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1.
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
2.
In this study the phylogeographic variation among isolates of the Sirococcus conigenus P group and the phylogenetic relationships of S. conigenus with Sirococcus clavigignenti‐juglandacearum and other species previously placed in the genus Sirococcus were investigated. A collection of 33 isolates originating from Picea, Pinus and Larix in Europe, North America and Bhutan were characterized by sequence analyses of the internal transcribed spacer (ITS) region (including ITS1, 5.8S ribosomal DNA, ITS2) of the nuclear rDNA and a portion of the β‐tubulin gene. In phylogenetic analyses most isolates from pine, spruce and larch formed a distinct clade, representing the P group of S. conigenus, which was separated from the T group of this pathogen. Four isolates from Picea in Europe and Canada formed a third clade within S. conigenus and these isolates are referred to as the S group. The P group consisted of five distinct ITS haplotypes, which partly differed in their optimum growth temperature and their growth rates at 25°C on malt extract agar. Nested clade analysis resolved the five haplotypes into three distinct clades and revealed significant genetic/geographic associations for some of the haplotypes. Parsimony analysis of the small subunit (18S) ribosomal DNA sequences confirmed the phylogenetic affinities between S. conigenus and S. clavigignenti‐juglandacearum. In contrast, Godronia cassandrae and Hormococcus conorum, which formerly had been placed in the genus Sirococcus, were found to be only distantly related to S. conigenus and S. clavigignenti‐juglandacearum. 相似文献
3.
In this study a Sphaeropsis sp. is recorded as causing cankers on cypress in South Africa. These cankers are either found alone or on trees which are infected with the well-known cypress canker pathogen, Seiridium unicorne. When the two fungi occurred together, lesions could not be distinguished from each other, although the greater number of lesions were caused by the Sphaeropsis sp. The fungus appears to be identical to that described as Sphaeropsis sapinea f.sp. cupressi, in Israel, which is a fungus very different from the pine pathogen, Sphaeropsis sapinea. Pathogenicity tests showed that the Sphaeropsis sp. is significantly more pathogenic to Cupressus lusitanica than to Pinus roxburgii and Pinus elliottii. S. sapinea was pathogenic only to the Pinus spp. tested, and not to C. lusitanica. In contrast, the cypress pathogen Seiridium unicorne, was pathogenic to C. lusitanica and also to the two Pinus spp. tested. 相似文献
4.
《Journal of Sustainable Forestry》2013,32(1-2):293-306
Abstract Fungal root pathogens are widespread and may cause substantial seedling losses in conifer nurseries. Furthermore, poor seedling survival and growth on reforestation sites results in reduced forest regeneration. Use of microbial inoculants for disease control and plant growth promotion has become an important endeavour. A microbial culture collection of 500 strains was assessed for biological control of fungal root pathogens and/or plant growth promotion of conifer seedlings. Seven of these strains showed significant suppres-sive effects on various soil-bome fungal pathogens. On Douglas fir, two strains, RAL3 and 64-3, reduced disease caused by Fusariumby. 7-42% in repeated growth room assays. The same strains significantly increased healthy stand of white spruce seedlings inoculated with Fusariumand Pythiumin a conifer nursery, and increased the survival of bare-root white spruce seedlings planted on a reforestation site by 19-23%. Both strains also significantly increased new root and total plant dry weights. Strain RAL3 in commercial formulation maintained a viable population of about log 8-9 cfu/ml for over a year when stored at 5°C. Strain survival on seed varied with conifer species. No decreases in bacterial populations were observed on seeds of jack pine or Douglas fir after 37 to 44 days storage at 5°C, but decreases were observed on seeds of white spruce and Scots pine. This study has provided candidate beneficial microbial inocu-lants which offer promise for development of commercial inoculants for the forestry industry. 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.
Pathogenicity of cherry‐spruce rust, Thekopsora areolata, was investigated by inoculations with aeciospores from seven Norway spruce, Picea abies, seed orchards that had suffered from successive severe rust epidemics in the 2000s in Finland. Detached leaves of Prunus spp. were inoculated in the laboratory using aeciospores from cones of various ages. In the greenhouse, live Prunus padus plants were inoculated, and possible autoecism of the rust was tested by inoculations of Picea abies seedlings. Thirty‐five spore sources from the seed orchards formed uredinia on Prunus spp. in the laboratory 2 weeks after incubation, but no telia developed. In the greenhouse, uredinia developed on live P. padus, but no rust symptoms, cankers or sporulation were detected on Picea abies. Thus, no evidence of autoecism was observed among the T. areolata populations and therefore all populations, suggesting all those tested from the Finnish seed orchards were heteroecious. 相似文献
7.
Paige E. Axelrood Melody Neumann David Trotter Reed Radley Gwen Shrimpton John Dennis 《New Forests》1995,9(1):35-51
Twelve Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seedlots from coastal British Columbia were assayed for seedborne Fusarium. All of the seedlots were contaminated with Fusarium. Percent of nonstratified seeds from individual seedlots harboring Fusarium ranged from 0.3% to 95.4%. Sixty-seven percent of the seedlots had Fusarium on less than 2% of the seeds. Post-stratification seedborne Fusarium levels were significantly less for running water imbibition compared to standing water imbibition. However, seedling growth at a container nursery was not consistently different for stratified seed imbibed initially in standing or running water. Fusarium disease symptoms were not observed in the nursery environment. The species of Fusarium isolated from seed were F. acuminatum, F. avenaceum, F. lateritium, F. moniliforme, F. oxysporum, F. poae and F. sambucinum. Twelve Fusarium isolates, comprising six species, were assessed for pathogenicity. Disease symptoms were observed after four weeks incubation and Fusarium isolates ranged in virulence from low to high. Fusarium oxysporum isolates were the most pathogenic. 相似文献
8.
T. Kirisits H. Konrad E. Halmschlager C. Stauffer M. J. Wingfield D. B. Chhetri 《Forest Pathology》2007,37(1):40-50
During a recent survey of forest tree diseases in Western and Central Bhutan, Sirococcus shoot blight and an associated Sirococcus sp. were found on saplings and mature trees of Eastern Himalayan spruce (Picea spinulosa). Based on morphological characteristics and DNA sequence comparisons of the ITS region of the rDNA operon, representative isolates from Bhutan were unequivocally identified as Sirococcus conigenus. The DNA sequence data also showed that these isolates belong to the P group of S. conigenus. To our best knowledge, this is the first report of Sirococcus shoot blight from the Himalayas or any other part of Asia. Sirococcus conigenus does not appear to cause dramatic damage at the moment, but this fungus has the potential to cause severe disease problems on P. spinulosa in Bhutan. 相似文献
9.
《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
10.
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
11.
《Scandinavian Journal of Forest Research》2012,27(1-4):547-556
Fungi were isolated from the roots and growth substrate of bare‐rooted and containerized Pinus sylvestris and Picea abies nursery seedlings displaying a root dieback. Isolations were also made from visually healthy seedlings. The potential pathogenicity of all isolated species was determined in laboratory trials. Cylindrocarpon spp., Fusarium spp. and Trichoderma viride were frequently isolated. The isolation frequency of a uninucleate Rhizoctonia‐like fungus, Pythium spp. and Phytophthora imdulatum from diseased containerized seedlings and their pathogenicity in tests suggest that these fungi are likely involved in the root dieback disease in containers. The pathogenic Rhizoctonia‐like fungus in addition to Pythium spp. was also isolated from bare‐rooted seedlings. In greenhouse tests Pythium spp. were more pathogenic to 4‐week‐old Scots pine seedlings grown before transplantation in unsterile substrate than to those seedlings grown axenically in agar. External factors are considered to have some role in the expression of disease. 相似文献
12.
The effect of pre-inoculation with VA mycorrhizae on Fusarium wilt of Albizia procera and Dalbergia sissoo was done in a green house trial. Inoculation with Fusarium spp. decreased plant growth compared to noninoculated controls. Mycorrhizal plants were significantly higher than nonmycorrhizal ones. In addition to plant growth, the disease severity caused by Fusarium spp. reduced significantly when inoculated with VA mycorrhizae. The lowest percentage of Fusarium spp. were found on plants when treated with VA mycorrhizae. The population of Fusarium spp. were higher in the rhizosphere of nonmycorrhizal roots. The P concentration in the leaves of mycorrhizal and nonmycorrhizal plants were higher in the absence of Fusarium spp. 相似文献
13.
Phytophthora cryptogea, Phytophthora cinnamomi, Phytophthora cambivora, Phytophthora megasperma and Pythium undulatum were isolated from diseased Noble fir (Abies procera) seedlings and soil associated with dead Noble fir in Ireland. Seedlings of four Christmas tree species (A. procera, Picea sitchensis, Picea abies and Pinus contorta) were inoculated with these oomycetes to test their pathogenicity and the susceptibility of the various tree species. Phytophthora spp. and Pythium undulatum caused root rot on all tree species. Disease symptoms included reddish brown cambial discoloration, crown symptoms, brown foliage, dark brown roots, root rot and seedling mortality. These symptoms were similar to those observed on Noble fir in naturally infested plantations. Pythium undulatum appeared as the most virulent pathogen followed by P. cinnamomi, P. cambivora, P. megasperma and P. cryptogea. Noble fir showed to be most susceptible and lodgepole pine most tolerant while Sitka spruce and Norway spruce were intermediate. 相似文献
14.
The number of fertile and infertile scales, filled and empty seeds, cone volume, seed efficiency and the incidence of insect and disease damage to seed were evaluated for seven jack pine (Pinus banksiana Lamb) and six black spruce (Picea mariana [Mill.] B.S.P.) seedling seed orchards in northern Ontario, Canada. On average, the seed potential of jack pine and black spruce cones was 50 and 82 seeds, respectively. Cone volume and the number of fertile scales were under strong genetic control and well correlated with one another for both species. Seed efficiency values were high for jack pine (60%) but poor for black spruce (24%). The incidence of seed insect damage was less than 2.5% for both species and nil for seed diseases. 相似文献
15.
《Journal of Sustainable Forestry》2013,32(3):37-54
Abstract Selected microorganisms (Laccaria laccata, Trichoderma viride, Bacillus subtilis, Pseudomonas corrugata and Azotobacter chroococcum) were used as inoculants to study their influence on seed germination, seedling survival and subsequent growth in Cedrus deodara. The microbial inoculations positively affected these parameters over control, in the following order: Azotobacter chroococcum Pseudomonas corrugata Bacillus subtilis Trichoderma viride Laccaria laccata.The major cause of seedling mortality was found to be (1) wilting of emerged seedlings by Fusarium oxysporum, and (2) cutworm attack. Bacterial inoculations were found to be superior in suppressing the proliferation of Fusariumsp., thereby enhancing seedling survival. One of the bacterial inoculants, B. subtilis, resulted in 76% seed germination, compared to 54% in control. Though inoculation with L. laccataresulted in maximum mycorrhizal infection (up to 72%) compared to48%in control seedlings, it afforded least protection against Fusariumsp., as well as minimal growth promotion. On the other hand, inoculation with T. viridesignificantly controlled wilting of seedlings and improved plant growth. Microbial inoculations were found to influence the soil microflora, nutrient status of the rhizosphere soil and that of different parts of seedlings. Enrichment of carbon was recorded in the rhizosphere soil. Enhanced nitrogen, phosphorus and potassium content of various plant parts indicated a positive influence also on nutrient uptake. The present study has implications for large scale forestry programs. 相似文献
16.
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
17.
The effect of inoculation of Hebeloma sp. on the growth of Norway spruce (Picea abies) seedlings was studied, in a controlled environment, with soil samples naturally infested by Pythium spp., Fusarium spp. and Rhizoctonia solani, and with samples of soil in which the pathogens had been controlled by solarization. The best results were obtained in solarized soil, but mycorrhizae also enhanced plant growth in the presence of the whole soil-borne mycoflora. The combined use of inoeulation of a mycorrhizal fungus and solarization is discussed. 相似文献
18.
Von H. Braasch 《Forest Pathology》1996,26(4):205-216
Pathogenicity tests with Bursaphelenchus mucronatus on pine and spruce seedlings in Germany Inoculation tests on Pinus sylvestris seedlings with a German, a Siberian and a French isolate of Bursaphelenchus mucronatus and on Picea abies seedlings using only the German isolate have clearly shown, under German field conditions, that the nematode can cause wilt symptoms on the apex of about 60% of the inoculated P. sylvestris plants. The nematodes in all these tests mostly remained near the inoculation site. However, further spread of the nematodes and wilt symptoms occured when a climate chamber, at 25°C, was used or when the French isolate was used outdoors. At 25°C, 10% of the inoculated plants with at least 1000 nematodes per seedling died. Seedlings' apices wilted if more than 50 nematodes per trunk were present, whereas smaller numbers of nematodes could cause partial wilting. Nevertheless, a few pine seedlings did tolerate high nematode-population densities, up to 966 per plant. No further progress of wilt of plants with symptoms was observed the following year. Inoculations of P. abies with a German isolate resulted in population development near the site of inoculation. Spruces largely tolerated nematode infestations without any development of wilt symptoms. 相似文献
19.
The properties of 64 heterokaryotic strains of Phlebiopsis gigantea, isolated mostly from Norway spruce stumps, were tested for asexual spore production, growth rate and competitive ability against Heterobasidion spp. on agar medium, and for growth rate in spruce wood. Eighteen isolates were also tested for the efficacy of control against Heterobasidion spp. in stem pieces of spruce. The results revealed high variation in traits between different P. gigantea isolates. The efficacy of control against Heterobasidion spp. and the growth rate in spruce wood were closely related to each other (r = 0.727, p < 0.001). These preliminary tests indicate that the growth rate of a P. gigantea strain in spruce wood is the most important characteristic determining its efficiency in controlling the infection and spread of Heterobasidion spp. in spruce stumps. 相似文献
20.
Interest in development of multicohort stands of red pine (Pinus resinosa) in the Great Lakes region of North America prompted an investigation of the potential impact of the shoot blight pathogen Sirococcus conigenus (syn. S. strobilinus) on understory red pine seedlings. In May 2002 and 2003 healthy, 1‐year‐old red pine seedlings were planted in the understory of a maturing red pine plantation in northern Wisconsin in an area with a history of presence of this pathogen. Occurrence of shoot blight symptoms was recorded periodically during the summer, and in each year seedlings were harvested in fall and examined for signs of shoot blight pathogens. By fall 2002 and 2003, respectively, shoot blight incidence was 89% and 98% and most seedlings were dying. Pycnidia with conidia of S. conigenus were present on almost all of the symptomatic seedlings. The conifer shoot blight and canker pathogen Diplodia pinea (syn. Sphaeropsis sapinea) was also detected, though less frequently. Pycnidia of S. conigenus tended to be found more frequently on symptomatic current year's shoots than symptomatic previous year's shoots; the opposite was true for pycnidia of D. pinea. Risk from S. conigenus to understory red pine seedlings should be considered in any plans for development of multicohort red pine stands in areas where the pathogen is present. 相似文献