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1.
Alex A. Appiah Isaac Y. Opoku Andrews Y. Akrofi 《European journal of plant pathology / European Foundation for Plant Pathology》2004,110(10):983-990
Epidemiological studies were conducted in five cocoa growing districts in the Eastern Region of Ghana solely infected by Phytophthora palmivora and five districts in the Ashanti and Brong Ahafo Regions prevalently infected by Phytophthora megakarya to determine the natural incidence, the vertical distribution on trees and the probable sources of stem canker infections, and to isolate and identify the causal pathogens. The incidence of canker in the solely P. palmivora infected area was higher (between 0% and 16.0%) than in the area mainly infected with P. megakarya (0.5–8.0%). Differences were found in the natural height distribution of cankers in the two areas, whilst the areas solely infected with P. palmivora showed a near normal curve, those prevalently infected with P. megakarya were positively skewed. Most of the cankers caused by P. megakarya were found at the base or near the base of the tree trunks (1–40cm above ground level), while those of P. palmivora were concentrated between 41 and 100cm from the ground level. The majority (71.8%) of cankers in the solely P. palmivora infected area were cushion-borne, followed by 24.3% from unknown sources and only 3.9% from the soil. In contrast, a significantly large proportion (32.6%) of the cankers in the prevalently P. megakarya infected area were soil-borne, although cushion-borne cankers formed the majority (48.4%) due to the presence of P. palmivora infection whilst those of unknown sources constituted 19.0%. Phytophthora megakarya was frequently isolated from all the three sources of canker infections, indicating P. megakarya readily causes stem canker on cocoa. These results emphasise the importance of different reservoirs as sources of primary inoculum for diseases caused by the two Phytophthora species particularly pod rot infection on cocoa. 相似文献
2.
Jenna F. Stonard Akinwunmi O. Latunde-Dada Yong-Ju Huang Jonathan S. West Neal Evans Bruce D. L. Fitt 《European journal of plant pathology / European Foundation for Plant Pathology》2010,126(1):97-109
Phoma stem canker, caused by Leptosphaeria maculans and L. biglobosa, is the most important disease of oilseed rape in Europe. Differences between L. maculans and L. biglobosa in their life-cycles enable the two species to co-exist on oilseed rape crops over a cropping season. This review considers
the factors affecting geographic variation in the severity of phoma stem canker epidemics and in the structure of the population
of the pathogens in the UK, where the most severe epidemics occur in the south of England and cankers do not develop in Scotland.
It is concluded that this variation is directly related to differences in climate, since weather-based models show that stem
canker severity increases with increasing winter/spring temperature and temperatures are greater in the south of the UK. It
may also be related to differences in pathogen populations, since surveys showed that the proportion of the more damaging
L. maculans in stem cankers was greatest in southern England, with most L. biglobosa in northern England. Regional variation in agronomic practices such as cultivar choice and fungicide use may also indirectly
influence phoma stem canker severity. Differences in cultivar choice result in differences in L. maculans race structure, which may influence the severity of epidemics. Differences in fungicide use may also influence pathogen populations,
since L. maculans and L. biglobosa differ in their sensitivities to different azole fungicides. These factors are discussed in relation to strategies for sustainable
production of oilseed rape by adaptation to threats posed by climate change. 相似文献
3.
Hiroshi Shiotani Terutaka Yoshioka Masashi Yamamoto Ryoji Matsumoto 《Journal of General Plant Pathology》2008,74(2):133-137
Susceptibility to Xanthomonas
axonopodis pv. citri of a citrus cybrid, in which the nuclear and cytoplasmic genomes were derived from Citrus
sinensis and C. unshiu, respectively, was evaluated. Bacterial growth in the leaves of the cybrid was similar to that in C. sinensis after pin-prick inoculation throughout the experiment, whereas growth was greater than that in C. unshiu from 8 days after inoculation. Lesion expansion and pustules that later developed from the lesions on the cybrid and on C. sinensis also appeared to be greater than those on C. unshiu. The incidence of citrus canker disease caused by the bacteria on the cybrid trees was in the field was equivalent to that
on C. sinensis but was severer than on C. unshiu. These results indicate that the nuclear genome of the cybrid plays a critical role in susceptibility to citrus canker disease.
However, the pathogenicity gene pthA of the bacteria is not likely to be involved in the difference in susceptibility to the bacteria between C. unshiu and C. sinensis because their susceptibility to a pthA-deficient mutant of the bacteria also differs. 相似文献
4.
Susan J. Sprague Barbara J. Howlett John A. Kirkegaard 《European journal of plant pathology / European Foundation for Plant Pathology》2009,125(2):189-202
The infection of above-ground tissues of Brassica napus by Leptosphaeria maculans is well understood. However, root infection (root rot) under field conditions, the development of root rot over time and
its relationship to other disease symptoms caused by L. maculans has not been described. A survey of B. napus crops was conducted in Australia to investigate the incidence and severity of root rot. Additionally, the pathway of root
infection was examined in field experiments. Root rot was present in 95% of the 127 crops surveyed. The severity and incidence
of root rot was significantly correlated with that of crown canker; however, the strength of this relationship was dependent
on the season. Root rot symptoms appeared before flowering and increased in severity during flowering and at maturity, a pattern
similar to crown canker suggesting that the infection of the root is an extension of the crown canker phase of the L. maculans lifecycle. All isolates of L. maculans tested in glasshouse experiments caused root rot and crown canker in B. napus and Brassica juncea. In the field, the main pathway of root infection is via invasion of cotyledons or leaves by airborne ascospores, rather
than from inoculum in the soil. Root rot was present in crops in fields that had never been sown to B. napus previously, in plants grown in fumigated fields, and in glasshouse-grown plants inoculated in the hypocotyl with L. maculans. 相似文献
5.
Bruna B. Brumer Valéria S. Lopes-Caitar Aline S. Chicowski Jessica D. Beloti Fernanda M. Castanho Danielle C. Gregório da Silva Sandremir de Carvalho Ivani O. N. Lopes Rafael M. Soares Claudine D. S. Seixas Ricardo V. Abdelnoor Francismar C. Marcelino-Guimarães 《European journal of plant pathology / European Foundation for Plant Pathology》2018,151(4):1009-1025
The complex of Diaporthe (asexual morph) species occurring on soybean constitutes an important pathogenic group associated with diseases such as pod and stem blight, seed decay and stem canker. Stem canker, caused by Diaporthe aspalathi, has been reported as the most aggressive form of canker and its occurrence has limited soybean crop productivity in the southern United States. The main form of pathogen control is the use of stem canker resistant soybean varieties. In this study, strains of Diaporthe and Phomopsis were isolated from stem and seeds of soybean in different locations in South America during the years 1989–2014. Genomic DNA from 26 isolates were analyzed by PCR-restriction fragment length polymorphism (RFLP) and Amplified Fragment Length Polymorphism (AFLP) techniques, and sequencing of internal transcribed spacer (ITS) regions of ribosomal DNA. The molecular analysis of ITS sequences by alignment with those of ex-type strains deposited in GenBank and morphological characteristics allowed the identification of Phomopsis longicolla, D. phaseolorum var. sojae, D. caulivora and D. aspalathi. An analysis of the pathogenicity of 13 isolates of D. aspalathi inoculated in soybean genotypes carrying different resistance genes to stem canker (Rdm1, Rdm2, Rdm3, Rdm4, Rdm5 and Rdm?) enabled us to identify the occurrence of at least three races of D. aspalathi occurring in Brazil. Among the isolates identified as D. aspalathi, both molecular and phenotypic analyses showed clustering depending on the date of collection and pathogenicity, which revealed the existence of variability of the pathogen. 相似文献
6.
Carla M. R. Varanda Marta S. M. R. Silva Maria do Rosário F. Félix Maria Ivone E. Clara 《European journal of plant pathology / European Foundation for Plant Pathology》2011,130(2):165-172
Transmission of three strains of OMMV by an Olpidium sp. was evaluated and compared. The three strains were 1) an OMMV wild type (WT) recovered from olive trees, 2) an OMMV variant
(L11) obtained after 15 serial passages of single local lesions induced in Chenopodium murale plants, and 3) a construct OMMV/OMMVL11 in which the coat protein (CP) gene replaced that of the wild type. A single-sporangial
culture derived from Chinese cabbage (Brassica pekinensis) used as a bait plant grown in soil of an olive orchard, was identified as Olpidium brassicae based on the size and sequence of the generated amplicon in PCR specific tests. Each of the three virus strains was soil
transmitted to cabbage roots in the absence of the fungus at similar rates of 30 to 40%. Separate plant inoculation by O. brassicae zoospores incubated with each viral strain resulted in enhanced transmission of OMMV, reaching 86% of infection whereas that
of the other two strains remained practically unaffected at ca. 34%. Binding assays showed that the amount of virus bound to zoospores, estimated spectrophotometrically, was 7% in the
case of OMMV, and practically nil in the case of the other two viral strains. Substitution of the coat protein (CP) gene of
OMMV by that of the OMMV L11 strain, drastically reduced viral transmissibility in the presence of zoospores to the level
of that observed in their absence. Our data shows that OMMV soil transmission is greatly enhanced by O. brassicae zoospores and that the viral CP plays a significant role in this process, most likely by facilitating virus binding and later
entrance into the host plant roots. 相似文献
7.
Effects simultaneous and sequential inoculations of Meloidogyne incognita, Ralstonia solanacearum and Phomopsis vexans were studied on the growth, chlorophyll and carotenoid contents of eggplants grown in 25% fly ash and 25% sand mix soil. Plants grown in 25% fly ash mix soil had lesser plant growth than grown in 25% sand ash mix soil. Inoculation of M. incognita / R. solanacearum or P. vexans caused reduction in plant growth, chlorophyll and carotenoid contents in both types of soils but these pathogens in combination caused a greater reduction in than individual inoculation. Inoculation of M. incognita 20 days prior to R. solanacearum caused a greater reduction in plant growth than inoculation of M. incognita prior to P. vexans. Inoculation of P. vexans prior to R. solanacearum caused a lesser reduction in plant growth, chlorophyll and carotenoid contents than inoculation of P. vexans prior to M. incognita. Inoculation of R. solanacearum 20 days prior to M. incognita caused a greater reduction in plant growth, chlorophyll and carotenoid contents than inoculation of R. solanacearum prior to P. vexans. Galling and multiplication of M. incognita was higher in plants grown in 25% sand amended soil than with 25% fly ash soil. R. solanacearum and P. vexans had adverse effects on galling and nematode multiplication. Wilt and blight indices caused by R. solanacearum and P. vexans were 3 respectively. Wilt and blight indices were 4 when two pathogens were inoculated together. 相似文献
8.
Luis Armando Alvarez Maela León Paloma Abad-Campos José García-Jiménez Antonio Vicent 《European journal of plant pathology / European Foundation for Plant Pathology》2011,129(1):103-117
Considerable tree losses have been observed during the past few years in Spain due to Phytophthora branch canker of clementines
caused by Phytophthora citrophthora. The emergence of this disease led to the speculation that either the pathogen has evolved increasing its aggressiveness
or specificity to clementines. A total of 134 isolates of P. citrophthora collected from 2003 to 2005 in 135 citrus orchards in Spain and 22 reference isolates were analyzed genotypically and phenotypically
to determine the structure of the population. Genotypic diversity was evaluated by means of Inter-Simple Sequence Repeat (ISSR)
markers. Among the phenotypic characteristics examined, sporangial characters, sexual behavior, growth rates and colony morphology
of the isolates at different temperatures were studied. The aggressiveness and host-specificity of selected isolates were
evaluated by pathogenicity tests on sweet oranges and clementines under field conditions. Phytophthora branch canker of clementines
was associated mainly with one genotype (P-1), which included 88% of the isolates obtained from branches. Strains isolated
years before the first disease outbreak clustered also with this major genotype, thus it may be considered as a predominant
population. Thirteen other minor genotypes were determined, but most contained only one isolate. Although there was wide variation
in the morphological and physiological characters, all Phytophthora isolates obtained from branch cankers were sexually sterile
and showed a characteristic petalloid colony pattern. As in previous greenhouse studies, pathogenicity tests under field conditions
demonstrated that clementines and their hybrids were more susceptible to P. citrophthora than sweet oranges. However, no evidence was found to support the hypothesis that the emergence of the disease was associated
with more aggressive or host-specific forms of P. citrophthora. 相似文献
9.
Khalid Pervaiz Akhtar Muhmmad Yussouf Saleem Muhammad Asghar Mushtaq Ahmad Nighat Sarwar 《European journal of plant pathology / European Foundation for Plant Pathology》2010,128(4):435-450
Sixty-nine tomato genotypes representing nine Solanum species were evaluated for resistance to Cucumber mosaic virus (CMV) subgroup IA and its aphid vector Myzus persicae. Resistance was assessed by visual scoring of symptoms in the field under natural conditions, and in the greenhouse by artificial
inoculations through aphid M. persicae and mechanical transmissions in the year 2007 and 2009. Considerable variation in responses was observed among the evaluation
methods used. Field evaluations were found liable to errors as different levels were observed for the same genotypes in the
different years, however mechanical inoculation was found to be the most useful in identifying CMV subgroup IA resistance,
in contrast aphid transmission was most useful in identifying insect transmission resistance. All genotypes observed as highly
resistant to CMV subgroup IA in the field or through vector transmission became systemically infected through mechanical inoculations.
Using mechanical inoculation, six genotypes (TMS-1 of S. lycopersicum, LA1963 and L06049 of S. chilense, LA1353, L06145 and L06223 of S. habrochaites) were found resistant and another six (L06188 and L06238 of S. neorickii, L06219 of S. habrochaites, L05763, L05776 and L06240 of S. pennellii) were found tolerant showing mild symptoms with severity index (SI) ranging 1-2 and with delayed disease development after
a latent period (LP) of 18–30 days. However, these genotypes were found to be resistant to highly resistant in the field and
through inoculation by M. persicae; and they also supported low population levels of M. persicae except TMS-1. Another nine genotypes (LA2184 of S. pimpinellifolium L., LA2727 of S. neorickii, LA0111, L06221, L06127 and L06231 of S. peruvianum L., LA1306, L06057 and L06208 of S. chmielewskii) showing a susceptible response after mechanical inoculation were highly resistant, resistant and tolerant after M. persicae transmission. The resistant genotypes, identified in the present study can be exploited in the breeding programmes aimed
at developing tomato varieties resistant to CMV subgroup IA and broadening the genetic base of CMV-resistant germplasm. The
differences observed between mechanical and aphid transmission suggests that one should consider both evaluation methods for
tomato germplasm screening against CMV subgroup IA. 相似文献
10.
Maria Lodovica Gullino Giovanna Gilardi Mattia Sanna Angelo Garibaldi 《Phytoparasitica》2009,37(5):461-466
Leaf spot of tomato, incited by Pseudomonas syringae pv. syringae, has been reported recently in Italy on grafted and non-grafted tomato plants (scion Cuore di Bue, rootstock Solanum lycopersicum x Solanum hirsutum cv. Beaufort). In some greenhouses, more than 80% of plants were affected, with a marked reduction in yield. This work was
undertaken in order to understand the effect of the number of hours of incubation at high relative humidity (r.h.) and temperature
as well as the effect of the presence of wounds at infection time on the development of leaf spot. A difference in sensitivity
to leaf spot was observed in the various cultivars tested, in terms of severity of P. syringae pv. syringae, with “Cuore di Bue” being the most susceptible of these cultivars. The development of leaf spot is mostly favored by the
presence of wounds, at temperatures between 15 and 20°C. The severity of the disease is lower at 10 and 25°C and very low
at 30°C. Under the most favorable temperature conditions, the presence of wounds is sufficient to allow the development of
the pathogen immediately upon incubation at high r.h. The effect of wounds and the relatively low requirement of hours of
incubation at high r.h. suggest the need for careful management and handling of plants when temperatures range between 15
and 25°C, and particularly within 15 and 20°C. All operations carried out, particularly at transplant and immediately after,
should avoid the creation of wounds. 相似文献
11.
Blackleg (Phoma stem canker) caused by Leptosphaeria maculans is the most damaging disease of Brassica napus (canola, rapeseed, colza) worldwide and is controlled by sowing blackleg resistant cultivars and crop management strategies that reduce exposure to inoculum and fungicide application. In experiments in south-eastern Australia, canola cultivars inoculated after the three to five leaf growth stage did not develop stem canker. Although mature canola plants are known to be less susceptible to blackleg than seedlings, this highlights for the first time the specific importance of protecting seedlings up to the three to five leaf growth stage in Australia. This would typically correspond to a period of four to six weeks after emergence. Canola plants are likely to be significantly less vulnerable to infection after this growth stage. However, this timing may vary due to the influence of environmental conditions. 相似文献
12.
Sakhr Ajouz Marc Bardin Philippe C. Nicot Mohamed El Maâtaoui 《European journal of plant pathology / European Foundation for Plant Pathology》2011,129(1):31-42
Botrytis cinerea is able to build-up resistance to pyrrolnitrin, an antibiotic produced by diverse biocontrol agents, possibly compromising
the durability of this method of disease control. The development of two near-isogenic lines of B. cinerea differing in their level of resistance to pyrrolnitrin was compared in tomato plants and on PDA medium. In tomato plants,
significant differences in the percentage of infected petioles 1 day after inoculation and in symptom progression on petioles
and stems were observed between the resistant mutant and the sensitive wild-type parent, suggesting a difference in their
level of aggressiveness. Cytohistological investigations revealed that conidia of both near-isogenic lines germinated 6 h
after inoculation and mycelium developed within petiole tissues 12 h after inoculation. However, while the wild-type parent
isolate spread throughout the petiole and rapidly invaded the stem tissues via the leaf-abscission zone 72 h after inoculation, the pyrrolnitrin-resistant mutant failed to extend beyond petiole tissues
to invade the stem. Moreover, 72 h after inoculation, the mycelial development of the pyrrolnitrin-resistant mutant was accompanied
by abnormal glycogen accumulation and chlamydospore-like cell formation. In contrast, wild-type parent mycelium was normally
structured with intensive colonization of stem tissues. Additionally, on PDA medium the mycelium of the pyrrolnitrin-resistant
mutant was less vigorous than the wild-type isolate. These results suggest that the acquisition of pyrrolnitrin-resistance
in B. cinerea is accompanied by changes in mycelial structure and reduction in mycelial growth, leading to a noticeable loss of aggressiveness
on tomato plants. 相似文献
13.
G. Rodríguez Z. K. Punja 《European journal of plant pathology / European Foundation for Plant Pathology》2009,124(3):483-493
Wasabi (Wasabia japonica) is grown for its highly-valued rhizome which is used as a condiment in Japanese food. Symptoms of vascular blackening in
the rhizome were first observed in 2005 in plants grown in British Columbia, Canada. Microscopic observations and microbial
isolation from infected tissues revealed that most of the xylem tracheid cells were blackened and bacteria were consistently
associated with symptomatic plants. The bacterium most frequently recovered was identified as Pectobacterium carotovorum subsp. carotovorum (Pcc) using BioLog™ and sequencing of a specific ~510 bp IGS region. Pathogen-free plants obtained using meristem-tip micropropagation
were inoculated with a wasabi isolate of Pcc. Vascular blackening symptoms developed in the rhizome after 8 weeks when the rhizome was first wounded by stabbing or cutting,
or if the roots were pre-inoculated with Pythium species isolated from rhizome epidermal tissues, followed by inoculation with Pcc at 1 × 108 cells ml−1. Xylem tracheid cells were blackened and Pcc was reisolated from all diseased tissues. The highest frequency of rhizome vascular blackening occurred at 22°C and 27°C
and these tissues occasionally succumbed to soft rot at higher temperatures, but not when inoculated tissues were incubated
at 10°C. The rooting medium used by growers for vegetative propagation of wasabi was shown to contain Pcc but the pathogen was not recovered from the irrigation water. Entry of Pcc through wounds on wasabi rhizomes and the host tissue response result in symptoms of vascular blackening. 相似文献
14.
Jose Francisco L. Figueiredo Gerald V. Minsavage James H. Graham Frank F. White Jeffrey B. Jones 《European journal of plant pathology / European Foundation for Plant Pathology》2011,130(3):339-347
Xanthomonas citri subsp. citri, the causal agent of citrus canker, relies extensively on a type III secretion system for infection by delivering type III
effectors into host cells. In the genus Xanthomonas, two major regulators, HrpG and HrpX, are involved in the expression of genes encoding the type III secretion system. Twenty-three
candidate type III effectors were identified as targets for analysis. The involvement in pathogenicity of 20 candidate effector
genes in X. citri strain 306 (Xcc-306) was investigated using site-directed mutagenesis. Pathogenicity assays in grapefruit of 19 genes using
site-directed mutagenesis revealed that none of the mutants demonstrated to have reduced ability to cause canker disease.
A mutation in the TAL effector pthA4
–
resulted in loss of hypertrophy although no changes were observed in bacterial growth in leaves. Mutations in hrpG, hrpX, or hrpA genes displayed a complete loss of pathogenicity. Moreover, all mutants maintained the ability to trigger a hypersensitive
response (HR) in non-host tomato. In contrast to previous studies, hrpG
–
, hrpX
–
and hrpA
–
mutants also retained the ability to elicit an HR in tomato, indicating the presence of an Hrp independent elicitor in Xcc-306. 相似文献
15.
Ahmed A. Kheder Yasunori Akagi Hajime Akamatsu Konomi Yanaga Nitaro Maekawa Hiroshi Otani Takashi Tsuge Motoichiro Kodama 《Journal of General Plant Pathology》2012,78(1):30-38
The tomato pathotype of Alternaria alternata (A. arborescens) produces the dark brown to black pigment melanin, which accumulates in the cell walls of hyphae and conidia. Melanin has
been implicated as a pathogenicity factor in some phytopathogenic fungi. Here, two genes of the tomato pathotype for melanin
biosynthesis, ALM1 and BRM2-1, which encode a polyketide synthetase and a 1,3,8-trihydroxynaphthalene (THN) reductase, respectively, have been cloned and
disrupted in the pathogen. The gene-disrupted mutants, alm1 and brm2-1, had albino and brown phenotypes, respectively. The wild-type and the mutants caused the same necrotic lesions on the leaves
after inoculation with spores. These results suggest that melanin is unlikely to play a direct role in pathogenicity in the
tomato pathotype A. alternata. Scanning electron microscopy revealed that the conidia of both mutants have much smoother surfaces in comparison to the
wild-type. The conidia of those mutants were more sensitive to UV light than those of the wild-type, demonstrating that melanin
confers UV tolerance. 相似文献
16.
L.?Tsror O.?Erlich S.?Lebiush M.?Hazanovsky U.?Zig M.?Slawiak G.?Grabe J.?M.?van der?Wolf J.?J.?van de?Haar 《European journal of plant pathology / European Foundation for Plant Pathology》2009,123(3):311-320
Suspected Dickeya sp. strains were obtained from potato plants and tubers collected from commercial plots. The disease was observed on crops
of various cultivars grown from seed tubers imported from the Netherlands during the spring seasons of 2004–2006, with disease
incidence of 2–30% (10% in average). In addition to typical wilting symptoms on the foliage, in cases of severe infection,
progeny tubers were rotten in the soil. Six strains were characterised by biochemical, serological and PCR-amplification.
All tests verified the strains as Dickeya sp. The rep-PCR and the biochemical assays showed that the strains isolated from blackleg diseased plants in Israel were
very similar, if not identical to strains isolated from Dutch seed potatoes, suggesting that the infection in Israel originated
from the Dutch seed. The strains were distantly related to D. dianthicola strains, typically found in potatoes in Western Europe, and were similar to biovar 3 D. dadanti or D. zeae. This is the first time that the presence of biovar 3 strains in potato in the Netherlands is described. One of the strains
was used for pathogenicity assays on potato cvs Nicola and Mondial. Symptoms appeared 2 to 3 days after stem inoculation,
and 7 to 10 days after soil inoculation. The control plants treated with water, or plants inoculated with Pectobacterium carotovorum, did not develop any symptoms with either method of inoculation. The identity of Dickeya sp. and P. carotovorum re-isolated from inoculated plants was confirmed by PCR and ELISA. 相似文献
17.
Cucumber mosaic virus (CMV) was isolated from a mosaic diseased plant of Eucharis grandiflora. The virus caused mosaic symptoms on leaves and slight distortion of flower petals in E. grandiflora by either mechanical or aphid inoculation. The virus was identified as a strain of CMV subgroup I from its biological and serological characteristics. 相似文献
18.
Erich Seemüller Eckard Moll Bernd Schneider 《European journal of plant pathology / European Foundation for Plant Pathology》2008,121(2):109-119
In three trials carried out over a period of 24 years, open-pollinated seedlings of Malus sieboldii and M. sargentii and 22 apomictic rootstock selections with either M. sieboldii, M. sargentii or M. hupehensis in their parentage were examined for apple proliferation (AP) resistance in comparison to clonal M. x domestica-based rootstocks M 9, M 11, M 13, stocks of the B (Budagovski) and the Polish P series and M. robusta seedlings. Following experimental inoculation or natural infection the Golden Delicious-grafted trees on most of the M. sieboldii-derived progenies showed a high level of AP resistance expressed by low cumulative disease indices, a high percentage of
non or little affected trees, low incidence of the small fruit symptom and non or little effect on vigour. Trees on M 9 and
M 11, B 118 and M. robusta seedlings were moderately susceptible while trees on progenies with M. sargentii and M. hupehensis parentage, rootstocks of the P series, B 9, B 490 and M 13 proved highly susceptible. The screening also showed that rootstocks
with M. sieboldii and M. sargentii parentage are often highly susceptible to latent apple viruses. Trees on most of the M. sieboldii-based progenies were more vigorous than trees on standard stock M 9, whereas the vigour of some progenies from selections
with M. sargentii parentage was in the range of M 9 or even lower. Productivity was often correlated with the vigour. 相似文献
19.
Alejandro Solla Olga Aguín Elena Cubera Luís Sampedro J. Pedro Mansilla Rafael Zas 《European journal of plant pathology / European Foundation for Plant Pathology》2011,130(4):477-488
Results of a greenhouse Armillaria ostoyae inoculation experiment, designed for screening resistant Pinus pinaster genotypes and for exploring the role of different phenotypic traits in seedling susceptibility, are reported. The experiment
included 39 open-pollinated pine families that comprised a random subset of the breeding population of P. pinaster in Galicia (NW Spain). We employed a non-parametric survival-time analysis to analyze patterns of survival times during 14 months
after inoculation with a local A. ostoyae strain. Results indicate (i) a significant correlation between seed weight and tree susceptibility, with seedlings originating
from large seeds being more susceptible, (ii) a positive family mean correlation between secondary root weight and size and
median life expectancy, and (iii) genetic variation of tree tolerance to A. ostoyae, with some families surviving significantly longer than others. Less susceptible families could be used in breeding programmes
or directly in forest plantations to reduce the losses caused by A. ostoyae. Large within-family variation in tolerance to the disease was also observed, suggesting that non additive genetic variance
was also important. Although being infected, 32 out of the 1200 inoculated trees survived the fungus infection. These tolerant
genotypes comprise an attractive collection to further investigate genetic, phenotypic and environmental factors affecting
pine susceptibility to Armillaria root rot. 相似文献
20.
Márcia Silva Helena Machado Alan J. L. Phillips 《European journal of plant pathology / European Foundation for Plant Pathology》2009,125(3):425-433
Mycosphaerella leaf disease (MLD) is caused by species of Mycosphaerella and several anamorphic form genera that have been connected to Mycosphaerella. Until recently, MLD of eucalypts was largely ignored in Portugal. However, serious damage to Eucalyptus globulus has been reported since 1999 when frequent and severe defoliation of young trees was observed. The severity of this disease
prompted a preliminary study of the Mycosphaerella species associated with major symptoms of a leaf blotch disease in commercial plantations of E. globulus in Portugal, which is presented here. The species were identified by molecular methods based on the ITS1-5.8S-ITS2 cluster,
together with morphological characters. In addition to confirming the species previously recorded, Mycosphaerella vespa is reported for the first time from Portugal, while the status of Mycosphaerella grandis remains to be resolved. 相似文献