rows of cells thicker than the layer of phellem observed in the respective naturally developed exophylactic periderms. Fifty days following wounding in the summer, stone phellem, one to three rows of cells thick, was observed in the necrophylactic periderm of 10‐year‐old trees. When fully developed, the necrophylactic periderm in 27‐year‐old western larch also had a layer of stone phellem three to five rows of cells thick in each band. Stone phellem development was only sporadic in 25‐year‐old Douglas‐fir. Wounds in the winter showed no signs of activity associated with repair until dormancy broke in the spring.     

Determination of growth loss of Pinus taeda L. caused by Heterobasidion annosus (Fr.) Bref.

The root system of 350 loblolly pine trees in 14 plots were excavated utilizing a bulldozer and evaluated according to the annosus root rot (Heterobasidion annosus) symptom expression of the roots, i. e. resin soaked and stringy. The annual increments of the healthy (<1% colonized) and diseased (<1% colonized) groups of trees were compared for each of the last five years growth. There was a significant growth difference between healthy and diseased trees for each of these last five years at about 4% per year or about 19% for the five year total.     

Epidemiology of Armillaria root disease in Douglas‐fir plantations in the cedar‐hemlock zone of the southern interior of British Columbia

Results are presented from several studies on the epidemiology of Armillaria ostoyae in Douglas‐fir plantations in the interior cedar‐hemlock (ICH) biogeoclimatic zone of British Columbia. Two plantations were monitored for mortality by A. ostoyae and other agents for 35 years after establishment. In these and other plantations ranging in age from 7 to 32 years, one or more of the following factors were determined: source of inoculum, mode of spread and characteristics of lesions on roots of excavated trees; symptom expression in relation to tree age and damage to the root system and years from initial infection to death on trees killed by the fungus. Mortality from A. ostoyae began in both plantations about 5 years after planting, reaching 30% in one and 11% in the other after 35 years. The spatial pattern of mortality was similar to that reported from New Zealand, France and South Africa; however, the temporal pattern differed, beginning later and, instead of declining, continuing at a nearly constant rate to the present. To age 10, nearly all infections were initiated by rhizomorphs; as plantations aged, the proportion of infections occurring at root–root contacts increased. In seven plantations, in moist and wet subzones of the ICH, from 23 to 52% of Douglas‐firs had root lesions, with the higher incidences occurring on moist sites. The occurrence of aboveground symptoms, reduced leader growth and basal resinosis, was related to the percentage of root length colonized by A. ostoyae on trees with more than 30% of root length killed. Average time from infection to death increased from 1 to 2 years at age 6 to 22 years at age 33. The outlook for timber yield from Douglas‐fir plantations in the cedar‐hemlock zone is discussed. Management alternatives for reducing damage from A. ostoyae when regenerating sites are reviewed.     

Necrophylactic periderm formation in the roots of western larch and Douglas‐fir trees infected with Armillaria ostoyae. II. The response to the pathogen

Periderm formation was studied in bark samples collected from the roots of western larch (Larix occidentalis) and Douglas‐fir (Pseudotsuga menziesii) trees infected with Armillaria ostoyae. Necrophylactic periderms were formed in advance of infection and successfully restricted continued fungal spread in 68 and 45% of the samples collected from 10‐ and 27‐year‐old western larch, respectively. However, all periderms formed in 11‐ and 25‐year‐old Douglas‐fir had been breached by the advancing fungus. In both species, necrophylactic periderms were commonly breached at the junction of the periderm with the vascular cambium. In western larch, stone phellem often comprised the external phellem layer of necrophylactic periderms with multiple bands of phellem. In 27‐year‐old western larch, infection was often confined to discrete lesions bounded by multiple periderms with multiple bands of phellem. In both tree species, phellem production was greater in response to infection than in response to abiotic wounding.     

Fine-root dynamics of coffee in association with two shade trees in Costa Rica

Fine-root dynamics (diameter < 2.0 mm) were studied on-farm in associations of Coffea arabica with Eucalyptus deglupta or Terminalia ivorensis and in a pseudo-chronosequence of C. arabica-E. deglupta associations (two, three, four and five years old). Coffee plants were submitted to two fertilisation types. Cores were taken in the 0–40 cm soil profile two years after out-planting and subsequently in the following year in depth layers 0–10 and 10–20 cm, during and at the end of the rainy season, and during the dry season. Fine root density of coffee and timber shade trees was greater in the coffee fertilisation strip as compared to unfertilised areas close to the plants or in the inter-rows. Coffee fine roots were more evenly distributed in the topsoil (0–20 cm) whereas tree fine roots were mostly found in the first 10 cm. Although the two tree species had approximately the same fine root length density, lower coffee / tree fine root length density ratios in T. ivorensis suggest that this shade tree is potentially a stronger competitor with coffee than E. deglupta. Coffee and tree fine root length density for 0–10 cm measured during the rainy season increased progressively from two to five-year-aged associations and coffee fine root length density increased relatively more than E. deglupta fine root length density in the four and five-year-aged plantations suggesting that contrary to expectations, coffee fine roots were displacing tree fine roots.     

Root recovery rates for Phytophthora cinnamomi and rate of symptom development from root rot on Abies fraseri trees over 7 years

Phytophthora root rot on Abies fraseri trees was monitored from 2001 to 2007 within the disease front of a 12‐year‐old Virginia plantation where trees had been dying of the disease since 1994. After a slow increase in early foliage symptom development from July 2001 to September 2002, the frequency of A. fraseri trees with early symptoms accelerated for about 15 months. While the slow increase occurred during a 18.7% lower than normal rainfall period and the acceleration occurred during a 31.2% higher than normal rainfall period, the percentage of trees with early symptoms continued to increase during the mid‐winter months (December–February) when the estimated mean minimum daily soil temperature (25 cm depth) was unfavourable (<10°C) to Phytophthora cinnamomi pathogenic activity. The time required for trees to progress from early foliage symptoms to completely dead foliage, from November 2000 to October 2007, was highly variable, ranging from 4 to 35 months. Root recovery rates for P. cinnamomi, assayed on a selective medium, were 6.4 times greater for symptomatic foliage trees than for asymptomatic foliage trees in this deep, silt‐loam soil. Following an atypical cold period in February 2007, when the mean minimum daily soil temperature was 0.8°C, symptomatic roots yielded only a low level of germinable propagules of P. cinnamomi. Further, during an atypical midsummer in 2007 (June–August), when the soil water potential was at or below ?9 bars for 68 of 92 days, symptomatic roots yielded no germinable propagules of P. cinnamomi. Addition of thiophanate‐methyl to the selective medium aided P. cinnamomi isolation by inhibiting many undesired pythiaceous colonies growing from symptomatic roots.