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1.
ABSTRACT The incidence of strawberry flower infection by Botrytis cinerea was monitored in unsprayed field plots in three successive years together with meteorological data and numbers of conidia in the air. There were large differences in conidia numbers and weather conditions in the 3 years. Three sets of models were derived to relate inoculum and weather conditions to the incidence of flower infection; by inoculum only, by weather variables only, and by both inoculum and weather variables. All the models fitted the observed incidence satisfactorily. High inoculum led to more infection. Models using weather variables only gave more accurate predictions than models using inoculum only. Models using both weather variables and inoculum gave the best predictions, but the improvement over the models based on weather variables only was small. The relationship between incidence of flower infection and inoculum and weather variables was generally consistent between years. Of the weather variables examined, daytime vapor pressure deficit and nighttime temperature had the greatest effect in determining daily incidence of flower infection. Infection was favored by low day vapor pressure deficit and high night temperature. The accuracy and consistency of the weather-based models suggest they could be explored to assist in management of gray mold. 相似文献
2.
Fusarium crown and root rot of tomatoes in the UK 总被引：1，自引：0，他引：1
Fusarium crown and root rot caused by Fusarium oxysporum f. sp. radicis-lycopersici was found in the UK in 1988 and 1989 mainly in rockwool-grown tomato crops. Up to 14% of plants were affected in individual crops. In experiments, leaf and stem symptoms did not appear until the time of first fruit harvest even when the plants were inoculated at planting, first flowers or fruit set. Conidial inoculum at 106 spores/plant applied at seed sowing killed 70–83% of tomato seedlings, whereas similar levels of inoculum applied to young plants caused root and basal stem decay, and eventually death but only after fruit harvest began. Disease incidence and symptom severity increased with inoculum concentration. Experimentally, the disease was more severe in peat- or compost-grown plants than in rockwool. Disease spread was only a few centimetres in 50 days in experimental rockwool-grown plants. All tomato cultivars tested were highly susceptible. Prochloraz-Mn was highly effective against the pathogen in vitro and controlled the disease in the glasshouse, but only when applied preventively. Non-pathogenic Fusarium oxysporum isolates and Trichoderma harzianum also reduced FCRR disease levels. 相似文献
3.
Grapevine cultivars Cabernet Sauvignon (susceptible to Eutypa dieback), and Merlot (tolerant), were pruned three times during the dormant season (mid-December, mid-January and mid-February) and wounds on the 1-year-old canes were inoculated weekly with ascospores of Eutypa lata after pruning. No differences in susceptibility to infection were observed between cultivars, although in the vineyard they differed in symptom expression. Infection by E. lata varied with pruning date and the age of the pruning wound, and was higher and of longer duration with early pruning (December). At low temperature, infection of the pruning wounds by E. lata was increased, whereas the growth of other microorganisms was reduced. Moderate temperatures encouraged the growth of other microorganisms, notably Rhodotorula sp. This natural colonizer of grapevine pruning wounds was able to reduce the infection capacity of E. lata . It was more effective when inoculation with E. lata was carried out with low numbers of ascospores and when it was delayed until 14 days after application of the wound colonizer, infection being reduced by 95–100%. 相似文献
4.
Experiments were conducted on olive plants in controlled environments to determine the effect of conidial concentration, leaf age, temperature, continuous and interrupted leaf wetness periods, and relative humidity (RH) during the drier periods that interrupted wet periods, on olive leaf spot (OLS) severity. As inoculum concentration increased from 1·0 × 102 to 2·5 × 105 conidia mL?1, the severity of OLS increased at all five temperatures (5, 10, 15, 20 and 25°C). A simple polynomial model satisfactorily described the relationship between the inoculum concentration at the upper asymptote (maximum number of lesions) and temperature. The results showed that for the three leaf age groups tested (2–4, 6–8 and 10–12 weeks old) OLS severity decreased significantly (P < 0·001) with increasing leaf age at the time of inoculation. Overall, temperature also affected (P < 0·001) OLS severity, with the lesion numbers increasing gradually from 5°C to a maximum at 15°C, and then declining to a minimum at 25°C. When nine leaf wetness periods (0, 6, 12, 18, 24, 36, 48, 72 and 96 h) were tested at the same temperatures, the numbers of lesions increased with increasing leaf wetness period at all temperatures tested. The minimum leaf wetness periods for infection at 5, 10, 15, 20 and 25°C were 18, 12, 12, 12 and 24 h, respectively. The wet periods during early infection processes were interrupted with drying periods (0, 3, 6, 12, 18 and 24 h) at two levels of RH (70 and 100%). The length of drying period had a significant (P < 0·001) effect on disease severity, the effect depending on the RH during the interruption. High RH (100%) resulted in greater disease severity than low RH (70%). A polynomial equation with linear and quadratic terms of temperature, wetness and leaf age was developed to describe the effects of temperature, wetness and leaf age on OLS infection, which could be incorporated as a forecasting component of an integrated system for the control of OLS. 相似文献
5.
Controlled-environment studies of conidial production by Phaeoisariopsis personata on groundnut are described. With constant relative humidity (RH), conidia were only produced above a threshold (94·5% RH) and there was a linear increase between 94·5% RH and 100% RH. Conidial production was less with continuous leaf wetness (resembling heavy dew) than with continuous 98–99% RH, but it was similar with intermittent leaf wetness and intermittent 98–99% RH (8 h at 70% RH each day). With alternate high (≥97% RH) and low humidity, daily conidial production depended both on the duration of high RH and on the low RH value. With 99% RH at night (12 h), night-time conidial production decreased with the previous daytime RH. After conidial production had started, small numbers of conidia were produced even when the RH was well below the threshold (94·5%). Conidia were produced in continuous light when the photon flux density was 2 μmol/m2 /s, but production was completely inhibited with 60 μmol/m2 /s. With constant RH, more conidia were produced with a 12 h photoperiod than in continuous darkness. However, more than 75% of the conidia were produced in the dark. With continuous darkness, more conidia were produced during the night (18.00–06.00 h) than during the day, but this biological rhythm was overcome with a (light-night)/(dark-day) regime. With constant 98–99% RH there was a linear increase in conidial production with temperature between 10 and 28°C, and virtually no conidia were produced at 33°C. The daily production of conidia increased with time for 2 to 6 days, depending on the treatment. 相似文献
6.
Pitch canker, caused by the fungus Fusarium circinatum , is a disease affecting many pine tree species. In California, Pinus radiata (Monterey pine) is the principal pine host affected by pitch canker. This investigation into factors affecting infection frequency by F. circinatum of P. radiata examined the influence of: (i) wound size; (ii) relative humidity; (iii) time of inoculation; (iv) inoculum density; and (v) wound age. Wounded branches sustained significantly more infections when large-diameter (1·6 mm) rather than small-diameter (0·5 mm) wounds were made. Infection frequencies tended to be higher at 100% RH than at ambient humidity, although these differences were not statistically significant. Infection frequencies were significantly higher on branches inoculated after 17·00 h than on branches inoculated before noon. Infection frequencies were significantly higher for wounded branches spray-inoculated with 5 × 107 rather than 1 × 107 spores mL−1 . Infection frequencies of pruning wounds declined as wounds aged. 相似文献
7.
Ganoderma boninense causes severe losses to oil palm in South East Asia. The disease typically manifests itself as basal stem rot, but there remains controversy over the route of infection and source of inoculum. Using isolates differing in aggressiveness, infection via roots was confirmed; it was also shown that large inoculum provided as Ganoderma -infested palm- or rubber-wood blocks (12 × 6 × 6 cm) is necessary for soil infection of seedlings after 6–8 months. Smaller blocks (3 × 3 × 3 cm) produced rapid (≤ 3 months) infection of roots and lower stem when physically attached to roots. Therefore fragmentation of infested palm wood from a felled, mature plantation before subsequent replanting may provide inoculum. Failure of G. boninense to grow through non-sterile soil or organic debris from frond bases, suggests it is a poor competitor and that roots must contact inoculum directly. Severe disease occurred after 8 months on inoculated seedlings under shade, but not on seedlings exposed to sun. Soil temperatures in sunlight frequently rose above 40°C and reached 45°C, whereas in shade they never exceeded 32°C. Ganoderma boninense is probably inhibited in exposed soil since optimal growth in vitro was 25–30°C, and there was no recovery from 45°C. Soil temperature may explain why symptoms often first appear in mature plantations when canopy formation creates shade. Infection is not peculiar to senescing palms but can occur throughout the growth cycle. 相似文献
8.
Inoculum prevalence, host infection and biological control of Colletotrichum acutatum: causal agent of blueberry anthracnose in British Columbia 总被引：1，自引：1，他引：0
To identify the causal organism of anthracnose (ripe-rot), which reduces yield and postharvest quality of blueberries grown in British Columbia, Canada, 80 isolates were recovered from diseased fruits collected from commercial blueberry fields during 2002–04 and identified as Colletotrichum acutatum using colony morphology, growth rate and species-specific PCR primers. In vitro incubation of replicated sets of inoculated detached berries at various temperatures produced infection at temperatures of 7–30°C, with an optimum at 20°C. Colletotrichum acutatum could not survive on the soil surface as mummified berries but the pathogen was detected mostly within flower buds and less so in blueberry twigs and fruit trusses. Infection of developing flower buds in May–June of the preceding growing season gave the highest inoculum recovery in the following year. Two commercial fungal biocontrol agents, Prestop ( Gliocladium catenulatum ) and PlantShield ( Trichoderma harzianum ), each reduced anthracnose development in 2003 and 2004 by up to 45% when sprayed three times onto plants between flowering and fruit ripening. 相似文献
9.
J. M. van der Wolf P. S. van der Zouwen L. van der Heijden 《European journal of plant pathology / European Foundation for Plant Pathology》2013,136(1):103-111
During seed production, Brassica seed may become infected with Xanthomonas campestris pv. campestris after systemic colonization of plants upon leaf infection, or alternatively, after flower infection. Polytunnel experiments were conducted in 2007 and 2008 to study the relative importance of these colonization routes resulting in seed infection. Cauliflower plants (Brassica oleracea) were spray-inoculated at the 8-leaf stage, after formation of cauliflowers or during flowering, at which stage leaves or blossoms were inoculated. Inoculation at all stages resulted in a relatively high percentage of systemic infection; the average estimated infection incidences for stem base and peduncle infections were 16 % and 19 %, respectively. When seed samples were examined by dilution plating for deep-seated infection following hot water treatment, Xcc was detected in 61 % of the 23 seed samples harvested from plants with inoculated flowers. However, symptom development in seedlings raised from the seeds could not be confirmed in a grow-out test under favourable conditions for Xcc infection at a high RH (>95 %) and a relative high temperature (28 °C). Xcc was not detected in 59 seed samples harvested from leaf-inoculated plants with the exception of one sample from plants inoculated at peduncle formation. In a third polytunnel experiment carried out in 2009, the population dynamics of Xcc on inoculated flowers was investigated. Following spray-inoculation of flowers, 52 % of the flowers were infected with Xcc. During development of siliques, infection incidence decreased slowly and at 56 dpi, 20 % of the superficially disinfected siliques were infected with Xcc. It was estimated that 0.18 % of the seeds was infected and that 1–10 % of the infected siliques contained infected seeds. The implications of these results for control of Xcc in a seed production crop are discussed. 相似文献
10.
The mode of infection ofColletotrichum musae, the main causal agent of tip rot of banana fruits in the Jordan Valley, was investigated. Immature, apparently healthy banana fruits cv. Dwarf Cavendish were inoculated by spraying spore suspensions on the distal end of the fruit. A correlation was found among type of flowers, age of fruits at inoculation time, concentration of spores in the inoculum, and the development of tip rot in the fruits. An infection rate of 100% was obtained with suspensions at a concentration of at least 5x104 spores/ml on fruit with persistent flower parts, not older than 3 weeks after the curling of the hand bract. On fruits with deciduous flower parts, only inoculations of very young fruits still under bracts was successful. Penetration of the fungus through the perianths was assessed. Virulent inoculum was found to be present in the plantation; 100% infection was obtained by using a suspension prepared from dry leaves and debris collected around banana plants. 相似文献
11.
R. P. Baayen H. Bonthuis J. C. M. Withagen J. G. N. Wander J. L. Lamers J. P. Meffert G. Cochius G. C. M. van Leeuwen H. Hendriks B. G. J. Heerink P. H. J. F. van den Boogert P. van de Griend R. A. Bosch 《EPPO Bulletin》2005,35(1):9-23
Laboratory (Spieckermann) tests, pot tests and field tests provided concordant evidence for the partial nature of resistance of potatoes to pathotypes 1 (D1) and 6 (O1) of Synchytrium endobioticum . Susceptible potato cultivars produced large warts (> 16 mm in diameter) in Spieckermann tests and had low field resistance levels (1–6). Field-resistant cultivars (levels 7–9) produced small warts or no warts at all in Spieckermann and field tests. In pot tests, at low inoculum levels (1 sporangium per 25 g soil) susceptible cultivars still developed warts, whereas field-resistant ones did not develop any warts below 25 sporangia per g soil. Above 35 sporangia per g soil, 100% disease incidence was observed in susceptible cultivars but only minimal wart development in field-resistant ones. Tests with continuous cultivation of potato cultivars in infected soil during three consecutive years showed that field-resistant cultivars will not support build-up of inoculum in soil. It is concluded that field-resistant cultivars do not create a risk of secondary infection, the criterion given for resistance in EU Directive 69/464/EC. 相似文献
12.
Microclimatic variables were monitored in cucumber crops grown in polyethylene-covered, unheated greenhouses in Israel during the winter of 1987/88. The winter was characterized by a relatively large number of rainy days. The relative humidity (RH) in the greenhouses was high (>97%) during most of the day, resulting in long periods of dew persistence. Dew point temperature and duration of dew deposition were calculated for the plant canopy. Disease incidence was monitored in 2-m-high plants, both on senescing female flowers (‘fruits’) and on stems. Multiple linear correlations were calculated for gray mold incidence and duration of air temperature and RH at specific ranges, and of leaf wetness (LW). Disease was characterized by two stages, according to the rate of its development and the microclimatic conditions influencing it. In the first phase of the epidemic a high correlation was found between infected fruits and air temperature in the range of 11–25°C, and RH in the range of 97–100% or LW. In the second phase, disease incidence was better correlated with air temperature in the range of 11–16°C and RH above 85% (R2 = 0.681); there was no correlation between disease and LW at this stage. Development of stem infections was correlated with air temperature in the range of 11–16°C during the first phase of the epidemic. By contrast, the second phase was characterized by a close correlation between stem infections and RH in the range of 80–100% but also with air temperature in the range of 11–16°C, or with air temperature in the range of 11–25°C and RH 80–100%, and LW. 相似文献
13.
Botrytis cinerea infects waxflower (Chamelaucium spp.) flowers and can induce them to abscise from their petioles before disease becomes evident. Botrytis cinerea infection of flowers was studied on two waxflower cultivars by light and electron microscopy. Pot‐grown waxflower flowers were harvested, inoculated with aqueous suspensions of B. cinerea conidia, incubated at 20–22°C and >95% RH and examined within 96 h post‐inoculation (hpi). Conidial germination on petals started 4 hpi, penetration via germ tube tips was 6 hpi and protoappressoria were formed 8 hpi. Germination on petals approximately doubled every 4–6 h to 18 hpi. Conidial germination was ca. 50% at 22–24 hpi. Botrytis cinerea infected most waxflower flower organs, including petals, anthers and filaments, stigma and hypanthium, within 24 hpi. Hyaline and lobate appressoria were observed 36 hpi. Infection cushions on stamen bases were formed 36 hpi by saprophytic hyphae that originated from anthers. This infection process can give rise to tan‐coloured symptoms typical of botrytis disease that radiate from this part of the flower. Subcuticular hyphae were present at high density near stamen bases and evidently resulted from multiple penetrations from single infection cushions. The subcuticular hyphae grew within the hypanthium and towards the centre of the floral tube. When flower abscission occurred, floral tube tissues close to the abscission zone remained uninfected. This observation infers possible transmission of a signal (e.g. ethylene) upon B. cinerea infection. Thus, B. cinerea causes flower abscission apparently as a defence response. 相似文献
14.
Alena Gaudinov Ji&#x;í Malbeck Petre Dobrev Darina Kubelkov Josef &#x;pak Radomira Vankov 《Physiological and Molecular Plant Pathology》2008,73(6):119-125
Blackcurrant reversion virus (BRV) infection, characteristic by flower malformation, resulted at the early flower stage in elevated levels of bioactive cytokinins and their biosynthetic precursors in flowers of white currant ‘Blanka’ and red currant ‘Vitan’. In healthy flowers, flower-to-berry transition was accompanied by an increase in bioactive cytokinins that was not observed in infected flowers, which were incapable of further development. Auxin levels increased during flower development, in ‘Vitan’ only in flowers with normal morphology (both healthy and infected). BRV infection did not have a significant effect on cytokinin or auxin levels in the leaves of either cultivar, it coincided with a mild elevation in the content of abscisic acid in the flowers of both cultivars. 相似文献
15.
Infestation of kiwifruit flowers by Thrips obscuratus , and inoculation with Botrytis cinerea , increased the amount of flower infection, external contamination and internal infection of fruit at harvest. Combination of these treatments was synergistic. The mechanisms of this role of T. obscuratus in the epidemiology of B. cinerea and development of stem-end rot after cool storage are discussed in relation to commercial production, harvesting and handling procedures. Significant reductions in inoculum available for fruit infection may be achievable by control of populations of T. obscuratus in orchards during flowering. 相似文献
16.
Pusey PL 《Phytopathology》2000,90(12):1352-1357
ABSTRACT Detached crab apple flowers were used as an experimental model to investigate the effect of relative humidity (RH), free moisture, and water potential Psi(w) on the interaction between Erwinia amylovora and pomaceous flowers. Flowers were maintained at 24 degrees C with the cut pedicel submerged in a sucrose solution. The bacterium multiplied on inoculated flower stigmas at between approximately 55 and 100% RH but not in the floral cup (hypanthium) until the RH was higher than 80%. To study the effect of free moisture, stigma-inoculated flowers were kept wet for different periods. Flowers became diseased only with wetting, and incidence was high (77%) even when water application was immediately followed by a 52-min drying period. In other experiments with hypanthium-inoculated flowers, RH or sucrose concentration in holding vials was varied to affect Psi(w) of flower nectar and ovary tissue. Population size of E. amylovora in the hypanthium increased with nectar Psi(w) following a sigmoidal curve (R(2) = 0.99). Disease incidence and severity, however, were more closely related to ovary Psi(w) (R(2) = 0.85 and 0.91, respectively) than to bacterial population size (R(2) = 0.25 and 0.67, respectively) as fitted to the quadratic equation. Maximum disease incidence and severity occurred at an ovary Psi(w) above -2.0 MPa, and disease severity continued to increase above -1.0 MPa. These results were confirmed with detached flowers of Delicious apple and d'Anjou pear. A practical implication is that disease might be partly managed in arid climates by limiting soil irrigation water during bloom and early fruit set. 相似文献
17.
A. Kerssies A. I. Bosker-van Zessen H. D. Frinking 《European journal of plant pathology / European Foundation for Plant Pathology》1995,101(2):201-216
Quantification and horizontal distribution of air-borne inoculum ofBotrytis cinerea in a rose crop in a glasshouse of 300 m2 was studied in 1991 and 1992. Conidia ofB. cinerea were caught in spore traps consisting of an agar medium selective forB. cinerea in Petri dishes placed within the crop, at flower height 1 m above the ground. Spore catches were counted as colonies, after incubation. Lesions due to conidial infection were counted on petals of rose flowers, also after incubation. Relative humidity (RH) and temperature within the glasshouse and global radiation and windspeed outside were recorded during the experiments. The horizontal distribution ofB. cinerea in a rose crop grown under glass was fairly uniform in both years. In 1991 a clear seasonal pattern in the number of colonies could not be found. In 1992 the number of colonies were high in August, September and October. The number of lesions on rose flowers showed a distinct pattern in both years. In August, September and October many lesions were counted whereas in the other months few lesions appeared. In linear regression analysis, variation in numbers of colonies (spore catches) could not be explained by environmental factors recorded during the experiments. Linear regression accounted for 76 and 63% of the variation in the number of lesions on rose flowers in 1991 and 1992, in terms of relative humidity (positively correlated), global radiation outside the glasshouse (negatively correlated) and, numbers of colonies on spore traps (positively correlated). The results in the rose crop suggest that RH, global radiation and spore density in glasshouses are important variables in regulating the numbers of lesions during storage and transport. The numbers of spores in glasshouses are dependent on the production system. A glasshouse with a system resulting in wet dead tissue on the ground give higher amount of spores in the glasshouse air and through that high numbers of lesions on flowers. On roses outside the glasshouses very high numbers of lesions were counted sometimes, mostly during and after rain showers, as a result of rain-deposition of spores onto the flowers. 相似文献
18.
Xiang-Ming Xu M.S. Ridout 《European journal of plant pathology / European Foundation for Plant Pathology》1998,104(5):511-519
Four experiments were conducted with potted trees of several apple cultivars to study the effects of several factors on the incidence of canker and the length of the incubation period following the inoculation of pruning cuts with conidia of Nectria galligena. These factors included wound age (the interval between pruning and inoculation), inoculum dose and environment (wet-period temperature and duration). The most important factors affecting the incidence of canker and the incubation period were inoculum dose, cultivar and wound age. Low inoculum dose resulted in low incidence of canker. The incidence of canker decreased as the age of the pruning wound increased. The incubation period lengthened with low inoculum dose and increasing age of the wound. The degree of resistance related to the age of the wound varied with cultivar; likewise, it also varied with the time of year, but this was not due to temperature alone. On fresh wounds, the incidence of canker and the incubation period were not affected by temperature during the wet period. The effect of duration of wetness on canker incidence was significant in only one out of three experiments: the longer wet periods resulted in a slightly lower incidence on fresh wounds. In another experiment, wet periods longer than 2 h resulted in shorter incubation periods. The results are discussed in relation to wound healing. 相似文献
19.
The effects of Coniothyrium minitans inoculum quality and an 8-week interval between inoculum application and crop planting on sclerotinia ( Sclerotinia sclerotiorum ) disease in three successive lettuce crops were investigated in a glasshouse trial. Spore suspensions of three isolates of C. minitans (Conio, IVT1 and Contans) applied at 108 CFU m−2 and a standard Conio maizemeal–perlite application (06 L m−2 , 1011 CFU m−2 ) were assessed for their ability to control S. sclerotiorum . Only the maizemeal–perlite inoculum (isolate Conio) consistently reduced sclerotinia disease. In the third lettuce crop only, isolates IVT1 and Contans formulated by Prophyta and isolate IVT as an oil–water formulation, all applied as spore suspensions, reduced disease at harvest compared with the untreated control. Recovery, viability and C. minitans infection of sclerotia buried during the 8-week period prior to each of the three lettuce crops, and of sclerotia formed on the crop, were tested. Only the maizemeal–perlite inoculum (isolate Conio) reduced the recovery of sclerotia buried in soil for weeks between inoculum application and crop planting, reducing their viability and increasing infection by C. minitans . Eight weeks was sufficient to enable C. minitans to infect sclerotia of S. sclerotiorum , and may account for disease control. After harvest of the second and third crops, maizemeal–perlite treatment (isolate Conio) reduced the number and viability of sclerotia recovered on the soil surface and increased infection by C. minitans compared with spore-suspension treatments. The effect of inoculum concentration and the influence of soil temperature (varying with time of year) on infection of sclerotia by C. minitans are discussed. 相似文献
20.
A. W. Doornik 《European journal of plant pathology / European Foundation for Plant Pathology》1981,87(4):139-147
Several isolates ofRhizoctonia solani obtained from tulip, iris or lettuce, infected various bulb crops either only at soil temperatures of 13 °C or higher (‘warmth preferring isolates’), or mainly at soil temperatures below 13 °C (‘cold preferring isolates’). Infection of the host by cold preferring isolates at temperatures above 13 °C was possible when the inoculum was in close contact with the host. Pathogenic activity under unfavourable temperature conditions was relatively brief but could recur if the temperature became favourable. Differences in the rate of sprout growth due to preplanting temperature treatment of bulbs influenced infection, but the main characteristic of the isolates with respect to the temperature-pathogenicity relationship prevailed. 相似文献