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Ascospores discharged at rainfall and dispersed by wind can provide long-distance spread of the European canker fungus, Neonectria ditissima. Ascospores are produced by perithecia which are the sexual reproductive stage. Diffuse knowledge exists on the seasonal pattern of perithecium formation under different climatic conditions. Therefore, the development of perithecia was observed for several successive seasons at five sites in three Northern European countries. In Norway and Finland, ripe perithecia were commonly recorded throughout the year, and on individual cankers continuously for up to 28 months. In contrast, asexual reproductive structures (sporodochia) were confined to the growing season in both countries. In Northern Germany an average of 51% of cankers developed ripe perithecia by late winter, and perithecial senescence ensued in late spring. On average, ripe perithecia were present on cankers for 22 weeks. In contrast, sporodochia were observed all year round. The timing of perithecium maturation correlated with the number of days with > 2 mm rainfall in July–September. The presence of mature perithecia and sporodochia for different lengths of time in different countries has implications for regional disease management strategies. [ABSTRACT FROM AUTHOR]

The combination of preharvest treatments with calcium chloride and fungicides, and storage of maturity graded fruit were assessed in five European plum cultivars. At harvest, samples of fruit within a commercially suitable range in ripening were divided into two categories: less-ripe (tree ripe-) and more-ripe (tree ripe+). The fruit were stored for 10–14 days at 4 °C followed by 2–3 days at 20 °C before the assessment of fungal decay. If calcium chloride was applied six times each season, postharvest fruit decay was significantly reduced in four of nine experiments, with a total mean reduction of around 50%. Two calcium applications in combination with a fungicide treatment reduced decay by approx. 60% compared to the untreated in one experiment. In six of seven experiments there was no effect of preharvest fungicide applications. In six of 10 experiments, fruit of the category tree ripe- had fewer fruit with fungal decay after storage than the tree ripe+fruit. The higher incidence in the category tree ripe+fruit was primarily due to brown rot, Mucor rot, and blue mould. For the category tree ripe+, there was two to ten times more decay than on tree ripe- fruit after a simulated shelf-life period. To ensure low incidence of fungal decay, fruit of commercial harvest maturity may thus be separated in two ripening categories, one for rapid distribution to the market (tree ripe+) and another for extended distribution time (tree ripe-). [ABSTRACT FROM AUTHOR]

Fungi within the Colletotrichum acutatum species complex occur asymptomatically on plant parts of many different plant species. Leaves from apple orchards in southern Norway were sampled, frozen for five hours and incubated for six days to reveal presence of asymptomatic infections of C. acutatum. Number of leaves (incidence) and leaf area covered (severity) with conidial masses of C. acutatum were assessed biweekly on cv. Aroma from late May to late September during three growing seasons. The first finding of conidial masses occurred in the second half of July, and there was a higher incidence occurring in August and September. Sampling of leaves from fruit spurs and vegetative shoots of cvs. Aroma and Elstar showed that conidial masses of C. acutatum developed on leaves on both shoot types, and there was no difference in incidence between these two types. The fungus was detected on leaves from six of eight commercial orchards of cv. Aroma over three years, with a mean incidence of 5.5 %. After storage, bitter rot was found on apple fruit from all eight orchards. There was no correlation between incidence of conidial masses of C. acutatum on leaves and on fruit. In all orchards and seasons investigated, incidence and severity on leaves varied from 0 to 67 % and 0 to 85 %, respectively. The discovery of apple leaves containing conidial masses of C. acutatum clearly indicate for leaves as a potential source of inoculum for fruit infections. [ABSTRACT FROM AUTHOR]

Infection of Malus x domestica cv. Royal Gala fruit by Colletotrichum acutatum causing bitter rot was studied in the temperate climate of New Zealand. Temperatures above 15 °C were required for lesions to develop on detached apple wound-inoculated or inoculated without wounding with C. acutatum spores, regardless of maturity. A wetness period of 72 h was required for infection of mature detached apple fruit without wounding. On wound-inoculated detached apple fruits, sporulation was related to temperature and followed a similar pattern. In the field, a mean temperature above 15 °C for 72 h after wound-inoculation was required for lesions to develop. Buds were a more important source of inoculum than twigs, and it was shown that C. acutatum could be isolated more frequently from outer bud scales than from inner scales. Asymptomatic infection of vegetative and reproductive buds was detected. C. acutatum was detected on asymptomic surface-sterilised petals and fruit, more commonly during summer than spring. Symptomless sterilised leaves generally yielded C. acutatum throughout the season, but isolations were more frequent in summer. Recovery of inoculum using a splash meter to detect vertical dispersal showed that in summer inoculum was primarily splashed up from the ground. In spring, inoculum was recovered in similar quantities from all heights up to a metre, suggesting that splash dispersal occurs from the canopy as well as from the ground. A disease cycle for C. acutatum infecting apples and causing bitter rot in New Zealand is suggested. [ABSTRACT FROM AUTHOR]

Neonectria fruit rot (NFR), an apple disease caused by the fungus Neonectria ditissima, is common in Brazilian orchards, but several aspects of its epidemiology are not well elucidated. The objectives of this study were to: i) test in vitro germination of ascospores at different temperatures and wetness periods and compare with conidia germination, ii) evaluate and compare the monocyclic components of NFR caused by conidia and ascospore infection in wounded and unwounded ripe detached 'Gala' apple and iii) evaluate and compare the monocyclic components of NFR caused by conidia infection in 'Rocha' pear fruit under different temperatures. Germination of conidia and ascospores occurred in the range of 12–28 °C. At 35 °C no germination occurred, for both ascospores and conidia, regardless of the wetness period (3–60 h). With the same wetness period, conidia germination was always higher than ascospores at any temperature. For ascospores, the optimal temperature for germination ranged from 18–21 °C, lower than the estimated for conidia, which ranged from 21 to 24 °C. In wounded detached apple fruit, the incubation period varied from 35 to 49 days after ascospore inoculation, and for conidia from 14 to 42 days. When comparing the same temperatures, mean lesion growth rate was always higher for fruits inoculated with conidia than with ascospores. Unwounded fruits inoculated in the calyx-end did not present Neonectria fruit rot symptoms. The disease on 'Rocha' pear fruit has shorter incubation and latent periods than those of 'Gala' apple and higher AUDPC at 25 °C. The fast monocycle development represents a risk if the disease spread to pear orchards but also sets pear fruit as a good option for future NFR control studies. [ABSTRACT FROM AUTHOR]

Over the past two decades, there has been a marked increase in Uruguayan olive production. However, the humid climate of Uruguay creates favorable conditions for the development of olive anthracnose, characterized by fruit rots and blossom blight, which are frequent and destructive symptoms. Several species of Colletotrichum are responsible for the disease, with C. acutatum sensu stricto (s.s) being the most prevalent. This study aimed to analyze the survival of Colletotrichum in an olive orchard with a history of olive anthracnose. For two consecutive years, samples of fruits, leaves, and woody organs were collected monthly from aerial parts of the olive tree. Colletotrichum spp. structures were recorded in a climate chamber, and C. acutatum s.s. was quantified. The study demonstrated that Colletotrichum can survive in different organs of the olive tree, with mummified fruit being the primary survival site, followed by leaves and branches. Among the leaf and woody organs, yellow leaves, leaves from defoliated branches, terminal dry branches, and healthy new branches were identified as important survival sites. Mummified fruits were not always present on the tree throughout the year, and leaves and branches can serve as the primary source of initial inoculum for infections of flowers and fruits in their absence. [ABSTRACT FROM AUTHOR]

European canker is one of the most devastating fungal diseases of apple in most temperate regions. The causal agent, Neonectria ditissima, infects trees through wounds in the bark forming cankers that girdle the stem and eventually cause tree death. Timely protection of the trees is challenged by stagnation of symptom expression after infections for a long period of time. The objective of this research is to use a novel TaqMan PCR assay to detect and quantify N. ditissima during the asymptomatic colonization of apple wood. Pruning wounds on branches of the cultivars Elstar and Gala were inoculated with N. ditissima and wood discs were sampled at 2–6, 10–14, and 30–34 mm distance from the inoculation site after 3 hours, 2 weeks, 4 weeks and 8 weeks for the detection and quantification of the pathogen. The TaqMan PCR assay detected N. ditissima in 51% of the inoculated apple tree samples. This was more sensitive than the culturing method detecting N. ditissima in 11% of the samples. An accumulation of N. ditissima DNA up to 34 mm distance from the inoculation site was observed without development of visible symptoms. To our knowledge this is the first time colonization of N. ditissima was detected and quantified in the absence of symptoms of European canker. The implications of this research are discussed. [ABSTRACT FROM AUTHOR]

In Northern Germany, a major share of postharvest losses of apple fruit is due to preharvest infections by pathogenic fungi. Little is known about their infection biology. Inoculation experiments were conducted with the most important storage-rot pathogen Neofabraea perennans, as well as with the recently discovered minor rot Phacidiopycnis washingtonensis, by spraying developing fruit on apple trees with conidial suspensions to drip wetness between June and harvest time (September / October). All inoculation events in three trial seasons were chosen to coincide with natural rainfall. Phenological stages and meteorological parameters of each infection event were used for correlation analyses. Both pathogens produced increasing fruit rot levels with inoculation dates closer to harvest. In addition, for N. perennans seven environmental factors were positively correlated with disease incidence, the most significant ones being the duration of post-infection leaf wetness and the scab infection quotient incorporating wetness and temperature. With P. washingtonensis, in addition to fruit maturity three environmental factors were identified. In a second step, multifactorial models for both pathogens were created using the phenological and meteorological factors. For N. perennans, scab infection quotient until first drying-off, dry hours within the leaf wetness period and post-inoculation precipitation levels were identified as important factors, whereas for P. washingtonensis only the average temperature during the leaf wetness period had a significant influence on the rot incidence. Either model was extended by the viability of conidia used for inoculation. Possibilities to deploy these models for a more accurate a priori prediction of the likely severity of storage rot and a more targeted use of pre- and postharvest fungicides and physical postharvest treatments are discussed. [ABSTRACT FROM AUTHOR]

This review focuses on biological control as a management strategy for brown rot disease on cherry. Specifically, the strain Monilina laxa as much of the research so far has been focused on Monilina fructicola and other stone fruit. Brown rot is one of the most economically important stone fruit diseases worldwide. Current control methods rely heavily on fungicide and costly physical controls. Biological control agents (BCAs) have been found which antagonise M. laxa and other Monilinia species. However, only a few have been developed into commercial products. This is primarily because they are still not as effective and consistent as the fungicides currently available to growers. Current biocontrol research focuses heavily on post-harvest applications but more could be done to look at the potential for BCAs to be used in the field to protect blossoms and fruits, reducing post-harvest losses. Future research needs to understand the ecology of these BCAs and their population dynamics in relation to external conditions, in order to optimise their use in integration with other management strategies. Disease management in the near future will rely more on the use of BCAs than conventional fungicides. [ABSTRACT FROM AUTHOR]

Second only to brown rot caused by Monilinia spp., grey mould caused by Botrytis spp. is one of the most important pre- and post-harvest diseases of stone fruit in northern Germany. Among 484 Botrytis isolates from sweet cherries produced under integrated pest management (IPM), 60.3% showed resistance to QoI fungicides and 54.6% to boscalid, reflecting the heavy use of these compounds in regional production. More modest resistance frequencies were recorded for fenhexamid (20.7%), fluopyram (8.3%), fludioxonil (9.1%) and cyprodinil (21.9%). A 7.6% share of isolates possessed multiple resistance to at least five of these fungicides. Resistance was also detected for two fungicides no longer registered in cherries, viz. thiophanate-methyl (15.7%) and iprodione (20.9%). Similar results were obtained for 141 Botrytis isolates from IPM plum orchards. In contrast, in organically produced cherries (88 Botrytis isolates) resistance frequencies were < 20% for all fungicides. The dominant species on cherries and plums was B. cinerea. The share of B. pseudocinerea, which is not known to have developed resistance to commercial fungicides, was 18.0% in cherries and 9.9% in plums from IPM, but 50.0% in organically produced cherries. A 10-year annual survey of a sweet cherry orchard under IPM showed the immigration of multi-resistant B. cinerea strains in 2011, followed by their increase and decline in subsequent years. An understanding of the effects of fungicide spray regimes on Botrytis population dynamics in stone fruit has implications for resistance management. In practice, a limitation of the number of pre-harvest sprays to a maximum of two will give a satisfactory control of brown rot in most situations, while a higher number will promote multi-resistant B. cinerea strains. [ABSTRACT FROM AUTHOR]

Postharvest diseases of pome fruit are typically caused by a wide diversity of fungal pathogens, and the list of confirmed causal agents is still growing. There is considerable knowledge on the epidemiology of wound pathogens, such as Botrytis cinerea and Penicillium expansum. In contrast, knowledge on the occurrence of the different postharvest diseases caused after latent (quiescent) infections during long-term storage and their epidemiology is limited. Well-known pathogens causing postharvest losses after latent infections are Neofabraea spp. and Colletotrichum spp., but in many cases the causal agents that occur in a specific region remain unknown and their control relies on the routine use of fungicide applications. However, due to the growing concern over the use of synthetic fungicides, alternative control measures are highly desired. Over the past years the use of physical treatments, natural compounds, and biocontrol agents have been investigated as alternatives. However, no single method has emerged that can robustly and reliably control postharvest diseases of pome fruit in practice. In this review it is argued to approach latent postharvest diseases as complex problems that require multiple interventions at different stages of the disease process in a systems intervention approach for their control. Such approach requires a deep understanding of the epidemiology of the causal agents in the orchard, fruit defence mechanisms against pathogens, and the molecular biology of host-pathogen interactions in order to develop novel disease control methods in which the deployment of resistant cultivars can be a cornerstone. [ABSTRACT FROM AUTHOR]

Colletotrichum spp. infections are an increasing threat to the fruit production industry worldwide, as a postharvest disease. Gaining knowledge on the susceptibility of apple fruit cultivars to Colletotrichum species is essential for specific breeding programs aiming to decrease the disease susceptibility of commercial apple cultivars. We investigated fruit susceptibility of nine apple cultivars at harvest and after storage, and studied the relationship of the susceptibility with fruit ripening characteristics. An accurate artificial inoculation technique, by wounding and injecting the spore suspension, was used to consistently follow-up the relative susceptibility symptoms of fruits. The nine apple cultivars studied, cvs. Pinova, Nicoter, Nicogreen, Golden Delicious, Gala, Elstar, Jonathan, Idared and Topaz, showed clear differences in susceptibility to C. fioriniae, main species causing problems in Europe, based on lesion expansion growth rate data. Cultivar Nicoter and Nicogreen were evaluated as less susceptible cultivars, while cv. Golden Delicious and cv. Pinova were classified as high susceptible cultivars. After three months of storage all fruit cultivars showed a higher susceptibility than at harvest. We further explored the link between fruit ripening characteristics and postharvest pathogen developments. Results showed significant higher Brix, ethylene production and respiration and significantly lower firmness and titratable acids after storage, with the extent of these changes being cultivar dependent. The ripening parameters respiration and Brix had a positive and the firmness a negative correlation with the lesion expansion growth rate of C. fioriniae after artificial wound inoculations. These experiments help to give a better insight in the susceptibility of different cultivars. Moreover, our data support the hypothesis that the extent of the necrotrophic fungal development depends on the fruit ripening stage. [ABSTRACT FROM AUTHOR]

Worldwide Colletotrichum spp. have been identified as a problem in the apple production. This is the first study executed and confirming the presence of Colletotrichum spp. causing the postharvest disease bitter rot on apple fruits in Belgium. The identification, genetic diversity of Colletotrichum isolates (present in Belgian apple orchards) their morphological traits and pathogenicity on two apple cultivars (cvs. Pinova and Nicoter) with a different level of susceptibility were studied. Based on sequence analysis of six different gene regions beta-tubuline (TUB2), histone H3 (HIS3), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), chitin synthase 1 gene (CHS-1), actin (ACT) and the Internal Transcriber Spacer (ITS) gene region, six different Colletotrichum spp., belonging to either the C. acutatum or C. gloeosporioides complexes, were isolated from twenty-one apple cultivars in three Belgian orchards: C. fioriniae, probably C. kahawae, C. salicis, C. rhombiforme, C. acutatum and C. godetiae. Colletotrichum godetiae was found to be the most present and pathogenic species in Belgian orchards. The species C. rhombiforme was found and identified on apple fruit for the first time. Reliable morphological discrimination between species, based on features such as in vitro growth rate, colony colour and spore measurements, is not possible. As such, molecular identification appears to outperform morphological analysis and was in this study the most ideal tool for identifying unknown isolates of Colletotrichum species. Inoculation assays on two apple cultivars revealed a significant difference in pathogenicity among isolates and among Colletotrichum species. The pathogenicity tests also showed that isolates coming from another host species, e.g. strawberry, are also pathogenic on apple fruits. Cultivar Pinova appeared to be more susceptible to bitter rot than cv. Nicoter. Given the difficulties with managing Colletotrichum infections, additional knowledge on the pathogen and the plant-pathogen interaction is essential for effective disease control. [ABSTRACT FROM AUTHOR]

Four Neofabraea species are responsible for bull's eye rot, which is an important postharvest disease of apples and pears. The species diversity of its causal agents in Europe has not been thoroughly explored using molecular genetic methods. Eighty-one Neofabraea isolates were obtained mostly from apples with bull's eye rot symptoms in the Czech Republic over a two year period. The isolates were identified using PCR fingerprinting and DNA sequencing of the ITS rDNA region, the mitochondrial SSU rDNA and the β-tubulin and EF1α genes. The most common species was N. alba (89 %), followed by N. perennans (5 %) and N. kienholzii (5 %). This is the third published record of N. kienholzii in Europe. The species identity of the isolate CPPF507, which was placed close to N. kienholzii, remains unclear. EF1α was shown to be a suitable marker for the identification of species of the genus Neofabraea and was comparable to the previously used β-tubulin gene. Furthermore, the aggressiveness of individual species was compared and species distribution across Europe was summarized. N. perennans and isolate CPPF507 proved to be the most aggressive, whereas the least aggressive was N. kienholzii. Two N. alba isolates isolated from symptomless apple fruits and leaves were pathogenic to apples in the infection tests. [ABSTRACT FROM AUTHOR]