Alternaria brown spot is one of the most important diseases of tangerines and their hybrids worldwide. To set up effective control strategy, the accurate detection and identification of the species responsible of the diseases is crucial. However, the characterization based on morphology and/or multilocus genetic approaches is time consuming, requires great expertise, and sometimes is not conclusive. Therefore, the setup of a rapid and efficient DNA-based assay might be of paramount importance. The High-Resolution Melting (HRM) analysis represents an interesting tool for the uncovering of nucleotide variations as small as one base difference, and as such, relevant to species characterization.

The efficacy of thin-film diamond coated electrodes (DiaCell® 101) for disinfection of water artificially contaminated with Penicillium digitatum and Pseudomonas spp. was tested. Electrolysis process was performed with different operation conditions: current densities set at 4, 8, and 12A and water flow rate at 150, 300, and 600 L/h. For both pathogens, the experiments were performed in water suspensions at a final concentration of 105 CFU/ml. Tap water was used as a control. The results showed that fungal spores and bacterial cells were affected by flow rate and current density applied. The higher the water flow rate the greater the inactivation of the two microorganisms which were completely suppressed at high recirculation flow (300-600 L/h/cell). Pseudomonas spp. cells were inactivated at the highest current density applied (8-12A) after 6 min of electrolysis, whereas for P. digitatum the complete inactivation was observed at the same current densities after 12 min. The results obtained suggest that the two parameters can be modulated in order to achieve significant suppression in relation to the target microorganism and to obtain an antimicrobial effect without generation of chlorine.

Several non-parasitic diseases are of primary significance for olive trees growing in the Mediterranean area and other warm-temperate regions of the world. As for other crops, they are generally poorly understood and often completely unrecognized, especially in olive which is considered a crop of marginal lands. The origin may rest with a lack/excess of essential nutrients or an excess of non-essential elements; it may be an unsatisfactory environment: too cold or hot, too wet or dry, or too windy; there may be unsuitable soil characteristics such as poor physical condition, water-logging, salinity, improper pH, and so on. Also pollution in the environment, spray and fire damage, and climatic extremes like lightning, hail, and snow can cause heavy losses to olive. This review focuses on the most important disorders of olive caused by environmental, physical, and chemical stresses that can affect the normal physiological processes in trees. An integrated view is utilized to highlight interactions with plant healthiness, production, and quality.

The role of some salts applied in combination with wax on the development of postharvest rots was examined on 'Tarocco' and 'Valencia late' oranges and 'Comune' Clementines. Sodium carbonate and bicarbonate, potassium carbonate and bicarbonate, ammonium bicarbonate, and potassium sorbate, at 6% concentration (w/v), in combination with a commercial wax, were evaluated for their activity against naturally occurring postharvest decay. Fruit were stored for one month at 4°C ('Tarocco' and 'Valencia late' oranges) or 6°C ('Comune' Clementine), followed by one week of shelf life at 20 ± 2°C and high RH.Most decay was from green and blue moulds, caused by Penicillium digitatum and P. italicum, respectively, with an average incidence of 11% for 'Comune' Clementines and 5% for both 'Tarocco' and 'Valencia late' oranges. Decay caused by Botrytis cinerea and Alternaria spp. was also observed. The incidence of postharvest rots on fruit treated with wax alone (11%) was higher than on those treated with water (7%), whereas in fruit treated with wax combined with different salts, decay incidence was significantly lower than with wax and water controls. In particular, potassium sorbate incorporated in wax significantly reduced the incidence of postharvest decay in all tested cultivars. The incidence of decay on fruit treated with imazalil was low, not exceeding 1%. Salts, except ammonium bicarbonate, interfered with the action of the wax to retard weight loss. The results indicate that the addition of the salts to wax may be an easy and effective mode of their application, since no additional equipment is needed.

The use of plant extracts could be a useful alternative to synthetic fungicides in the management of rot fungi during postharvest handling of fruit and vegetables. The aim of this study was to assess the in vitro and in vivo activity of extracts obtained from nine wild edible herbaceous species (Borago officinalis, Orobanche crenata, Plantago coronopus, P. lanceolata, Sanguisorba minor, Silene vulgaris, Sonchus asper, Sonchus oleraceus, and Taraxacum officinale) against some important postharvest pathogens, i.e. Botrytis cinerea, Monilinia taxa, Penicillium digitatum, P. expansum, P. italicum, Aspergillus carbonarius, and A. niger. Phenolic composition of all extracts was evaluated by HPLC. Several derivatives of caffeic acid, of the flavones apigenin and luteolin, and of the flavonols kaempferol and quercetin, were identified. Extracts from S. minor and O. crenata showed the highest efficacy in all the trials. In particular, S. minor completely inhibited in vitro the conidial germination of M. laxa, P. digitatum, P. italicum, and A. niger and strongly reduced those of B. cinerea; O. crenata extract showed a lower but still significant reduction of conidial germination on all the tested fungi. Moreover, the extracts from both species were effective in reducing the germ tube elongation also when a slight inhibition of conidial germination was observed. In many cases, a dose effect was observed, with an increase of antifungal activity as the phenolic concentration increased. In trials performed on wounded fruit, S. minor extract completely inhibited brown rot on apricots and nectarines; O. crenata extract strongly reduced grey mould, brown rot, and green mould on table grapes, apricots and nectarines, and oranges, respectively. The inhibition efficacy of extracts was ascribed to the presence of some caffeic acid derivatives and/or flavonoids. HPLC phenolic analyses provided useful information to identify the possible active compounds. (C) 2011 Elsevier By. All rights reserved.

Sodium salts are a promising alternative treatment to substitute/integrate the use of synthetic fungicides for controlling postharvest decay of citrus. In vitro studies indicated a direct activity of these salts against Penicillium attacking citrus, however, differences in their effectiveness on various citrus species were observed in in vivo trials, suggesting other modes of action. In this study, changes in enzymatic activity and gene expression level of phenylalanine ammonia lyase (PAL) in ‘Valencia late’ sweet oranges treated with Na2CO3 and NaHCO3 (3% w/v) were investigated. Both salts proved to increase PAL activity in orange tissues, upregulation being confirmed by transcriptomic analyses, particularly at 12 h after treatment. Thus, although other pathways cannot be excluded, the defense response induced by Na2CO3 and NaHCO3 in citrus fruit seems to be associated with the phenylpropanoid pathway, which has a role in the adaptation process to various stresses. This response could enhance the citrus natural reaction to wounding and pathogen attack, improving its protective effect. Thus induced resistance should be considered as one of the possible mechanisms of salts in controlling postharvest citrus decay.

The characterization of Basidiomycetes associated with wood rots in commercial citrus orchards in southern Italy revealed that both white and brown rot fungi are implicated in this disease. Fomitiporia mediterranea was the most prevalent species causing a white rot, followed by Fomitopsis sp. which, by contrast, was associated with brown rot wood decay. Furthermore, Phellinus spp. and other nonidentified basidiomycetous fungi showing genetic affinity with the genera Phellinus and Coniophora were occasionally isolated. Artificial inoculations on lemon (Citrus limon) branches showed a faster wood colonization by Fomitopsis sp. compared with F. mediterranea, indicating that the former species as a potentially serious pathogen of citrus trees. The analysis of F. mediterranea internal transcribed spacer (ITS) sequences revealed a high level of genetic variability, with 13 genotypes which were both homozygous (6 genotypes) and heterozygous (7 genotypes). The presence of heterozygous genomes based on ITS sequences has never been reported before for F. mediterranea. This, together with the high frequency of basidiomata on infected wood, unambiguously confirms the outcrossing nature of reproduction in F. mediterranea and the primary role of basidiospores in the dissemination of inoculum. Similarly, high genetic variability was observed analyzing Fomitopsis sp. Because basidiomata of this fungus have not been observed on citrus trees, it can be hypothesized that basidiospores are produced on alternative host plants.

In previous trials the flavonoid quercetin proved to be effective in reducing Penicillium expansum infections and patulin accumulation in apples. Since quercetin resulted more effective in in vivo than in in vitro trials, a possible role of this substance in enhancing host resistance was hypothesized. To verify this hypothesis, a cDNA library of genes differentially expressed in response to quercetin application was constructed by using the suppression subtractive hybridization (SSH) approach. A total of 89 unique sequences were obtained. By homology search and functional analysis the identified sequences were putatively categorized as belonging to “metabolism”, “subcellular localization” and “protein with binding functions or cofactor requirement” classes. Similarity was also found with genes coding proteins whose role in defence mechanisms is still unknown.

The effectiveness of sodium bicarbonate (SB), sodium carbonate (SC), sodium silicate (SS), potassium bicarbonate (PB), potassium carbonate (PC), potassium sorbate (PS), calcium chloride (CC), and calcium chelate (CCh) against naturally occurring postharvest decay on 'Comune' clementine and 'Valencia late' orange fruit was investigated. Aqueous salt solutions (2%, w/v, 20hlha -1) were applied according to three strategies: (i) by spraying before harvest, (ii) by dipping after harvest, and (iii) by the combination of pre- and postharvest applications. Decay was assessed after two months at 4±1°C (oranges) or 6±1°C (clementines) and 95-98% RH, followed by 7 days of shelf life at 20±2°C. For both species, preharvest sprays and the combination of pre- and postharvest applications were more effective in suppressing decay than postharvest dipping. With regard to preharvest application, several salts completely inhibited the incidence of decay as compared to the water control, namely, SC and PC on both species, and SS on 'Valencia late' oranges. In combined applications, all salts were effective in reducing the decay as compared to the water control with an efficacy varying between 66-100 and 78-100% for oranges and clementines, respectively. When salts were applied after harvest, the activity was in general less pronounced, SC and PC being the most effective on both species. In in vitro tests, the minimum inhibitory concentration (MIC) for both Penicillium digitatum and P. italicum, was achieved at 0.25% SB, SC, PB, PC, PS, and SS. The filamentous fungal population on fruit treated once in the field and with the double treatment was reduced as compared to the water control, whereas no statistical differences were observed for postharvest application. Based on these results, field application of salts can be considered a useful strategy to be included in an integrated approach for controlling postharvest diseases of citrus fruit.

In recent years quantitative PCR (qPCR) detection methods have been widely utilised to detect phytopathogenic fungi and oomycetes and have greatly contributed to the advancement of knowledge in plant pathology. However, major drawbacks and common errors, most typical of earlier reports, still affect many methods currently available in the literature. Errors can be made throughout the entire process for the development of qPCR methods, at the level of selection of appropriate DNA extraction and purification protocols, identification of suitable target regions, choice of the chemistry, design and validation of specific primers and probes, analysis of sensitivity, choice of an absolute and/or relative quantification approach and analysis of the risk of detecting target DNA from dead sources. In the present review the above mentioned steps are analysed, highlighting their critical aspects and providing a practical guide for the users.

Detection of Botrytis cinerea latent infections on grapes before storage is essential for effective control strategies. In the present study, a molecular detection method was developed to detect and quantify B. cinerea in grape tissues. Preliminary investigations, conducted on local varieties by fruit freezing, identified the ‘Red Globe’ variety as the less contaminated one and confirmed the preferential localization of latent infections in the berry-pedicel attachment zone (berry calottes) and pathogen presence on stamens. A quantitative real-time PCR (qPCR) detection method, based on a probe designed on B. cinerea intergenic spacer (IGS) regions and a reported probe for Vitis vinifera as internal control, was utilized to reveal the presence of symptomless infections on bunches. The system proved to be highly specific and sensitive, enabling quantification of as little as 10 fg of B. cinerea DNA and detection of single conidia in artificially inoculated grape berries; moreover, it allowed reliable detection of the pathogen in naturally infected asymptomatic tissues. In particular, the qPCR assay revealed the presence of B. cinerea in 80 and 65% of apparently healthy calottes and stamens, respectively, with an efficiency higher than that obtained from freezing and plating techniques. Furthermore, significant correlations (R2 = 0.89 and 0.94) were found between qPCR results and the actual disease incidence on bunches from which calottes and stamens were sampled.

The efficacy of the novel potassium bicarbonate formulation Karma (Certis Europe) for controlling Penicillium decay of orange fruit was tested. In vitro trials were carried out by amending potato dextrose agar (PDA) medium with different Karma concentrations, thereby revealing a complete inhibition of Penicillium digitatum, P. italicum, and P. ulaiense growth at 0.3, 0.3, and 0.2% (w/v), respectively. In vivo trials using dipping and spraying application strategies were conducted on Valencia late and Tarocco, two sweet orange cultivars with different degrees of susceptibility to Penicillium rot. Fruit treated with unformulated potassium bicarbonate (PB) or water served as controls. When applied by dipping, Karma and PB at 3% significantly reduced the incidence of Penicillium decay of cv. Valencia late oranges, i.e. by 79 and 31%, respectively. On the other hand, when applied by spraying, 6% Karma and PB were needed to completely inhibit decay incidence. On cv. Tarocco oranges, Karma and PB applied at 3% by dipping reduced the percentage of Penicillium decay, by a significant 87 and 68%, respectively. However, when applied by spraying at 6%, no difference was observed between the two treatments. Overall, Karma performed better than PB in controlling Penicillium rots and dipping proved to be the best application strategy.

Two organic media in comparison with the conventional medium, which were set up at MAIB, were tested alone or in combination with two commercial bioproducts. The media composition differentiates for the type and quantity of peat moss/compost and fertilizers. The micro and macro nutrients of the conventional medium were replaced in the two organic media by 1% (v/v) of a bio-fertilizer obtained from poultry manure. In the organic IAMB-ECOS medium, 30% of peat moss was replaced by a commercial certified compost. Trials with these media treated with a suspension of the bioproducts were carried out on grafted olive plantlets (‘Leccino’). Before transplanting, olive plantlets were inoculated by dipping roots in a conidial suspension of Verticillium dahlia. Uninoculated plantlets were used as a control. The effects of the different media, alone or in combination with bioproducts, on vegetative parameters of olive plantlets (plant height and root weight) as well as on V. dahlia infection were evaluated. Olive plantlets grown in Verticillium free media showed a significant increase in all vegetative parameters. Mainly in the organic IAMB media. Moreover, plantlets growing in the organic IAMB-ECOS, in combination with the commercial bioproducts, showed the best vegetative parameters, as well as a significant reduction of V. dahlia infection.

Stored citrus fruit suffer huge losses because of the development of green mould caused by Penicillium digitatum. Usually synthetic fungicides are employed to control this disease, but their use is facing some obstacles, such public concern about possible adverse effects on human and environmental health and the development of resistant pathogen populations. In the present study quercetin, scopoletin and scoparone—phenolic compounds present in several agricultural commodities and associated with response to stresses—were firstly tested in vitro against P. digitatum and then applied in vivo on oranges cv. Navelina. Fruits were wound-treated (100 µg), pathogen-inoculated, stored and surveyed for disease incidence and severity. Although only a minor (≤13%) control effect on P. digitatum growth was recorded in vitro, the in vivo trial results were encouraging. In fact, on phenolic-treated oranges, symptoms appeared at 6 days post-inoculation (DPI), i.e., with a 2 day-delay as compared to the untreated control. Moreover, at 8 DPI, quercetin, scopoletin, and scoparone significantly reduced disease incidence and severity by 69%–40% and 85%–70%, respectively, as compared to the control. At 14 DPI, scoparone was the most active molecule. Based on the results, these compounds might represent an interesting alternative to synthetic fungicides.

In 2015, rot symptoms were observed during storage on pomegranate fruit (Punica granatum L.) cvs Wonderful and Mollar de Elche from a packinghouse in Apulia (Southern Italy). Symptoms, observed on 26% of fruit, consisted of circular brownish-yellow lesions, beginning in the crown area and quickly expanding to entire fruit, with softening of the tissues including arils. Tissue portions were cut from surface-sterilized fruit and incubated on semi-selective PDA at 28±1°C in the dark. Colonies were white to creamy, leathery, and covered by abundant dark-greenish- brown to black spherical pycnidia (80-140 μm in diameter) with thin membranous walls. Hyphae were septate, and conidia hyaline, one-celled, 10-17.5×2-5 μm, ellipsoid to fusiform, straight or slightly curved. These characteristics corresponded to Pilidiella granati (Saccardo) (syn. Coniella granati Sacc.) Petr. & Syd.). For molecular confirmation, fungal DNA was amplified using universal primers ITS5/ITS4. BLAST analysis of the 506 bp amplicon (GenBank accession No. KU821701) showed 100% identity with other P. granati ITS sequences. For pathogenicity tests, surface-sterilized fruit of both cvs were wounded (5×5 mm), inoculated by a mycelial plug and incubated as reported above. Sterile plugs were used as controls. Lesions were visible after five days only on inoculated fruit. The re-isolated fungus corresponded to P. granati, which was reported as pomegranate postharvest rot agent in Spain (Palou et al., 2010) and recently associated with a crown rot in Italy (Pollastro et al., 2016). To our knowledge, this is the first report of P. granati rot on harvested pomegranate fruit in Southern Italy that might represent a serious threat for marketing of this promising crop.

Blue mould, caused by Penicillium expansum, is one of the most economically damaging postharvest diseases of pome fruits, although it may affect a wider host range, including sweet cherries and table grapes. Several reports on the role of mycotoxins in plant pathogenesis have been published, but few focussed on the influence of mycotoxins on the variation in host preference amongst producing fungi. In the present study the influence of the host on P. expansum pathogenicity/virulence was investigated, focussing mainly on the relationship with patulin production. Three P. expansum strain groups, originating from apples, sweet cherries, and table grapes (7 strains per host) were grown on their hosts of isolation and on artificial media derived from them. Strains within each P. expansum group proved to be more aggressive and produced more patulin than the other two groups under evaluation when grown on the host from which they originated. Table grape strains were the most aggressive (81% disease incidence) and strongest patulin producers (up to 554 μg/g). The difference in aggressivenessamongst strainswas appreciable only in the presence of a living host, suggesting that the complex pathogen–host interaction significantly influenced the ability of P. expansum to cause the disease. Incidence/severity of the disease and patulin production proved to be positively correlated, supporting the role of patulin as virulence/pathogenicity factor. The existence of genetic variation amongst isolates was confirmed by the High Resolution Melting method that was set up herein, which permitted discrimination of P. expansum from other species (P. chrysogenum and P. crustosum) and, within the same species, amongst the host of origin. Host effect on toxin production appeared to be exerted at a transcriptional level.

In order to evaluate the efficacy of a hot water (HW) treatment against postharvest diseases of peaches, four cultivars, ‘Springebelle’, ‘Rich Lady’, ‘Symphonie’ and ‘Benedicte® Meydicte*’, were dipped for 20 s in water at 60°C. After treatment, fruits were stored at 0°C for 4 days, followed by another 4 days of shelf life. Fruits dipped in water at room temperature represented the positive control (PC) and fruits not dipped in water were the negative control (NC). The HW treatment significantly reduced brown rot in naturally infected peaches with a decay reduction of approximately 80%. The HW treatment also significantly affected the epiphytic microflora population. In fact, the fungal population on HW treated fruit was reduced by 70%, the yeast population by 20%, and the bacteria population was completely inhibited compared to PC-treated fruits. A physico-chemical analysis revealed no substantial differences between HW, PC, and NC treated fruits, although there was a slight improvement in acceptability for HW treated fruits. Based on our results, HW treatment may be of commercial interest for the control of brown rot, reducing the pathogen inoculums, and the general population of microflora on the fruit surface, maintaining quality, and prolonging shelf life in several cultivars of peaches.

Recent results on hot water as an alternative treatment open a new perspective in disease incidencereduction. In the present work peach fruit were wounded, inoculated with conidia of Monilinia laxa and15 min, 3, 6, 12, 24 and 48 h after inoculation treated by dipping in hot water (HT) at 60◦C for 20 s. Theeffect of heat treatment on some cell wall genes involved in ripening such as -galactosidase (-GAL),pectin lyase (PL), polygalacturonase (PG) and pectin methyl esterase (PME), was analyzed by qRT-PCR.The expression levels of defense related genes, phenylalanine ammonia lyase (PAL) and chitinase (CHI),heat stress-related genes such as heat shock proteins 70 and 90 (HSP70, HSP90), and reactive oxygenspecies (ROS) scavenging genes were also evaluated by qRT-PCR. A 100% disease incidence reduction, ascompared to untreated fruit, was obtained by treating 6 and 12 h after inoculation. Moreover, brown rotwas inhibited by 85.7% when fruit were heat-treated 48 h after inoculation. The expression levels of cellwall genes (-GAL, PL, PG and PME) showed a general decrease in HT fruit as compared to the control,whereas PAL, CHI, HSP70 and ROS-scavenging genes increased their expression level in HT samples withrespect to the untreated ones. Our results show a curative activity of heat on peach inoculated withM. laxa 48 h before treatment. Each analyzed gene proved to be differentially expressed following heattreatment.

The severe outbreaks of olive anthracnose observed in Apulia during the last years, caused by the occurrence of climatic conditions conducive to the disease, the reduction of cultural interventions, and the new features about the aetiology and the disease cycle, have been investigated, focusing on some epidemiological and control aspects. In particular, data on the inoculum density of Colletotrichum spp. and the incidence of latent infection on drupes have been collected. In addition, field trials on the efficacy of new QoI-based fungicides applied at different timing (new shoot growth, pre-blooming, fruit set, veraison) have been conducted. Results indicated a good efficacy of pyraclostrobin, alone or in tank mixture with copper, and of the mixture trifloxystrobin+tebuconazole in reducing the disease. Moreover, the same fungicides significantly reduced the inoculum density of Colletotrichum spp. on fruit surface and the incidence of latent infections, as compared to the traditional copper applications.

"Mal secco", an Italian name meaning "dry disease", is a severe tracheomycotic disease of citrus caused by the mitosporic fungus Phoma tracheiphila (Petri) Kantsch. et Gik. It appeared in 1894 in two Aegean Greek islands, from which it spread almost to the whole Mediterranean basin and the Black Sea. Due to its high susceptibility, lemon is the most damaged citrus species. Disease damage consists of substantial reduction of the quality and quantity of the crop, mainly due to the difficulties of controlling the disease and the replacement of susceptible valuable cultivars by others which are less vulnerable, but have low productivity and scarce fruit quality. Control of mal secco disease has relied on a number of diverse chemical and nonchemical strategies, but is still faced with efficacy problems. Host resistance remains a most desirable goal, but it will not be ultimately achieved until the genetic basis of resistance to P tracheiphila are not fully elucidated. The present paper reviews the different aspects of citrus mal secco as studied worldwide over almost a century of research, from the first appeareance of the disease in Italy (1918) to date. Milestones and pitfalls about the symptomatology, aetiology, host-parasite relationship, diagnosis, epidemiology, and control are discussed in a historical perspective, emphasizing the advancements in knowledge. Finally, some issues and challenges are highlighted that need to be more comprehensively addressed prior to deployment of effective disease control measures.

The present invention relates to a method for post-harvest treating citrus fruit comprising a step of washing citrus fruit, said step of washing citrus fruit comprising: a) a step of bringing water into contact with citrus fruit; b) a step of electrolyzing said water which has been brought into contact with citrus fruit; and c) a step of using said electrolyzed water as washing water of the citrus fruit.

Harvested fruit and vegetables often undergo a period of storage and shelf life, whose length can be influenced by several parameters, such as physiological properties, biotic/abiotic stresses, and final market destination. During these phases a portion of the product is lost, mainly due to fungal diseases, which are often not only of economic concern but also a threat to human and animal health due to presence of mycotoxins. Indeed, some species, primarily belonging to Aspergillus, Fusarium, Penicillium and Alternaria genera, produce secondary metabolites, mycotoxins, which pose a health risk to humans and animals. In fact, maximum permitted contents of mycotoxins in harvested commodities and derived products have been established by national and international organizations. Although in some instances mycotoxins have been shown to be toxic to competing microrganisms or plants, their biological-role has not yet been unequivocally established. Recent studies support their role as pathogenicity/virulence factors in host-pathogen interaction, so that a reduction in mycotoxin production might be relevant even from a plant disease perspective. Unfortunately, the use of traditional control measures, such as synthetic fungicides, is not always possible or effective in a postharvest setting because of restrictions on residue content and the appearance of resistant strains. Thus, the demand for alternative control means (as microbial antagonists, natural or generally regarded as safe compounds, and physical means), as well as for tools for the early detection of spoilage fungi, is increasing. In our research group, particular interest has been devoted to alternative means of control of blue mould caused by Penicillium expansum and consequent patulin accumulation in apples. To this purpose, the role of patulin in disease development was investigated.

Several abiotic diseases are of primary significance for growing olive trees in warm-temperate regions of the world. Diseases caused by environmental stresses including temperature, light, moisture, soil, and air are generally poorly understood and often completely unrecognized in olive which is considered a crop of marginal lands. The condition may be a lack/excess of an essential nutrient or excess of non-essential elements; it may be an unsatisfactory environment: too cold or hot, too wet or dry, or too windy; there may be unsuitable soil characteristics such as poor physical condition, improper pH, and so on. Also pollution in the environment and climatic extremes like lightning, hail and snow can cause heavy losses to olive. This review focuses on the most important diseases of olive caused by stresses of the physical and chemical environment in an integrated view of their interactions with plant healthiness, production, and quality

A survey on Phytophthora spp. in the soils and roots of citrus groves was carried out in the main Syrian growing areas of Lattakia and Tartous. Traditional assays (selective medium with soil dilution plates) were used for pathogen detection, and molecular (PCR) assays were used for unanmbiguous identification of P. nicotianae and P. citrophthora in 38.5% of the collected samples. In both locations, P. citrophthora was the predominant species.

Phytophthora root rot is considered to be the most destructive disease to citrus production in Egypt. Phytophthora species are generally present in citrus nurseries, where soil pots containing the survival propagules are considered responsible for their spread into new orchards. The goal of this study was to investigate the distribution and seasonal variation of Phytophthora species in soil and feeder roots in two Egyptian citrus nurseries, characterized by different management, and to identify Phytophthora species associated with root rot. Soil and root samples were collected at monthly intervals from Sour orange and Volkameriana lemon rootstocks during March-July period. The inoculum density of Phytophthora species, and the percentage of infected feeder roots, were estimated using the plate dilution method in conjunction with selective media. Phytophthora isolates were identified according to their morphological characteristics and on the basis of the ITS regions of the rDNA. Phytophthora nicotianae was the predominant isolated species, followed by P. citrophthora and P. palmivora. Phytophthora nicotianae was detected in both nurseries, while P. citrophthora and P. palmivora were recovered only in one nursery. Inoculum density of Phytophthora species fluctuated during spring and summer according to the environmental conditions, rootstock, and nursery management practices.

The effectiveness of eight protein hydrolysates of natural origin (soybean, lupin, pea, yeast, casein, and malt hydrolysate) for controlling Penicillium digitatum, the main postharvest pathogen of citrus fruit, was evaluated by both in vitro and in vivo trials. The in vitro screening showed no significant effect of the different compounds on pathogen radial growth, whereas the application of the different protein hydrolysates (1.6 mg/ml) to wounded fruits proved their ability to induce resistance against P. digitatum by reducing significantly disease incidence and severity. The best activity was observed on fruits treated with soybean, lupin, and casein hydrolysates. Although further studies are needed, the results obtained are encouraging and potential application against green mould on citrus fruit is foreseen.

The use of alternative control means to reduce water contamination and postharvest decay of fruit and vegetables is becoming increasingly important to enhance food safety and minimize chemical contamination of fresh produce. In the present investigation, the effects of electrolyzed salt solutions using thin-film diamondcoated electrodes on Penicillium spp. population of citrus fruit wash water and fruit decay were evaluated. Different organic and inorganic salts were tested. Electrolyzed water (EW) in combination with sodium bicarbonate (SBC) resulted the most effective treatment in inhibiting spore germination of Penicillium spp. and among the best in reducing Penicillium rot, with no deleterious effects on the fruits. Commercial trials conducted in packinghouses in Sicily (insular Italy) confirmed that the electrolyzed SBC solution was more effective than the electrolyzed tap water in reducing the population of Penicillium spp. Indeed, in the presence of SBC a 93% reduction of the pathogen population was observed 1 h after the beginning of the electrolysis process, whereas in the absence of the salt similar results were observed only after 7 h. In addition, rot incidence in fruit exposed to electrolyzed SBC solution was reduced by up to 100%, as compared to 70% in the absence of the salt. These results demonstrate that among the range of salts tested, the combination of electrolysis and SBC has a synergic effect and is a promising strategy for controlling postharvest Penicillium decay of citrus fruits.

The aim of this study was to investigate the ability of two salts, sodium carbonate and bicarbonate, to activate defence mechanisms in citrus fruit against postharvest green mould caused by Penicillium digitatum. In particular, once confirmed salt antifungal activity in absence of direct contact with the pathogen, changes in enzymatic activity and expression level of chitinase, ß-1,3-glucanase, peroxidase and phenylalanine ammonia lyase (PAL), and, consequently, in phytoalexin (scoparone, scopoletin, umbelliferone) and sugar (glucose, fructose, sucrose) content in treated oranges were analyzed. Overall, sodium carbonate and bicarbonate proved to increase the activity of ß-1,3-glucanase, peroxidase, and PAL enzymes in orange tissues. Gene expression analyses confirmed PAL up-regulation particularly at 12 h after treatment application. Furthermore, HPLC analyses of peel extracts showed increased amounts of the tested sugars and phytoalexins, as compared to those found in control tissues, with sucrose and scoparone being the most represented. The obtained results suggest that, although salts exert a direct antifungal effect on P. digitatum, they are also able to induce citrus fruit defense mechanisms to postharvest decays. The defense response seems correlated with the up-regulation of phenylpropanoid pathway, which has a role in the adaptation to various stresses. This response could sum up to citrus natural reaction to wounding and pathogen attack, enhancing its protective effect. As a consequence, the fruit might have a better chance for a successful defence against the decay.

Plasmopara viticola, the causal agent of grapevine downy mildew, is one of the most devastating grape pathogen in Europe and North America. Although phytochemicals are used to control pathogen infections, the appearance of resistant strains and the concern for possible adverse effects on environment and human health are increasing the search for alternative strategies. In the present investigation, we successfully tested two protein hydrolysates from soybean (soy) and casein (cas) to trigger grapevine resistance against P. viticola. On Vitis vinifera cv. Marselan plants, the application of soy and cas reduced the infected leaf surface by 76 and 63%, as compared to the control, respectively. Since both hydrolysates might trigger the plant immunity, we investigated their ability to elicit grapevine defence responses. On grapevine cell suspensions, a different free cytosolic calcium signature was recorded for each hydrolysate, whereas a similar transient phosphorylation of two MAP kinases of 45 and 49 kDa was observed. These signalling events were followed by transcriptome reprogramming, including the up-regulation of defence genes encoding pathogenesis-related (PR) proteins and the stilbene synthase enzyme responsible for the biosynthesis of resveratrol, the main grapevine phytoalexin. Liquid chromatography analyses confirmed the production of resveratrol and its dimer metabolites, δ- and ε-viniferins. Overall, soy effects were more pronounced as compared to the cas one. Both hydrolysates proved to act as elicitors to enhance grapevine immunity against pathogen attack.

Abstract: Although the antibacterial activity and toxicity to humans and animals of the mycotoxin patulin are well known, its role in the postharvest decay of apples by Penicillium expansum has never been investigated. In the present study the gene disruption technique was used to alter the sequence of 6-methyl-salicylic acid synthase, an enzyme involved in the first committed step of patulin biosynthesis. Thirty-nine mutants were obtained, however only two of them (M5 and M21) passed the sub-cultural and molecular confirmation tests. They proved to produce 33-41% less patulin than their wild-type (WT) strain, although no difference in the growth and morphology of the colony was observed. Moreover, the mutants showed a significantly reduced pathogenicity and virulence on artificially inoculated apples. In particular, a 33-34% and 47-54% reduction of disease incidence and severity were recorded for M5 and M21, respectively. As confirmation, when the biomass of the mutants was quantified in vivo by Real-time PCR, a significant difference was recorded as compared to the WT and even between mutants. Moreover, when patulin production potential of mutants was restored by exogenous application of the mycotoxin, their ability to cause the disease was not significantly different from that of WT. Finally, mutants showed an increased susceptibility to the application of the antioxidant quercetin, their pathogenicity and virulence being significantly reduced at only 1/100 of the concentration needed for the WT. Based on these findings, patulin seems to have a role in the development of blue mold decay on apples. Copyright 2011 Elsevier B.V. All rights reserved.

Patulin ecological role has never been elucidated. Gene disruption was used to alter the sequence of 6-methyl-salicylic acid synthase. Disrupted mutants were significantly less pathogenic and virulent on apples. Mutants were more susceptible to the antioxidant quercetin than the wild type. Patulin seems to have a role in blue mould pathogenic development on apples.

This work aimed to find out patterns of virulence variability of a Phoma tracheiphila population of 51 isolates, to determine geographic distribution of Mal Secco disease in citrus orchards of six Mediterranean countries and also to establish correlation between geographic distribution and pathotypic distance of P. tr population structure over our sampling spatial scale. Based on unweighted pair-group method with arithmetic averaging clustering and mean disease rating scores, three distinct virulence groups were identified. The 51 isolates were classified into 20 pathotypes. Extensive virulence variability was detected in 51 isolates of P. tr causing MSD of citrus in the Mediterranean basin. Regression plot between pairwise virulence and geographical distance showed that virulence is independent of the geographical origin and that isolates collected from the same country have different degrees of virulence. The lack of significant correlation between virulence and geographic structure confirmed the absence of isolation-by-distance pattern, suggesting non-regular and non-gradual dispersal of the pathogen over this spatial scale.