ACTIVITY OF NATURAL PRODUCTS AGAINST SOME PHYTOPATHOGENIC FUNGI.

The requirement of environmental protection and food safety is perceived with always major interest by public opinion and it is consistent with European Union legislation on the sustainable use of pesticides (Directive 2009/128/EC). This directive requires member states to promote low pesticide-input, giving priority to non-chemical methods and low risk plant protection products. In order to contribute to the achievement of these objectives antifungal activity of natural substances, characterized by a good toxicological and ecotoxicological profile, was tested. Essential oil of Melaleuca alternifolia, essential oil of Syzygium aromaticum and extract from Mimosa tenuiflora were tested against Alternaria alternata, Botrytis cinerea and Fusarium oxysporum f. sp. lycopersici (races 1 and 2). In vitro tests involved determination of radial growth of the colonies of fungi in the presence of varying concentrations of tested products in agar media and determination of germination percentage in the presence of tested product at various concentrations. The products based on essential oil of M. alternifolia were also tested in vivo on tomato fruits wounded and artificially inoculated with A. alternata or with B. cinerea. The in vitro tests showed the antifungal activity of both essential oils instead the extract from M. tenuiflora exhibited poor antifungal activity and only against A. alternata and B. cinerea. The results on tomato fruits showed inhibition of grey mould and black mould by essential oil of M. alternifolia. The antifungal activity increased with increasing concentrations. In conclusion, the obtained results in the present study showed promising prospects for the utilisation of investigated products to reduce the using of antifungal chemicals and to achieve a more sustainable use of pesticides.

Natural resistance against pre- and post-harvest pathogens in Sardinian pears germoplasm.

Natural resistance against Venturia pirina and Botrytis cinerea was investigated within the Sardinian pears germplasm. The natural occurrence of V. pirina was monitored at the orchard level for 5 years, while resistance against B. cinerea was evaluated by a bioassay using methanolic extracts of the fruit rind or by artificially inoculation. Methanolic extracts of the leaves were employed for the Cladosporium bioassay on TLC plates. Among the accessions, 8 resulted sensitive to V. pirina, vegetation and fruit are severely affected every year. Seven showed an intermediate behaviour and the sole vegetation was affected slightly in two out of the 5 years. Two inhibition spots, in the methanolic extract of the leaves, were clearly evidenced in 55 accessions and a positive correlation was found between the presence of these antifungal compounds in the leaves and the resistance to V. pirina in the field. The artificial inoculation of fruit with B. cinerea evidenced a great variability in resistance, with about 12 accessions that could be considered having a good resistance. The fruit rind methanolic extracts evidenced several inhibition spots in most accessions, but no correlation could be found with fruit resistance to B. cinerea. In addition, the activity of the polygalacturonase inhibiting protein (PGIP), determined with an agarose diffusion bioassay, indicate a positive correlation between the PGIP activity evidenced in the core tissue and the infection degree by B. cinerea.

Import risk analysis of fruit from Spain to Italy.

The International trade has to ensure food security and preserve both human health and the diffusion of animal and plant diseases among different countries. While organic horticultural production and trade are regulated by global guidelines, no specific restrictions relay to conventional commodities and almost free import-export occurs among UE countries. Consequently, the safety characteristics of imported fresh crops have become an important issue. On the basis of these considerations, the aim of the present study is to monitor the epiphytic microflora (particularly yeasts and fungi) carried by fresh fruit, imported from Spain to Italy. Particular attention was given to pathogenic microrganisms and to natural antagonists. In addition, the resistance to a few postharvest fungicides was determined for the isolated strains and compared to the local ones. Apples, Citrus fruits, stone fruits, and persimmon fruit were sampled at arrival of the container from Spain at the wholesale market in Sassari (Italy), this to prevent fruit contamination by local strains of microrganisms. The isolation was performed by rinsing and shaking (30 min at 100 rpm) the fruit in a beaker with 500 mL of sterile water. After concentration (7.5 mL), 100 microl of the rinse water was plated on potato dextrose agar (PDA). Isolation of pure colonies was performed by multiple streaking on plates, until unicellular cultures were obtained. Fifty three microrganisms, mainly fungi and yeasts, have been isolated and assayed in vitro and in vivo. Pathogenic behavior of isolated fungi was tested on fruits artificially wounded and only 7 strains out of 18 isolates caused decay. The resistance to different concentrations of imazalil (IMZ), tiabendazolo and azoxystrobin were tested in vitro for the pathogenic isolates. All isolates were completely inhibited with 1000 ppm IMZ evidencing that no resistant strains were present on the imported fruit. Since the baseline resistance, found for all isolates, was similar to the indigenous strains, we may conclude from this risk analysis that the import of the studied fruits produced in the 4 geographical areas of Spain does not increase the local baseline resistance.

Effect of acetic acid repeated treatments on post-harvest quality of "Taloppo" table grape.

The most important pathogen for table grapes is Botrytis cinerea which causes a rapid deterioration of fruit. Postharvest losses are controlled with SO2 fumigations carried out every 7 or 10 days, but the use of this gas is becoming more difficult to justify because of undesirable effects on the fruit and the increasing concern for human health. Acetic acid, classified as a GRAS compound, can be employed with no restriction as preservative and represents a possible substitute to sulphur dioxide. The aims of the present work were: (1) to evaluate if repeated treatments with AAC during storage preserve table grapes fruit quality; (2) to verify the effectiveness of 3 different concentrations and time intervals between each treatment and compare the effects with SO2 treatment; The amounts of AAC used in each fumigation, performed for 15 minutes, were 30, 50 and 75 microL/L, and treatments were carried out 5, 3 and 2 times respectively during storage, in order to have the same final concentration (150 microL/L). Table grapes were also fumigated with SO2. Fruit was stored for 8 weeks at 5 degrees C and 95% of RH, followed by 4 days of a simulated shelf-life (SSL) at 20 degrees C and 85% RH. At the end of experiment decay, weight loss and visual assessment were evaluated. After eight weeks of storage the incidence of grey mould, with respect to untreated fruit, was reduced in all treatments. The comparison among the different treatments did not show significant differences between the fumigations performed 3 and 2 times, with 24.9% and 27.2% of rots respectively. A better decay control was achieved with 5 fumigations carried out every 2 weeks, (18.1% of rots), while decay in fruit treated with SO2 was 26.2%. During the SSL period no particular differences were observed among all treatments. None of the treatments affected weight loss, as well as no differences were found in the score attributed for the external quality (rachis browning and berries appearance). The results showed that a good control of grey mould could be achieved on table grapes by repeated fumigations during storage. AAC could be a promising compound to be used as alternative to SO2 in keeping fruit quality.

Ultrasound application for the control of decay on apple at different stage of ripening.

Ultrasonic technology is known for many years and is used for several purposes such as sonochemistry, extraction of natural compounds, degassing of solvent, inactivation of enzymes and microorganism. In postharvest ultrasound is applied in not destructive analysis of crop for the determination of the maturation stage. Until now, however, the potential of the sonication as a physical mean for not conventional postharvest treatment of fresh fruit has been little investigated. Here we report on the results obtained with apple fruit (Malus domestica Borkh. cv San Giovanni, from Sardinian germplasm) dipped in a solution of potassium sorbate with or without sonication. Treatment was carried out with an ultrasonic processor (1500 W, 20Khz) connected to a 25 mm phi probe immersed in 10 L of deionized water placed in a steel vessel. Fruit at different ripening stages, inoculated or not inoculated with Penicillium expansum, was sonicated before or after the inoculation. Following the treatment, fruit was left to dry, put into boxes and cold-stored. Results showed that ultrasound alone enhanced the natural resistance of ripe fruit when inoculated after sonication. No effect was observed when the ultrasound application was carried out after inoculation with P. expansum on un-ripe or ripe apples. Potassium sorbate showed to be ineffective in controlling the decay regardless of the ripening stage and the time of inoculation. On the contrary, a significant enhance in decay control was observed when the application of potassium sorbate was performed in the presence of ultrasound.

Alternative methods to control postharvest decay caused by Penicillium expansum in plums (Prunus domestica L.).

In the latest years, investigation on postharvest treatments has been increasingly addressed to preserve human health and environment safeguard. Several preservative compounds, physical treatments and biological control agents to restrain postharvest pathogens on horticultural products have been widely studied. Among them potassium sorbate (KS) has been generally recognized as safe for use in foods and personal care products. It acts as microbial growth inhibitor and fungistatic agent in foods, including vegetable and fruit products. The efficacy of KS, used alone or combined with heat treatments or biocontrol agents, has been demonstrated in Citrus and stone fruits. Here we report the results of 3 experiments aimed at controlling Penicillium expansum Link decay with the use of KS on a yellow ('Shiro') and a red ('Sanguigna di Bosa II', from the Sardinian germplasm) plum cultivar. An integrated approach, combining ultrasounds (US) as a physical mean and KS solutions at different concentrations, has been employed. In the first experiment, 360 fruits were wounded twice and divided into 6 sets (6 x 60), three of which were inoculated with an isolate of P. expansum (20 microl of a 10(5) cfu x mL(-1)). Then, 180 fruit (half inoculated) were treated by pipetting into each wound 20 microl of a KS solution containing 0, 1.5 or 3% (w/v), respectively. In exp. 2, all fruit (number) was wounded and inoculated, and after 24 h treated by immersion (1 min) into solutions containing 0, 1.5 or 3% (w/v) of SK, with or without the use of US. In exp. 3, wounded fruits were treated by immersion or sonication like in exp. 2, while inoculation took place after 24 h. Then, plums were kept at 25 degrees C and 75-80% RH and the infection degree was monitored after 3 and 6 days. In both cultivars, the 1.5% KS solution significantly reduced the natural infection, while the 3% KS solution resulted effective only on the red one. Moreover, the 1.5% solution was effective in controlling decay of artificially inoculated fruit, achieving a 56% reduction compared to control. Similar results were attained in exp. 2 and 3, where the combination of salt and sonication improved the efficacy, likely by increasing the salt diffusion into the wounds.

Postharvest physio-pathological disorders in table grapes as affected by UV-C light.

To gain knowledge on the influence of postharvest treatments with ultraviolet-C light upon the keeping quality of table grapes, a trail was performed employing commercially mature 'Corina', 'Dawn Seedless', 'Centennial Seedless' and 'Gran Perlon' grape cultivars (cvs). After grading, bunches were subjected to 0.0, 0.5, 1.5 or 3 kJm(-2) and then stored at 5 degrees C and 90% relative humidity (RH) for 6 weeks followed by a 2 day shelf-life at 25 degrees C and 70% RH. A weekly inspection was performed and a visual evaluation of the appearance, treatment damage, stems browning and berry shrivelling was performed. Weight loss, decay and shatter were quantified at the end of storage and shelf-life. Regardless the cv and UV-C dose, fruit appearance was acceptable until the end of storage and shelf-life. Among the cvs, the highest score was held by 'G. Perlon'. After the fourth week of storage, the berries of 'Centennial S.' turned light brown and darkened over time when treated with 3.0 kJm(-2). Stem browning was not induced by the light treatment, but resulted cv depended and was pronounced for 'Centennial S.' and 'Dawn S.'. Berry shrivelling was insignificant, while shatter was very high in 'Corina' and did not depend upon UV-C treatment. Regarding weight loss, differences could not be attributed to the light treatment and after storage it ranged from 3 up to 5%. Decay was significantly reduced by light treatment and the efficacy increased by raising the dose. Botrytis cinerea was the main cause of decay with 'Corina' being the most jeopardized, followed by 'Dawn S.' and 'Centennial S.', whereas 'G. Perlon' resulted the less affected. In conclusion, hormetic effects of postharvest light treatment on table grapes were observed in almost all cvs with 'G. Perlon' having the best performance.

In vitro studies on the effect of some chemicals on the growth and sporification of Penicillium expansum and Botrytis cinerea.

Penicillium expansum and Botrytis cinerea are among the pathogens most frequently affecting apples and grapes after harvest, respectively. We studied the behaviour of these moulds when subjected to different concentrations of methanol (MeOH) and dimethyl sulfoxide (DMSO) as a alternative method to fungicides in controlling postharvest decay of horticultural products. The experiments were performed with 5 cm Petri dishes containing PDA amended with 0, 5, 10, 20, 30, 40 or 50 microL/mL of the two tested chemicals. Freshly prepared conidia of B. cinerea and P. expansum were sown onto the media and then kept into an incubation chamber at 21 degrees C up to 3 and 6 days, respectively. Daily, the colony forming units (cfu), the colony diameter and the degree of sporification were monitored. Compared to the control, both chemicals affected the growth rate of the two pathogens. The P. expansum and B. cinerea cfu value was not significantly inhibited but the colony diameter and the sporification degree decreased when concentration was raised. B. cinerea cultured on DMSO showed a significant drop of sporification up to the tested concentration of 10 microL/mL, and a complete inhibition of cfu when the concentration was higher than 20 microL/mL.

Influence of curing times on the effectiveness of treatments with acetic acid on the control of P. digitatum on lemons.

The restricted number of postharvest fungicides used in packing houses is leading to the selection of resistant strains of Penicillium digitatum (citrus green mould), one of the most common and serious pathogens during storage and marketing of lemons. Furthermore a growing concern for human health and a greater awareness for environmental conservation have multiplied the studies on new ecological technologies. Among the alternatives to synthetic postharvest fungicides, the use of acetic acid (classified as GRAS) together with a physical method such as curing, have led to encouraging results. In the present study is reported the combined use of curing, performed at reduced times compared to those reported to be effective, followed by acetic acid (AAC) treatments. Lemons of the variety "Limone di Massa" artificially inoculated with P. digitatum at a concentration of 10(4) spores/mL were cured for 0, 3, 6, 12 and 24 hours and then treated with three different concentrations of AAC (25, 50 and 75 microL/L) for 15 min. Fruit was then stored at 20 degrees C and 80% relative humidity (RH) for 9 days, when the number of decayed fruits was monitored. The same combined treatments were also carried out on naturally infected lemons, stored for 6 or 8 weeks at 5 degrees C and 90% RH. After 9 days of storage the lowest percentage of infected wounds, in artificially inoculated fruit, was 0% after 6 hours of curing followed by AAC fumigation performed at 50 microL/L, while lemons untreated or cured for three hours showed the worst results with 71.4 and 61.9% of rotted fruit respectively. In naturally infected lemons the best results were achieved with curing performed for 24 hours followed by AAC fumigation at 50 microL/L. In these cases the combined treatment reduced decay by the 91.0 and 66.5% after 6 or 8 weeks of storage respectively, if compared to untreated fruit. The weight loss was not affected by any of the treatments. These results show that a good control of green mould during storage could be achieved, on lemon fruit, by combining a reduced curing time of 24 hours to the effect of AAC. The best results were obtained after 6 week of storage even if a satisfactory control was observed after 8 weeks of storage.

Sequential application of NaHCO3, CaCl2 and Candida oleophila (isolate 13L) affects significantly Penicillum expansum growth and the infection degree in apples.

The employment of biocontrol agents to restrain postharvest pathogens is an encouraging approach, although, efficacy and consistency are still below those of synthetic pesticides. Up to date, the 'integrated control strategy' seems to be the most promising way to overcome this gap. Here, we report the feasibility to control postharvest decay caused by Penicillium expansum in apples by a 2 min, single or sequential, immersion in water with an antagonistic yeast (Candida oleophila, isolate '13L'), 2% NaHCO3 (SBC) or 1% CaCl2. The treatments were carried out, on appels cv 'Miali' either un-wounded, wounded or wound-pathogen inoculated and then stored at 2 degrees C for 30 d followed by a 6 d simulated marketing period at 20 degrees C or alternatively stored only for 7 d at 20 degrees C. As a general role, the best results were attained when CaCl2 was applied with the yeast or when preceded by the SBC treatment. When the wounding and inoculation took place 24 h before the treatment, the latter application sequence of the two salts was three times more effective compared to the treatment with the sole antagonist, and one time when performed 24 h after the treatment. Interestingly, apples immersed in the sole 2% SBC solution had the highest percentage of decay during storage and when inoculated before moving to the simulated marketing period at 20 degrees C.

Synergic interactions between 2-deoxy-D-glucose and Candida saitoana enhances citrus green mould control.

The activity of 2-deoxy-D-gLucose (2-DG) alone or in combination with a biocontrol yeast (Candida saitoana, strain 8C) was evaluated in vitro and in vivo against citrus green mould (Penicillium digitatum Sacc.). The in vitro assays were performed on amended potato dextrose agar (PDA) containing 0, 1.5, 3.0, 6.0, 15.0, 30.0 or 60.0 mM of 2-DG. P. digitatum conidia were sown on the amended media and growth inhibition occurred starting from 6.0 mM. A nearly total inhibition of the growth and spore germination occurred with 60.0 mM of 2-DG. The antagonist was not affected by any of the 2-DG concentrations employed and the amended plates resulted well colonized within 2 d post-treatment. In vivo assays were carried out with 'Hamlin' oranges, inoculated with P. digitatum 24 h before treating with: the antagonist; the above reported concentrations of 2-DG, or by combining the two treatments. Seven days post-treatment the inhibition activity exerted by 3.0, 6.0, 15.0, 30.0 and 60.0 mM of 2-DG combined with the yeast was 15, 37, 42, 63 and 84%, respectively. While that exerted by the antagonist was 22% and that by the different concentrations of 2-DG were 7, 11, 27, 42 and 57%, respectively. Compared to single treatments, the co-application significantly and in a synergic mode improved the control of decay. Alterations to the hyphae were observed by SEM when the pathogen was cultured on amended media and into the wounds of inoculated oranges.

In vitro studies on the effect of some chemicals on the growth and sporification of Penicillium digitatum and P. italicum.

The behaviour of Penicillium digitatum and P. italicum was investigated when subjected to different concentrations of methanol (MeOH) and dimethyl sulfoxide (DMSO). The experiments were performed in 9 cm Petri dishes containing PDA amended with 0, 5, 10, 20, 30, 40 or 50 microL/mL of each of the single or combined chemicals. Daily, the formed colonies (cfu), the colony diameter and the degree of sporification were monitored during incubation at 20 degrees C for 5 day. Additionally, the pathogen development and its performance were studied by scanning electron microscopy (SEM). According to the chemical, the mycelium growth rate was affected differently and, compared to the control, only MeOH inhibited the expansion of the colony diameter. This effect was more pronounced for P. italicum. A nearly linear drop of cfu was observed as the concentration of the two chemicals was raised, and a complete inhibition of the two pathogens was attained with 50 microL/mL MeOH. With respect to the sporification degree the two pathogens were influenced similarly, but the tested compounds had opposite effects. Indeed, with MeOH, sporification took place earlier (24-36 h postinoculation) compared to the control (60 h), while during the whole experiment, DMSO at concentrations higher than 0.5 microL/mL, drastically inhibited the sporification. SEM observations of P. digitatum growth on DMSO amended media evidenced a marked increase of mycelium branching and alterations to the conidiophore, while MeOH reduced the mycelium length and fastened the conidiophore formation. The combination of the two compounds produced a synergistic interaction reducing by 40% the concentration required to inhibit completely the germination and growth of P. digitatum.

Immersion of 'Coscia' pear fruit in water at 55 degrees C for 60 sec controls Penicillium expansum decay and delays ripening during short storage.

'Coscia' is an early ripening pear with a short postharvest Life (1 month) and chemical treatments to prevent decay are generally not undertaken. This, along with the fast deterioration under shelf-life conditions, makes it difficult to contain postharvest moulds. 1-methylcyclopropene (1-MCP) has been employed with success to delay ripening and, as a co-effect, the development of decay was contained, but this treatment is not allowed for organically grown crops. Here we report the results of an alternative approach employing immersion treatments in water at 45, 50, 55 or 60 degrees C for 0 (control), 15, 30, 45 or 60 sec. Fruit was harvested after the climacteric peak, immediately subjected to the heat treatment and stored for 2 weeks at 1 degrees C followed by a 3 days of a simulated shelf-life at 17 degrees C and 75% RH. Half of the fruit was wounded (3 x 3mm) and inoculated with Penicillium expansum (20 microL of 10(4) conidia mL(-1). Decay inhibition and fruit appearance, rated from 0 to 3 (0 = excellent; 1 = good; 2 = scarce; 3 = not marketable), were monitored and compared to the control after storage and shelf-life. All heat treatments affected the mould development when performed for 45 or 60 sec. The best result in terms of decay control and appearance after storage and shelf-life occurred when fruit was immersed at 55 degrees C for 60 sec with a decay reduction of about 85% compared to control (75% decay) and with a good appearance.

Postharvest behaviour of two Sardinian apple varieties following immersion in heated sodium bicarbonate solution.

'Miali' and 'Caddina' are apple varieties of Sardinian germplasm, mainly produced under sustainable conditions. Fruit is rarely subjected to cold storage and postharvest losses are generally high. In order to prolong the marketing period and contain postharvest decay of these local varieties, we investigated on their storage behaviour and on the efficacy of combined alternative postharvest treatments. Pre-climateric fruit was harvested and immersed for 0 (control), 15, 30, 45 or 60 sec. in water at 20, 50, 55 or 60 degrees C with or without 2% (W/V) NaHCO3 (SBC). Then, fruit was stored for 4 months at 5 degrees C and 90% RH followed by a 6 day simulated marketing period (SMP) at 10 degrees C and 75% RH. Decay was monitored at the end of storage and after the SMP, while appearance and physiological disorders were evaluated after SMP. During storage 56 and 62% of the untreated 'Caddina' and 'Miali' apples rotted, respectively. During the SMP, an additional 3% of 'Caddina' and 5% of 'Miali' was lost. Among the treatments the best decay control, for both varieties, was attained when fruit was immersed in the SBC solution at 55 degrees C for 60 sec. Compared to control, decay was reduced by 91 and 95% for 'Caddina' and 'Miali', respectively. This combination induced some rind damage, mainly on 'Caddina' fruit. Superficial scald was evident on 'Caddina' and scored as medium while, cold storage induced a significant deposition of epicuticular wax in 'Miali' fruit, affecting significantly fruit appearance. A significant reduction of decay was also achieved when fruit was immersed at 60 degrees C for 30 or 45 sec., attaining for 'Caddina' a reduction of 82 and 88% of decay, respectively. Other combinations were lesser effective or produced rind damages and most decay was caused by Penicillium expansum.

Postharvest behaviour of five Sardinian prune varieties as affected by immersion in heated sodium bicarbonate solution.

Storage behaviour of 'Core', 'Core Columbu', 'Fradis' and 'Meloni' white prunes, and a black one ('Sighera') of Sardinian germplasm were evaluated following immersion for 0 (control), 15, 30, 45 or 60 sec in water at 20, 50, 55 or 60 degrees C with or without 2% (w/v) NaHCO3 (SBC). As international varieties, fruit from one white plum ('Shiro') and one black prune ('Stanly') were subjected to the same treatments. Fruit was harvested at commercial maturity, treated and then stored for 1 month at 5 degrees C and 90% RH followed by a simulated marketing period at 20 degrees C and 80% RH for 6 days. Fruit appearance, external damage, firmness and decay percentage were monitored after storage and SMP. Treatments did not induce rind damage (browning or discoloration) to any variety. SBC at 20, 45, 50 or 55 degrees C for 15 or 30 sec was not effective in controlling decay and compared to controls no improvement was observed. Immersion for 45 or 60 sec with SBC at all temperatures improved decay control with respect to controls and best results were obtained at 50 or 55 degrees C. Immersions at 60 degrees C improved decay control, but differences were not significant compared to the control attained with solutions of SBC heated at 55 degrees C. The overall appearance of 'Core', 'Core Columbu', 'Fradis' and 'Shiro' decreased significantly after the SMP period, especially when treated at 55 or 60 degrees C for 60 sec. Fruit shrivel was the main cause of the low rating. SBC did not affect shrivel indicating that heat treatment may be the probable cause. In general, local varieties were less affected by decay than other varieties and they performed well during storage.

Treatments with acetic acid followed by curing reduce postharvest decay on Citrus fruit.

Citrus fruit are susceptible to many postharvest diseases and disorders, but Penicillium digitatum and Penicillium italicum are the most common and serious pathogens during storage and marketing. The continuous employ in packing houses of synthetic fungicides such as imazalil (IMZ) or thiabendazote for the control of these pathogens is promoting the selection of resistant biotypes. These considerations together with an increased attention for human health and the environment have multiplied the studies on new ecological technologies. In recent years researchers studies focused on alternatives to the chemical control of post-harvest decay, such as the utilization of GRAS compounds as well as physical methods. In the present study is reported the sequential use of acetic acid (AAC) followed by curing. The lemon variety "Verna" and the orange variety "Jaffa", naturally inoculated, were treated with vapours of AAC performed at three different concentration (15, 25 and 50 microL/L) for 15 minutes, after an incubation period of 24 hours at 27 degrees C and 90% relative humidity (RH). After treatments fruits were cured at 36 degrees C for 36 hours with 90% RH and subsequently stored at 8 degrees C and 90% of RH for eight weeks. Both citrus varieties were also treated with IMZ at a concentration of 200 mL/HL. At the end of the experiment decay and weight loss were evaluated. After 8 weeks of storage, in the lemon variety, the lowest percentage of infected wounds was 1.5% for both the fruit treated with IMZ or with AAC at 25 microL/L. Fruit treated with 15 mciroL/L or untreated (control) showed similar results with 13.6% and 16.6% of rotted fruit respectively. Different results were obtained with the orange variety, in this case the synthetic fungicide was the most effective at the end of the storage period, with 18.0% of decay. AAC treatments were not a successful as on lemons, the best result was achieved even in this case with AAC performed at 25 pL/L, but with 39.9% of decay. In both species the weight loss was not affected by the treatments. These results show that a good control of postharvest decay could be achieved, on lemon fruit, by combining the effect of a GRAS compound such as AAC with curing. Conversely the results obtained, by applying this control method to the orange variety were not so promising. Further researches are needed to shed light on the different behaviour between the two species.

Acetic acid treatments to keep postharvest quality of "Regina" and "Taloppo" table grapes.

The most important postharvest pathogen for table grape is Botrytis cinerea (gray mold), which cause a rapid deterioration of fruit. An effective control of the disease during storage is difficult and remains an unsolved problem since no pesticide treatments are allowed by European legislation. GRAS compounds, employed with no restriction as preservatives in Europe and North America, are possible candidates to fulfil this gap. The aim of this work is to study the efficacy of Acetic Acid (AAC), used as postharvest treatment to control Botrytis cinerea on "Regina" and "Taloppo" table grapes, by Laboratory and storage tests. The activity of this compound was first assessed with laboratory tests, treating at different concentrations (0, 5, 10, 20, 50, 75 and 100 microl/L) of AAC vapors, for 15 minutes, single berries inoculated with B. cinerea. After treatments fruit was incubated at 20 degrees C for one week. The in vivo experiment took place by using the most promising AAC concentrations (50, 75 and 100 microl/L) followed by eight weeks of storage at 5 degrees C and 95% of relative humidity (RH) and four days at 20 degrees C and 85% RH (simulated shelf-life conditions). At the end of the in vivo experiment decay, weight loss and visual assessment were evaluated. Almost all treatments, after eight weeks of storage, reduced the incidence of gray mould. The best results were achieved by using 50 ppm of AAC, gaining a reduction of decay, compared to untreated "Taloppo" and "Regina" grapes of 61.0% and 41.4%, respectively. Following the simulated shelf-life period differences between treated and untreated (control) became no significant for "Taloppo" grape, while the lowest decay percentage was reached with 50 microl/L of AAC for "Regina" grape (52% of reduction if compared to control). Regarding fruit weight loss all treatments did not affect significantly this parameter that ranged between 8.2% and 11.5% after eight weeks of storage and 13.5% and 18.2% after shelf-life. At the end of storage the highest visual score was attributed to fruit treated with 50 microl/L of AAC evidencing a clear better keeping quality. During this period slight treatment damages were observed on berries following application of AAC at 75 and 100 microl/L. The reported results obtained with these experiments showed that Acetic Acid could be a promising compound to be used as alternative to SO2 in keeping grapes quality and controlling decay during storage.

Induction of phytoalexins biosynthesis in orange fruit by the biocontrol yeast Rhodotorula glutinis.

The biocontrol yeast Rhodotorula glutinis, isolate 21A, obtained from tomato fruit was used to control Penicillium digitatum, P. italicum and Botrytis cinerea on artificially wounded citrus fruit. Orange and satsuma mandarin fruit were treated with the biocontrol yeast, inoculated with the pathogens and stored for 7 days at 23 degrees C. On orange fruit the antagonist compared to the control reduced decay by 92.2, 88.4 and 96.2% for P. digitatum, P. italicum and B. cinerea, respectively. On satsuma mandarin fruit the same pathogens were inhibited by 96.2, 91.2 and 90.0%, respectively. Scanning electron microscope observations, focusing on the antagonist-pathogen interactions, revealed a fast colonization of the growing fungal mycelia by the yeast cells, but no sign of lytic activity on hyphae was observed. Moreover, the fruit accumulated the phytoalexins scoparone and scopoletin into artificial wounds previously treated by the yeast and either inoculated or uninoculated with the pathogen. The concentration of scoparone, which showed higher accumulation in fruit tissues, varied significantly in relation to the time lag between the application of the antagonist and the inoculation with the pathogen. In particular, the concentration of scoparone 4 days after application of the sole yeast was 69.0 microg x g(-1) fresh weight (FW), 6.3 times higher than in the uninoculated wounded tissues (11.0 microg x g(-1) FW). The phytoalexin accumulation was low (13.0 microg x g(-1)FW) applying the yeast jointly with P. digitatum into wounds, while it increased consistently (74.0 microg x g(-1)FW) when the antagonist was applied 24 h before the pathogen.

Postharvest decay reduction of fig fruit (Ficus carica) by hot water sodium carbonate solutions dip.

Treatments as hot water dips or high temperature conditioning have been proven to be effective to control postharvest decay on various horticultural crops. These treatments reduce chilling injury and rot losses without causing detrimental effects on fruit firmness, flavour, taste or peel appearance. These technologies, aimed to control postharvest pathogens, can be easily matched with the use of "Generally Recognized as Safe" (G.R.A.S.) compounds and employed alternatively to pesticides, known to be harmful to health and environment. In this respect we studied the combined effect of sodium carbonate (SC) and hot water on the storability of black fig fruit cultivar 'Niedda Longa' of Sardinian germplasm. Second crop fig fruit, harvested in the middle of September, was dipped for one minute in water solutions containing 0, 0.05, 0.5, and 1% (w/v) of SC at 25 or 60 degrees C and then stored at 5 degrees C and 90% relative humidity (RH) for two weeks. After one and two weeks of storage decay, weight loss were monitored and visual assessment was scored. Treatments with hot solutions were more effective in controlling decay compared to cold ones and the best results were achieved with 0.5% of SC at 60 degrees C. This combination reduced the decay rate from 26% (control) to 0% after 1 week and from 50% to 14% after two weeks of storage, respectively. Lower or higher SC concentrations applied at 60 degrees C were less effective and, after two weeks of storage, decay percentages were 38 and 43.6%, respectively. Water dip at 60 degrees C did not affect the weight loss as compared to dips at 25 degrees C either after one or two weeks of storage. At the same time, a significant reduction was found only with 1% of SC at 25 degrees C. The fruit treated with 0.5% of SC at 60 degrees C also had the best visual assessment up to two weeks of storage.

Inhibitory activity of 2-deoxy-D-glucose and Candida saitoana against Penicillium digitatum.

The toxic activity of 2-deoxy-D-glucose (2-DG) alone or combined with the biocontrol yeast Candida saitoana strain 8C was evaluated in vitro and in vivo against the postharvest fungal pathogen Penicillium digitatum. In order to assess the effect of the 2-DG on both the biocontrol yeast and fungal pathogen, in vitro tests were performed in Petri dishes containing potato dextrose agar amended with different concentrations (1.5, 3.0, 6.0, 15.0, 30.0, 60.0 mM) of the sugar. The plates were then seeded with 25 microl of a P. digitatum conidial suspension at 10(5) conidia/mL. Result of the assays showed an enhanced inhibitory activity as concentration increased from 15.0 to 60.0 mM. Corroborated by SEM observations showing a reduced growth and the appearance of damaged hyphae were found. At 60 mM of 2-DG, a total inhibition occurred while concentrations from 1.5 to 6.0 mM resulted ineffective. The same tests evidenced no adverse effects on the yeast 8C at all tested concentrations. In vivo assays were carried out on orange fruit cv 'Biondo comune', wounded in 5 sites around the calyx. Each wound (2.5 wide and 3.4 mm depth) was first filled with 25 microl of a 0, 3.0, 6.0, 15.0, 30.0 or 60.0 mM 2-DG-water solution alone or combined with the yeast 8C at 10(8) cells/mL and then a 25 microl of the P. digitatum conidial suspension was added. Each treatment consisted of 3 replicates of 8 fruit (5 wounds/fruit) for a total 120 wounds per treatment. Oranges were maintained at 20 degrees C and high RH (95-98%) for up to 5 days, during which infection was monitored and the inhibitory activity calculated. The tests in vitro evedenced a significant slowing of the pathogen growth with the highest concentrations of 2-DG (15.0, 30.0 and 60.0 mM) with respect to the control; while at lower concentrations (1.5, 3.0, 6.0 mM) the development of the fungi was not significantly reduced. C. saitoana was resistant to all the doses employed to the abovementioned compound. In vivo the yeast alone was more effective compared to the sugar alone up to 6.0 mM while, at higher concentrations an additive effect was founded.