共查询到20条相似文献，搜索用时 31 毫秒
1.
R. S. C. Christiano M. Dalla Pria W. C. Jesus Junior L. Amorim A. Bergamin Filho 《European journal of plant pathology / European Foundation for Plant Pathology》2009,124(1):1-7
The combined effect of temperature (15°C, 20°C, 25°C, 30°C, 35°C, 40°C and 42°C) and leaf wetness duration (0, 4, 8 12, 16,
20 and 24 h) on infection and development of Asiatic citrus canker (Xanthomonas citri subsp. citri) on Tahiti lime plant was examined in growth chambers. No disease developed at 42°C and zero hours of leaf wetness. Periods
of leaf wetness as short as 4 h were sufficient for citrus canker infection. However, a longer leaf duration wetness (24 h)
did not result in much increase in the incidence of citrus canker, but led to twice the number of lesions and four times the
disease severity. Temperature was the greatest factor influencing disease development. At optimum temperatures (25–35°C),
there was 100% disease incidence. Maximum disease development was observed at 30–35°C, with up to a 12-fold increase in lesion
density, a 10-fold increase in lesion size and a 60-fold increase in disease severity. 相似文献
2.
O. Pruvost T.R. Gottwald C. Brocherieux 《European journal of plant pathology / European Foundation for Plant Pathology》1999,105(1):23-37
Asiatic citrus canker is a potentially severe disease of several citrus species and cultivars in many tropical and subtropical areas. In such areas, infected nursery plants constitute an important source of primary inoculum for newly established citrus groves. The influence of overhead, drip, and mist irrigation systems on the development of Asiatic citrus canker was studied in simulated, Mexican-lime nurseries in Reunion Island. Overhead irrigation exacerbated the increase of disease incidence and severity caused by a streptomycin-resistant strain of Xanthomonas axonopodis pv. citri. The temporal development of Asiatic citrus canker for overhead irrigated nursery plots was best described by an exponential model, because disease incidence in these plots did not come close to an asymptote during the experimental period. This can be explained by the continuous production of new growth, susceptible to infection by Xanthomonas axonopodis pv. citri, and splash dispersal of Xanthomonas axonopodis pv. citri associated with overhead irrigation. Based on spatial correlation and spatio-temporal analyses, aggregated disease patterns were found irrespective of the irrigation system. In overhead-irrigated plots, the spread of Xanthomonas axonopodis pv. citri lacked directionnality. Rainstorms of short duration and high intensity were apparently associated with disease increase in drip-irrigated plots. There is a need to improve cultivation practices in Reunion Island citrus nurseries to minimize Asiatic citrus canker incidence in nurseries and to minimize the introduction of Xanthomonas axonopodis pv. citri to new groves. 相似文献
3.
柑橘溃疡病是重要的柑橘细菌性病害,为探明壳聚糖和枯草芽孢杆菌对柑橘溃疡病的防治潜力,本文用平板菌落计数法评价了3种粘度壳聚糖对柑橘溃疡病菌的杀菌效果,以改良的纸碟法测定2株枯草芽孢杆菌(Bacillus subtilis)发酵液对柑橘溃疡病菌的抑菌效果。综合处理0.5 h、3 h和6 h的结果显示,3种粘度壳聚糖对柑橘溃疡病的杀菌强弱依次为:粘度12粘度100粘度20。枯草芽孢杆菌菌株BS 101和54-6在YPG培养基中有氧发酵3 d产生发酵液原液的抑菌圈直径分别为3.45 cm和3.21 cm,比0.1 g/mL氨苄青霉素的抑菌圈分别大45%和35%。可见,发酵液中存在对溃疡病菌高度有效的成分。因此,认为粘度12的壳聚糖和芽孢杆菌菌株BS 101和54-6具有防治柑橘溃疡病的潜力。 相似文献
4.
Experiments in controlled environments were carried out to determine the effects of temperature and leaf wetness duration on infection of oilseed rape leaves by conidia of the light leaf spot pathogen, Pyrenopeziza brassicae . Visible spore pustules developed on leaves of cv. Bristol inoculated with P. brassicae conidia at temperatures from 4 to 20°C, but not at 24°C; spore pustules developed when the leaf wetness duration after inoculation was longer than or equal to approximately 6 h at 12–20°C, 10 h at 8°C, 16 h at 6°C or 24 h at 4°C. On leaves of cvs. Capricorn or Cobra, light leaf spot symptoms developed at 8 and 16°C when the leaf wetness duration after inoculation was greater than 3 or 24 h, respectively. The latent period (the time period from inoculation to first spore pustules) of P. brassicae on cv. Bristol was, on average, approximately 10 days at 16°C when leaf wetness duration was 24 h, and increased to approximately 12 days as temperature increased to 20°C and to 26 days as temperature decreased to 4°C. At 8°C, an increase in leaf wetness duration from 10 to 72 h decreased the latent period from approximately 25 to 16 days; at 6°C, an increase in leaf wetness duration from 16 to 72 h decreased the latent period from approximately 23 to 17 days. The numbers of conidia produced were greatest at 12–16°C, and decreased as temperature decreased to 8°C or increased to 20°C. At temperatures from 8 to 20°C, an increase in leaf wetness duration from 6 to 24 h increased the production of conidia. There were linear relationships between the number of conidia produced on a leaf and the proportion of the leaf area covered by 'lesions' (both log10 -transformed) at different temperatures. 相似文献
5.
柑橘溃疡病检疫与防治 总被引：1，自引：0，他引：1
细菌性溃疡病是严重危害世界柑橘产业的重大检疫性病害之一,柑橘溃疡病引起落叶、枯枝和落果,溃疡病斑导致果品质量降低,影响外贸出口。世界各国长期以来对病害采取严格苗木检疫、疫区病树铲除、零星病害药剂防控的综合治理措施;新近美国农业部推出"柑橘健康种植行动计划";2007年7月中国农业部正式启动"柑橘非疫区建设和维护"项目,总体目标在于防控柑橘溃疡病的发生和传播,确保柑橘产业的安全。 相似文献
6.
L. FIGUEROA B. D. L. FITT S. J. WELHAM M.W. SHAW H. A. McCARTNEY 《Plant pathology》1995,44(4):641-654
In controlled environment experiments to study early development of light leaf spot, lesions developed with leaf wetness durations of 16 to 48 h after inoculation of oilseed rape with conidial suspensions of Pyrenopeziza brassicae at 12 or 18°C, but not with leaf wetness durations of 0 to 13h. The incubation period was 21 to 22 days at 12°C and 14 to 18 days at 18°C for leaf wetness durations of 16 to 48 h. The latent period was 21 to 23 days at 12°C and 18 to 19 days at 18°C, and the total number of lesions increased with increasing leaf wetness duration at both temperatures. In field experiments, light leaf spot always developed on oilseed rape with a leaf wetness duration of 48 h after inoculation in both 1990/1991 and 1991/1992, but the percentage leaf area affected was less on plants placed in an oilseed rape crop than on those placed in a glasshouse. Plants moved to an oilseed rape crop immediately after inoculation nearly always developed light leaf spot symptoms when they were inoculated between 19 October 1990 and 1 March 1991 or between 27 September 1991 and 14 February 1992, but plants inoculated between 31 August and 16 October 1990 or on 20 September 1991, when estimated leaf wetness duration was less than 16 h for several days after they were placed in crops, did not develop symptoms. The latent period of light leaf spot on plants transferred to the oilseed rape crop was 15 to 40 days, and there was an approximately linear relationship between 1 (latent period) and mean temperature during this period. The accumulated temperature during the latent period ranged from c. 150 to 250 day-degrees. The severity of lesions on these plants increased with increasing temperature from 5 to 15°C. 相似文献
7.
In controlled environment experiments, sporulation of Pyrenopeziza brassicae was observed on leaves of oilseed rape inoculated with ascospores or conidia at temperatures from 8 to 20°C at all leaf wetness durations from 6 to 72 h, except after 6 h leaf wetness duration at 8°C. The shortest times from inoculation to first observed sporulation ( l 0 ), for both ascospore and conidial inoculum, were 11–12 days at 16°C after 48 h wetness duration. For both ascospore and conidial inoculum (48 h wetness duration), the number of conidia produced per cm2 leaf area with sporulation was seven to eight times less at 20°C than at 8, 12 or 16°C. Values of Gompertz parameters c (maximum percentage leaf area with sporulation), r (maximum rate of increase in percentage leaf area with sporulation) and l 37 (days from inoculation to 37% of maximum sporulation), estimated by fitting the equation to the observed data, were linearly related to values predicted by inserting temperature and wetness duration treatment values into existing equations. The observed data were fitted better by logistic equations than by Gompertz equations (which overestimated at low temperatures). For both ascospore and conidial inoculum, the latent period derived from the logistic equation (days from inoculation to 50% of maximum sporulation, l 50 ) of P. brassicae was generally shortest at 16°C, and increased as temperature increased to 20°C or decreased to 8°C. Minimum numbers of spores needed to produce sporulation on leaves were ≈25 ascospores per leaf and ≈700 conidia per leaf, at 16°C after 48 h leaf wetness duration. 相似文献
8.
Infection of onion by Alternaria porri and Stemphylium vesicarium was investigated under a range of controlled temperatures (4–25°C) and leaf wetness periods (0–24 h). Conidia of A. porri and S. vesicarium germinated within 2 h when incubated at 4°C. Terminal and intercalary appressoria were produced at similar frequencies at or above 10°C. The maximum number of appressoria was produced after 24 h at 25°C. Penetration of leaves by both pathogens was via the epidermis and stomata, but the frequency of stomatal penetration exceeded that of epidermal penetration. There was a strong correlation ( R 2 > 90%) between appressorium formation and total penetrations at all temperatures. Infection of onion leaves occurred after 16 h of leaf wetness at 15°C and 8 h of leaf wetness at 10–25°C, and infection increased with increasing leaf wetness duration to 24 h at all temperatures. Interruption of a single or double leaf wetness period by a dry period of 4–24 h had little effect on lesion numbers. Conidia of A. porri and S. vesicarium separately or in mixtures caused similar numbers of lesions. Alternaria porri and S. vesicarium are both potentially important pathogens in winter-grown Allium crops and purple leaf blotch symptoms were considered to be a complex caused by both pathogens. 相似文献
9.
Experiments are described to quantify the effects of temperature and leaf wetness duration on infection of groundnut by Phaeoisariopsis personata. Temperature response curves for conidial germination and infection were similar, with optima close to 20°C and minimum and maximum temperatures of about 8°C and 34 C, respectively. The effect of temperature on infection between 15°C and 26°C was slight. Lesions developed only if the leaf wetness period exceeded about 20 h, and the total wetness period necessary for maximum infection exceeded 160 h. The number of lesions resulting from a fixed amount of inoculum was several times greater if leaves were exposed to alternate wet and dry periods (intermittent wetness), compared with continuous wetness. With intermittent wetness the length of the dry period had little effect on the number of lesions, providing it exceeded 2 h. The response curve relating total wetness periods to lesion density was an exponential asymptote. 相似文献
10.
The infection efficiency and severity of leaf blotch on spring barley inoculated with three pathotypes of Rhynchosporium secalis from central Norway were studied under different temperature and humidity regimes. Seedlings of the cultivar Arve were subjected to two constant temperatures, 13° or 18°C. Dry periods of 8 h or longer before or after a wet period of 4 h, carried out in the first 48 h postinoculation, reduced disease severity assessed 16 days after inoculation. The effect of dry periods of up to 24 h was nullified when plants were subjected to high humidity for 48 h after the dry treatment. The disease developed most rapidly when the wet period was 48 h and the temperature 18°C. At or near the optimum temperature for R. secalis (18°C), leaf wetness duration as short as 2 h resulted in considerable disease. Isolates reacted differently to temperature. The most aggressive isolate caused severe disease irrespective of temperature (56–70% of the leaf area infected); however, disease severity caused by the least aggressive isolate was significantly higher at the optimum temperature compared with a lower temperature (13°C). This information can facilitate evaluation of weather data in relation to predicting leaf blotch for advisory purposes. 相似文献
11.
Monocyclic components (development rate during the incubation period or latent period, lesion density, lesion size and disease severity) of rust ( Uromyces appendiculatus ) and of angular leaf spot ( Phaeoisariopsis griseola ) in two bean ( Phaseolus vulgaris ) cultivars (Rosinha G-2 and Carioca), pre-infected or not with bean line pattern mosaic virus (BLPMV), were determined. Trials were conducted at temperatures in the range from 9 to 27°C for rust and from 12 to 30°C for angular leaf spot. Regardless of viral pre-infection, the effect of temperature on the four monocyclic components followed an optimum curve and could be described by a generalized beta function. Generally, angular leaf spot was favoured by higher temperatures with an optimum for disease severity between 24.2 and 28.3°C compared with 15.9–18.5°C for rust. Pre-infection with BLPMV did not change the shape of the optimum curves for all components, but significantly reduced lesion density and disease severity on both cultivars. The development rates during incubation and latent periods for both fungal diseases were not affected by BLPMV. Pre-infection with virus did not alter the ranking of cultivars with respect to resistance to both fungal diseases. 相似文献
12.
In vitro effects of temperature and wet periods on infection of oilseed rape by Alternaria brassicae
The influence of temperature and duration of wet periods on infection of oilseed rape by Alternaria brassicae was studied on detached leaves and pods, leaf disks and intact seedlings. Infections increased with age of leaf and the interaction between temperature and leaf age was highly significant. On older leaves infection was optimal at 25°C. There were many infections also at 15, 20 and 29 C but relatively few infections at 10°C. On pods most infections were observed at 20 C, the highest temperature studied. Infection at each temperature increased progressively with duration of surface wetness. The minimum wet periods for infection of leaves were 3 h at 20–25°C, 4 h at 15°C, 6–9 h at 10 C and 12–24 h at 5 C and for infection of pods, between 6 h and 9 h at 10°C and 6 h (or less) at 15°C and 20 C. On leaves, dry periods interrupting wet periods limited lesion development to that obtained with the initial wet period only; on pods some further infections developed when pods were re-wetted. Dry periods of 3 h and 6 h following the inoculation of pods reduced subsequent infection but there was no further reduction by longer periods of drying to 48 h. 相似文献
13.
14.
During the period 1986–1988 field studies were conducted on the epidemiology of the tar spot disease complex (TDC) of maize ( Zea mays ) caused by Phyllachora maydis, Monographella maydis and Coniothyrium phyllachorae. Under field conditions we found that P. maydis symptoms always appeared first, followed by symptoms of either M. maydis or C. phyllachorae. M. maydis causes leaf necrosis and has the most devastating effect. The primary symptoms covered about 12% of the leaf area below the ear leaf, whereas the total necrotic leaf area amounted to 30–60%, here considered as a secondary effect. Maximum TDC severity occurred during the winter season of 1988, which was characterized by a temperature range of 17–22°C, a mean RH >75%, and > 7h of leaf wetness per night. The highest numbers of windborne ascospores of P. maydis were trapped at an RH > 85% and at temperatures of 17 to 23°C in the winter of 1987 and 1988, although large numbers were also caught at temperatures of >23°C and RH <70%. Spore release was strongly influenced by light conditions and followed a similar diurnal curve throughout three seasons, reaching a maximum at 17.00–21.00 hours. The spread off. maydis within the field was very homogeneous. The incubation period of P. maydis was 12 to 15 days, and most of the ascospores were released within 3 weeks after formation of the ascostromata. M. maydis inoculum in plant debris was reduced by 90% within 3 to 4 months. 相似文献
15.
ABSTRACT Gray leaf spot is a serious disease of perennial ryegrass (Lolium perenne), causing severe epidemics in golf course fairways. The effects of temperature and leaf wetness duration on the development of gray leaf spot of perennial ryegrass turf were evaluated in controlled environment chambers. Six-week-old Legacy II ryegrass plants were inoculated with an aqueous conidial suspension of Pyricularia grisea (approximately 8 x 10(4) conidia per ml of water) and subjected to four different temperatures (20, 24, 28, and 32 degrees C) and 12 leaf wetness durations (3 to 36 h at 3-h intervals). Three days after inoculation, gray leaf spot developed on plants at all temperatures and leaf wetness durations. Disease incidence (percent leaf blades symptomatic) and severity (index 0 to 10; 0 = leaf blades asymptomatic, 10 = >90% leaf area necrotic) were assessed 7 days after inoculation. There were significant effects ( alpha = 0.0001) of temperature and leaf wetness duration on disease incidence and severity, and there were significant interactions ( alpha = 0.0001) between them. Among the four temperatures tested, 28 degrees C was most favorable to gray leaf spot development. Disease incidence and severity increased with increased leaf wetness duration at all temperatures. A shorter leaf wetness duration was required for disease development under warmer temperatures. Analysis of variance with orthogonal polynomial contrasts and regression analyses were used to determine the functional relationships among temperature and leaf wetness duration and gray leaf spot incidence and severity. Significant effects were included in a regression model that described the relationship. The polynomial model included linear, quadratic, and cubic terms for temperature and leaf wetness duration effects. The adjusted coefficients of determination for the fitted model for disease incidence and severity were 0.84 and 0.87, respectively. The predictive model may be used as part of an integrated gray leaf spot forecasting system for perennial ryegrass turf. 相似文献
16.
ABSTRACT Asiatic citrus canker (ACC) is a severe disease of several citrus species and hybrids in many tropical and subtropical areas. Populations of Xanthomonas axonopodis pv. citri in leaf and twig lesions are the most important inoculum source for secondary infections. In areas with a marked winter season (e.g., Argentina and Japan), low temperatures induce a decrease of 10(2) to 10(4) in population sizes in lesions, thus creating a discontinuity in the X. axonopodis pv. citri life cycle. The purpose of this study was to evaluate the dynamics of X. axonopodis pv. citri populations in leaf lesions exposed to the mild winter temperatures prevailing in a tropical environment. Internal X. axonopodis pv. citri population levels in Mexican lime leaf lesions reached 10(6) to 10(7) CFU lesion(-1) whatever the lesion size. These densities, however, were not strongly negatively affected by winter temperatures prevailing under experimental conditions. The estimated decrease in internal X. axonopodis pv. citri population sizes was approximately 10-fold. When exposed to 35 mm h(-1) of simulated rainfall, internal population sizes decreased over time by approximately 1 log unit for lesions 1 and 2 months old, but did not for older lesions. A microscopic examination indicated that lignin-like compounds are present in lesions more than 6 months old. The slow decrease over time of X. axonopodis pv. citri population sizes in leaf lesions may be the balanced result of defense reactions by the host at late stages of disease development, and the concomitant multiplication of the pathogen at the margin of old lesions. We conclude that the epidemiological significance of overwintered leaf lesions in the tropics is higher than that reported in other areas. 相似文献
17.
柑桔溃疡病菌PCR快速检验检疫技术研究 总被引：11，自引：0，他引：11
柑桔溃疡病是严重影响全世界柑桔生产的重大检疫性病害,根据柑桔溃疡病菌(Xanthomonas axonopodis pv. citri)新近公布的全基因组中独有的保守蛋白基因序列,设计筛选出一对种特异性引物(JYF5/JYR5),能专一地扩增检出柑桔组织表面所带溃疡病菌的DNA靶带(413 bp)。而柑桔叶面附生的非致病性黄单胞菌、野油菜黄单胞菌近缘种以及健康柑桔样品都不能扩增;靶细菌DNA检测下限1.56 pg/μL,靶细菌悬浮液检测下限10 cfu/μL;在不同PCR仪及各种控温方式下都能稳定地扩增出特征性靶带。这一特异、准确的柑桔溃疡病菌PCR检验技术和研制的预包被固相化PCR检测试剂盒已开始用于我国非疫生产区建设中柑桔苗木、果实的病害检疫检验。 相似文献
18.
When the influence of host species, inoculum density, temperature, leaf wetness duration, and leaf position on the incidence
of gentian brown leaf spot caused by Mycochaetophora gentianae, was examined, the fungus severely infected all seven Gentiana triflora cultivars, but failed to infect two cultivars of G. scabra and an interspecific hybrid cultivar. Inoculum density correlated closely with disease incidence, and a minimum of 102 conidia/mL was enough to cause infection. In an analysis of variance, temperature and leaf wetness duration had a significant
effect upon disease incidence, which increased with higher temperature (15–25°C) and longer duration of leaf wetness (36–72 h).
No disease developed at temperatures lower than 10°C or when leaf wetness lasted <24 h. At 48-h leaf wetness, disease incidence
was 0, 28, 77, and 85% at 10, 15, 20, and 25°C, respectively. Middle and lower leaves on the plant were more susceptible than
upper leaves. In microscopic observations of inoculated leaves, >50% of conidia germinated at temperatures >15°C after 24-h
leaf wetness. More appressoria formed at higher temperatures (15–25°C) with extended duration of leaf wetness (24–72 h). At
48-h leaf wetness, appressorium formation was 0, 8, 26, and 73% at 10, 15, 20, and 25°C, respectively. These results suggest
that temperature and leaf wetness duration were important factors for infection of gentian leaves. 相似文献
19.
Environmental conditions influencing Sclerotinia sclerotiorum infection and disease development in lettuce 总被引：1，自引：0，他引：1
C. S. Young † J. P. Clarkson J. A. Smith M. Watling K. Phelps J. M. Whipps 《Plant pathology》2004,53(4):387-397
The environmental factors that influence infection of lettuce by ascospores of Sclerotinia sclerotiorum , and subsequent disease development, were investigated in controlled environment and field conditions. When lettuce plants were inoculated with a suspension of ascospores in water or with dry ascospores and exposed to a range of wetness durations or relative humidities at different temperatures, all plants developed disease but there was no relationship between leaf wetness duration or humidity and percentage of diseased plants. Ascospores started to germinate on lettuce leaves after 2–4 h of continuous leaf wetness at optimum temperatures of 15–25°C. The rate of development of sclerotinia disease and the final percentage of plants affected after 50 days were greatest at 16–27°C, with disease symptoms first observed 7–9 days after inoculation, and maximum final disease levels of 96%. At lower temperatures, 8–11°C, disease was first observed 20–26 days after inoculation, with maximum final disease levels of 10%. Disease symptoms were always observed first at the stem base. In field-grown lettuce in Norfolk, 2000 and 2001, inoculated with ascospore suspensions, disease occurred only in lettuce planted in May and June, with a range of 20–49% of plants with disease by 8 weeks after inoculation. In naturally infected field-grown lettuce in Cheshire, 2000, disease occurred mainly in lettuce planted throughout May, with a maximum of 31% lettuce diseased within one planting, but subsequent plantings had little (≤ 4%) or no disease. Lack of disease in the later plantings in both Norfolk and Cheshire could not be attributed to differences in weather factors. 相似文献
20.
The influence of temperature, wetness duration, and planting density on infection of olive fruit by Colletotrichum acutatum and C. simmondsii was examined in laboratory and field experiments. Detached olive fruit of 'Arbequina', 'Hojiblanca', and 'Picual' were inoculated with conidia of several isolates of the pathogen and kept at constant temperatures of 5 to 35°C in humid chambers. Similarly, potted plants and stem cuttings with fruit were inoculated and subjected to wetness periods of 0 to 48 h. Infection occurred at 10 to 25°C, and disease severity was greater and the mean latent period was shorter at 17 to 20°C. Overall, C. acutatum was more virulent than C. simmondsii at temperatures <25°C. When temperature was not a limiting factor, disease severity increased with the wetness period from 0 to 48 h. Disease severity was modeled as a function of temperature and wetness duration; two critical fruit incidence thresholds were defined as 5 and 20%, with wetness durations of 1.0 and 12.2 h at the optimum temperature. In the field, anthracnose epidemics progressed faster in a super-high-density planting (1,904 olive trees/ha) than in the high-density plantings (204 to 816 olive trees/ha) and caused severe epidemics in the super-high-density planting even with the moderately resistant Arbequina. Data in this study will be useful for the development of a forecasting system for olive anthracnose epidemics. 相似文献