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1.
Young Theobroma cacao pods, known as cherelles, are commonly lost to physiological thinning known as cherelle wilt. Cherelles are susceptible to frosty pod rot caused by Moniliophthora roreri. We studied the cherelle wilt process and its impact on M. roreri infection using microscopic, metabolite, and gene expression analyses. Wilt was associated with increased levels of tricarboxylic acid cycle intermediaries and decreased levels of major metabolites. Expression changes of cacao ESTs in response to wilt suggest induction of the polyamine, ethylene, and jasmonic acid biosynthetic pathways and regulation of abscisic acid and cytokinin levels. M. roreriinfection caused little alteration of cherelle physiology. M. roreri responded to the late stage of wilt by altering the expression of M. roreri ESTs associated with metabolite detoxification and host tissue degradation. The environment of the wilting cherelles may truncate the disease cycle of frosty pod rot, by limiting M. roreri sporulation and stopping the lifecycle. 相似文献
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ABSTRACT Experiments were conducted in three prune orchards in California. In each orchard, inoculations with Monilinia fructicola, the causal agent of brown rot of stone fruits, were performed on branches of trees at bloom and fruit developmental stages. Five inoculum concentrations were used in each inoculation. Six and four wetness durations were created for each inoculum concentration at bloom and fruit developmental stages, respectively. Fruit were harvested 3 weeks before commercial harvest. The overnight freezing incubation technique was used to promote sporulation and to determine incidence of latent infection (ILI) of fruit brown rot. No differences in ILI among locations were found. A seasonal pattern of bloom and fruit susceptibility to latent infection was determined. Susceptibility to latent infection at bloom stage was at a moderate level and increased to reach the highest level at pit hardening stage. Subsequently, fruit susceptibility to latent infection decreased, reaching the lowest level in early June at embryo growth stage. Thereafter, the susceptibility increased again with fruit development and maturity until harvest. Linear relationships between ILI and inoculum concentration were obtained for most combinations of growth stage and wetness duration. Incidence of latent infection increased linearly with increased wetness duration at bloom stage and increased exponentially with increased wetness duration at early and late fruit developmental stages. The optimum temperatures for latent infection at pit hardening stage ranged from 14 to 18 degrees C, but the effect of temperature on latent infection was reduced at resistant stages. The temperature range favorable to latent infection varied for different wetness durations. 相似文献
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Heloisa Thomazi-Kleina Cristiano Nunes Nesi Lilian Amorim Louise Larissa May De Mio 《Plant pathology》2022,71(5):1131-1141
Brown rot is the main disease of stone fruits in Brazil, but the susceptibility of peaches to brown rot at different stages of development in the field has not been studied under subtropical conditions. This information is relevant to guide the management of the disease. The objective of this research was to determine the influence of inoculating peaches with Monilinia fructicola at different stages of development on the infection and progress of brown rot at postharvest. Two experiments were carried out: one ex vivo with two cultivars and the other in the field for two seasons. Peaches were inoculated at different sizes for both experiments. In the field, peaches were bagged to avoid natural infection, and M. fructicola inoculum was monitored. The ex vivo incidence of the disease was lower at pit hardening than at other fruit stages for both cultivars. The incidence of brown rot for peaches attached to the trees increased with fruit ripening. Conversely, the time for symptom expression was reduced according to peach diameter. Peaches inoculated with a diameter smaller than 2 cm showed a lower incidence of brown rot and longer periods for disease expression than fruit inoculated near harvest. In conclusion, in areas with high inoculum in the orchard, a common condition in the subtropics, the grower must prevent infection at all stages of fruit development, thus avoiding losses during marketing. 相似文献
5.
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
6.
Neonectria galligena can cause European canker of apple as well as fruit rot. Healthy unwounded fruits on potted trees of cvs Cox, Bramley and Gala were inoculated with conidia of N. galligena to investigate the effects of wetness duration and fruit maturity on rot development. Overall, the incidence of fruit rot was influenced more by fruit maturity at the time of inoculation than by duration of wetness (6–48 h). Young fruit were most susceptible to infection, with 50% of fruit infected when inoculated up to 4 weeks after full bloom. The susceptibility decreased initially until c. 2 months after full bloom and then increased gradually until harvest. Almost all preharvest symptoms (eye rot) developed only on the fruit inoculated up to 4 weeks after full bloom. All other rots were observed after six‐month postharvest storage under controlled atmospheric conditions. However, the relative proportion of preharvest eye rots and postharvest storage rots varied greatly among three years. The effect of wetness duration was only significant for fruit inoculated in their early stages of development but not for those inoculated near harvest. Regression models were developed to describe the observed effects of fruit maturity and wetness on the incidence of total nectria rots. 相似文献
7.
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
8.
Spatiotemporal analyses of rhizopus rot progress in peach fruit inoculated with Rhizopus stolonifer 
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下载免费PDF全文 Rhizopus rot, caused by Rhizopus stolonifer, is one of the main postharvest diseases in stone fruits, but there is little known about the processes of disease development during transport and postharvest storage. The objective of this study was to characterize temporal progress and spatial distribution of the disease in peach fruit. Rhizopus rot development was evaluated using two different fruit arrangements. Only one fruit of each arrangement was inoculated with a R. stolonifer spore suspension. Disease incidence and severity were assessed daily for all the fruit. Nonlinear models were fitted to the quantity of fruit and to the area of fruit that became infected over time and distance in relation to the source of inoculum. Disease‐free fruit placed next to the artificially inoculated peaches showed disease symptoms due to pathogen dissemination by mycelial stolons. The disease incidence and severity progress rates varied from 0.33 to 0.53 day?1 and from 0.30 to 0.49 day?1, respectively. The spatial spread of the disease followed a dispersive wave pattern with increasing speed over time, but decreasing speed with disease severity. For disease severity y = 0.5, the velocity at day 3 varied from 0.14 to 0.32 fruit diameter day?1, while it ranged from 0.38 to 1.46 fruit diameter day?1 at day 12. 相似文献
9.
ABSTRACT Brown rot, caused by Monilinia fructicola, is a destructive disease of stone fruit in California. Disease management requires information on inoculum dynamics and development of latent and visible fruit infections during the season to help make decisions on timing of fungicide treatments and choice of cultural practices. In this study, the daily spore concentration (ascospores and conidia) of M. fructicola in the air was monitored with spore traps in two prune orchards during the growing seasons in 2001 and 2002. The spore concentrations were low to moderate at early bloom, increased at full bloom, and decreased to the lowest level at the end of bloom. Improper timing of fruit thinning and irrigation in midseason increased spore concentration in the air and fruit infections late in the season. Artificial fruit inoculations were conducted periodically in 10 prune orchards in 2002 and 2004, and incidence of fruit rot at different inoculation dates was assessed. Fruit rot development rate increased linearly with inoculation date during the growing season. Natural blossom and fruit infections were monitored periodically in 10 prune orchards, and incidence of latent fruit infection was determined by using the overnight freezing-incubation technique. Incidence of fruit rot also was assessed 2 weeks before harvest in these orchards. The incidence of latent fruit infection at the pit hardening stage significantly correlated with that at the late stages and with the incidence of fruit rot at harvest. 相似文献
10.
C. Rodriguez-Brljevich C. Kanobe J. F. Shanahan A. E. Robertson 《European journal of plant pathology / European Foundation for Plant Pathology》2010,126(3):343-347
Maize seed that was either treated with the fungicide Cruiser Extreme 250 ® (fludioxonil + azoxystrobin + mefenoxam + thiamethoxam) or not treated was planted at two Iowa locations in 2007. Root, mesocotyl and crown rot severity, incidence of Fusarium spp. colonisation and chlorophyll florescence (CF) were assessed at growth stages V2, V4 and V6, and stalk rot severity at R6. At both locations, seed treatment reduced disease severity and incidence of Fusarium spp. infection at all growth stages assessed. Measurements of CF decreased significantly with increased disease severity and incidence of Fusarium spp. at V2 and V4 at both locations, indicating that seedling disease negatively affected photosynthetic performance. Mesocotyl rot severity at V4 predicted crown rot severity at V6 at both locations, as well as crown rot at V6 and stalk rot at R6 at one location. 相似文献
11.
亚洲玉米螟为害对玉米镰孢穗腐病发生程度的影响 总被引：4，自引：0，他引：4
为了明确亚洲玉米螟[Ostrinia furnacalis(Guenée)]在玉米雌穗不同发育期为害对玉米镰孢穗腐病发生程度的影响,分别在春播和夏播玉米吐丝、灌浆和乳熟期,以亚洲玉米螟为试虫,以轮枝镰孢菌为供试菌,单独或复合接种侵染。结果表明,无论春播还是夏播玉米,镰孢穗腐病病情指数均以复合处理最高,为31.57～88.80,单独接虫处理为16.27～55.00,单独接菌处理为19.02～59.47;玉米镰孢穗腐病的发生程度受玉米雌穗发育期和亚洲玉米螟为害程度的影响,其玉米螟为害级别为吐丝期>灌浆期>乳熟期;受螟害的介导作用,春播玉米雌穗被害率、螟害级别和镰孢穗腐病的发病率均显著重于夏播玉米,但夏播玉米镰孢穗腐病的病情指数高于春播玉米。螟害的介入明显加重了玉米镰孢穗腐病的发生,严重程度与雌穗发育时期密切相关。 相似文献
12.
ABSTRACT The quantitative relationships between incidence of latent infection (ILI) of prune by Monilinia fructicola and wetness duration (WD) for different bloom and fruit developmental stages and different inoculum concentrations were obtained. Three levels of ILI were considered as criteria for low, moderate, and high risks of latent infection, respectively. Seasonal patterns of WD leading to different risk levels of latent infection were obtained for low (IP(L)) and high (IP(H)) inoculum potential conditions in orchards. Longer WD was needed at a resistant than at a susceptible fruit developmental stage to induce similar levels of latent infection. The curves of WD leading to different levels of ILI over the growing season (risky WD curves) were used in risk analysis for latent infection. Multi-year historical WD data from 10 prune-growing locations in California were compared with risky WD curves. The percentage of days (P) with WD leading to a certain risk level of latent infection was calculated for each month from historical weather data. Under the IP(L) condition, the P distributions for low risk of latent infection were higher in March and April than in May and were the lowest in June for most locations. Under the IP(H) condition, the number of days that WD leading to low risk of latent infection in May increased compared with those under the IP(L) condition. The risk analysis approach was evaluated by using separate experimental data as incidence of fruit brown rot obtained from different prune orchards over years. Consistency between predicted overall risk levels of latent infection and observed incidence of fruit brown rot was obtained. The results demonstrated the usefulness of the risk analysis in decision support system for disease management. 相似文献
13.
Apple bitter rot caused by Colletotrichum acutatum sensu lato results in fruit decay before and after harvest. We investigated the epidemiology of the disease in terms of conidial formation and dispersal as well as the change in susceptibility of fruits in Iwate, Japan. Conidia of C. acutatum were detected in rainwater collected from inside the tree canopy from May to August with peaks in production in mid-May to early June and mid- to late July. The first peak corresponded to the most conidia being produced on fruit scars, but the second peak was due to conidiation on mummified fruitlets and peduncles collected in July. Inoculation experiments revealed that fruits were susceptible to the pathogen between 20 and 90 days after petal fall and that immature fruits infected as early as 20 days after petal fall frequently developed lesions on the lower fruit half as growth progressed. These results suggest that C. acutatum sporulates on infested fruit scars to infect immature fruits, resulting in bitter rot and that the fungus also colonizes mummified fruitlets and peduncles, contributing to survival of the pathogen on fruit scars. Thus, infested fruit scars represent the primary source of inoculum. 相似文献
14.
M. B. Spósito L. Amorim R. B. Bassanezi A. Bergamin Filho B. Hau 《Plant pathology》2008,57(1):103-108
Guignardia citricarpa , the causal agent of citrus black spot, forms airborne ascospores on decomposing citrus leaves and water-spread conidia on fruits, leaves and twigs. The spatial pattern of diseased fruit in citrus tree canopies was used to assess the importance of ascospores and conidia in citrus black spot epidemics in São Paulo State, Brazil. The aggregation of diseased fruit in the citrus tree canopy was quantified by the binomial dispersion index ( D ) and the binary form of Taylor's Power Law for 303 trees in six groves. D was significantly greater than 1 in 251 trees. The intercept of the regression line of Taylor's Power Law was significantly greater than 0 and the slope was not different from 1, implying that diseased fruit was aggregated in the canopy independent of disease incidence. Disease incidence ( p ) and severity ( S ) were assessed in 2875 citrus trees. The incidence-severity relationship was described ( R 2 = 88·7%) by the model ln( S ) = ln( a ) + b CLL( p ) where CLL = complementary log-log transformation. The high severity at low incidence observed in many cases is also indicative of low distance spread of G. citricarpa spores. For the same level of disease incidence, some trees had most of the diseased fruit with many lesions and high disease severity, whereas other trees had most of the fruit with few lesions and low disease severity. Aggregation of diseased fruit in the trees suggests that splash-dispersed conidia have an important role in increasing the disease in citrus trees in Brazil. 相似文献
15.
The effects were investigated of fruit maturity and duration of wetness on infection of apple fruits by Venturia inaequalis , and subsequent scab development. Incubation rate (inverse of median incubation period) increased linearly with increasing temperature (5–20°C) on detached 5-week-old fruits of cv. Royal Gala. Fruits were highly susceptible in the early stages of development, but became increasingly resistant as they matured. Inoculation of attached 12-week-old and detached near-mature fruits did not result in any lesions, while inoculation of attached 4-, 5-, 7- and 9-week-old fruits resulted in various levels of infection. Fruits of cv. Mondial Gala were more susceptible than those of cv. Cox's Orange Pippin. On cv. Mondial Gala, a wet period of 9 h resulted in ≈ 90% infection of 4-week-old fruits, but only 9% infection of 9-week-old fruits. Numbers of scab lesions on an apple generally followed a Neyman type A rather than a Poisson distribution, indicating a certain degree of aggregation of lesions on a fruit. A two-parameter generalization of the Poisson model described the observed incidence–density relationship well. A longer duration of wetness was required to result in a similar level of scab infection on old fruits to that on young fruits. On cv. Mondial Gala, wet periods of 9 and 32 h were required for ≈ 90% incidence of fruit scab on 4- and 7-week-old fruits, respectively. A mathematical model was developed to relate the incidence of fruit scab to duration of wetness and fruit maturity. The potential use of these results in practical disease management is discussed. 相似文献
16.
近年随着乡村产业调整和果业发展, 褐腐病在我国的发生呈加重趋势。本文对重庆地区核果类果树褐腐病的发生状况做了调查分析, 在室内通过平板及离体果实试验, 筛选拮抗菌和化学药剂, 为田间防治实践提供科学依据。主要结果如下:桃褐腐病在重庆普遍发生, 核果类果树均易感, 病原菌经鉴定为果生链核盘菌Monilinia fructicola; 系统调查初步分析发现, 降雨时间与李褐腐病发生发展关系最密切, 其与病情指数增幅的相关系数R=0.94(P<0.05); 平板对峙和离体桃果筛选, 获得2株有生防潜力的放线菌YLS5-2和YYDB3-1, 二者的抑菌率分别为91.3%和84.5%, 相对防效分别为65.1%和67.1%, 可能具有较好的应用前景; 平板毒力测定和离体桃果控病试验, 效果最优的化学药剂分别为戊唑醇、苯甲·丙环唑, 其中戊唑醇在推荐浓度处理96 h其离体果实防效仍维持在100%水平。 相似文献
17.
Effects of fruit maturity, wound age, temperature and the duration of wetness periods on infection of apple fruits by conidia of the brown rot fungus, Monilinia fructigena , were studied. Inoculation of fruits on potted apple trees and harvested mature fruits showed that wounding was essential for infection by M. fructigena . On potted trees, there was a significant difference between the susceptibility of cvs Cox and Gala and this difference depended on wound age. The incidence of brown rot was affected greatly by fruit maturity and wound age. Wounds on younger fruits were more resistant to infection than those on older fruits, whilst the older the wound, the more resistant it was to infection. Furthermore, the degree of wound age-related resistance was greater on younger fruits than on older fruits. These relationships were well described by regression models. The effect of the duration of wetness periods was very small: increasing the duration of wetness periods reduced the incidence of brown rot on older wounds. For detached fruits, all those wounded were rotted after inoculation, except for those in two treatments under 20°C on fruits with wounds which were 8 days old. The incubation period of the fungus was generally very short. Wound age was the single most important factor influencing the length of the incubation period; the incubation period increased as wound age increased. 相似文献
18.
Seedlings of six cauliflower cultivars ( Brassica oleracea convar. botrytis var. botrytis ) were assessed for resistance to a Danish isolate of Peronospora parasitica , under controlled conditions. Resistance, characterized by restricted sporulation and necrotic dark flecks at the inoculation site on the cotyledons, was expressed in the hybrids 9306 F1, 9311 F1, and the open pollinated cultivar Perfection. Testing of the parent lines and F2 generations of the two resistant hybrids suggested that resistance was a dominantly inherited trait controlled by a single gene. Inoculation of the cultivars with seven isolates, from different geographical origins, showed that the resistance was isolate specific. The two hybrid cultivars expressing cotyledon resistance and two hybrids expressing susceptibility were assessed for adult plant resistance under field conditions. The AUDPC (Area Under the Disease Progress Curve), based on disease incidence and severity, revealed significant differences between the cultivars. At harvest, the cultivars exhibited significantly different levels of defoliation and curd attack. The cultivars 9306 F1 and 9311 F1 showed high levels of resistance in all assessments, whereas the two cultivars exhibiting susceptibility at the seedling stage, 9304 F1 and 9305 F1, also exhibited susceptibility through the adult plant stage. Thus, the resistance exhibited under field conditions resembled that identified at the seedling stage under controlled conditions. The results suggest that cotyledon resistance similar to that described could provide resistance throughout the adult plant stage, including curds. 相似文献
19.
在辽宁地区,苹果炭疽病菌主要以菌丝在苹果树上的小僵果、死果台、粗皮、爆皮枝等部位越冬。翌年在适宜温湿度条件下产生分生孢子,进行传播侵染。越冬后的分生孢子已失去萌发力,落地病果在初侵染中不起什么作用。
病菌可以直接穿透表皮侵入果实。苹果在幼果期即感病,此时不抗侵入但抗扩展,潜育期长达一个月左右。七月中旬以后病害大量发生,直至9月中旬持续为害。根据果园中病菌孢子出现期,约在6月15至25日喷施第一次药,以后每隔20天左右连续喷施160~200倍波尔多液或锌铜石灰液三次,可以有效地控制炭疽病的为害。1964年和1965年,在辽宁地区进行大面积防治试验表明效果良好,可以大面积推广。 相似文献
病菌可以直接穿透表皮侵入果实。苹果在幼果期即感病,此时不抗侵入但抗扩展,潜育期长达一个月左右。七月中旬以后病害大量发生,直至9月中旬持续为害。根据果园中病菌孢子出现期,约在6月15至25日喷施第一次药,以后每隔20天左右连续喷施160~200倍波尔多液或锌铜石灰液三次,可以有效地控制炭疽病的为害。1964年和1965年,在辽宁地区进行大面积防治试验表明效果良好,可以大面积推广。 相似文献
20.
Christelle Deytieux-Belleau Laurence Geny Jean Roudet Valérie Mayet Bernard Donèche Marc Fermaud 《European journal of plant pathology / European Foundation for Plant Pathology》2009,125(4):551-563
This work investigated the structural and biochemical changes during grape berry development which account potentially for
the onset and increase in susceptibility to Botrytis cinerea. Using the cv. Sauvignon blanc, we quantified at seven developmental growth stages from herbaceous to over-mature berries:
(1) fruit ontogenic resistance using three strains (II-transposa), (2) the morphological and maturity fruit characteristics and (3) preformed biochemical compounds located in the berry skin.
From the mid-colour change stage onwards, susceptibility of unwounded fruit increased sigmoidally in both rot and sporulation
severities at the berry surface. A principal component analysis identified a very close connection between fruit susceptibility
and the level of fruit maturity. Berry susceptibility was significantly and positively correlated with the phenolic compounds
in the skin cell walls and negatively correlated with the total tannin content in the skin and with water activity (Aw) at
the fruit surface. On the berry, Aw decreased from 0.94 at bunch closure to 0.89 at berry maturity, with a relatively low
value (0.90) at the stage of mid-colour change. Using artificial media, different Aw levels led to significant differences
in mycelial growth (Aw ≤0.95 resulted in the lowest growth rate ≤0.34 mm day−1). Thus, besides the level of fruit maturity, both water activity on the fruit and the total tannin content in the skin may
affect fungal growth and berry colonisation. The potential of these variables for use as indicators of grape berry susceptibility
as well as associated mechanisms for the development of disease are discussed. 相似文献