Cancro batterico dell’albicocco: dalla diagnosi alla difesa

Le infezioni di Pseudomonas syringae pv. su albicocco causano dapprima deprezzamento della produzione e successivamente il deperimento dell’intera pianta. Scelta varietale, materiale vivaistico sano e ambienti con limitata frequenza di gelate sono i principi alla base di una corretta prevenzione della malattia, mentre a oggi il rame resta l’unico agrofarmaco ammesso in grado di garantire effi cacia battericid

Respiratory symptoms in children living near busy roads and their relationship to vehicular traffic: results of an Italian multicenter study (SIDRIA 2)

BACKGROUND: Epidemiological studies have provided evidence that exposure to vehicular traffic increases the prevalence of respiratory symptoms and may exacerbate pre-existing asthma in children. Self-reported exposure to road traffic has been questioned as a reliable measurement of exposure to air pollutants. The aim of this study was to investigate whether there were specific effects of cars and trucks traffic on current asthma symptoms (i.e. wheezing) and cough or phlegm, and to examine the validity of self-reported traffic exposure. METHODS: The survey was conducted in 2002 in 12 centers in Northern, Center and Southern Italy, different in size, climate, latitude and level of urbanization. Standardized questionnaires filled in by parents were used to collect information on health outcomes and exposure to traffic among 33,632 6-7 and 13-14 years old children and adolescents. Three questions on traffic exposure were asked: the traffic in the zone of residence, the frequency of truck and of car traffic in the street of residence. The presence of a possible response bias for the self-reported traffic was evaluated using external validation (comparison with measurements of traffic flow in the city of Turin) and internal validations (matching by census block, in the cities of Turin, Milan and Rome). RESULTS: Overall traffic density was weakly associated with asthma symptoms but there was a stronger association with cough or phlegm (high traffic density OR = 1.24; 95% CI: 1.04, 1.49). Car and truck traffic were independently associated with cough or phlegm. The results of the external validation did not support the existence of a reporting bias for the observed associations, for all the self-reported traffic indicators examined. The internal validations showed that the observed association between traffic density in the zone of residence and respiratory symptoms did not appear to be explained by an over reporting of traffic by parents of symptomatic subjects. CONCLUSION: Children living in zones with intense traffic are at higher risk for respiratory effects. Since population characteristics are specific, the results of validation of studies on self-reported traffic exposure can not be generalized

First report of Colletotrichum grossum causing apple bitter rot worldwide (Italy)

Apple bitter rot is a globally widespread disease that is observed on bothpreharvest and postharvest fruits, contributing to considerable economiclosses. While the Colletotrichum acutatum species complex is predominantin Europe (Baroncelli et al. 2014; Amaral Carneiro and Baric 2021),in recent years, the Colletotrichum gloeosporioides species complex isemerging, raising many concerns (Amaral Carneiro et al. 2023). Circular,slightly sunken, brown lesions with acervuli produced in concentric spotswere observed on the cultivar Story Inored harvested in September2022 from an organic orchard in Masi (Padova Province, Italy), with adisease incidence close to 30%. Tissue samples were excised under asepticconditions from 10 surface-cleaned diseased fruits at the margin betweenhealthy and diseased pulp tissues, transferred to potato dextrose agar me-dium, and incubated in the dark at 25°C for 7 days, whereafter five single-spore cultures were obtained. Pure colonies grown at 25°C for 7 daysappeared light gray-white on the upper side with floccose aerial mycelium,whereas the reverse side was dark gray with a distinct margin. Conidia werehyaline, cylindrical in shape with both ends rounded or one end acute, andmeasured 16.6 ± 1.4 × 6.1 ± 0.5 μm (mean ± SD) (n = 50) as described byDiao et al. (2017). To identify the species, genomic DNA of a represen-tative isolate (C38) was extracted, and beta-tubulin (TUB2), calmodulin(CAL), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), glutaminesynthetase (GS), and Apn2-Mat1-2 intergenic spacer (ApnMat) genes andthe internal transcribed spacer (ITS) region were amplified by PCR andSanger sequenced (Rojas et al. 2010; Weir et al. 2012). The obtainedDNA sequences of TUB2, CAL, GAPDH, GS, ApnMat, and ITS weresubmitted to GenBank under the accession numbers OR025589, OR025586,OR025587, OR025588, OR025585, and OR004800, respectively.A MegaBLAST analysis resulted in 100% identity to the epitype CAUG7 ofColletotrichum grossum (Diao et al. 2017) for GAPDH (KP890159) andTUB2 (KP890171), 99.85% for CAL (KP890147), and 99.5% for ITS(KP890165). The phylogenetic tree constructed by concatenation withthe obtained sequences, as well as references, revealed that the isolateC38 clustered within C. grossum, confirming the BLAST approach.Pathogenicity tests were performed on 40 ‘Story Inored’ apples. The appleswere cleaned, wounded with a sterilized needle, and exposed to two differentconditions: 20 apples (10 inoculated with 20 μl of a spore suspension [104spores/ml] and 10 inoculated with sterile water as controls) were incubated at20°C with a 12-h photoperiod for 14 days, whereas the remaining 20 apples,prepared with the same approach, were placed at 1°C for 3 months and thenat room temperature for 14 days. Symptoms appeared after 6 days on applesincubated at 20°C, whereas those stored at 1°C displayed symptoms at11 days after being placed at room temperature. In both conditions, lesionswere similar to those observed on the original fruits, whereas the controlsremained asymptomatic. Identity of reisolated fungal colonies was confirmed byCAL, GAPDH, and GS region sequence analysis. C. grossum has been reportedrarely: in 2017 on Capsicum annuum var. grossum in China, in 2018 onMangifera indica leaves in Cuba, and in 2021 on Rhyncospermum jasminoidesin Italy (Diao et al. 2017; Guarnaccia et al. 2021; Manzano Le ́on et al. 2018). Tothe best of our knowledge, this is the first report of apple bitter rot caused byC. grossum worldwide

Equations for the distribution of Venturia inaequalis ascospores versus time during infection periods

Distribution of Venturia inaequalis ascospores versus time during an infection event was investigated by integrating in a dynamic simulation model the available knowledge on the biology of infection processes and the effect of environmental conditions. Processes of spore immigration on leaf surface, germination, appressorium formation, and successful infection establishment were incorporated into the model by elaborating mathematical equations depending on air temperature and length of the wet period. Survival of spores belonging to different development stages (ungerminated, germinated, with appressorium) was also included in the model as a function of temperature, relative humidity, and duration of wetness interruption. Based on comparison with previously published data the architecture of the model and its algorithms can be considered accurate and robust. Nevertheless, validation of model simulations under orchard conditions will be necessary before its use in management decisions

Influence of air temperature on the release of ascospores of Venturia inaequalis

The influence of air temperature on the release pattern of Venturia inaequalis ascospores was studied by volumetric spore samplers in two spore sampling periods. In the first period (1991-1996; Passo Segni, Ferrara), 15 ascospore dispersal events were considered occurring in daylight, with high spore counts (168-5892 ascospores per m3 air per event), at an average temperature between 8.4 and 20.3\ub0C. Both the length of the ascospore release period and distribution of airborne spores over time were significantly influenced by temperature. A logistic regression model was used to fit the proportion of ascospores trapped from the orchard air as a function of time after the beginning of the discharge event and air temperature. The accuracy of this equation was tested against data collected in the second spore sampling period (1997-2000; Sala Bolognese, Bologna, and Castelfranco, Modena); 16 dispersal events were considered, triggered by rainfall that occurred both in the dark and in daylight, with low to high spore counts (29-458 ascospores per m3 air per event), at an average temperature between 2.8 and 14.3\ub0C. There was a general agreement between the proportion of ascospores trapped from the orchard air during these events and that estimated by using the logistic equation - in most cases, actual and estimated values showed a high coincidence. Statistical comparison showed a significant correlation (r = 0.93, P < 0.01) between observed and estimated data

Weather conditions triggering ascosporedischarge in Venturia pirina

A 5-year study (2002-2006) was carried out in two pear orchards in northern Italy, by trapping air-borne ascospores of Venturia pirina. Characteristics of 155 ascospore discharge events (hour of the day, duration, ascospore number) and weather conditions of the hours preceding the beginning of the discharge (WD, wetness duration; R, rainfall; Tw, temperature during wetness) were analysed with the aim of better defining environmental conditions favouring ascospore discharge. Ascospore discharge showed a diurnal periodicity, with the 92% of total spores trapped in daylight. Thirty-seven percent of ascospore discharge events were triggered by rainfall, 55% by leaf wetness, while 8% occurred under dry conditions. The probability of ascospore discharge to occur was calculated using a logistic regression procedure with a stepwise selection of the independent variables. The variable \u2018WD 7 Tw\u2019 was selected as the most influential, while Tw, WD and R were not. The logistic equation provides the probability of an ascospore discharge to occur based on the combination of wetness duration and average temperature during the wet period preceding the beginning of the ascospore discharge. Probability was higher than 0.5 when \u2018WD 7 Tw\u2019 was higher than 197.5\ub0C 7h, while it was 0.9 when \u2018WD 7 Tw\u2019 was 585\ub0C 7h. This result showed that ascospore discharge in V. pirina is mainly influenced by wetness and temperature, while in V. inaequalis it depends mainly on rainfall. Calculation of the infection periods for controlling pear scab should take account of this difference

Virulence of Stemphylium vesicarium isolates from pear and other host species

Brown spot, caused by Stemphylium vesicarium, is one the most important pear disease in Europe. The disease is caused by fungal strains producing host-specific toxins which are responsible for the disease symptoms on some pear varieties. It is known that there is a high degree of differentiation in host specificity among the different isolates of S. vesicarium. Pathogenicity and virulence of 78 S. vesicarium strains obtained from pear and other host species were studied by a leaf necrosis assay on 3 pear varieties showing different susceptibility to natural brown spot epidemics. The bioassay was performed using conidial suspensions and autoclaved fungal culture filtrates. Strains of S. vesicarium showed high variability for both progress of necrotic spot appearance and final disease incidence. Four virulence groups were defined using a multivariate data analysis. Group I included 49 strains from pear, which caused severe necrosis on all the varieties. Group II included only 5 strains isolated from pear which caused severe necrosis on \u2018Abate F\ue9tel\u2019 and \u2018Conference\u2019, as the strains of group I did, but symptoms on \u2018William\u2019 were very light. In group III there were 19 strains from pear which showed less severe symptoms on all the varieties. Finally, group IV was formed by the S. vesicarium strains isolated from asparagus, pea, and onion, as well as the un-inoculated test. These fungal strains showed only small sporadic necrosis at the end of incubation

Prediction of Xanthomonas harboricola pv. pruni infection on peaches

X. arboricola pv. pruni (Xap) is present on Prunus spp. in some European countries, and it is listed as an A2 quarantine pest by EPPO; its importance in Northern Italy has increased in the last decade. An empiric model predicting Xap infection has been developed in late \u201890s. Occurrence of the first seasonal infection was monitored in peach orchards of Romagna, in 1992 to 2008, and compared to model predictions: an infection was predicted when there were at least 3 successive rainy days, with temperature between 14 and 19\ub0C; symptom\u2019s onset was expected after one to four weeks of incubation. Xap symptoms appeared in 10 out of 17 years; first seasonal symptoms become visible between 19 May and 12 July. These infections were always correctly predicted by the model, with an average incubation period of three weeks. Five infection periods were predicted by the model that did not result in actual infection. In five years the disease did not appear at all. In four of these years the model did not predict infection all season long, while in one year it wrongly predicted two possible infection periods. Sensitivity, specificity and accuracy of the model showed that one would have somewhat more confidence in predictions of non-infections than in predictions of infections. In a practical use of the model, this would lead to some unjustified alarms