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1.
Pinus ponderosa seedlots from eight seed orchards in Western Patagonia, Argentina, were evaluated for the presence of Fusarium species, and isolates obtained were subjected to pathogenicity tests. The following species were isolated: Fusariumoxysporum, Fusarium equiseti, Fusarium verticillioides, Fusarium incarnatum, Fusarium acuminatum, Fusarium graminearum and Fusarium proliferatum. With the exception of F. proliferatum and F. graminearum all Fusarium species were recovered from P. ponderosa seedlings with symptoms of damping‐off. Five Fusarium species were re‐isolated from necrotic roots of seedlings showing chlorosis (F. oxysporum, F. equiseti, F. incarnatum, F. acuminatum and F. verticillioides). High damping‐off losses occurred in Fusarium‐contaminated seed of P. ponderosa and low disease incidence occurred on less contaminated seed. The role of seed‐borne inoculum in disease spread within forest nurseries is discussed. 相似文献
2.
Eastern white pine (Pinus strobus L.) seeds weresown in soil infested with Fusarium proliferatum, rootnecrosis developed on seedling roots, and F. proliferatumwas reisolated from symptomatic roots; thus, demonstrating thatF. proliferatum is pathogenic toeastern white pine seedlings. Soils infested with F.acuminatum or F. sporotrichioides resulted infew diseased seedlings. Seedlings with root rot generally showed reductions inseedling height. All Fusarium species tested wererecoveredfrom rhizosphere soil samples. Three seedlots of Pinusstrobus were examined for Fusarium infestation.Fusarium species were recovered from most seeds in twoseedlots. Fusarium proliferatum and F.sporotrichioides were the predominant species isolated. Additionalspecies not previously reported from P. strobus included:F. acuminatum, F. chlamydosporum,F. equiseti, F. graminearum,F. moniliforme, F. poae, F.polyphialidicum, F. heterosporum, F.sambucinum, and F. semitectum. 相似文献
3.
J. E. Stewart Z. Abdo R. K. Dumroese N. B. Klopfenstein M.‐S. Kim 《Forest Pathology》2012,42(3):220-228
Fusarium species can cause damping‐off and root rot of young conifer seedlings, resulting in severe crop and economic losses in forest nurseries. Disease control within tree nurseries is difficult because of the inability to characterize and quantify Fusarium spp. populations with regard to disease potential because of high variability in isolate virulence. Fusarium isolates were collected from healthy and diseased seedlings of Douglas‐fir (Pseudotsuga menziesii) and western white pine (Pinus monticola) from a nursery in Idaho, USA. Molecular markers such as DNA sequences (mitochondrial small subunit and nuclear translation elongation factor 1‐alpha) and amplified fragment length polymorphism were used to identify isolates as either F. oxysporum or F. commune. In addition, diagnostic primers were developed to detect and distinguish F. commune from F. oxysporum. In vitro and greenhouse virulence tests were completed on Douglas‐fir germinants and seedlings. For Douglas‐fir germinants and seedlings, F. oxysporum isolates generally caused less severe symptoms, whereas most F. commune isolates caused mortality through damping‐off. This is the first report of direct evidence that F. commune can cause damping‐off disease on Douglas‐fir seedlings under greenhouse conditions. 相似文献
4.
We examined the influence of nursery soil cover on germination of Thujopsis dolabrata var. hondai. Seeds were sown under seeding bed conditions: (1) nursery soil (andosol) without soil cover, (2) Kanuma pumice without soil
cover, (3) nursery soil with nursery soil cover, and (4) nursery soil with sterilized sand cover. Germination percentages
were compared between these conditions. The germination percentage (8.8%) at 10 weeks after sowing under condition 3 was significantly
lower than under conditions 1, 2, and 4 (56.8%, 52.0%, and 47.2%, respectively). Of the nongerminated seeds under condition
3, 75.0% were decayed and several fungi were isolated from decayed seeds. An inoculation test of isolated fungi Cylindrocarpon tenue, Cylindrocarpon sp., Fusarium oxysporum, and Botrytis sp. to seeds showed that these fungi caused seed decay. Our results indicated that nursery soil cover may not be suitable
for T. dolabrata var. hondai seeds sown in nursery soil because of seed decay by pathogens. 相似文献
5.
Fusarium verticillioides may be responsible for causing significant damping-off damage similar to that incited by F. oxysporum on forest seedlings, resulting in considerable losses in nurseries in northwest of Spain. Traditionally, F. oxysporum has been considered the most important agent of this disease in Spanish forest nurseries. However, recent studies have showed that F. verticillioides also has been frequently isolated from diseased plants. This has increased the necessity for a more comprehensive knowledge of the behaviour and pathogenicity of both Fusarium spp. isolated from these sites. The effect of Fusarium spp. on seed germination and on seedling mortality was analysed by inoculating the fungus at seeding. The in vitro growth of the two species was studied and is discussed in relation to in vivo virulence. Both species caused a reduction in seed germination and an increase in seedling mortality. Mortality caused by F. verticillioides treatments occurred sooner than that for F. oxysporum and the growth rate of F. verticillioides was also greater. 相似文献
6.
In forest and conservation nurseries in the Pacific Northwest USA, seedling production can be limited by root diseases caused by fungi in the genera Fusarium Link:Fr., Cylindrocarpon Wollenw., Phytophthora de Barry, and Pythium Pringsh. Fusarium, Cylindrocarpon, and Pythium are the most ubiquitous, whereas incidence of Phytophthora is mostly associated with coastal bareroot nurseries. All of these root pathogens are encouraged by water saturated soils or media. Seedlings infected with Fusarium, Phytophthora, or Pythium often appear chlorotic or necrotic with extensive root decay. Cylindrocarpon often causes serious root decay without shoot symptoms. The best approach to mitigate losses from these diseases is to use a holistic integrated pest management program. This program should combine chemical controls with cultural practices, particularly those that increase soil permeability and drainage and reduce potential sources of inoculum, especially by disinfesting seeds and containers reused for crops. In general, we found that seedlings meeting nursery specifications for outplanting on forest soil (proper height, root collar diameter, healthy shoot color, lack of disease symptoms) but having these disease organisms on their root systems perform as well as non-infected seedlings. 相似文献
7.
Species of Fusarium cause damping off of forest seedlings resulting in considerable losses and oftentimes fungicides are used to control the disease. Such chemicals may be detrimental to the environment. Protection of forest seedlings against this disease must be focused on integrated management for in which biological control is one of the most important tools. Mycorrhizal fungi may provide protection against pathogen invasion of seedlings. In this study, the interactions between the mycorrhizal fungi Boletus edulis, Rhizopogon roseolus, Laccaria laccata and Lactarius deliciosus and damping off pathogens (Fusarium oxysporum and F. moniliforme) were investigated in vitro and mechanisms involved in the protection of damping off in P. nigra seedlings are also discussed. The effect of filtrates from mycorrhizal species on spore germination of F. oxysporum varied throughout the tests. At the end of the assay, the inhibitory effect only could be observed in the L.␣deliciosus treatment. None of the filtrates reduced spore germination in F. moniliforme. Finally, three of the four mycorrhizal species grown for 2 months in the substrate, L. laccata, L.␣deliciosus and B. edulis, increased the survival of Fusarium inoculated P.␣nigra seedlings. 相似文献
8.
Pablo Martín Pinto Juan Alberto Pajares Alonso Valentín Pando Fernández Julio Javier Díez Casero 《New Forests》2006,31(1):41-56
Fungal endophytes in container-grown seedlings in forest nurseries located in the North Plateau of Spain have been studied.
Influences of nursery, season (spring and autumn), host genus and plant part on those fungal assemblages have been also evaluated.
Four nurseries were sampled in spring and three in autumn. Analysed material consisted of stems, roots and rhizosphere from
five host species, Quercus ilex, Q. pyrenaica, Pinus pinea, P. nigra and P. sylvestris. A total of 581 isolates corresponding to 13 taxa were found in this study. Fusarium moniliforme, F. oxysporum and Trichoderma viride were the most frequently isolated fungi. Number of fungal species per observation differed significantly among the sampled
parts. Multivariate Correspondence Analysis allowed the discrimination of samples in five groups based on nursery, season,
host genus and plant part. Isolation frequencies of F. moniliforme and F. oxysporum were higher in the roots and in spring, whereas those of T. viride were higher in the rhizosphere and in autumn. A relationship was observed between presence of T. viride and absence of Fusarium spp. in forest nurseries. T. viride, could serve as a biological control agent against Fusarium spp. in forest nurseries. 相似文献
9.
Italian seed lots of Norway spruce (Picea abies) were analysed by agar plate tests and seedling symptom test. Fusarium spp., Phoma spp. and Sirococcus conigenus were present on seeds, together with some saprophytes, but only S. conigenus and Fusarium spp. caused mortality in the seedling symptom test. Pathogenicity tests with 19 isolates belonging to nine Fusarium species showed that only some were pathogenic. Fusarium dlamini, reported for the first time in Italy, caused only some pre-emergence mortality. Pathogenicity tests with S. conigenus indicated that the isolate was pathogenic and that temperature can greatly affect the results. Seed dressing with prochloraz was suitable for controlling the seedborne pathogens. Agar plate tests are effective and practicable methods for the detection of spruce seed mycoflora. 相似文献
10.
Greenhouse-grown Douglas-fir (Pseudotsuga menziesii var.glauca [Beissn.] Franco) seedlings with roots infected with eitherFusarium oxysporum Schlect. orFusarium proliferatum (Matsushima) Nirenberg were outplanted on a forest site in northern Idaho, U.S.A. No residentFusarium populations were detected in the forest soil.Fusarium persisted the first four years on roots initiated during the greenhouse phase, but occurred sparingly or was absent on roots that grew after outplanting. Height growth was unaffected, and mortality was not often associated withFusarium. A seasonal pattern ofFusarium activity was observed. Low levels (10–40%) of initial root infection apparently have little adverse effect on outplanting performance of Douglas-fir seedlings.University of Idaho, Idaho Forest, Wildlife and Range Experiment Station Contribution No. 640. 相似文献
11.
Scots pine (Pinus sylvestris) and Stone pine (Pinus pinea) are two important species used in re-forestation that are subject to damage by damping-off fungi in forest nurseries. Twenty-two isolates of Fusarium oxysporum and F. verticillioides from diseased seedlings of eight different hosts were tested for aggressiveness on seeds and seedlings of both pine species, including the effects on seedling emergence and mortality. Scots pine was more susceptible to damping-off than Stone pine, as indicated both by reduced seedling emergence and elevated seedling mortality. The impact of F. oxysporum and F. verticillioides on seeds and seedlings did not differ significantly for either pine species. Our findings support previous studies that found that these are damping-off pathogens on the studied pines. Whereas most isolates proved to be pathogenic, some isolates of both Fusarium species showed to be non-pathogenic. 相似文献
12.
J. D. Sweeney Y. A. El-Kassaby D. W. Taylor D. G. W. Edwards G. E. Millers 《New Forests》1991,5(4):327-334
Douglas-fir seedlots were treated with the Incubation Drying Separation (IDS) method to test whether seeds infested with the seed chalcid, Megastigmus spermotrophus Wachtl, could be separated from non-infested seeds. Seeds were soaked in distilled water for 24 h, drained, placed in plastic bags and incubated at 15 °C for 3 days. The seeds were dried for either 0.5, 1, or 2 h at 25 °C, and then separated into floaters and sinkers in a water column. An average of 97% of the infested seed floated. The drying period did not affect the separation of infested seeds but significantly fewer sound seeds floated in the seedlots dried for 0.5 h than those dried for 1 h. Germination capacity of IDS-treated seeds did not differ from that of untreated seeds but the germination rate was significantly faster for IDS-treated seeds when all lots were stratified. 相似文献
13.
A diverse mycoflora was associated with slash-pine seeds from cones obtained at seed orchards and cone-processing facilities in the southeastern USA. Potentially pathogenic fungi, including Lasiodiplodia tbeobromae, Sphaeropsis sapinea, and Fusarium spp., were isolated from seeds of cones obtained at all locations. Fusarium proliferatum and F. semitectum were the Fusarium spp. most often associated with seeds; F. subglutinans was rarely isolated. Many other species of fungi were associated with seeds from all locations. Incidence of fungus-damaged seeds ranged from 2 to 11% among collection sites. Disease incidence was found to increase during cone storage. Types of fungi and the incidence of fungus-damaged seeds were similar for damaged/discoloured cones and apparently healthy cones. The potential for slash-pine seeds to become colonized by pathogenic fungi, such as S. sapinea and the various Fusarium spp., could have important implications for the establishment of these fungi in forest-tree nurseries, as well as their introduction into foreign countries. 相似文献
14.
Hiromitsu Kisanuki Hisae Oguro Arisa Nakai Suzuki Setsuko Naoyuki Nishimura Nobuhiro Tomaru 《Journal of Forest Research》2008,13(2):143-146
We studied seed bank formation of the threatened star magnolia, Magnolia stellata, to examine the early stage of regeneration. Forty-five seedling plots (2 × 2 m), each including a soil-sampling quadrat
(40 × 40 cm), were established randomly under or around the crowns of mature M. stellata trees. Seeds of M. stellata were collected from each quadrat to a depth of 5 cm. Only four seeds of M. stellata were found (0.56 seeds/m2) and all were located under mature crowns. Current-year seedlings were abundant in water channels, on moss, or under mature
crowns, suggesting that the seeds may require wet soil conditions for germination. Magnolia stellata seeds show considerable germination below the crowns of mature trees in the year following masting, while some seeds remain
dormant in the soil. Considering the soil seed bank and the current-year seedling bank of M. stellata, a frequent supply of seed is essential for the regeneration of this species. Thus, it is important to maintain mature trees
in addition to promoting seed production. 相似文献
15.
Seed and root rot of pine and cypress seedlings cause heavy annual losses to forest nurseries in Fars Province. Root and crown samples of various species of conifers, such as Tehran pine (Pinus eldarica), brutia pine (Pinus brutia), Arizona cypress (Cupressus arizonica), Shirazian cypress (Cupressus sempervirens var. fastigiata), common cypress (C. sempervirens var. horizontalis) and oriental arborvitae (Thuja orientalis), showing chlorosis, necrosis, stunted growth, defoliation and root and crown rot symptoms were collected from pine and cypress nurseries across Fars province at various time intervals. Infected tissues were washed and cultured on acidified potato dextrose agar (PDA) and corn meal agar (CMA) amended with Delvocide and ampicillin, with and without surface sterilization, respectively, and incubated at 25°C for 3–5 days. Decaying seeds of all plant species were also collected from nursery seed stocks and cultured on PDA. Hyphal tip isolates were used for further studies. Species of Phytophthora, Pythium, Rhizoctonia and Fusarium were isolated from symptomatic seedlings of pine and cypress at different times during the growing season. Pathogenicity of isolates of Phytophthora, Pythium and Rhizoctonia was confirmed on seedlings of all plant species, whereas Fusarium sp. isolated from the seeds of Tehran pine was only pathogenic on seedlings of Tehran pine and Arizona cypress. Virulent isolates identified as Phytophthora nicotiana var. parasitica, Pythium ultimum, Pythium paroecandrum, Rhizoctonia solani and binucleate Rhizoctonia‐like fungus caused root and crown rot of pine and cypress seedlings. Pathogenic isolates of Fusarium identified as Fusarium proliferatum also caused pre‐emergence seed decay of pine and cypress. Isolates of Phytophthora and Pythium were the most virulent of these fungal isolates. 相似文献
16.
Twenty‐nine fungi that were isolated from seeds and female cones of Podocarpus falcatus from natural forests in Ethiopia, were assessed for their impact on seeds and seedlings of the same host. Based on the results from in vitro seed inoculation tests, we could group the fungi into five categories as: (i) isolates that were pathogenic only to seeds and had no obvious impacts on the germlings; (ii) isolates that were pathogenic only to the germlings; (iii) isolates that were pathogenic both to seeds and the emerging germlings; (iv) isolates that were more or less harmless; and (v) isolates that were germination promoters. Inoculation tests were also performed on 4–7‐day‐old aseptically grown seedlings. Fusarium oxysporum and Polyporus sp., were strongly pathogenic to both seeds and seedlings, while Nectria gliocladioides, Peniophora cinerea and Pestalotiopsis neglecta also demonstrated pathogenicity but to a lesser extent. Other isolates, e.g. Diaporthe spp. resulted in increased germination of P. falcatus seeds and no pathogenicity to seedlings. However, further investigations are required in order to find out how these fungi behave under nursery or field conditions. 相似文献
17.
The effects of nursery practices on genetic composition and structure were studied inChamaecyparis obtusa by analyzing seeds and one-, two-, and three-year-old seedlings. Enzyme polymorphisms of the6Pgd-2, G6pd, Got, Gk, Shd-2, Pod, Dia-1, andPgm loci were used. OnlyDia-1 indicated significantly different allelic frequencies between seeds and three-year-old seedlings. Most of the genetic diversity
of the parental clones in this seed orchard could be transferred to the offsprings. Genetic diversity on the basis of an average
expected heterozygosity did not differ between seeds and seedlings. A slight excess of homozygotes in seeds and a significant
excess of heterozygotes in seedlings of different ages to the expected panmictic proportions were found. Most of the differences
in genotypic distributions among the seed and seedling stages, probably resulted from viability selection favoring outcrosses,
and selective removal of inbred offsprings including self-fertilized ones prior to their transplantation in the nursery.
A part of this paper was orally presented at the 107th Annual Meeting of the Japanese Forestry Society (1996). 相似文献
18.
The germination of common alder (Alnus glutinosa (L.) Gaertn.) and downey birch (Betula pubescens Ehrh.) seeds is often poor in bare-root nurseries. The effect of a variety of seed coverings and a few seed pretreatments
on seedling emergence was examined in this study in an attempt to address this problem. Seeds of each species were sown in
trays containing nursery soil, covered with grit, gravel, sand, combinations of these coverings, a hydromulch or a sealed
plastic cloche and then incubated for 6 weeks at 17–20°C. The grit combined with sand or gravel, the hydromulch and the cloche
increased seedling emergence when compared with the standard grit. In another experiment, seeds of each species were fully
imbibed (FI) (>50% moisture content, MC), as per standard practice, or adjusted to target MC (TMC) (30–35% MC) levels, and
then chilled to release dormancy. Some seeds of each MC treatment were primed at 20°C for 2 days following chilling, after
which all seeds were evaluated in laboratory tests and a nursery trial. Germination potential of the FI seeds declined in
the lab tests by the second test date, which was reflected in low seedling emergence in the nursery in birch. The primed FI
seeds of alder germinated most rapidly in the nursery, but other effects were not significant. Seedling emergence was better
in the nursery in response to the TMC than the FI pretreatment in birch.
相似文献
| Conor O’ReillyEmail: |
19.
Picea asperata is a unique tree species in China. It has important economic and ecological values. In this study, the disease symptoms resembling needle blight, a new disease of P. asperata (10- to 15-year-old), were detected in a forest area in Tianshui City, Gansu Province, China, in August 2020. Affected needles turned yellow, the colour became darker at the junction of infected and healthy areas, the needles wilted and even fell off the tree. Through pathogenicity tests, the two pure fungi strains isolated from diseased needles caused distinct needle blight symptoms on P. asperata, with symptoms similar to those observed in the forest. It was observed that they had sickle-shaped conidia. Subsequently, multilocus phylogenetic analysis of partial sequences of the internal transcribed spacer region (ITS), translation elongation factor 1-α (TEF-1α) and RNA polymerase II second major subunit (RPB2) genes was performed. They were found closely clustered with Fusarium oxysporum and F. avenaceum, respectively. Based on morphological and molecular biological determinations, the two pathogens were identified as F. oxysporum and F. avenaceum. To our knowledge, this is the first report of needle blight caused by F. oxysporum and F. avenaceum on P. asperata in China. 相似文献
20.
《Scandinavian Journal of Forest Research》2012,27(1):1-6
Abstract The effect of soaking on germination and occurrence of fungal infections on Norway spruce (Picea abies (L.) Karst.) seeds and germinants was studied in three commercial seed lots. Treatments in which seeds were soaked in water for 24 h or in which the water was changed during the soak did not have an effect on the species diversity or on the abundance of the fungi isolated from the seeds. Different fungi were found in different seed lots. Most of those isolated are saprophytic or weakly pathogenic, but pathogens such as Sirococcus conigenus (D.C.) P.F. Cannon &; Minter and Trichothecium roseum (Pers.) Link were also isolated. Soaking increased germination energy but had no effect on final germination percentage. The number of mouldy seeds and germinants with disease symptoms was different among seed lots when seeds were germinated on water agar. When germinated in low humified Sphagnum peat, no differences in the emergence of disease symptoms were observed among seed lots. The frequency of disease was lower in peat than in water agar. Soaking had no effect on disease emergence in germination trials on either water agar or in Sphagnum peat. 相似文献