Alternative technologies to control postharvest diseases of kiwifruit

The review deals with alternative technologies to conventional synthetic fungicides to control kiwifruit postharvest diseases. Prolonged and intensive use of these fungicides raises concerns regarding the safety of their residues in fruit and has caused the emergence of fungicide resistant pathogen strains. Alternative treatments were investigated, such as hot water, biological control agents (BCAs), and natural substances. Kiwifruit production is economically important in many parts of the world, but little is known about means of controlling its postharvest diseases. Many fungi cause postharvest rot of kiwifruit, and their occurrence varies among the production areas. Ripe-rot caused by Botryosphaeria dothidea and stem-end rot caused by Diaporthe actinidiae prevail in New Zealand, while stem-end rot caused by Botrytis cinerea is the most important postharvest disease of the kiwifruit cultivated in Europe and USA, while in these regions skin pitting by Cadophora luteo-olivacea and Mucor rot caused by Mucor piriformis are less important. In terms of control technique, curing, which is a delay between harvesting and cool storage of fruit, remains an important and safe tool to reduce postharvest losses, but improvements in it are needed. Innovative non-chemical treatments include hot water dipping (45°C for 10 min) for controlling several diseases which has received commercial attention. The application of BCA following curing for 96 h was demonstrated to be effective against B. cinerea. Some natural compounds controlled grey mould well in artificially and naturally infected fruit

Ripe indexes, hot water treatments, and biocontrol agents as synergistic combination to control apple bull’s eye rot

DA-meter hand-held instrument, hot water treatment (HWT) and biocontrol agents (BCAs) represent an alternative solution to synthetic fungicides. In the present study, the three strategies were combined to reduce Neofabraea vagabunda virulence on apple fruit cv ‘Cripps Pink’. In vitro assays were conducted by testing different heat treatment timing (10, 5, and 3 min at 45°C) influence on pathogen mycelial growth together with BCAs (Aureobasidium pullulans L1 and L8, and Trichoderma harzianum Th1). The combined activities of HWT 45°C × 5 min and both BCAs volatile and no-volatile compounds displayed the complete control of the pathogen. In vivo, DA-meter was used to measure the index of absorbance difference (IAD) of chlorophyll-α content on apple and to separate fruit into two different ripening classes, immediately wound inoculated with N. vagabunda conidial suspension, and treated with HW and BCAs. In vivo results showed how the combined action of HW and BCAs completely inhibited the pathogen. Also, the less ripe apple class showed a decrease of fungal incidence by 16.2% with respect to the riper class. At harvest and after four months of storage at 0°C, quality parameters of both apple classes heat treated and untreated, such as firmness (FF), soluble solid contents (SSC), and pH were measured without showing any substantial differences. Obtained results open new perspectives on organic apple productions

First identification of Venturia asperata from atypical scab-like symptoms in Italian apple orchards

Atypical scab symptoms were reported for the first time at the end of July in 2012 in Northern Italy (Cesena province, Emilia Romagna region) on fruit apple cultivar CIVG198 Mod\uec\uae carrying the Rvi6 (=Vf) major resistance gene to Venturia inaequalis; it is a hybrid of \u2018Gala\u2019 x \u2018Liberty\u2019 with more than half the total world production area of cv \u2018Mod\uec\u2019 located in Italy. The symptoms were also established in all the following years and Venturia asperata was identified as a causal agent of these atypical scab symptoms through morphological studies and molecular analysis of conidia from fruits and ascospores from overwintered leaves, using specific primers for V. asperata, V. inaequalis and V. pirina. Pathogenicity tests carried out on fruit at different phenological stages showed only light symptoms. Venturia asperata could represent an emergent disease for cv \u2018Mod\uec\u2019 and disease control may be necessary

Influence of harvest date on Bull's eye rot of 'Cripps Pink' apple and control chemical strategies

The influence of four different harvest times on the bull\u2019s eye rot of \u2018Cripps Pink\u2019 apple caused by Neofabraea spp. was investigated in two orchards harvested at four different times. In addition, a control strategy based on chemical treatments performed in preharvest or postharvest was evaluated. Regression analysis between harvest time and disease incidence revealed high r2 values (>0.75). All preharvest fungicide treatments significantly (P < 0.0085) reduced the bull\u2019s eye rot incidence; however, thiophanate-methyl (achieving >87% control) was more effective than a mixture of pyraclostrobin and boscalid (<80.7%) or fludioxonil (<57.6%), in all trials. Compared with nontreated control fruit, a postharvest treatment with the ethylene inhibitor 1-methylcyclopropene (1-MCP) halved the incidence of infection in three of four experiments. However, a combination of two preharvest treatments with a mixture of pyraclostrobin plus boscalid and one postharvest 1-MPC treatment suppressed bull\u2019s eye rot to a significantly (P < 0.00001) greater degree (achieving >87.5% control) than the single treatments with pyraclostrobin and boscalid (<65%) and 1-MCP (<80%) tested alone

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

Strategie per contenere la batteriosi delle drupacee

CONTRO XANTHOMONAS arboricola pv pruni sono stati provati tra il 2012 e il 2019 non solo diversi agrofarmaci, ma anche concimi fogliari e un corroborante che agiscono positivamente contro la batteriosi. Il rame resta l’elemento che garantisce maggiori risultati. È comunque necessaria una strategia più ampia che comprenda non solo il rame, che può dare fenomeni di fitotossicità, ma anche altri formulati, valutando però se sono accessibili all’impiego (mancanza di una etichetta specifica) o quanto meno utilizzabili in qualità di agrofarmaci