Abstract: Potassium sorbate, a program of four fungicides, or one of three chitosan formulations were applied to clusters of ‘Thompson Seedless’ grapes at berry set, pre-bunch closure, veraison, and 2 or 3 weeks before harvest. After storage at 2oC for 6 weeks, the natural incidence of postharvest gray mold was reduced by potassium sorbate, the fungicide program, or both together in a tank mixture, in 2009 and 2010. In 2011, the experiment was repeated with three chitosan products (OII-YS, Chito Plant, and Armour-Zen) added. Chitosan or fungicide treatments significantly reduced the natural incidence of postharvest gray mold among grapes. Berries harvested from vines treated by one of two of the chitosan treatments or the fungicide program had fewer infections after inoculation with Botrytis cinerea conidia. None harmed berry quality, and all increased endochitinase activity. Chitosan decreased berry hydrogen peroxide content. One of the chitosan formulations increased quercetin, myricetin, and resveratrol content of the berry skin. In another experiment, ‘Princess Seedless’ grapes treated with one of several fungicides before 4 or 6 weeks of cold storage, had less decay than the control. Fenhexamid was markedly superior to the other fungicides for control of both the incidence and spread of gray mold during storage.
Abstract: This study compared the effectiveness in controlling postharvest diseases of strawberry of practical grade chitosan when used as solutions obtained by dissolving it in acetic, glutamic, formic and hydrochloric acids, with a water-soluble commercial chitosan formulation. The commercial chitosan formulation and other resistance inducers based on benzothiadiazole, oligosaccharides, soybean lecithin, calcium and organic acids, and Abies sibirica and Urtica dioica extracts were also tested, to evaluate their effectiveness in the control of postharvest decay of strawberry. The commercial chitosan formulation was as effective as the practical grade chitosan solutions in the control of gray mold and Rhizopus rot of strawberries immersed in these solutions and kept for 4 days at 20 ±1 °C. Moreover, the treatment with commercial and experimental resistance inducers reduced gray mold, Rhizopus rot and blue mold of strawberries stored 7 days at 0 ±1 °C and then exposed to 3 day shelf life. The highest disease reduction was obtained with the commercial chitosan formulation, followed by benzothiadiazole, calcium and organic acids. The compounds that provided the best results in postharvest applications could be tested in further trials thought preharvest treatments to control storage decay of strawberries, applied at flowering and a few days before harvest.
Notes: Highlights
- A commercial chitosan formulation controls decay as well as chitosan dissolved in acids
- Commercial chitosan formulation and benzothiadiazole show best strawberry decay control
- Those compounds have potential for application in strawberry IPM strategies
Abstract: The effectiveness of alternatives to synthetic fungicides for the control of pathogens causing postharvest diseases of sweet cherry was tested in vitro and in vivo. When amended to potato dextrose-agar, oligosaccharides, benzothiadiazole, chitosan, calcium plus organic acids, and nettle macerate reduced the growth of Monilinia laxa, Botrytis cinerea and Rhizopus stolonifer. Treatment of sweet cherries three days before harvest or soon after harvest with oligosaccharides, benzothiadiazole, chitosan, calcium plus organic acids, nettle extract, fir extract, laminarin, or potassium bicarbonate reduced brown rot, gray mold, Rhizopus rot, Alternaria rot, blue mold and green rot of cherries kept 10 d at 20±1 °C, or 14 d at 0.5±1 °C and then exposed to 7 d of shelf life at 20±1 °C. Among these resistance inducers, when applied either preharvest or postharvest, chitosan was one of the most effective in reducing storage decay of sweet cherry, and its antimicrobial activity in vitro and in field trials was comparable to that of the fungicide fenhexamid. Benzothiadiazole was more effective when applied postharvest than with preharvest spraying. These resistance inducers could represent good options for organic growers and food companies, or they can complement the use of synthetic fungicides in an integrated disease management strategy.
Abstract: Grapevine Bois noir (BN) is a phytoplasma disease that is widespread in most viticultural regions of the World, and it can result in heavy reductions to yields and grape juice quality. At present, there is no effective strategy to reduce the incidence of BN-infected grapevines. However, phytoplasma-infected plants can recover through spontaneous or induced symptom remission. Five elicitors (chitosan, two glutathione plus oligosaccharine formulations, benzothiadiazole, phosetyl-Al) were applied weekly to the canopy of BN-infected cv. Chardonnay grapevines, from early May to late July. The best and most constant recovery inductions were obtained with benzothiadiazole and the two glutathione plus oligosaccharine formulations. The plants that recovered naturally or following the elicitors showed qualitative and quantitative parameters of production no different from healthy plants. In another vineyard, diseased plants showed reduced shoot length and production, as compared to healthy plants, and there were no negative effects on these parameters for grapevines sprayed with a glutathione plus oligosaccharine formulation. The application of resistance inducers promoted the recovery of BN-infected grapevines with no adverse effects on the plants. Therefore, grapevine can be used as a model species to test this innovative strategy to contain phytoplasma diseases.
Abstract: Bois noir is a grapevine disease caused by stolbur phytoplasma. It is widespread in all European and Mediterranean viticultural areas, and it can induce severe damage to the quality and quantity of production. The recent disease recrudescence has encouraged studies on the use of molecular markers to assess the genetic diversity of stolbur strains. The aim of this study was to evaluate the presence of Bois noir symptoms and to monitor the spatial genetic structure of the stolbur population according to vmp1 genotypes, through 2011 and 2012 in a cv. Chardonnay vineyard. In both years, there were increased symptomatic vines from July to September. The analysis of dispersal indices showed that the spatial distribution was uniform in the vineyard. However, the two-dimensional contour maps show that Bois noir severity was higher in plants located on the borders than in the central parts of the vineyard. Stolbur population was composed of two prevalent vmp genotypes (V14, V12) across both years, along with other minor haplotypes (V3, V4, V9, V11, V15, V18, in 2011; V3, V18 in 2012). Our data indicate that the vmp1 gene is an efficient marker to study the population structure of stolbur phytoplasma, to track the movement of the pathogen, and to identify the inoculum source, which will all serve in the planning of control strategies.
Abstract: Gray mold, caused by Botrytis cinerea, is the main postharvest decay of table grapes. It can develop in the vineyard and spread rapidly among berries after harvest, during long distant transport, cold storage and shelf life. In conventional agriculture, bunches are sprayed with fungicides after flowering, at pre-bunch closure, at veraison, and later depending on the time of harvest. Harvested bunches are usually stored in the presence of sulfur dioxide. However, the use of synthetic fungicides and of sulfur dioxide is not allowed on organic grapes and the study of alternative means to control postharvest decay has developed during several decades, along with the demand for safer storage methods. This review summarizes the results published in the field within the last five years (2006-2010). We can group these approaches as follows: i) biocontrol agents; ii) natural antimicrobials; iii) GRAS type decontaminating agents; and iv) physical means. Two biocontrol agents, Muscodor albus and Hanseniaspora uvarum, have shown equal or better effectiveness than conventional means to control gray mold of table grapes in laboratory scale experiments. Currently, the bottleneck for the commercial use of biocontrol agents is that the registration process is comparable to that of fungicides, with similar costs but often with a narrower market. This issue delays their transition from experimental to practical use. Natural antimicrobials, such as salts, chitosan, and plant extracts, demonstrated good results and often were applied in various scales. Several GRAS-classified sanitizers were tested to extend postharvest storage of table grapes, including acetic acid, electrolyzed oxidizing water, ozone, and ethanol. Physical means in reference to variations in temperature, UV-C irradiation, pressure or changing atmospheric composition are all postharvest practices which require significant adaptation by the industry which is accustomed to minimal intervention during harvest. Overall, the use of ozone and of calcium chloride are two promising examples of treatments that are beginning to be adopted in a commercial scale. The requirements from the optimal treatment of grapes against gray mold before harvest or during storage are summarized.
Abstract: To evaluate wood colonization and interactions with Vitis spp. of Phaeomoniella chlamydospora (Pch), a fungal agent involved in Esca disease, isolate CBS 229.95 was transformed using a pCT74 construct which contained the genetic markers for synthetic green fluorescent protein (sGFP) and hygromycin B phosphotransferase. Nine stable Pch fungal transformants (Pch-sGFP lines) were obtained using polyethylene-glycol-mediated transformation of protoplasts. These were characterized for sgfp and hph genome insertions and for sGFP fluorescence emission, using quantitative polymerase chain reaction and fluorimetric systems, respectively. No correlation was observed between sgfp copy number genome insertion and sGFP fluorescence expression. Cuttings of Vitis vinifera cvs. Montepulciano, Verdicchio, Sangiovese, Biancame, and Cabernet Sauvignon, the grapevine rootstocks Kober 5BB, SO4, 420A, and Vitis rupestris were inoculated by immersion in a conidial suspension of the selected fungal Pch-sGFP71 line and incubated at 4 ± 1°C and 25 ± 1°C. Wood colonization was estimated through epifluorescence microscopy, and was affected by incubation temperature. After 6 months at 4 ± 1°C, the fungal growth was completely inhibited. At 25 ± 1°C, the highest extent of wood colonization was recorded in cvs. Montepulciano and Verdicchio, with the lowest in the rootstocks SO4 and V. rupestris. The expression of the Pch-sGFP71 transformed line was localized in the xylem area, primarily around the vessels. The use of sGFP-transformed Pch helped to clarify different aspects associated with the location of this pathogen in grapevine tissue, before disease symptom expression.
Notes: Fig. 4B is the cover of March issue of the journal
Abstract: Leucostoma cinctum and L. persoonii are the two species involved in Leucostoma canker, a disease that causes dieback of twigs and branches, bark cankers, gummosis, and tree decline of stone fruits. The aim of this study was to identify the causal agent of Leucostoma canker in Italian stone fruit orchards. More than 200 isolates of Leucostoma spp. were obtained from branches and twigs of sweet and sour cherry, apricot, and European plum trees that showed typical symptoms of Leucostoma canker. These trees were in commercial orchards of two Italian regions, Marche and Apulia, in central-eastern and south-eastern Italy, respectively. After isolation, all of the colonies that grew on potato dextrose agar were white in color, and after about 10 days they became olive-green. Growth was not observed at 33 °C, and the pycnidia were larger than 1 mm diam. This information led to the identification of L. cinctum as the causal agent of these Leucostoma cankers. To our knowledge, this is the first report of L. cincta on sweet cherry and European plum in Italy.
Abstract: Bois noir (BN) is one of the main phytoplasma diseases of grapevine (Vitis vinifera L.). It is widespread, and can cause severe losses in European vineyards. The infective agent colonizes phloem elements and induces visible symptoms of leaf yellowing or reddening after a relatively long incubation period. As the most sensitive cultivars to BN, Chardonnay plants were grouped as healthy or symptomatic in spring, based on the records from the previous year. Leaf gas exchange and chlorophyll a fluorescence were measured weekly from July to September in healthy plants, and in symptomatic and asymptomatic leaves from symptomatic plants. The relative water content at midday was measured once per month. The detection of phytoplasma DNA by nested-PCR revealed BN infection in symptomatic leaf samples at the end of September. A significant decrease in pigment content and maximum quantum efficiency of PSII (Fv/Fm) of these symptomatic leaves was detected from July to September, although in the asymptomatic leaves of the symptomatic plants the net photosynthesis (Pn) decrease was not significant. In the leaves from the healthy plants, Pn and transpiration were relatively stable. Of note, in July, an initially healthy plant showed a strong Pn reduction that was followed by visible leaf yellowing symptoms only in August. The phytoplasma infection also stimulated significant reductions in midday relative water content of the symptomatic leaves, with a final large decrease in yield.
Abstract: Although Bois noir is one of the main phytoplasma diseases of grapevine, the gene expression and enzyme activities which underlie physiological changes occurring in symptomatic and recovered (with spontaneous or induced symptom remission) plants are mostly unknown. Bois noir symptomatic leaves (September 2006, 2007) and symptomless leaves from infected symptomatic plants (September 2007) of Sangiovese (moderately susceptible) and Chardonnay (highly susceptible) cultivars were collected. Moreover, leaves from infected symptomless plants of both cultivars were harvested in June 2007. Leaves from recovered plants were also collected in the same periods. In recovered plants of both cultivars, class III chitinase and almost every times phenylalanine ammonia-lyase and chalcone synthase expression were increased for all collection periods. In symptomatic leaves of both cultivars, the expression of the same genes were up-regulated, and also of ï¢-1,3-glucanase and flavanone 3-hydroxylase. The activities of chitinase, phenylalanine ammonia-lyase, ï¢-1,3-glucanase and superoxide dismutase generally correlated with gene expression. For the moderately susceptible Sangiovese, the defense genes were generally up-regulated in both symptomatic and symptomless leaves (for all collection periods). This behavior was not observed in the highly susceptible Chardonnay, where changes in gene expression were linked to evident symptom display. Therefore, the physiological response of the plants to this pathogen infection appear to be the reason for the resistance of the cultivar to the disease.
Abstract: Aim: Evaluation of the genetic variability of stolbur phytoplasma infecting grapevines, bindweeds and vegetables, collected in different central and southern Italian regions.
Materials and Results: Phytoplasma isolates belonging to stolbur subgroup 16SrXII-A were subjected to molecular characterization by PCR/RFLP, to investigate two different non-ribosomal genes: tuf and vmp1. In grapevines, 32% of samples were infected by tuf-a type and 68% by tuf-b type, with different relative incidences in the regions surveyed. All herbaceous samples (bindweeds, tomato, tobacco, pepper, celery) were infected by tuf-b. The gene vmp1 showed higher polymorphism in grapevines (nine profiles) than herbaceous plants (six) by RFLP analysis, in agreement with nucleotide sequences’ analysis and virtual digestions.
Conclusions: The phylogenetic analysis of vmp1 gene sequences supports the RFLP data and demonstrates the accuracy of RFLP for preliminary assessments of genetic diversity of stolbur phytoplasmas and for screening different vmp types.
Significance and Impact of the Study: Stolbur represents a serious phytosanitary problem in the areas under investigation, due to heavy economic losses in infected grapevines and vegetables. Molecular information about the complex genotyping of the vmp1 gene provides useful data towards a better understanding of stolbur epidemiology. Moreover, this study clarifies some different vmp1 genotype classifications of stolbur, providing molecular data for comparison with previous investigations.
Abstract: Phytoplasmoses are severe diseases of grapevine and other crops, for which no effective means of control are available. However, plants infected by phytoplasma can undergo spontaneous symptom remission (recovery), a long-known phenomenon. A strategy to reduce the number of symptomatic plants could thus arise from the stimulation of plant defence systems to induce recovery. The aim of the present study was to evaluate the effectiveness of field treatments with resistance inducers to promote recovery in Bois noir (BN) infected grapevines. Five commercial products (Chito Plant, Aliette, Kendal, Bion, and Olivis) described as plant defence promoters were sprayed on the canopy of BN-infected grapevines of cv. Chardonnay. Treatments consisted of weekly sprays in spring-summer 2007 (seven applications) and 2008 (thirteen applications). All treatments increased the number of recovered plants with respect to the control. The best results were obtained with Kendal, Olivis and Bion, while Aliette and Chito Plant performed better in the first than in the second year. Molecular analysis of leaf vein extracts from recovered plants failed to detect the phytoplasma. An induction of host defence is likely to be responsible for the effectiveness of these resistance promoters in the control of BN.
Abstract: Gray mold is caused by Botrytis cinerea Pers.:Fr., a cosmopolitan and polyphagous fungus that is responsible for significant losses on several fruit crops, including kiwifruit (Actinidia deliciosa), both in the field and during storage (2). The hardy kiwifruit, A. arguta, is a kiwifruit with a smooth skin grown in several countries (e.g Japan, China, Korea, Russia, USA) (1,3) and regions of Italy, including Apulia (south eastern), Basilicata (southern), Marche (central eastern), Tuscany (central western), Piedmont, Friuli Venezia Giulia and Trentino Alto Adige (northern) (4). A. arguta produces fruit with edible thin skin in large clusters. The oblong-to-oval shaped fruit bear tips with a persistent style, and weight about 5 to 15 g (1,3,4). Several fruits of cv. Ananasnaya selection “Anna red†harvested from September to October in 2007 and 2008 in the Apulia and Marche regions, showed browning and depressions in the surface, and a decay of the flesh. The disease affected about 5% of 420 examined fruits; symptoms mainly developed in the equatorial zone, eventually expanding through the entire fruit. Severely infected fruit showed deformation, followed by drying. In the field or after storage in an environment with high RH, fungal mycelia with sporulation appeared on the surface of the symptomatic areas of the fruit. Nineteen symptomatic fruit were surface disinfested by immersion in a 0.5% sodium hypochlorite solution for 2 min, then rinsed in sterile distilled water. Portions of the flesh were plated onto Petri dishes containing potato dextrose agar (PDA) supplemented with 250 mg/l each ampicillin and streptomycin sulphate. Colonies that originated from symptomatic portions of the fruit were transferred to new PDA plates, and identified as B. cinerea by the morphological features of conidiophores and conidia. Conidia were produced on dichotomously branched conidiophores, which had globose basal cells from mycelia. The conidia were hyaline or pigmented, ellipsoid-obovoid, globoid, and without septa (2). Conidia were collected from an isolate (accession n. CBS 125087) of B. cinerea, recovered from diseased A. arguta fruit grown in Monopoli (BA), Apulia, in September 2007, and maintained in pure culture on PDA. A spore suspension was created by flooding plates with a small volume of sterile distilled water plus surfactant (0.05% Triton X-100). The suspension was filtered through four layers of cheesecloth and diluted with sterile water to an absorbance of 0.25 at 425 nm as determined by a spectrophotometer. This suspension contained about 1.0 × 106 conidia/ml and was diluted with sterile water to 1 × 104 spores/ml. Twenty μl droplets of spore suspension were deposited within the equitorial zone on each of ten non-wounded fruits of cv. Ananasnaya selection “Anna redâ€. All of these fruit developed the typical gray mold symptoms after 4 to 5 days of incubation at 20±2°C and 95 to 98% RH. Reisolation from the decayed tissues on PDA produced pure colonies of B. cinerea. To our knowledge, this is the first report of B. cinerea infection on A. arguta in Italy.
Abstract: Chitosan is a natural biopolymer that must be dissolved in an acid solution to activate its antimicrobial and eliciting properties. Among 15 acids tested, chitosan dissolved in 1% solutions of acetic, L-ascorbic, formic, L-glutamic, hydrochloric, lactic, maleic, malic, phosphorous, and succinic acid. To control gray mold table grapes were immersed 10 s in these chitosan solutions that had been adjusted to pH 5.6. The reduction in decay among single berries of several cultivars (Thompson Seedless, Autumn Seedless, and grape selection B36-55) inoculated with 1 × 105 Botrytis cinerea conidia per ml before or after immersion in chitosan acetate or formate, followed by storage at 15°C for 10 days, was about 70%. The acids alone at pH 5.6 did not control gray mold. Decay among clusters of two cultivars (Thompson Seedless and Crimson Seedless) inoculated before treatment was reduced about 60% after immersion in chitosan lactate or chitosan acetate followed by storage for 60 days at 0.5°C. The viscosity of solutions was 1.9 cp (ascorbate) to 306.4 cp (maleicate) and the thickness of chitosan coating on berries was 4.4 ïm (acetate) to 15.4 ïm (ascorbate) which neither was correlated with solution effectiveness. Chitosan acetate was the most effective treatment which effectively reduced gray mold at cold and ambient storage temperatures, decreased CO2 and O2 exchange, and did not injure the grapes.
Abstract: Coltsfoot (Tussilago farfara L.) is a perennial herb with a creeping rhizome and long runners. It is an invasive weed that prefers heavy clay soils throughout Europe, North Africa, Asia and the USA. Bois noir (BN), caused by phytoplasma belonging to the stolbur group (16SrXII-A), is spread in the main Italian viticultural areas and it is common in vineyards of the Abruzzi region (Romanazzi et al., 2007). BN is transmitted to grapevines by its vector, Hyalesthes obsoletus, that can feed on BN-infected wild plants.
In 2007, during a survey carried out in a cv Chardonnay vineyard with a 30% of BN-infected plants (Romanazzi et al., 2007), at Atri (TE) in the Abruzzi region, spontaneous T. farfara plants were collected. Most of these showed typical symptoms ascribed to phytoplasma infection, such as foliar reddening and rolling (Fig. 1). The DNA was extracted from leaf samples of symptomatic and symptomless T. farfara plants using the DNeasy Plant Mini Kit (Qiagen, Hilden, Germany). The samples were amplified with the P1/P7 universal primers and nested-PCR was carried out with group-specific primers: R16(I)F1/R1, R16(III)F1/R2 and R16(V)F1/R1. Five-µl aliquots of the R16(I)F1/R1 amplicon were digested with 3 U restriction endonuclease MseI (New England BioLabs, Beverly, MA, USA), overnight at 37°C. Further molecular characterization was carried out by amplifying the tuf gene in nested-PCR and digesting the amplicon with 3 U HpaII (New England BioLabs), overnight at 37 °C (Langer and Maixner, 2004).
All symptomatic samples of T. farfara were infected by stolbur, showing an identical restriction pattern to that in the reference strain (STOL, kindly provided by C. Marzachì, IVV-CNR, Turin, Italy). No phytoplasma of groups 16SrI, 16SrIII and 16SrV were detected. The pathogen was not found in samples from symptomless plants, which developed disease symptoms on the entire plant when inoculated by grafting with samples from infected symptomatic ones. Leaf samples from these artificially inoculated plants tested positive for the presence of the phytoplasma. The molecular characterization of the stolbur isolates revealed tuf type II infections (Fig. 2).
Several infection of phytoplasma have been detected on different yellows diseased weeds in Italy (Credi et al., 2006; Borgo et al., 2008), although stolbur infection has not previously reported for T. farfara. The information on weeds that can be sources of BN phytoplasma in the vineyard is basilar for the disease management on grapevine. This is thus the first report of stolbur infection in symptomatic T. farfara in Italy, and worldwide.
Abstract: Esca is one of the most important grapevine trunk diseases, and it can induce severe declines. In the past, the disease occurred mostly with mature vines, but today it is also present in young vineyards. The aim of this study was to investigate the incidence of esca in young (less than 7 years old) and mature (more than 11 years old) vineyards with cvs. Montepulciano, Sangiovese, Verdicchio and Passerina located in the main viticultural areas of the Marche Region, central-eastern Italy. The average incidence of diseased plants was higher in mature (32.58%) than young (5.21%) vineyards, and Verdicchio and Passerina appeared to be the most sensitive among the cultivars considered, followed by Sangiovese and Montepulciano. The analysis of the spatial spread of esca carried out in two mature vineyards with cv. Verdicchio and a young vineyard with cv. Sangiovese showed a fluctuation in the numbers of infected plants over the three years of observation. The fungi associated with symptomatic plants were detected by classical and, in part, molecular tools. Isolation on agar media yielded colonies of Phaeomoniella chlamydospora (Pch), Botryosphaeria spp. (Bot), Fomitiporia mediterranea (Fomed) and, sporadically, Phaeoacremonium aleophilum (Pal). In samples from young plants, Bot and Pch were recurrent, while Pch and Fomed were found with mature vines and old rootstocks. Molecular detection with specific primer pairs for Pch, Pal and B. dothidea confirmed the data obtained using classical tools, and in some cases it was more sensitive. This study thus provides a further contribution as to the presence of different causal agents in the expression of esca symptoms, and it confirms the importance of molecular tools for the sensitive detection of associated pathogens, which can also be present in propagative materials.
Abstract: Grapevine virus A (GVA) is considered one
of the viruses associated with rugose wood (RW), one
of the most economically important diseases of
grapevine. Thirty-seven GVA isolates collected from
grapevine cultivars from Marche (central-eastern Italy),
Apulia and Campania (southern Italy), were subjected
to molecular characterization. The genetic and population
diversity was studied in the coat protein (CP) gene
by RT-PCR-RFLP analysis with three restriction
enzymes (MseI, AluI, and AciI), and nucleotide
sequencing. A new primer pair (CP1F/R) allowing
amplification of the whole CP gene (621 bp) was
developed. RFLP with AciI yielded the highest number
of variants in GVA isolates, showing seven different
‘simple’ profiles (A, B, C, D, E, F, and G). ‘Complex’
profiles were also found, and the most common variant
combination was A+B in 39% of isolates. The analysis
of GVA sequences confirmed the presence of plants
infected with more than one GVA variant and
suggested that RT-PCR-RFLP is suitable for evaluating
population diversity of GVA enabling a screening of
different haplotypes. The distribution of RFLP profiles
and the phylogenetic analysis were not correlated with
the location of infected plants, showing the presence of
a GVA population with genetic diversity in the average
with those of RNA viruses.
Abstract: Ulmus L. and Zelkova Spach are two species of the
family Ulmaceae occuring in Europe. Ulmus (elm) comprises
about 45 species that show a range of susceptibilities
to Elm Yellows (EY), the most widespread and serious
phytoplasma disease for these hosts. Japanese elm
(Zelkova spp.) is known for its resistance to a wide
range of diseases and pests, although Zelkova Yellows
(ZY) has recently been reported on Z. serrata. Since
June 2006, we have carried out surveys to identify the
causal agent of the decline of Ulmus spp. and Z. serrata
in the Marche Region of Italy. Twenty-five leaf samples
were collected from pre-bonsai and bonsai elms (U.
parvifolia and Ulmus sp.), and Z. serrata, either symptomless
or showing typical EY symptoms, and these
were analysed by nested-PCR and RFLP based on the
phytoplasma 16S rRNA gene. These analyses detected a
single infection of ‘Candidatus Phytoplasma ulmi’
(16SrV-A) in all of the symptomatic leaf samples. Sequence
analysis revealed 99% nucleotide homology
with the EY reference strain EY-627 (Genbank accession
no. AY197658). This appears to be the first report
of ‘Ca. Phytoplasma ulmi’ associated with EY in Ulmus
spp. and Z. serrata that have been trained as bonsais.
Abstract: The effectiveness of short hyperbaric treatments to control postharvest decay of sweet cherries (Prunus avium L., cv Ferrovia) and table grapes (Vitis vinifera L., cv Italia) was investigated. Sweet cherries and table grape berries were exposed to the pressure of 1140mmHg (1.5 atm) for 4 and 24 h, respectively, in 64 L gas-proof tanks. Fruit kept at ambient pressure (near 760 mmHg, 1.0 atm) served as a control. Postharvest rots of sweet cherries arose from naturally occurring infections, whereas table grape berries were artificially wounded, exposed to the hyperbaric treatment, then the wounds inoculated with 20 L of a Botrytis cinerea conidial suspension (5×104 sporesmL−1). Sweet cherries were stored at 0±1 ◦C for 14 d, followed by 7 d at 20±1 ◦C. Table grapes berries were kept at 20±1 ◦C for 3 d. On sweet cherries, hyperbaric treatment reduced the incidence of brown rot, grey mould, and blue mould, with respect to the control. Similarly, on treated table grapes a significant reduction of lesion diameter
and percentage of B. cinerea infected berries was observed. Induced resistance was likely to be responsible for the observed decay reduction. To our knowledge, this is the first report on the effectiveness of short hyperbaric treatments in controlling postharvest decay of sweet cherries and table grapes.
Abstract: The Japanese Elm (Zelkova spp.) is a temperate broad-leaved deciduous tree genus, which includes species that are nowadays distributed in east Asia (three species), western Asia (one species) and the Mediterranean (two species), while it is absent from north America (Denk and Grimm, 2005). Even though a member of the Elm family, the Japanese Elm has no disease or pest problems of significance, including Dutch elm disease.
Since June 2006, several plants of Zelkova serrata grown in Ancona, Marche region (central eastern Italy), showed symptoms of chlorosis which involve the whole plant or some of the branches, foliar reddening on one or more branches, attenuation of apical dominance and proliferation of lateral shoots, witches’ brooms, reduced growth and stunting of the plant.
Leaf samples from symptomatic and symptomless plants were collected and the DNA was extracted using the Plant DNeasy mini kit (Qiagen, Hilden, Germany). A molecular diagnosis was carried out to detect phytoplasma by PCR with universal primers P1/P7 (Seemüller et al., 1998) followed by a nested PCR with specific group primers 16Sr(V)F1/R1 (Lee et al., 1994). All of the five symptomatic samples yielded a PCR product of the expected size (1100 bp), both during 2006 and 2007. This PCR product was purified from the 1% agarose gels using Spin Column Wizard SV Gel and the PCR Clean–Up System (Promega), and eluted with sterile ultrapure water, according to the manufacturer instructions. Five-µl aliquots of the PCR product were digested with 3U of restriction endonuclease BfaI (New England BioLabs, Beverly, MA, USA), over night at 37°C. The restriction pattern was characterized by two bands of 650 and 450 bp, identical to those in the reference strain of ‘Candidatus Phytoplasma ulmi’ (EY, kindly provided by C. Marzachì, IVV-CNR, Torino, Italy) (Lee et al., 2004). The pathogen was not found in samples from symptomless plants. Those plants were inoculated by grafting with samples from infected symptomatic plants, and disease symptoms appeared on the whole plant. Leaf samples from artificially inoculated plants tested positive to the presence of the phytoplasma. The sequenced isolate from Z. serrata showed more than 99% identity with ‘Ca. Phytoplasma ulmi’ strain EY1T (GenBank accession number AY197655) (Lee et al., 2004).
Several natural infections of ‘Ca. Phytoplasma ulmi’ have been described on different species of the genus Ulmus (Lee et al., 2004), although it has not been reported on Zelkova spp. This thus appears to be the first report of ‘Ca. Phytoplasma ulmi’ infection in symptomatic Z. serrata, in Italy and worldwide.
Abstract: Grapevine yellows (GY) are diseases caused by
phytoplasmas, which are able to induce severe loss of
production and death of plants. Bois noir (BN) and
Flavescence dore´e are the most important GY diseases
prevalent in several European countries. As of now,
there are no known effective disease-control methods
for application in grapevines infected by these phytoplasmas.
In these plants, it is possible to have, remission
of these symptoms, better known as recovery. In
April 2006 in the Marche region, central-eastern Italy,
grapevines cv. Chardonnay, Verdicchio and Sangiovese
grafted onto Kober 5BB; rootstock symptomatically
infected by VK type II BN were subjected to partial
uprooting, which was effected by breaking most of
their roots using a small excavator. Almost all of these
plants failed to show disease symptoms in the autumn
of 2006 and 2007. Similar trials were carried out on
BN-infected plants cv. Chardonnay grafted onto 420A
rootstock in 2006 and 2007; in this case, the treatment
was only partially successful in both these years. In
another trial in April 2007, BN-infected plants cv.
Chardonnay grafted onto 420A rootstock and cv.
Primitivo grafted onto Kober 5BB, rootstock were
pulled and some of these showed no disease symptoms
in the following autumn, whereas others had
only mild infections. Partial uprooting and pulling are
agronomical practices that induce stress in the plants.
In the case of grapevines affected by GY, such stress
can result in the recovery of the vines. However, the
effectiveness in the induction of recovery in these treatments
can depend on the rootstock.
Abstract: Gray mold, caused by Botrytis cinerea, is the most important postharvest disease of table grapes. Chitosan, a natural biopolymer with antifungal and eliciting properties, and ethanol, a common food additive with antifungal properties, are both able to reduce postharvest decay of table grapes. The effectiveness of reduced doses of chitosan and ethanol, applied alone or in combination, to control gray mold of table grapes was evaluated. Artificially inoculated single berries or clusters were immersed in chitosan (0.1 and 0.5%), ethanol (10 and 20%), or their mixture. The combination of 0.5% chitosan with 10 or 20% ethanol improved decay control with respect to their single treatments, while combinations of 0.1% chitosan with 10 or 20% ethanol did not improve gray mold control compared to the treatments applied alone. On single berries stored 7 days at 15±1 ◦C, the highest levels of decay control were observed on grapes treated with the combination of 0.5% chitosan and 10 or 20% ethanol (reductions of
94 and 97% on cv Autumn Seedless and 69 and 73% on Thompson Seedless, respectively, compared to controls). On small clusters stored 60 days at 0.5±1 ◦C, the highest percent reduction was observed on grapes treated with the combination of 0.5% chitosan and 10 or 20% ethanol (reductions of 47 and 60% in Thompson Seedless, and 70 and 94% in Autumn Seedless, respectively, compared to controls). The tests with small clusters were carried out to simulate commercial prolonged cold storage of table grapes. The combination of reduced doses of chitosan and ethanol improved the control of gray mold of table grapes compared to their application alone, and the effect was at least additive and at times synergistic.
Abstract: The effectiveness of chitosan treatment of table grapes, alone or in combination with ultraviolet-
C (UV-C) radiation, to control postharvest gray mold caused by Botrytis cinerea, was determined
in California, United States. The influence of these treatments on catechin and resveratrol
contents and chitinase activity in grape berry skins also was assessed. Clusters of cvs. Thompson
Seedless, Autumn Black, and Emperor were sprayed in the vineyard with 1% chitosan, then
harvested daily for 5 days. Promptly after harvest, they were inoculated with B. cinerea. Decay
incidence and disease severity were significantly reduced by chitosan, which was most effective
on berries harvested 1 or 2 days after treatment. In another experiment, grape berries were
sprayed in the vineyard with chitosan, harvested 2 days later, irradiated for 5 min with UV-C
(0.36 J/cm2), and inoculated with B. cinerea 2 days later. Combined chitosan and UV-C treatments
applied to cv. Autumn Black or selection B36-55 were synergistic in reducing gray mold
incidence and severity compared with either treatment alone. Preharvest chitosan treatment increased
neither concentration of catechin or resveratrol nor activity of chitinase in berry skin.
Conversely, UV-C irradiation, alone or combined with chitosan treatment, induced catechin in
cv. Autumn Black berries and trans-resveratrol in both cv. Autumn Black and selection B36-55.
Abstract: Germination of Botrytis cinerea spores on potato dextrose agar after a 30 s immersion in 10 or 20% ethanol was 87 and
56%, respectively, compared to 99% among untreated controls. After similar immersion in 0.5 or 1.0% potassium sorbate, 84
and 68% of the spores germinated, respectively. Addition of 0.5 and 1.0% potassium sorbate to 10 and 20% ethanol solution
significantly increased the inhibition of spore germination. The germination of spores after 30 s immersion in 20% ethanol plus
0.5% potassium sorbate was 9.7%. The incidence of gray mold, caused by B. cinerea, on detached berries of ‘Flame Seedless’
grapes immersed for 30 s in water, 10 and 20% ethanol, and 0.5 or 1.0% potassium sorbate was 55.2, 42.1, 31.0, 37.7, or 24.4%,
respectively. Addition of 0.5 and 1.0% potassium sorbate to 10 and 20% ethanol reduced decay to 10% or less and was more
effective than either alone. After 30 days of storage at 1 â—¦C, the combination of 20% ethanol either with 0.5 or 1.0% potassium
sorbate was equal in efficacy to commercial SO2 generator pads in reducing the incidence of gray mold on ‘Thompson Seedless’
grapes. None of the combinations of ethanol and potassium sorbate injured the berries.
Abstract: To collect information on the incidence of Verticillium
wilt of olive in Apulia (southern Italy), about 6,000
woody samples from 1,390 young and old olive orchards
were analysed. Moreover, 565 soil samples from
commercial orchards and nurseries located all over
Apulia region were tested for the presence of V. dahliae
microsclerotia. Verticillium wilt was found in the 18%
of the surveyed orchards, mainly in seaside-located intensive
plantations, which are usually intercropped with
vegetables susceptible to V. dahliae. However, the disease
was also found in young plantations established on
soil which resulted free of the pathogen, thus indicating
a role of the propagating material in the spread of the
disease. On the whole, 16% of surveyed fields and 50%
of nurseries were contaminated by the pathogen. Overall,
the results suggest that preventive diagnostic tests of
leafy cuttings, soil and soil mix are mandatory to obtain
V. dahliae-free propagative material to limit the spread
of the disease. The analysis of more than 60 V. dahliae
isolates by RAPD-PCR technique indicated a low level
of genetic diversity in the Apulian population of the
pathogen from infected olive trees. A distinct cluster including
few isolates was found, but no correlation could
be established among the isolates and olive cultivars and
location. Molecular tests to characterize the pathotype
of V. dahliae from infected trees indicated that all the
isolates belong to the non-defoliating pathotype, except
one for which the results were not conclusive.
Abstract: The effectiveness of chitosan and short hypobaric treatments, alone or in combination, to control storage decay of
sweet cherries, was investigated over 2 years. In single treatments, chitosan was applied by postharvest dipping or
preharvest spraying at 0.1, 0.5, and 1.0% concentrations; hypobaric treatments at 0.50 and 0.25 atm were applied for 4
h. In combined treatments, sweet cherries were dipped in 1.0% chitosan and then exposed to 0.50 and 0.25 atm, or
sprayed with chitosan (0.1, 0.5, and 1.0%) 7 days before harvest and exposed to 0.50 atm soon after harvest. Untreated
sweet cherries kept at normal pressure (near 1.00 atm) were used as controls. Rot incidence was evaluated after 14 days
storage at 09/1 8C, followed by a 7 day shelf life. In both years, chitosan and hypobaric treatments applied alone
significantly reduced brown rot, grey mould, and total rots, the latter also including blue mould, Alternaria, Rhizopus
and green rots. A combined treatment with 1.0% chitosan and 0.50 atm was the best in controlling decay, showing in
the first year, a synergistic effect in the reduction of brown rot and total rots. The results indicate that the combination
of hypobaric and chitosan treatments is a valid strategy for increasing the effectiveness of the treatments in controlling
postharvest decay of sweet cherries.
Abstract: The effectiveness of pre- and postharvest treatments with chitosan (0.1, 0.5, and 1.0%) to control Botrytis
cinerea on table grapes was investigated. In postharvest treatments, small bunches dipped in chitosan solutions and
inoculated with the pathogen showed a reduction of incidence, severity, and nesting of grey mold, in comparison
with the control. Single berries artificially wounded, treated with the polymer, and inoculated with B. cinerea
showed a reduced percentage of infected berries and lesion dia. Higher chitosan concentrations demonstrated
greater decay reduction. All preharvest treatments significantly reduced the incidence of grey mold, as compared to
the control. Table grapes treated with 1.0% chitosan showed a significant increase of phenylalanine ammonia-lyase
(PAL) activity. Consequently, besides a direct activity against B. cinerea, chitosan produces other effects contributing
to reduce decay.
Abstract: The effectiveness of short hypobaric treatments against postharvest rots was investigated by exposing sweet
cherries, strawberries and table grapes to sub-atmospheric pressures (0.25, 0.50, and 0.75 atm) for different times
(from 1 to 24 h). Postharvest rots of sweet cherries and strawberries arose from natural infections, whereas small table
grape bunches and artificially wounded single berries were inoculated with Botrytis cinerea after hypobaric treatment.
Sweet cherries exposed to 0.50 atm for 4 h had the lowest incidence of gray mould, brown rot and total rots, while
a 1 h treatment was not effective. On strawberries, the greatest reductions of gray mould and Rhizopus rot were
observed on fruits treated for 4 h at 0.25 and 0.50 atm, respectively. On table grape bunches treatment with 0.25 atm
applied for 24 h significantly reduced the incidence of gray mould. In experiments performed with artificially wounded
single table grape berries exposed to 0.50 atm for 24 h and then inoculated, the percentage of infected fruits and the
diameter of the lesions were significantly reduced, in comparison with the controls. As a sub-atmospheric pressure of
0.25 atm did not affect radial growth of B. cinerea and Monilinia laxa, induced resistance was likely to be responsible
for the observed reduction in decay.
Abstract: Table grapes, strawberries and sweet cherries are perishable fruits and can be affected by different diseases, both in the field and even more during postharvest storage. The main decay is gray mold (caused by Botrytis cinerea), which infects all three fruit, and Rhizopus rot (induced by Rhizopus stolonifer), which attacks mainly strawberry, at times sweet cherries, and rarely table grapes. Moreover, sweet cherries can suffer heavy losses mainly by brown rot (due to Monilinia spp.), and to a lesser extent, by blue mold (caused by Penicillium expansum, at times this can infect table grapes and strawberries, too), Alternaria rot, and Cladosporium rot (induced by Alternaria alternata and Cladosporium spp., respectively). Table grapes, strawberries and sweet cherries are often cold stored at 0°C soon after harvest, to retain quality, delay senescence, and reduce decay development. In several countries the use of synthetic fungicides after harvest is not allowed or there is a very short list of approved active ingredients. Therefore, together with consumer demand for food free of pesticide residues, the use of alternative means to control postharvest decay of fruit has gained increasing interest. Among these, chitosan has been identified as having the properties of an ideal coating for fruit. Preharvest and postharvest chitosan treatments of table grapes, strawberries and sweet cherries reduce their decay in the field and during storage, with the best performance at the highest tested concentration (usually 1%). Chitosan-based commercial products are available, and they have shown the same effectiveness as the biopolymer dissolved in an acid solution. Chitosan has a double mechanism of action: it reduces the growth of decay causing fungi, and it induces resistance responses in host tissues. With this double effectiveness, chitosan can be considered as the first compound of a new class of plant protection products.
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