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1.
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   

2.
ABSTRACT Inoculations were performed six to eight times in each of 10 prune orchards located in nine counties of California. In each inoculation, branches that bore 40 to 60 blossoms or 30 to 40 fruit were inoculated with conidial suspensions of Monilinia fructicola. Three inoculum concentrations and 14 to 16 h of humidity were used for each inoculation. All inoculated fruit were maintained on trees and harvested separately 2 weeks before commercial harvest. The incidence of latent infection (ILI) and percentage of branches with fruit rot (PBFR) were determined for each inoculation in each orchard. As the ILI increased, the PBFR also increased linearly. Five conditions that lead latent infection to fruit rot include (i) latent infection level; (ii) fruit developmental stage; (iii) inoculum concentration; (iv) total hours of relative humidity greater than 90% (hRH); and (v) total hours of dew period (hDEW) from mid-July to mid-August. Three levels of PBFR, 1, 5, and 10% were assigned, and threshold conditions that lead to these levels were determined based on the experimental results. The relative probabilities that lead latent infection to fruit rot (r_PBFR) at different fruit developmental stages were calculated. A preliminary decision support model to guide fungicide application was developed based on the above results. One of the four recommendations, safe, wait, check historical weather as a reference, and apply a fungicide immediately, could be provided based on the level of latent infection and the decision process developed through this study.  相似文献   

3.
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   

4.
Experiments under controlled environmental conditions were conducted during bloom of prune (Prunus domestica, L.) in 1999 and 2000 to assess the effects of inoculum concentration (IC), wetness duration (WD), temperature, and bloom stages on development of brown rot blossom blight of prunes. Branches from trees of a prune orchard were inoculated with Monilinia fructicola at different bloom stages and incubated at different temperatures with different periods of WD. The proportion of blighted blossoms (PBB) for each inoculated branch was determined. Bloom stage, IC, temperature, and WD significantly affected blossom blight of prunes. PBB at popcorn and full bloom stages was significantly greater than PBB at later bloom stages (P 30 degrees C and less than 4-h WD. However, longer than 4-h WD linearly increased incidence of blossom blight. A risk assessment table of blossom blight was produced for different environmental conditions to guide the control of prune brown rot.  相似文献   

5.
Five field experiments were performed in commercial orchards located in Lleida (Spain) over three growing seasons, 2000–2002, in order to estimate the relationship between the incidence of latent infection caused by Monilinia spp. in peaches and the incidence of post-harvest brown rot. No latent infection was recorded at popcorn and the maximum incidence occurred pre-harvest; in some orchards a second peak was detected during the pit hardening period. Monilinia laxa is the most prevalent species isolated from peaches with brown rot. There was a positive correlation between the incidence of latent infection and that of post-harvest brown rot. The average incidence of latent infection during the crop season explained 55% of the total variation in the incidence of post-harvest brown rot. The effect of temperature (T) and duration of wetness (W) on the incidence of latent infection in peach and nectarine orchards was analysed using multiple regression. The regression analysis indicated that T and W jointly explained 83% of the total variation in the incidence of latent infection. The model predicts no latent infections when T < 8°C, and >22 h wetness are required when T = 8°C but only 5 h at 25°C are necessary for latent infection to occur. The incidence of brown rot and latent infection of peaches caused by M. laxa under controlled experimental conditions were also affected by T and W, as well as by fruit maturity and inoculum concentration. Latent infections were produced in fruit when T was not suitable for the development of brown rot symptoms. In these experiments more than 4–5 h of daily wetness were required after embryo growth in fruit sprayed to run-off with an inoculum concentration higher than 104 conidia ml−1 of M. laxa for brown rot and latent infections to develop. The fitted model obtained from the field data was able to predict the observed data obtained under controlled environmental conditions.  相似文献   

6.
To evaluate the effect of conidial density of Monilinia spp. on the fruit surface on the incidence of latent infection and brown rot in peaches, eleven field surveys were performed in commercial orchards located in Cataluña, Spain over four growing seasons from 2002 to 2005, and nine surveys were conducted to determine the sources of overwintered Monilinia spp. inoculum. There was a significant positive relationship (r?=?0.69) between the numbers of conidia of Monilinia spp. on the fruit surface and the incidence of latent infections, but not with brown rot at harvest. Although mummified fruit, twigs and pits have been identified as being able to carry the pathogen from year to year in peaches grown in Spanish orchards, no relationships between any of these sources and the numbers of conidia on the fruit surface, or incidence of latent infection or brown rot were found. The effect of temperature (T), solar radiation (SR), rainfall (R) and wind speed (WS) on the area under the number of conidia of Monilinia spp. curve (AUncC) on peach surfaces was analysed. Regression analysis revealed that T, SR, R, and WS could account for 99% of the total variation in the area of the AUncC on peach surfaces. Thus, in order to reduce the incidence of latent infection and brown rot it is essential not only to remove the sources of primary inoculum but also to reduce the number of Monilinia spp. conidia on the fruit surface. Furthermore, the sources of airborne conidia of Monilinia spp. should be taken into consideration in disease management programmes in Spain.  相似文献   

7.
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   

8.
Eight field surveys over three growing seasons (April to October in 2006, 2007, and 2008) were done in three commercial peach and nectarine orchards in order to determine the secondary inoculum dynamics of Monilinia spp. and relationship to the weather conditions and incidence of postharvest brown rot in the Ebro Valley, which is the main peach fruit growing region in Spain. After regression analysis of the epidemiological data of postharvest brown rot and the climatic variables, a disease outbreak can be predicted from (i) the times of the first appearance of airborne conidia, the first appearance of conidia on the surface of flowers and fruits, and the first latent infection, all of which occur 2?months before harvest (ii) the number of conidia on the fruit surface, 2?weeks and 1?week before harvest, (iii) the preharvest incidence of brown rot, and (iv) the mean environmental temperature from popcorn to harvest. From these results, we confirmed the importance of the secondary inoculum dynamics of Monilinia spp. and the utility of these dynamics to predict an outbreak of brown rot in peaches on the day of their harvest and after their harvesting.  相似文献   

9.
Cucumber plants of different cultivars grown under various levels of nutrient supply, climatic conditions and different pruning practices were inoculated withDidymella bryoniae (Auersw.) Rehm. Increased concentration of the nutrient solution in the rockwool, slabs leading to a higher amount of dry matter content in the plant tissue resulted in a lower percentage of internal and external fruit rot in the cultivars Daleva and LD 290/82 (Dæhnfeldt), and in lower percentage of internal fruit rot in cv. Aminex, whereas the effect on cv. Dalibor was insignificant. Differences between cultivars were observed, cv. Dalibor showing the highest level of resistance against internal fruit rot and lowest incidence of nodal and internodal lesions. Separate factors appear to affect the establishment of the pathogen in the nodal tissue and its invasion of the internodal tissue. By raising the temperature to daytime level 3 h before sunrise, the risk of extended periods with high humidity was limited and the incidence of internal fruit rot was reduced. An increased incidence of nodal and internodal lesions and external fruit rot was observed at reduced pruning, leaving wilted leaves and shoots on the plants.  相似文献   

10.
Seventeen field surveys were done in four commercial orchards during six consecutive fruit-growing seasons from 2006 until 2011 in order to determine the current frequencies of occurrence of M. laxa, M. fructigena, and M. fructicola and their relative contributions to postharvest brown rot in peaches and nectarines in the Ebro Valley. The relative frequencies of occurrence of Monilinia spp. were determined on three sources of primary inoculum and on three sources of secondary inoculum. The major relative frequencies of Monilinia spp. were significantly recorded (P?=?0.05) from mummified fruit on the trees (approx. 42 %) and 7-day-old harvested fruit with brown rot (32 %), followed by that recovered from mummified fruit on the orchard bed (14 %), pruned branches on the orchard bed (8 %) and latent infections of immature fruit (3 %). We found that: (a) the relative frequency of M. fructicola has increased over the years to coexist on the same level as at the time M. laxa, (b) M. fructigena is no longer a cause of brown rot in harvested peaches, (c), a progressive reduction in the time of the first appearance of Monilinia airborne conidia (r?=??0.30, P?=?0.003), and the time of the first latent infection (r?=??0.44, P?=?0.0001) was detected along years after correlation analysis, and (d) these displacements are not associated with an increased incidence of brown rot disease. The M. fructicola increase was due to its significantly increased presence in 7-day-old harvested fruit with brown rot (r?=?0.73, P?=?0.0009), in latent infections of immature fruit (r?=?0.68, P?=?0.002), on pruned branches on the orchard bed (r?=?0.56, P?=?0.018), and on mummified fruit sampled on the trees (r?=?0.53, P?=?0.03). This progressive increase was accompanied by a progressive reduction in the relative frequency of occurrence of M. laxa in 7-day-old harvested fruit with brown rot (r?=??0.55, P?=?0.021) and M. fructigena on mummified fruit sampled on the trees (r?=??0.51, P?=?0.03).  相似文献   

11.
Dispersal of Phytophthora capsici and P. parasitica from point sources buried near the upper end of 74 m-long irrigation furrows was studied with three annual host crops. Furrows next to tomato were inoculated with either P. capsici or P. parasitica , while furrows next to pepper and squash were inoculated with P. capsici only. Irrigation was carried out on a 14-day cycle. Dispersal of each fungus in the water was monitored by transplants in the furrows and the incidence of infected tomato fruit along furrows. Disease gradients on roots and shoots of all hosts were also measured. Repeated irrigations dispersed P. capsici and P. parasitica up to 70 m from the source. Fruit infection increased with increasing distances downstream, suggesting an accumulation of secondary inoculum with the repeated flow of water. Conversely, gradients of disease severity on roots of tomato and pepper peaked at the source and rapidly decreased to low levels up to 32 m downstream. Fruit and root infection upstream from source was negligible. Root and crown rot in squash was highly variable, being confined to locations near the initial inoculum in some units while developing to severe levels several meters downstream in other units. Unlike the other hosts, squash petioles were in contact with the irrigation water and may have served as routes of invasion by P. capsici. Transport of inoculum from the furrow water to the roots was limited. P. capsici isolates were more virulent on tomato roots and caused a higher incidence of buckeye rot on tomato fruit than did isolates of P. parasitica.  相似文献   

12.
The effects of cuticular crack surface area and inoculum density on the infection of nectarine fruits by conidia of Monilinia laxa were studied using artificial inoculations with conidial suspensions and dry airborne conidia during the 2004 and 2005 seasons, respectively. Additionally, the effect of ambient humidity on fruit infection was evaluated in the 2005 experiment. An exploratory analysis indicated that (i) ambient humidity did not significantly explain the observed variability of data, but that (ii) the incidence of fruit infection increased both with increasing inoculum density and increasing surface area of cuticular cracks. The product of these two variables represented the inoculum dose in the cracks, and was used as a predictor of fruit infection in the model. Natural infection in the orchard was observed to increase throughout the season in both 2004 and 2005. The relationship between the probability of fruit infection by M. laxa and the artificially inoculated dose in the cuticular cracks was well described by a logistic regression model once natural inoculum density was taken into account (pseudo R2 = 65%). This function could be helpful for estimating the risk of fruit infection at harvest based on fruit size and natural inoculum density.  相似文献   

13.
Pod rot causes up to 30 % losses in world cocoa production. In order to predict the risk evolution of disease, it is important to take into consideration the developmental stage of fruits. In fact, it has been shown that the risk of attack by pod rot depends amongst others on the developmental stage of fruits. We proposed here to estimate the susceptibility at different stages. Susceptibility of fruit to disease was investigated at three fruit developmental stages (cherelle, young pod and adult pod); disease severity was assessed in laboratory conditions, on detached, artificially inoculated fruits, while disease incidence was assessed in the field, under natural inoculum pressure. In both assessment fruits at the cherelle stage were the most susceptible whereas the young and adult fruits were equally susceptible. The vertical position of the fruits on the tree did not influence their susceptibility. Estimates of the fruit susceptibility and of the infectious potential were derived from the severity and incidence measurements, using a model assuming that the number of spores on a fruit follows a Poisson distribution with the mean, the density of spores per fruit as the parameter. The estimated parameter values allowed the evaluation of the probability of attack of a fruit by the disease, which could be implemented in a disease warning system.  相似文献   

14.
The effects of apple fruit maturity, temperature of fruit or dip solution, period of time in fungicidal dip, storage conditions, and spore inoculum concentration, on the efficacy of fungicides for control of blue mould ( Penicillium expansum ) were examined in various experiments.
Iprodione and imazalil were only effective when inoculum concentration was low, whilst prochloraz was highly effective in controlling rot on fruit inoculated with 3 × 106 spores/ml. There was no consistent effect of dip temperature or fruit maturity on the efficacy of the fungicides. Iprodione was more effective on warm fruit (19°C) than cold fruit (6°C) whilst the reverse was true of imazalil. Extended periods of immersion in the fungicides slightly reduced the incidence of rotting but not to any useful degree.
The incidence of rotting in fruit treated with prochloraz and etaconazole was less in fruit stored under controlled-atmosphere cold storage conditions than in fruit stored in air cold-storage. Both fungicides were also effective for short-term storage at 20 C in air. Captan, benomyl, captan plus benomyl or vinclozolin were either ineffective or of poor efficacy under all storage conditions.  相似文献   

15.
Several factors influencing the incidence of internal fruit rot of cucumber caused byDidymella bryoniae were studied.Internal infection of fruits is achieved via the flower. However, in most cases the majority of the fruits escaped infection after flower inoculation. It took more than two days for the fungus to reach the fruit after infection of the style. A mechanical barrier was not detected in the fruit tip within three days after inoculation of the open flower.Inoculation of wilted flowers resulted in 60% less infection than inoculation of fresh flowers. Blossom excision reduced fruit infection with ca 75%. Growing plants under drought stress markedly increased the incidence of internal fruit rot.Neither the method of inoculation, nor the composition of the inoculum, nor the relative humidity influenced the incidence of internal fruit rot. Fruit thinning, duration of fruit growth, flowering period and the removal of parts of the flower had no effect either on fruit infection.Cultivars resistant to powdery mildew were also resistant to internal fruit infection. The resistance was associated with a long style and a short flowering period.Growing cultivars in which the flowers quickly fall away from the fruitlets or in which the flowers have no style may solve the problem of internal fruit rot in cucumber.Samenvatting Factoren die van invloed kunnen zijn op het ontstaan van inwendig vruchtrot van komkommer, veroorzaakt doorDidymella bryoniae, werden onderzocht.Inwendige vruchtinfectie vindt plaats via het bloempje. Bijna altijd ontsnapte echter het grootste deel van de vruchten aan een aantasting als de bloem werd geïnoculeerd. Het duurde meer dan twee dagen voordat de schimmel via de stijl de vrucht had geïnfecteerd. In de punt van de vrucht werd binnen drie dagen na inoculatie van de open bloem geen mechanische barrière gevonden.Na inoculatie van verwelkte bloemen kwam 60% minder aantasting voor dan na inoculatie van bloemen die pas open waren. Het verwijderen van het bloempje reduceerde de aantasting met ca. 75%. Het optreden van inwendig vruchtrot nam aanzienlijk toe door de planten onder droge omstandigheden te telen.Noch de methode van inoculatie, noch de samenstelling van het inoculum, noch de relatieve luchtvochtigheid beïnvloedden het optreden van inwendig vruchtrot. Vruchtdunning, duur van de vruchtgroei, bloeiduur en het verwijderen van delen van de bloem hadden ook geen effect op de aantasting.Cultivars die resistent waren tegen echte meeldauw vertoonden ook resistentie tegen inwendige vruchtaantasting. De resistentie was gecorreleerd met een lange stijl en met een korte bloeiduur.De teelt van cultivars waarvan de bloemdelen snel van de vruchtbeginsels afvallen, of waarvan de bloempjes geen stijl hebben, zou het probleem van inwendig vruchtrot bij komkommer kunnen oplossen.  相似文献   

16.
Tree canopies are architecturally complex and pose several challenges for measuring and characterizing spatial patterns of disease. Recently developed methods for fine-scale canopy mapping and three-dimensional spatial pattern analysis were applied in a 3-year study to characterize spatio-temporal development of pre-harvest brown rot of peach, caused by Monilinia fructicola, in 13 trees of different maturity classes. We observed a negative correlation between an index of disease aggregation and disease incidence in the same tree (r?=??0.653, P?<?0.0001), showing that trees with higher brown rot incidence had lower aggregation of affected fruit in their canopies. Significant (P?≤?0.05) within-canopy aggregation among symptomatic fruit was most pronounced for early-maturing cultivars and/or early in the epidemic. This is consistent with the notion of a greater importance of localized, within-tree sources of inoculum at the beginning of the epidemic. Four of five trees having >10 blossom blight symptoms per tree showed a significant positive spatial association of pre-harvest fruit rot to blossom blight within the same canopy. Spatial association analyses further revealed one of two outcomes for the association of new fruit rot symptoms with previous fruit rot symptoms in the same tree, whereby the relationship was either not significant or exhibited a significant negative association. In the latter scenario, the newly diseased fruit were farther apart from previously symptomatic fruit than expected by random chance. This unexpected result could have been due to uneven fruit ripening in different sectors of the canopy, which could have affected the timing of symptom development and thus led to negative spatial associations among symptoms developing over time in a tree.  相似文献   

17.
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   

18.
Wheat powdery mildew, caused by the fungal pathogen Blumeria graminis f. sp. tritici (Bgt), is a destructive wheat disease worldwide. The key issue for the disease forecast is to timely and accurately estimate and quantify the latent infection levels in volunteer seedlings where the pathogen over-winters or over-summers to serve as sources of initial inoculum of epidemics. To improve the conventional method, a real-time PCR assay had been established in this study to quantify latent infection level of wheat leaves. Artificially and naturally infected leaves in wheat fields at different geographical locations in China were collected and processed to determine the latent infection levels. Linear relationships between the molecular disease index (MDX) and the observed disease index (DX) were obtained from artificial inoculation experiments. Field experiments showed that the spatial distribution patterns of MDX matched well with those of DX in the most cases. This study demonstrated that the real-time PCR assay was a useful tool to rapidly and accurately quantify the latent infection levels of wheat powdery mildew and to efficiently estimate the initial inoculum potentials of epidemics in the fields.  相似文献   

19.
Sphaeropsis rot, caused by Sphaeropsis pyriputrescens, is an important postharvest disease of apple in the United States. The objectives of this study were to determine the timing of apple fruit infection in the orchard in relation to development of Sphaeropsis rot in storage and to identify infection courts and mode of penetration by S. pyriputrescens on apple fruit. Fruit of apple cvs Red Delicious, Golden Delicious, and Fuji were inoculated in the orchard from 3 weeks after petal fall to 2 weeks before harvest at 5 to 6-week intervals in three consecutive seasons. All fruit were harvested and stored at 0?ºC to monitor decay development. Light and scanning electron microscopy were used to examine the infection courts and mode of penetration of the fungus on/in the host tissues. At harvest, the fungus was re-isolated from the stem (pedicel), sepal, anther, or filament of the inoculated fruit, but decay did not develop on fruit. Sphaeropsis rot developed on inoculated fruit during cold storage beginning 1–3 months after harvest. Stem-end rot was prevalent on cv. Golden Delicious, whereas calyx-end rot was prevalent on cv. Fuji. Both stem- and calyx-end rots were common on cv. Red Delicious. Infection also occurred at lenticels on fruit skin, particularly on cv. Golden Delicious, but at low incidence. Relationships between the incidence of Sphaeropsis rot in stored apple fruit and the timing of inoculation in the orchard varied with cultivar and year. On cv. Red Delicious apples, the incidence of Sphaeropsis rot generally increased as the timing of infection approached harvest. Histological studies indicated that infection took place through natural openings of plant organs such as stomata on stems and sepals and lenticels on fruit skin. Fungal penetration also was observed at micro-cracks on the stem and sepal and at trichome sockets where mechanical damage occurred in sepals. Direct penetration was observed on the stem and sepal of fruit, but most invasions were restricted between the cuticle and the epidermis. Our results indicate that wounding is not required for infection of apple fruit by S. pyriputrescens, though it may facilitate infections.  相似文献   

20.
In a 4-year study, the incidence of various types of injuries (caused by insects, birds, growth cracks, mechanical wounding, and other, unidentified factors) was assessed in relation to brown rot development (caused by Monilinia fructigena) on fruit of three apple cultivars (Prima, Jonathan, and Mutsu) in integrated and organic blocks of two apple orchards in Hungary. In addition, populations of male codling moths (Cydia pomonella) were monitored with pheromone traps season-long in both management systems. On average, injury incidence on fruit at harvest was 6.1 and 19.2% in the integrated and organic treatments, respectively. Insect injury, which was caused primarily by C. pomonella, had the highest incidence among the five injury types, accounting for 79.4% of the total injury by harvest in the organic blocks and 36.6% in the integrated blocks. Levels of all other injury types remained close to zero during most of the season, but the incidence of bird injury and growth cracks increased markedly in the final 3 to 5 weeks before harvest in both production systems. Brown rot developed more slowly and reached a lower incidence in the integrated (6.4% final incidence on average) compared with the organic blocks (20.1% average incidence). In addition, the disease developed later but attained higher levels as the cultivar ripening season increased from early-maturing Prima to late-maturing Mutsu. Overall, 94.3 to 98.7% of all injured fruit were also infected by M. fructigena, whereas the incidence of brown-rotted fruit without visible injury was very low (0.8 to 1.6%). Correlation coefficients (on a per plot basis) and association indices (on a per-fruit basis) were calculated between brown rot and the various injury types for two selected assessment dates 4 weeks preharvest and at harvest. At both dates, the strongest significant (P < 0.05) relationships were observed between brown rot and insect injury and between brown rot and the cumulative number of trapped C. pomonella. At the harvest assessment, two additional significant correlations were between brown rot and bird injury and between brown rot and growth cracks. In every case, correlation coefficients were larger in organic than in integrated blocks. Although it is well established that brown rot in pome fruits is closely associated with fruit injuries, this is the first study to provide season-long progress data on different injury types and quantitative analyses of their relative importance at different times in the growing season and across two distinct management systems.  相似文献   

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