Differences in composition of endophytic mycobiota in twigs and leaves of healthy and declining Quercus species in Italy

The composition of the endophytic fungal assemblages in Quercus cerris, Q. pubescens and Q. robur, three oak species most susceptible to decline, was investigated in Fagarè (Padova), Ulignano (Pisa), and Radda in Chianti (Firenze). The endophytic assemblages were studied as a function of health status of the whole tree and of twigs and leaves. The effect of station altitude was tested on Q. cerris. Samples were gathered from healthy and declining trees. In April (bud opening time) 20 twigs and 10 leaves were collected from each tree. Fungi were isolated from twig segments and leaf portions. A total of 23 fungal genera with 27 different species were isolated, in addition to a few sterile mycelia. Eleven species were found to be common to all three oak species, while other species were found only on one oak species, suggesting host specificity. Among the fungal species isolated, some were known to be pathogenic (Apiognomonia quercina, Colpoma quercinum, Diplodia mutila, Phomopsis quercina). The colonization frequency (CF) of pathogenic species varied between 0.9% for A. quercina in Q. cerris and 60.2% for P. quercina in Q. robur. Analysis of variance showed a statistically significant difference among the oak species tested. The CF was higher in declining trees in comparison with healthy trees, and also in twigs vs. leaves. The CF was found to be higher for Q. cerris trees growing at sea level as compared with those situated at an elevation of 350–400 m. In stands where, on account of particular ecological conditions, pathogenic behaviour is displayed simultaneously by more than one endophytic fungal species, trees accentuate their decline.     

The effect of bagging branches on levels of endophytic fungal infection in Japanese beech leaves

The species composition of the endophytic mycobiota in leaves of Japanese beech trees (Fagus crenata) and the sources for leaf infections were studied in a forest reserve situated in central eastern Honshu, Japan. To clarify the mechanism of infection of leaves, half of the branches were covered with polyethylene bags and species composition and levels of endophytic fungal infection were then compared with those of unbagged controls. Isolations were carried out from the leaves, petioles, and current‐year twigs of both, bagged and unbagged branches. Additionally, species composition was detected in overwintered terminal buds of beech trees and in the leaves of potted seedlings that had been placed in the field in different seasons. The species assemblage of the unbagged leaves, petioles, and current‐year twigs was dominated by Mycosphaerella buna, Ascochyta fagi, Periconiella sp., and Tritirachium sp. Other frequently recovered species were Xylaria sp., Phomopsis sp., and Tubakia dryina. Mycosphaerella buna and A. fagi were never isolated from leaves on bagged branches. A. fagi was, however, detected on both bagged and unbagged petioles and current‐year twigs at comparatively low isolation frequencies. The detection of Periconiella sp. on all occasions in both bagged and unbagged leaves was a characteristic feature that differs from those of the other three dominant endophytic fungi. The fungus was also detected without significant differences in bagged and unbagged petioles and current‐year twigs on most sampling dates. Furthermore, Periconiella sp. was isolated from immature twigs inside the bud scales. Tritirachium sp. was frequently detected in unbagged leaves and petioles and in both bagged and unbagged current‐year twigs, and rarely in bagged leaves and petioles, but was never recovered from terminal buds. The results of the potted seedling experiments revealed that all four dominant species had airborne inocula. The infection of leaves by M. buna occurs exclusively by airborne propagules, i.e. ascospores in spring and conidia in autumn. In Periconiella sp. hyphal growth of the fungus from immature twigs inside the buds into the leaf tissues was suggested in addition to infection by airborne inocula. Tritirachium sp. hyphae were suggested to grow from previous‐ to current‐year twigs. Ascochyta fagi was present in the outermost scales of overwintered terminal buds, but no systemic growth of the fungus into the petioles and current‐year twigs was observed. Our technique of covering the branches before new leaves unfolded was effective in preventing infection by airborne inocula of endophytic fungi.     

Discula quercina as a possible causal agent of dieback on oak trees in Iran

During spring and summer of 2016, dieback symptoms including blights of leaves, twigs, and acorns were observed on current year shoots of Quercus infectoria in the Zagros oak forests of Iran. The fungus isolated from damaged tissues was identified as Discula quercina based on both morphological characteristics and ITS sequencing. To fulfil the Koch's postulates, a representative isolate was inoculated onto shoots of Q. infectoria and Quercus libani in both laboratory and forest conditions. Responses of the two oak species to inoculation with D. quercina were examined under laboratory and forest conditions in a completely randomized experiment. Discula quercina was clearly involved in oak dieback, and Q. infectoria was more susceptible than Q. libani to damage by the pathogen. This is the first record of the occurrence and pathogenicity of the fungus Discula quercina on Quercus infectoria. The fungus is considered as an emerging pathogen on oak trees in Zagros forests in Iran. Furthermore, the pathogenicity of the Discula quercina on Q. libani under laboratory and forest conditions increases the potential importance of this pathogen in Zagros forests.     

Decomposition and nutrient release from leaves,twigs and roots of three alley-cropped tree legumes in central Togo

The decomposition of leaves, twigs and roots of two diameter classes (<1.5 mm, 1.5–5 mm) were examined in an alley cropping experiment withGliricidia sepium, Calliandra calothyrsus andSenna sianea in the subhumid savanna of Central Togo using the litterbag technique. The effect of the application of leaves and twigs as mulch or green manure was examined. Gliricidia showed the most rapid mass loss. For all species, leaves decomposed faster than roots. Twigs had the lowest decomposition rate except forCalliandra. The two diameter classes of roots decomposed differently in the three species:Gliricidia fine roots decomposed faster than its coarser root fraction, the coarse roots ofSenna decomposed faster than the fine roots.Termites influenced the mass loss of twigs and roots to varying extents for the different species. In the case of twigs this was markedly influenced by the mode of application: green manure showed more termite frass than mulch.Nutrient release resembled the mass loss patterns of the prunings except for K, which was leached independently from mass loss. The release of the different nutrients was in the order CaGliricidia andSenna seemed to be best for mulch and green manure production at our site.     

Sybassoorte in Suid-Kaapland / SILKY BARK SPECIES IN THE SOUTHERN CAPE

The differences between the leaves and fruit of Maytenus acuminata and Cassine eucleiformis were investigated experimentally. Leaf differences alone are sufficient to distinguish between the two species having the common characteristics of silky threads in the leaves and twigs. Cassine maritimum is the third species in the Southern Cape which possesses the characteristic of silky threads.     

Endophytische Pilze in Blättern und Ästen gesunder und geschädigter Buchen (Fagus sylvatica L.)

Endophytic fungi in leaves and twigs of healthy and diseased beech trees (Fagus sylvatica L.). Endophytic fungi were isolated from surface-sterilized leaves and twigs of healthy and diseased trees. Three fungal species could be isolated frequently: Apiognomonia errabunda, Diaporthe eres and Bisporella sp. D. eres occurred in leaves of healthy trees more frequently, than in those of diseased trees. It has been hypothesized, that less capacity of water and nutrient uptake of diseased trees is responsible for this effect. A mutualistic symbiosis of A. errabunda and D. eres with beech trees is supposed and discussed.     

Antagonism of Acremonium mucronatum towards Diplodia mutila in tests in vitro and in situ

Tests in vitro and in situ showed that both mycelial and conidial suspensions of Acremonium mucronatum were antagonistic for Diplodia mutila, a common pathogen on the apical twigs of declining Quercus cerris, Quercus frainetto, Quercus pubescens and Quercus robur. Antagonism was greater with the mycelium than with the conidial suspensions, and was strongest at a test temperature of 20°C. The results suggest that pathogenicity of D. mutila on declining trees may be significantly reduced by the presence of A. mucronatum.     

Temporal variations in endophytic fungal assemblages of Ginkgo biloba L.

We isolated endophytic fungi from living healthy leaves, petioles, and current-year twigs of Ginkgo biloba L. from April to November 2004 with the objective of identifying the dominant endophytic fungal taxa, and monitoring their occurrence and frequency. A total of 9 fungal taxa were identified to the genus level. Diversity measures inferred from the Shannon–Wiener, Morisita–Horn, and S?rensen indices indicated that leaves and petioles harbored more diverse endophytic fungal assemblages than twigs, and that fungal taxa involved in twigs shared less with those in leaves and petioles. Among the organs, the occurrence pattern of overall endophytic fungi differed significantly, and two taxa, Phomopsis sp. and Phyllosticta sp., were the most frequently isolated and thus regarded as the dominant endophytic fungi. Phomopsis sp. was isolated frequently from twigs (84.8%) but rather few from leaves (16.1%) and petioles (24.3%). Phyllosticta sp. was isolated frequently from leaves (72.9%) and petioles (65.7%) but was never isolated from twigs. Temporal changes in relative frequency of total endophytic fungi tended to differ among sampling dates for all three organs. The occurrence of Phyllosticta sp. in both leaves and petioles was first detected in August and peaked in October. Phomopsis sp. was detected in twigs throughout the growing season. These results suggest that the distribution of the two dominant endophytic fungi was organ-specific and differed within seasons.     

Cultural characteristics and pathogenicity of Pestalotiopsis funerea on Cupressus arizonica

The fungal pathogen Pestalotiopsis funerea principally attacks conifer species, causing necrosis on infected tissues, and sometimes death of plants. The main objectives of this study were to determine optimal in vitro growth conditions for Spanish isolates of P. funerea and to evaluate the virulence of these isolates on Cupressus arizonica under field and laboratory conditions, with the goal of verifying possible correlations between these variables. Eight isolates of P. funerea derived from C. sempervirens, C. arizonica and Quercus pyrenaica were used in the assays. In the growth rate experiment, five culture media (PDA, MEA, WA, PCA and TAKAY medium) and six temperatures (5, 10, 15, 20, 25 and 30°C) were evaluated. In the pathogenicity tests, two different experiments were carried out: (i) laboratory inoculations used 30‐mm‐long twigs of C. arizonica; (ii) in field inoculations, twigs of C. arizonica were inoculated with mycelia through wounds. Four months after inoculation, length of the twigs affected by necrosis were measured. The results suggested that Spanish P. funerea isolates had optimum growth at 25°C on TAKAY medium. The fungus caused substantial necroses on C. arizonica twigs after inoculation in both excised twigs and on adult C. arizonica trees. A positive relationship between inoculations carried out under laboratory and field conditions was found. No clear relationships were found between cultural characteristics and pathogenicity for P. funerea.     

Productivity of deciduous woody and fodder species in relation to air temperature and precipitation in a Mediterranean environment

Productivity and its relation to air temperature and precipitation of 11 deciduous woody fodder species was studied in a semi-arid Mediterranean environment with cold winters in Macedonia, Greece. The species studied included six shrubs: Amorpha fruticosa L., Carpinus orientalis Mill, Colutea arborescens L., Corylus avellana L., Fraxinus ornus L. and Ostrya carpinifolia Scop.; and four trees: Pirus amygdaliformis Vill., Quercus pubescens Wild., Quercus sessiliflora Salish. and Robinia pseudoacacia L., with two accessions, common and spineless. Fodder species were established as one-year-old seedlings in 1987 and studied through 1994. Productivity was measured by clearcutting of the aboveground annual biomass (DM) at the end of each growing season. Samples of biomass were hand separated to determine the grazeable material (leaves and twigs). In addition, monthly values of air temperature and precipitation were correlated with annual biomass through a multiple linear regression analysis. It was found that annual biomass was statistically different among species in all the study years with Robinia being the most productive of all the species tested followed by the other two legumes Colutea and Amorpha. Proportion of grazeable material ranged widely among species and years with an overall mean of 50%. Robinia produced grazeable biomass more than 1000 kg/ha followed by Amorpha and Colutea with about 800 and 700 kg DM/ha, respectively, while all the other species produced less than 500 kg DM/ha. Yearly variation in annual biomass was found to be affected much more by air temperature, especially during the beginning of the growing season (March), than by precipitation. Coefficients of determination (r ²) were found to be high (0.50–0.80) in Amorpha, Pirus, Quercus and Robinia but only in the latter two species they were high enough (>0.70) so that the relations produced can be used for predictive purposes. This revised version was published online in June 2006 with corrections to the Cover Date.     

Fusarium species in declining wild apple forests on the northern slope of the Tian Shan Mountains in north‐western China

Wild apple forests in the Tian Shan Mountains in north‐western China have been adversely affected by an unknown disease in recent years. Symptoms attributed to this disease that affects wild apple trees include xylem browning and dieback which are suggestive of infection by Fusarium species. Therefore, the research team conducted the first survey for Fusarium in the afflicted wild apple forests. Twig samples with symptoms of xylem browning and dieback were collected in the Xinyuan, Gongliu, Yining and Huocheng Counties of Xinjiang Uighur Autonomous Region in China. Based on phylogenetic analyses and morphological observation, sixty strains of Fusarium accounted for 48% of the total number of fungi isolated from samples were subsequently classified into six species including twenty‐four F. avenaceum, seventeen F. solani, ten F. tricinctum, five F. proliferatum, two F. sporotrichioides and two unfamiliar Fusarium sp. 1. The five previously known species of Fusarium were then tested for pathogenicity to leaves and twigs in vitro. The results indicated that all of the species, except for F. tricinctum, can cause obvious lesions on the leaves of host plants and on the twigs of Fuji and wild apple. This is the first report of Fusarium species pathogenicity in Xinjiang wild apple forests, confirming a new host for these pathogens in this study.     

Manipulation of tannins in oaks by galling cynipids

We measured the protein precipitation capacity of tannins in the tissues of Quercus crispula and Quercus serrata galls induced by a cynipid (Trigonaspis sp.) to examine the nutrition hypothesis on gall induction. The protein precipitation capacity was significantly lower in the nutritive tissues of galls, on which the cynipids feed, than in ungalled sound leaves and in the outer gall tissues. In addition, the protein precipitation capacities in the leaves and in the outer gall tissues were significantly larger in Q. crispula than in Q. serrata samples, whereas that of the nutritive tissues did not differ between these oak species. These results suggest that gall induction is one of the adaptations of galling cynipids to host–plant defensive compounds, and support the nutrition hypothesis.     

Experiences with tree fodders in temperate regions of Bhutan

Tree fodders are traditionally used in temperate and subtropical parts of Bhutan and provide approximately 20% of the fodder requirement of the country's livestock. Willow (Salix babylonica), Quercus semecarpifolia and Euonimus spp. were considered the most important species for temperate areas. Crude protein content of willow leaves decreased from 24.8.% in April to 11.3% in October. Bulls' voluntary intake was 77.7, 58.4, and 28.6 g DM/W^0.75 for willow, Popular robusta and Quercus semecarpifolia, respectively. Compared to temperate grasslands under the absence of phosphate inputs, tree fodders have a higher production potential and produce better quality fodder. Tree fodders may complement, but will not replace herbaceous fodder species in temperate areas. Assessment of yield potential in comparison to and in association with herbaceous temperate species is considered the most important research area.     

Über das Auftreten von Splintholznematoden in erkrankten Eichenbeständen Österreichs

Zusammenfassung Aus Ast- und Stammproben erkrankter Eichen aus dem Schadensgebiet Ostösterreichs konnten Splintholznematoden der GattungBursaphelenchus isoliert werden. Ein Schwerge wicht der Befallsdichte war an durchColpoma quercinum (=Conostroma didymum) geschädigten Eichenästen zu verzeichnen. Die Artbestimmung, sowie die Frage der Übertragung und Pathogenität ist Gegenstand weiterer Untersuchungen.

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On the occurrence of sap wood nematods in diseased oak wood stands in Austria

Out of wood samples of twigs and trunks of white oak (Quercus petraea andQ. robur) in Eastern Austria showing oak decline symptoms, sap wood nematods could be isolated. Highest density of nematode attack could be found in twigs inhabited by the fungusColpoma quercinum (=Conostroma didymum).The exact identification of the hematode species, the question of transfer by insect vectors and testing of pathology are to be carried out in the near future.

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Cardamom, mandarin and nitrogen-fixing trees in agroforestry systems in India's Himalayan region. I. Litterfall and decomposition

Litterfall and decomposition were studied in agroforestry systems involving large cardamom (Amomum subulatum) and mandarin (Citrus reticulata) in the Sikkim Himalaya, India. There were stands with N₂-fixing trees (Alnus nepalensis over large cardamom, and Albizia stipulata over mandarin agroforestry) or without them (native non-symbiotic mixed tree species) in both systems. The total annual litter (litter + crop residue) production was higher in the Alnus-cardamom than in the forest-cardamom stand and in the mandarin than in the Albizia-mandarin stand. The ratio of litter production to floor litter was higher in the N₂-fixing stands than in the non-N₂-fixing stands, indicating a faster litter turnover in the former. Tree litterfall occurred throughout the year, but with marked peaks during November to April. Total soluble polyphenolics of fresh litter were higher in N₂-fixing species than in mixed tree species and crops. Half-life values for ash-free mass were shortest in the leaves of N₂-fixing species. N loss was higher from N₂-fixing Alnus and Albizia leaves, whereas P loss was faster and nearly equal in Alnus leaf litter and cardamom residue in cardamom, and Albizia leaf litter and crop residue in mandarin agroforestry systems. The P turnover in N₂-fixing Alnus and Albizia twigs was faster than in the twigs of mixed tree species. The N₂-fixing tree species increased the N and P cycling through production of more above-ground litter and influenced greater release of these nutrients.     

Changes in water status in seedlings of six species in the Fagaceae after inoculation with Raffaelea quercivora Kubono et Shin-Ito

To clarify the differences in susceptibility of six species in the Fagaceae (Quercus crispula, Quercus serrata, Quercus acutissima, Quercus phillyraeoides, Quercus glauca, and Castanopsis cuspidata var. sieboldii) to Raffaelea quercivora, we inoculated this fungus on seven potted 5-year-old seedlings of each species, observed symptom development, and measured xylem pressure potential (XPP) after inoculation. The first death was observed on the 11th day in Q. crispula and on the 56th day in Q. serrata. The number of dead seedlings of Q. crispula and Q. serrata were five and one, respectively, whereas no mortality was observed in the other four species. The XPP of inoculated seedlings in both Q. crispula and Q. serrata decreased after inoculation. In contrast, the XPP of inoculated seedlings of the other four species remained almost the same as in the control seedlings. These results indicate that R. quercivora is pathogenic to Q. crispula and Q. serrata and that the susceptibility of the six Fagaceae species in our study differed among species.     

Leaf dynamics and protein content of six important fodder trees of the western Himalaya

Leaf production, leaf fall, leaf protein and net primary productivity have been reported for 4-year-old fodder trees in the mid-western Himalaya (altitude 1350 m; rainfall 1100 mm). The species include; Grewia optiva, Robinia pseudoacacia and Celtis australis growing in the open and Quercus glauca, Q. leucotrichophora and Ilex odorata growing in the forest. G. optiva, R. pseudoacacia and C. australis showed two distinct periods of leaf flush, and their leaves were short-lived (180 to 360 days) compared with the remaining three species which retained their leaves for more than two years, and had only one flush period during March–April. The open site species showed much higher leaf production, and the leaves contained a significantly (P < 0.05) higher protein content, compared with the forest group. Net primary productivity of G. optiva, C. australis and R. pseudoacacia was significantly (P < 0.05) higher than the forest species, which may be related to their high leaf production and rapid turnover rate of the leaves. The results are useful for management of these species in agroforestry systems.     

Nutritive value of botanical fractions of Moringa oleifera and Moringa stenopetala grown in the mid-Rift Valley of southern Ethiopia

Nutritive value of botanical fractions (leaves, twigs, pods and whole forage) of Moringa oleifera and Moringa stenopetala were evaluated based on chemical composition, in sacco dry matter (DM) degradability, in vitro gas production and in vitro organic matter digestibility. The objective was to characterize the nutritive value of the different morphological fractions in order to determine their potential as alternative sources of livestock feed. The crude protein content (g/kg DM) was highest (P < 0.05) in M. oleifera leaves (361.2) followed by M. stenopetala leaves (334.4) and lowest in M. oleifera twigs (79.1) and M. stenopetala pods (89.2). The fiber (NDF, ADF and ADL) contents were higher (P < 0.05) in the twigs and pods than the leaves and whole forage in both species. The different morphological fractions of both species had high mineral content, although the Na content was low or marginal in most fractions except whole forage and green pods of M. stenopetala. The in sacco DM degradability ranked the morphological fractions in the order of leaves > whole forage = pods > twigs after 24 h of incubation time. The potential degradability (A + B) was highest (P < 0.05) in M. oleifera twigs (97.9 %) and M. stenopetala leaves (98.5 %) and lowest in the pods of both species (64.4–69.5 %) with intermediate values in all other fractions. No significant differences were observed in the instantly fermentable fraction (a) and rate of gas production (c), whereas lower (P > 0.05) insoluble but slowly fermentable (b) and potential gas production (a + b) were recorded in the pods than in the other morphological fractions of both species. The study showed that the different morphological fractions of the two Moringa species are good source of nutrients with high degradability which could be used as potential supplements to low quality tropical roughages.     

Characterization and pathogenicity of six Cytospora strains causing stem canker of wild apple in the Tianshan Forest,China

Cytospora species are capable of causing destructive cankers of stems belonging to a wide range of woody plant species. In severe cases, cankers may lead to dieback of twigs and branches. Little is known about the Cytospora species causing canker disease of wild apple (Malus sieversii) trees in the Wild Fruit Forest Reserve in Tianshan Forest, Xinjiang Uygur Autonomous Region, China. In this study, six Cytospora isolates belonging to two species were isolated from cankerous lesions of wild apple twigs. Based on multi‐locus phylogenetic analysis using three DNA markers (ITS, tef1‐α and tub2) and morphological characterization, these isolates were identified as Cytospora mali and Cytospora parasitica. Temperature trials (15, 20, 25 and 30°C) showed that the optimal growth temperature for six isolates was 25°C. At a variety of temperatures, C. mali isolates tended to grow faster than isolates of C. parasitica, with the C. mali isolate, EGI1 performing better than others with regard to growth rate. Morphological observations showed that these species exhibited a single locule without conceptacles, and the conidia length was 3–5 μm. In vitro inoculation trials of twigs and leaves of M. sieversii seedlings revealed that the C. mali isolates were highly virulent phytopathogenic fungi, whereas the C. parasitica isolates were less virulent. The isolate EGI1 was the most virulent isolate among the six isolates. This paper presents the first report of pathogenic Cytospora spp. of the M. sieversii Tianshan Wild Fruit Forest Reserve of Yili, Xinjiang in China. It will aid in the understanding of how apple tree cankers are induced and provide disease management guidelines for M. sieversii forest conservation.     

Late leaf development in pedunculate oak (Quercus robur): An antiherbivore defence?

Abstract

Two phenological forms of the pedunculate oak co-occur in the same habitats throughout the species range: the early trees (Quercus robur var. praecox) develop leaves up to 5 weeks before the late ones (Quercus robur var. tardiflora). This study tests the idea that late leaf flushing serves as an antiherbivore defence, i.e. late trees, which develop leaves asynchronously with eclosion of folivorous caterpillars, avoid the costs of defoliation, which could offset the costs of a later onset of the growing season. Effects of folivorous caterpillars foraging on oaks were observed in 1998–2006 in remnants of primeval temperate lowland forest preserved in the Bia?owie?a National Park (eastern Poland). Observations covered trough and outbreak years of the major defoliator, the winter moth [Operophtera brumata L. (Geometridae)]. In seven out of nine seasons, including all peak caterpillar years, the amount of frass produced by folivorous caterpillars on late trees (n=8–18) was significantly (up to 7.1 times) lower than on the early ones (n=12–32). Assessment of the degree of defoliation in 2002–2006 showed that the late oaks were visibly defoliated only during a caterpillar peak (2003), while the early trees were affected in all years and in 2003 almost completely lost their leaves. The results confirm the effect of late budburst on lowering herbivore damage, and give support to the idea that late leaf flushing acts as an antiherbivore defence.