Apple Rot Research Articles

Paecilomyces niveus: Pathogenicity in the Orchard and Sensitivity to Three Fungicides.

Paecilomyces rot of apples is a postharvest disease caused by the thermotolerant fungus Paecilomyces niveus (Byssochlamys nivea). The etiology of disease and the activity of fungicides against P. niveus are not yet well understood. This study evaluated the ability of P. niveus to infect 'Gala' apples growing in a conventionally managed orchard. In addition, the sensitivity of P. niveus isolates to postharvest fungicides difenoconazole, fludioxonil, and pyrimethanil was characterized for isolates from both agricultural and nonagricultural environments. Apples were wounded and mock-inoculated or inoculated with P. niveus in early July. At the time of harvest, 8 weeks after wounding, the inoculated apples had significantly larger lesions than mock-inoculated apples (P < 0.005). The average diameter of lesions on wound-inoculated apples was 11.17 mm ± 6.82 SD, while the average diameter of mock-inoculated lesions was 3.34 mm ± 1.85 SD. Disease symptoms in the orchard were similar to postharvest symptoms of Paecilomyces rot. Symptoms included a brown, flattened, circular lesion with faint concentric rings. The necrosis of mesocarp was firm and roughly U-shaped. Baseline isolates of P. niveus, from nonagricultural environments, were used to determine the effective fungicide dose at which growth was inhibited by 50% (EC50). Furthermore, fungicide sensitivity of P. niveus isolates was examined using relative growth assays at the mean baseline EC50 values to compare baseline isolates with isolates obtained from commercial apple orchards where they were likely exposed to fungicides. Among the exposed isolates, reduced sensitivity to all fungicides was observed, but significant differences between baseline and exposed isolates were only observed with fludioxonil (P < 0.0001). This is the first report demonstrating that P. niveus can infect apples that are wound-inoculated in the orchard and that isolates from agricultural environments are less sensitive to common fungicides, especially fludioxonil. This finding may have implications for the control of this postharvest diseases. Whether natural infections of apples by P. niveus is initiated in the orchard or during postharvest has yet to be determined.

CCDF: Automatic system for segmentation and recognition of fruit crops diseases based on correlation coefficient and deep CNN features

In the agriculture farming business, plant diseases are the major reason for monetary misfortunes around the globe. It is an imperative factor, as it causes significant diminution in both quality and capacity of growing crops. Therefore, detection and taxonomy of various plants diseases is crucial, and it demands utmost attention. In plants, fruits act a major source of nutrients worldwide, however, various range of diseases adversely affect the production as well as the quality of the fruits. Therefore, utilization of an efficient machine vision technology not only detects the diseases at their early stages but also classify them accordingly. This research is primarily focusing on the detection and classification of various fruits diseases based on correlation coefficient and deep features (CCDF). The proposed technique incorporates two major steps of infected regions detection and finally feature extraction and classification. In the first step, initially contrast of input image is enhanced by utilizing a hybrid method - followed by proposed correlation coefficient-based segmentation method which separates the infected regions from the background. In the second step, two deep pre-trained models (VGG16, caffe AlexNet) are utilized for feature extraction of selected diseases (apple scab, apple rot, banana sigotka, banana cordial leaf spot, banana diamond leaf spot and deightoniella leaf and fruit spot). Parallel features fusion step is embedded to consolidate the extracted features prior to max-pooling step. Selection of most discriminant features are being performed using genetic algorithm before subjecting to the final stage of classification using mutli-class SVM. Experiments are being performed on publicly available datasets - plant village and CASC-IFW datasets to achieve the classification accuracy of 98.60%. Qualitative analysis of achieved results clearly shows that the proposed method outperforms several existing methods in terms of greater precision and improved classification accuracy.

Infection criteria, inoculum sources and splash dispersal pattern of Colletotrichum acutatum causing bitter rot of apple in New Zealand

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.

Study of the Major Pathogens That Lead to Apple Fruit Decay During Storage

Different pathogenic fungi (e.g. Penicillium spp., Monilinia fructigena, Venturia inaequalis, Glomerella cingulata, Diaporthe eres etc.) can cause apple rot by producing pectic enzymes that break down apple pectin to expose the nutrients of the cells to the fungi. This study aimed to identify the pathogens that lead to the degradation of apples from five different varieties (‘Granny Smith’, ‘Topaz’, ‘Imperial Gala’, ‘Jonagold’ and ‘Golden Reinders’) and also the incidence of those pathogens under different treatment conditions. The results reveal different frequent attacks on distinct varieties ranging from 5 to over 50%. Of the pathogens that infect and occur in vegetation and deposit it can be seen that Venturia inaequalis has been identified in all varieties in most test variants. The highest frequency was recorded in the variant where during the vegetation period no treatments with fungicides against apple diseases were applied. Of the pathogens that infected and appeared during storage, isolated on the fruits, only Fusarium spp. and Penicillium spp. had a higher frequency. Applying treatments during the growing season reduced the rotting attack degree of apple fruits during storage. The best response to rot attack in the warehouse was ‘Topaz’ and ‘Jonagold’, the attack degree ranged between 0.3 and 10% on treated variants. By applying chemical treatments, the spectrum and the share of pathogens that lead to fruit degradation is different. This means that chemical treatments must be chosen depending on the nature of the pathogens and the apple variety.

Efficacy of Pseudomonas fluorescens for control of Mucor rot of apple during commercial storage and potential modes of action.

The ability of Pseudomonas fluorescens isolates 1-112, 2-28, and 4-6, to control Mucor piriformis (Mucor rot) on Gala, McIntosh, Ambrosia, and Spartan apple cultivars in commercial cold storage and their possible mechanisms of action were investigated. Isolates 1-112 and 2-28 provided significant levels of disease control on McIntosh and Spartan apples, while isolate 4-6 provided control of Mucor rot on Gala and Spartan apples, compared with control fruits after 15 weeks of storage at 0 °C. Mycelial growth of M. piriformis was markedly inhibited by cell-free supernatant and volatile organic compounds produced by P. fluorescens isolates, in vitro. In filter-sterilized apple juice, living cells of all 3 P. fluorescens isolates or their metabolites significantly inhibited spore germination by 99.8% and 61.6%, on average, respectively. Electron microscopy indicated that all 3 isolates of P. fluorescens colonized the hyphae of M. piriformis, but only isolate 1-112 was observed to colonize M. piriformis spores in vitro. In the wounds of apple, all 3 isolates formed a biofilm on the fungal hyphae and on the fruit tissue. Potential mechanisms of antagonism utilized by P. fluorescens against M. piriformis may include competition for nutrients and space, production of inhibitory metabolites and volatiles, and biofilm formation, leading to inhibition of spore germination and mycelial growth.

Use of local bioresources for post-harvest management of white rot of apple caused by Botryosphaeria dothidea

Post-harvest fungal pathogens are reported to cause 10 to 25 percent losses in apple. Among various pathogens, white rot caused by Botryosphaeria dothidea is one of the important post-harvest diseases. Incidence of white rot was recorded between3.0-14.1 percent in important marketing yards of Himachal Pradesh. Golden Delicious variety of apple has been found to be most susceptible to white rot pathogen. Two botanical formulations by mixing equal quantity of leaves of Karu (Roylea elegans), Artemisia (Artemisia roxburghiana), Neem (Azadirachta indica), Bana (Vitex negundo), Tulsi (Ocimum sanctum) and seeds of Darek (Melia azedarach) made in water and cowurine were evaluated against the white rot pathogen. Fruit dip for 30 minutes in cow urine based formulation did not allowed the disease development to form lesions in artificially inoculated apple fruits. Also, fruits dipped in cow urine based formulation followed by their storage in card board boxes at room temperature (25± 30C) for 30 days storage had minimum incidence (2.8%) of white rot disease. Therefore, dip treatment of apple fruits with different bio -resources including water and cow urine based botanical formulation separately proved effective in the management of white rot (Botryosphaeria dothidea) of apple.

Recovery Plan for Monilinia polystroma Causing Asiatic Brown Rot of Stone Fruit

Stone fruit are an economically important group of specialty fruit crops in the United States. Species of the fungal genus Monilinia are some of the most important pathogens of stone fruit worldwide. These pathogens cause blossom blight, shoot blight, and brown fruit rot in temperate production regions. The most common species of Monilinia pathogenic on stone fruit include Monilinia fructicola, M. laxa, M. fructigena, and M. polystroma. Presently, neither M. polystroma, the causal agent of “Asiatic brown rot”, nor M. fructigena, one of the causal agents of “European brown rot”, have been reported in North America. Interestingly, both species can also cause brown rot of apple, which is densely planted in the eastern United States. This recovery plan was produced as part of the National Plant Disease Recovery System (NPDRS), called for in Homeland Security Presidential Directive Number 9 (HSPD-9) to ensure that the tools, infrastructure, communication networks, and capacity required to mitigate the impact of high-consequence plant disease outbreaks are such that a reasonable level of crop production is maintained. It is intended to provide a brief primer on the disease, assess the status of critical recovery components, and identify disease management research, extension, and education needs.

Identification and Characterization of Postharvest Apple Rot caused by Fusarium tricinctum and Alternaria alternata

Postharvest apple rot causes severe economic losses and lowers apple quality, and is one of the most important limiting factors of apple exports. Apples with rot symptoms were sampled from Geochang, South Korea. Isolation of the causal fungus was performed by culturing small pieces of diseased tissues on potato dextrose agar. Two different rot genera, Fusarium and Alternaria, were identified according to their morphological characteristics. To confirm the identity of the causal fungus, we sequenced the DNA of the complete internal transcribed spacer(ITS) rDNA gene region and translation elongation factor 1-alpha(EF1-α) region. Koch’s postulates were supported by pathogenicity tests conducted on apple fruit. Based on mycological characteristics, molecular identification, and pathogenicity tests, the two fungi were identified as Fusarium tricinctum and Alternaria alternata. To the best of our knowledge, this is the first report of postharvest apple rot caused by F. tricinctum and A. alternata in South Korea.

Efficacy of botanical formulations and fungicides against Botryosphaeria dothidea, causing white rot in apple (Malus × domestica Borkh.)

The present study was conducted to determine inhibitory effect of plant extracts, their botanical formula-tions (BF1 and BF2) and safer fungicides against Botryosphaeria dothidea cause white rot of apple (Malus × domes-tica) during storage. Poisoned food technique was performed to evaluate the efficacy of different plant extracts, their botanical formulations and safer fungicides. Out of twelve botanicals evaluated under in vitro conditions against the white rot pathogen, leaf extract of Ocimum sanctum was found most effective among all the treatments with 54.07 per cent average inhibition in mycelial growth. Out of twelve plants evaluated for their efficacy, six effective plants Karu (Roylea elegans), Artemisia (Artemisia roxburghiana), Neem (Azadirachta indica), Bana (Vitex negundo), Tulsi (Ocimum sanctum) and Darek (Melia azedarach) were selected for making two botanical formulations (BF1 and BF2). While, BF1 was water based formulation and BF2 was cow urine based formulation. Among these botanical formulations, BF2 inhibited mycelial growth of white rot pathogen by 72.70 per cent and BF1 66.37 per cent at 100 % concentration. Whereas, among the tested fungicides, Score at 100 ppm concentration was found to be most effective with 75.01 % average inhibition in mycelial growth of the white rot pathogen.

Influence of storage temperature and cultivars on T‐2 toxin and neosolaniol accumulation in apples inoculated with Trichothecium roseum

Trichothecium roseum is one of the most dreadful postharvest pathogens responsible for core rot of apples. Besides causing economic loss, the disease is also associated with mycotoxins contamination. The effects of storage temperature and lesion diameter on T-2 toxin and neosolaniol (NEO) accumulation were evaluated in genetically diverse apple cultivars. The results showed T-2 concentration was much higher in Fuji than that in Ralls, while NEO was only detected in Red Delicious. The room temperature is favorable for T-2 and NEO accumulation compared with low temperature. We also noticed the positive relationship between the size of lesion diameter and the concentrations of NEO and T-2. NEO and T-2 were found not only in the rotten part, but in the adjacent asymptomatic tissue, indicating that the spread of the trichothecenes to non-infected of the fruits, and trichothecenes concentration showed a trend of decline with increase in distance from the rotten parts. Practical application Trichothecium roseum is one of the most important postharvest pathogens, and can cause core rot of apples. The disease not only causes economic loss, but also results in trichothecene contamination. Storage temperature and the size of lesion diameter significantly affected T-2 and neosolaniol accumulation in genetically diverse apple. The results showed T-2 toxin concentration was much higher in Fuji than that in Ralls, while neosolaniol was only detected in Red Delicious. The room temperature was favorable for T-2 toxin and neosolaniol accumulation compared with low temperature. In addition, the positive relationship between the size of lesion diameter and the concentrations of neosolaniol and T-2 toxin was observed. T-2 toxin and neosolaniol were found not only in the rotten part, but also in the adjacent asymptomatic tissue, and the concentration showed a trend of decline with increase in distance from the rotten parts. The study will be useful not only for apple post-harvest storage and reduce the health risk of exposure to the trichothecenes of T-2 toxin and neosolaniol, but also provide baseline information for the introduction of EU-limits for T-2 toxin and neosolaniol.

First report of Neofabraea kienholzii causing bull's eye rot of apple in the UK

Apple rot surveys have been conducted since the 1930's in the UK. Together they help build a picture of how the rot profile has changed over time. In surveys conducted in the 1930's and the 1960's (Wilkinson, 6; Preece, 3), Neofabraea was the dominant causative agent of rot, but losses due to this pathogen became negligible in the 1980's (Berrie, 1). More recent surveys found a resurgence of this disease in susceptible varieties (including cv. Cox's Orange Pippin) prompting identification of the species of Neofabraea responsible. Total actual losses due to rots have reduced significantly over the surveying period (for example total losses in cv. Cox's Orange Pippin have reduced 10 fold from 26.3% in the 1930's to 2.6% in the 2010's) thanks to advances in storage technologies. Rots attributed to Neofabraea spp. have reduced from nearly 50% to 15% in the same period but this still constitutes an economic loss to growers and packers (Saville et al., 4). Apple samples that exhibited discreet, circular “cheek” lesions which were light to dark brown, flat or slightly sunken, and firm, were collected from the packhouse during 2013 and 2014 surveys. Samples were returned to the lab and rinsed with sterile water and surface disinfected with 70% ethanol. Tissue from the leading edge beneath the skin was isolated and placed on potato dextrose agar. Plates were incubated at 20°C with a 16 hr photoperiod. Isolates were slow growing producing colonies of varying colour but with colony morphology characteristics typical of Neofabraea species (Fig. 1). DNA was extracted from axenic, single spore derived cultures, β-tubulin and ITS regions were amplified and sequenced. BLAST analysis revealed that in addition to N. perrenans and N. vegabunda isolates, which have been previously reported in the UK (Edney, 2), a single isolate (G48) out of 49 tested matched Neofabraea kienholzii with 100% identity. Repeating the above with a collection curated during the 2015 rot survey (growing season 2014), using the more phylogenetically informative β-tubulin region only, a single isolate (R4/15_2) out of 20 isolates tested had 100% identity to Neofabraea kienholzii. The sequences have been deposited in GenBank: Accession Nos. MF977989 (G48, ITS), MF983810 (G48, β-tubulin) and MF983809 (R4/15_2, β-tubulin). To prove pathogenicity, Koch's postulates were conducted with isolate G48 (Fig. 2). Apples cv. Cox's Orange Pippin were surface sterilised, wounded with a sterile hypodermic needle and inoculated with 20 μl of conidial suspension (3 × 104 conidia ml-1). Inoculation points were coated with petroleum jelly to maintain humidity. After 60 days incubation at 2°C, simulating commercial storage conditions for cv. Cox's Orange Pippin, lesions had developed on all inoculated apples characteristic of those caused by Neofabraea (Fig. 3). Non-inoculated control fruit showed no symptoms. Isolations from the leading edge of the lesion, as described above, confirmed the presence of Neofabraea. This is the first report of Neofabraea kienholzii in the UK, where before only N. perrenans and N. vegabunda isolates were believed to be present (Edney, 2). Previously named ‘Neofabraea sp. nov.‘, Neofabraea kienholzii was first described by Spotts et al (5) and has since been reported in many apple (and pear) growing territories around the world. This data is important to contribute to a global picture of the distribution of this genus and so that control strategies can be tailored for the UK industry to mitigate losses due to apple rot diseases.

First Report of Neofabraea kienholzii Causing Bull’s Eye Rot on Pear (Pyrus communis) in the Netherlands

Pear (Pyrus communis L.) is an important fruit crop in the Netherlands, with a total production of 349,000 tons in 2014, and ‘Conference’ is the main cultivar. In the Netherlands, pears are kept in controlled atmosphere cold storage up to 11 months after harvest. Symptoms of bull’s eye rot were observed in 2015 on ‘Conference’ pears in storage in the Netherlands. Bull’s eye lesions on apple and pear fruits are generally caused by four Neofabraea species: N. alba Jacks, N. malicorticis Guthrie, N. perennans Kienholz, and N. kienholzii Seifert, Spotts & Levesque (Gariepy et al. 2005). N. alba is the major pathogen causing bull’s eye rot on pear fruits in the Netherlands. Independent of the species, the symptoms appear as flat or slightly sunken lesions, which are brown, often lighter brown in the center (Spotts et al. 2009). To isolate the causal agent, fruit were rinsed with sterile water, lesions were sprayed with 70% ethanol until droplet runoff, the skin was removed aseptically with a scalpel, and tissue under the lesion was isolated and placed onto potato dextrose agar (PDA). PDA plates were incubated at 20°C in the dark, and single spores were transferred to fresh PDA plates. The isolates produced colonies with white-yellowish to brownish mycelium. Microconidia were produced on feathery fascicles of aerial mycelium, with a white, powdery, or sugary appearance on the surface of the agar colony. Microconidia were 2.5 to 6.5 × 1.5 to 2.5 µm, ellipsoidal, slightly asymmetrical to a curved form. The identity of a representative isolate (PPO 45010) was confirmed by means of multilocus gene sequencing. To this end, genomic DNA was extracted using the LGC Mag Plant Kit (Berlin) in combination with the Kingfisher method (Waltham, MA). Segments of the internal transcribed spacer region (ITS), 28S ribosomal RNA (28S rRNA) and beta-tubulin (TUB2) loci were amplified, sequenced with primers ITS1/ITS4, LR0R/LR5, and Btub2Fd/Btub4Rd (Chen et al. 2016), and deposited in GenBank under accession nos. KX424942 (ITS), KX424941 (28S rRNA), and KX424940 (TUB2). MegaBLAST analysis revealed that the ITS, 28S rRNA, and TUB2 sequences matched with 99 to 100% identity to N. kienholzii isolates in GenBank (KR859082 and KR859083 [ITS], KR858873 and KR858874 [28S rRNA], KR859288 and KR859289 [TUB2]). Alcohol surface sterilized fruits were inoculated in pathogenicity tests in two ways: (i) with an agar disk (10 mm diameter) with actively growing mycelium of N. kienholzii prepared from a 14-day-old culture grown on PDA; and (ii) with 20 μl of a spore suspension (105 conidia ml-1) prepared from a 21-day-old PDA culture after wounding with a needle. Both experiments were performed on 10 ‘Conference’ pears. Inoculated fruits were sealed in plastic bags and were incubated in darkness at 20°C. Typical symptoms appeared between 7 and 14 days. Mock-inoculated controls with water and PDA-only controls remained symptomless. Fungi isolated from the lesions had morphological characteristics that resembled the original isolates from infected pears. The identity of these isolates was confirmed as N. kienholzii by sequencing, thus completing Koch’s postulates. Bull’s eye rot of apple and pear is an important postharvest disease, occurring in major fruit growing areas of North America, Chile, Australia, and Europe (Henriquez et al. 2004; Spotts et al. 2009). N. kienholzii was reported twice on apple in Europe (Michalecka et al. 2016). To the best of our knowledge, this is the first report of N. kienholzii causing bull’s eye rot of pear in Europe.

First Report ofTruncatella angustataCausing Postharvest Rot on ‘Topaz’ Apples in the Netherlands

In the Netherlands, about 30% of the organic apple (Malus domestica Borkh.) production consists of apple scab resistant cultivars, such as Topaz and Santana. However, organic ‘Topaz’ apples show a high incidence of fungal rot after storage. Hot-water treatment (HWT) of freshly harvested apple fruit prior to long-term storage is an important strategy for the control of postharvest diseases, especially in the organic production sector (Maxin et al. 2012). The recommended treatment temperatures and times vary according to the cultivar because of the risk of heat damage to the fruit peel. In January 2016, light peel damage caused by HWT was observed on ‘Topaz’ apples from an organic orchard. Also, up to 15% of the ‘Topaz’ apples showed typical rot lesions of an unknown causal agent. The lesions showed brown, irregular necrosis and were slightly sunken. To isolate the causal agent, fruits were rinsed with sterile water, lesions were sprayed with 70% ethanol until droplet runoff, the skin was removed aseptically with a scalpel, and tissue under the lesion was placed onto potato dextrose agar (PDA). The PDA plates were incubated at 20°C in the dark, and single spore isolates were transferred to fresh PDA plates. The colonies that appeared on PDA were cottony to woolly, dull white to brown in color, with black acervuli mainly in the center of the PDA plates. The isolates produced four-celled conidia, 16 to 19 × 7 to 9 µm, straight to slightly curved, with two brown to dark-brown median cells that had thick walls. More than one hyaline apical appendage, variable in size and branched dichotomically, were observed and a basal appendage was absent. The fungus was morphologically identical to Truncatella angustata (Pers.) S. Hughes (Sutton 1980). The identity of two representative isolates (PPO-45246 and PPO-45321) was confirmed by means of gene sequencing. To this end, DNA was extracted using the LGC Mag Plant Kit (Berlin, Germany) in combination with the Kingfisher method (Waltham, MA). Sequences of the ITS region were amplified using primers ITS1/ITS4, sequenced, and deposited in GenBank under accession numbers KX085227 and KX085228. MegaBLAST analysis revealed that both of our ITS sequences matched 99% with T. angustata isolates in GenBank (EU342216, JX390614, and KF646105). Koch’s postulates were fulfilled using 10 ‘Topaz’ apples. Surface sterilized fruits were inoculated with 20 μl of 10 5 conidiospores ml –1 in water, prepared from a 15-day-old PDA culture of the isolate PPO-45246, after wounding with a needle. Inoculated fruits were sealed in a plastic bag and incubated in darkness at 20°C. Symptoms appeared after 7 days on 100% of the fruits while mock-inoculated controls with water remained symptomless. Fungal colonies isolated from the lesions and cultured on PDA morphologically resembled the inoculated isolates. The identity of the reisolations was confirmed as T. angustata by sequencing. T. angustata has a worldwide distribution and has also been reported to cause leaf spot on Rosa canina (Eken et al. 2009), canker and twig dieback on blueberry (Vaccinium spp.) (Espinoza et al. 2008), and fruit rot of olive (Olea europaea) (Arzanlou et al. 2012). To the best of our knowledge, this is the first report of T. angustata causing fruit rot of apples. Importantly, we note that the occurrence of this fruit rot may be enhanced by wounding, in this case as a result of hot water treatment.

Fungal pathogens associated with crown and collar rot of apple trees in southern Syria

Crown and collar rot of apple trees is a destructive and widespread disease in most areas of the world. Surveys have been done to describe disease symptoms, estimate the disease incidence, and identify the pathogens associated with this disease in southern Syria. Disease incidence was 0.08 – 10 % in most studied sites, only in Alroom location it was up to 14.7 % in 2014 and 17.8 % in 2015, with average of 11.8 %. Symptoms included small pale green leaves, sparse foliage, and a reddish-brown discoloration of inner bark of the infected area at the base of infected tree. The isolated fungi belonged to genera and form genera Phytophthora, Rosellinia, Rhizoctonia, Phialophora, Acremonium, Pestalotiopsis, Cylindrocarpon and Verticillium. Phytophthora was isolated from all infected trees, and was the most frequent pathogen (53.7 % of total isolates). Phytophthora isolates recovered from crown cankers of apple were identified as P. cactorum (91.5 %) and P. cambivora (8.5 %). The results of this study are the first report of crown and collar root rot of apple in Syria.

Control of postharvest storage rots of apples and pears in The Netherlands

Postharvest diseases are a major problem in long storage of apples and pears in The Netherlands. Despite intensive preharvest spraying programs significant losses occur. Over 150 heavily affected many apples (mainly 'Elstar') and pears (mainly 'Conference') from packinghouses in different regions of The Netherlands were evaluated for decay symptoms and causal organisms. Assessments showed that the most important pathogens are Neofabraea spp. (apples and pears) and Cadophora spp. (pears). Infection by these two pathogens occurs in the orchard but remains latent until storage. Other pathogens such as Botrytis spp., Pencillium spp., Fusarium spp., Alternaria spp., and Cladosporium spp. were isolated at low frequencies and are considered of minor importance. However, new problems with sooty blotch and lenticel rot of apple were noticed, most likely caused by other, not yet identified pathogens. Pathogenicity testing and characterization of isolates are on-going. For major pathogens, qPCR assays are developed. Samples of substrates (e.g., leaves, cankers, soil) were monthly taken from 10 apple and 10 pear orchards in 2012. Samples were assessed using the qPCR assays for presence and dynamics of pathogen populations. This information on the pathogen life cycles is needed for the development of innovative strategies to prevent postharvest losses. Storage conditions may significantly influence disease development. Recently, the project “KWALIFRUIT” was launched to identify the optimum harvest stage of pome fruit and optimal storage conditions for maximum fruit quality and storage life and minimal postharvest losses.

Control of blue mould and bitter rot of apples, and brown rot of peaches by Citrus aurantium extract-based product BIOLASTING®

Control of blue mould and bitter rot of apples, and brown rot of peaches by <i>Citrus aurantium</i> extract-based product BIOLASTING^®

Monilinia Species Associated with Brown Rot of Cultivated Apple and Pear Fruit in China.

Monilinia isolates were collected from major apple and pear production regions in China from 2004 to 2011 and identified based on their morphological characteristics and three highly conserved loci. The 247 isolates belonged to three species: Monilinia fructicola, Monilia yunnanensis, and Monilia polystroma. M. yunnanensis was the most prevalent (77%), followed by M. polystroma (20%) and Monilinia fructicola (3%). Monilia yunnanensis is primarily distributed in the south, north, and west of China; M. polystroma is limited to the north and east; and Monilinia fructicola was detected only from a few samples from the north and east. Phylogenetic analysis based on internal transcribed spacer, β-tubulin, and laccase (lcc2) genes suggested that Monilia yunnanensis, M. polystroma, and Monilinia fructigena are closely related, and Monilia yunnanensis is more distantly related. We also found that these three species do not show consistent differences in morphological characteristics, including colony morphology, colony expansion rate, conidial characteristics, and the amount of stroma produced in culture. Thus, these three species are more like phylogenetic species in the process of speciation. In addition, a set of species-specific primers based on single-nucleotide polymorphisms and deletions in the lcc2 gene region were designed and a conventional polymerase chain reaction method successfully developed for differentiating Monilinia fructicola, Monilia yunnanensis, M. polystroma, and Monilinia laxa from the other species.

First Report of Fusarium avenaceum Causing Wet Core Rot of ‘Elstar’ Apples in the Netherlands

Apple (Malus domestica) is an important fruit crop in the Netherlands. ‘Elstar’, the main cultivar, occupies 40% of the apple production area. Symptoms of apple wet core rot were observed on Elstar in January to March 2013 after 4 to 6 months’ storage in different packing houses at controlled atmosphere. The disease was present in a large number of lots harvested at orchards from different locations across the Netherlands, and incidences up to 25% were recorded. Apples exhibited light-brown wet rot, initially developing in the core and subsequently spreading into the surrounding cortex, often with a white to rose-reddish mycelium. Apples from five lots with infections (four apples per lot; 20 in total) were rinsed with sterile water, sprayed with 70% ethanol until droplet runoff and halved aseptically with a scalpel. The tissue next to the core rot was isolated and placed onto potato dextrose agar (PDA). The PDA plates were incubated at 20°C in the dark, and single-spore isolates were propagated on fresh PDA plates. All cultures formed abundant white aerial mycelium with yellow to rose pigment and a dark pink to red reverse. Macroconidia were slightly falcate, thin-walled, usually 5 septate, with a tapering apical cell, and 40 to 80×3.5 to 5 μm. Pathogen characteristics were similar to those described for F. avenaceum, causal agent of wet core rot of apple (Sanzani et al. 2013;Sorenson et al. 2009). The identity of two representative isolates (Fu1-44145 and Fu2-44145) from different apple lots was confirmed by means of multilocus gene sequencing. Genomic DNA was extracted and sequences of ITS region, TEF1-α, and histone H3 loci were amplified and sequenced. The sequences have been deposited in GenBank (Accession Nos. KT350586 and KT350587 [ITS], KT350603 and KT350604 [TEF1], KT935567 and KT935568 [HIS3]). MegaBLAST analysis revealed 99.8 to 100% identity to Fusarium spp. belonging to the F. avenaceum-F. tricinctumspecies complex. The TEF1 and HIS3 sequences of both isolates were 100% identical with F.avenaceum sequences JQ429374, GQ915502, JQ435857, and GQ915469, confirming their identity as F. avenaceum. Koch’s postulates were satisfied in two experiments, with 15 Elstar apples per isolate. In the first experiment, surface-sterilized fruits were inoculated with 20 μl of a suspension of 105conidiospores/ml prepared from a 15-day-old PDA culture after wounding with a needle. Inoculated fruits were sealed in a plastic bag and incubated in darkness at 20°C. In the second experiment, apples were surface sterilized, cut in half longitudinally, and one half was inoculated with 20 μl of the conidiospore suspension into the core of the apple. Control apple halves were inoculated with sterilized water. After inoculation, the halves were covered with plastic foil and incubated in darkness at 20°C. In both experiments, symptoms appeared after 4 to 6 days on 100% of the fruits; controls remained symptomless. Fungal colonies isolated from the lesions and cultured on PDA plates morphologically resembled the original isolates. Fusarium avenaceum is a wound pathogen that has been isolated from apple fruit in Croatia and in the United States (Kou et al. 2014; Sever et al. 2012). Only few reports describe wet core symptoms associated with F. avenaceum on apple (Sanzani et al. 2013; Sorenson et al. 2009). This is the first report of wet core rot caused by F. avenaceum on apple fruit in the Netherlands. As wet core of apple is undetectable until the fruit is cut or consumed, it affects consumer confidence. Due to potential mycotoxin production during infection, F. avenaceum infections potentially pose a safety issue (Sorenson et al. 2009).

Impact of Pre- and Post–Harvest Applications of Natural Antimicrobial Products on Apple and Pear Soft Rot Disease

Three natural antibacterial compounds including bacteriocin like substance (BLS) produced from lactic acid bacteria (LAB), ethanolic extract of propolis (EEP), and nine plant extracts were evaluated against soft rot Bacillus strains. Testing in vivo these compounds were evaluated to control pear and apple soft rot disease. Among eight BLS tested, BLS of LAB2, LAB105 and LAB 107 exhibited the highest antibacterial activity as indicated by the formation of clear inhibition zone. Propolis extracts exhibited significant antibacterial activity against all tested soft rot Bacillus strains and it was noticed that the antibacterial activity was concentration dependent. Among nine plant extracts tested, extracts of Eucalyptus globulus and Psidium guajava exhibited the highest antibacterial activity. All tested antibacterial products significantly decreased apple and pear soft rot severity caused by Bacillus altitudinis compared to untreated control. The highest reduction percentage of soft rot severity was recorded for EEP followed by BLS from LAB and plant extracts tested, respectively. Combined pre-and post-harvest treatments of apple and pear with antimicrobial compounds proved to be more effective in reducing the soft rot severity and improved the physical and chemical properties of fruits during storage in both years of the study. The natural antimicrobial agents used in this study were promising compounds, since it seems to be more safe, economical and great potential for extending the shelf life and improve the quality of fruits. Therefore, the application of these compounds in the control of apple and pear soft rot could be advantageous for consumers, producers, and the environment.

A New Accurate Genotyping HRM Method for Alternaria Species Related to Fruit Rot Diseases of Apple and Pomegranate

Alternaria core rot and Alternaria black heart rot of apple and pomegranate fruit, respectively, are major pre- and postharvest diseases worldwide. However, it is very difficult to differentiate the rot related Alternaria species in the Alternaria complex as they are not always correlate to species-groups based upon morphological characteristics and due to the limited genetic variation these species exhibit among each other. Therefore, it is crucial to exploit novel assays towards the accurate identification and differentiation of these Alternaria species. We have developed, a real-time PCR assay [using species specific primers targeting the endopolygalacturonase (EndoPG) gene] combined with a high-resolution melting (HRM) curve analysis for discrimination of the 14 single nucleotide polymorphisms (SNPs)-based Alternaria haplotypes, which were assigned based on the aligned sequence profiles of 138 Alternaria spp. strains previously isolated from apple and pomegranate rotted fruit. This analysis specifically generated 14 unique HRM curve haplotype profiles among the Alternaria complex species tested. The results showed that HRM curve analysis allows the rapid and adequate identification and genotyping of the three Alternaria species (A. alternata, A. tenuissima and A. arborescens) responsible mostly for the apple and pomegranate fruit rot diseases.