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  • Disease incidence of shot-hole disease of plum in two training systems

    Of the foliar diseases of European plum, Wilsonomyces carpopilus is the most commonly occurring fungal pathogen. The aim of this two-year study was to investigate the susceptibility of ‘Čačanska lepotica’ plum variety to shot-hole disease (Wilsonomyces carpophilus) in two different training system with 4 x 1.5 m and 6 x 3 m tree spacings. The obtained results showed that the cultivar is susceptible to this disease and by the end of the vegetational period disease incident was above 50% in both years in both tree spacings. In 2018 disease incidence was higher in both spacing than in 2019, reaching almost 90% at the 4 x 1.5 m tree spacing plot. There were few significant differences between high and low density tree spacings. The results highlighted the importance of inoculum accumulation late in the season.

  • Loss and Disease Development of Monilinia fructigena (Aderh. & Ruhl.) Honey in an Organic Apple Orchard

    In a two-year-study, yield loss and temporal development of incidence of Monilinia fructigena were quantified in organic apple orchards and the importance of fruit wounding agents was determined. The first infected fruits were observed at the beginning of August in 2001 and 2002. Disease development was continuous until fruit harvest in both years. Pre-harvest yield loss caused by Monilinia fructigena amounted on average 27.2% in 2001 and 41.6% in 2002 by fruit harvest. The growth rate of disease development was almost double in 2002 compared to 2001. All infected fruits were injured by wounding agents such as aboitic and mechanical injury factors, codling moth (Cydia pomonella), common earwig (Forficula auricularia) and birds. In this study, the most important wounding agents were codling moth and mechanical injury factors in organic apple orchards. In both years, our results showed that 70-80% of the infected fruits were damaged by codling moth in organic apple production. Moreover, 10-15% of the infected fruits were mechanically injured in the two years. Our results indicated that most of the damaged fruits fell on the orchard floor before harvest and they became an important secondary inoculum source of M. fructigena. Biological and practical implications of the results are discussed.

  • The efficacy of combining paraffin oil with conventional fungicide treatments against grape powdery mildew in Eger

    We aimed to test the combination of paraffin oil (PFO) with regular fungicide treatment to assess its efficacy against grape powdery mildew (GPM) in a small spraying experiment on two Vitis vinifera L. cultivars (Chardonnay and Kékfrankos) with different susceptibility to Erysiphe necator. The visual symptoms of GPM on leaves and clusters were examined at three phenological states. The harvest yield was characterized by two methods, data were analyzed with one-way ANOVA and Tukey post-hoc test. Regular fungicide treatment (CT) and its combinations with PFO showed better results in both varieties to repress GPM in 2015 relative to sole PFO treatments. Mean values of combined treatments were often lower than CT but did not differ significantly from each other. The same was observed in 2016, despite the higher pressure of GPM, and missed the third survey. No significant differences were detected between treatments in yield. In contrast, the mean cluster weight of CT and combined treatments resulted in (insignificantly) higher values in each variety and year. In summary, the sole PFO showed some disease control capability as reported earlier, but this effect was greatly affected by the given vintage. Combining PFO with CT resulted in increased protection against GPM relative to the solely applied fungicides. However, this effect was not significant in all cases. It also depended on the vintage and cultivar characteristics. The beneficial impact of paraffin oil as an additive to CT may be due to the induction of plant stress responses and/or its ability to support the adherence and absorption of the combined agents.

  • The effect of reduced sprinkler programs on the main fungal pathogens of apple in environmentally sound production systems

    Aim of our two-year study was to evaluate the possibilities of chemical use against key fungal pathogens (apple scab, apple powdery mildew and brown rot) in integrated and organic apple production. Therefore, first, disease incidence was compared in standard and reduced spray programmes and then each technological variation was evaluated from practical point of view. Altogether four spray programmes were compared. Standard and reduced spray programmes were performed in the integrated production. The same pesticides were used in the reduced spray
    programme compared to standard one but numbers of spray were reduced by 25% at the second half of the season. Standard and reduced spray programmes were also performed in the organic production and the numbers of spray were reduced by 40% in the reduced spray programme. Incidence of diseases was low in both standard and reduced spray programmes in integrated production. Diseases level was high in the organic production and disease increased significantly in the reduced spray programmes compared to standard programmes. Results showed that reduction in spray numbers at the second half of the season can be used practically in integrated production. Omission of sprays in organic
    production resulted in serious disease management risk; therefore, it is not recommended for practical use. 

  • Effect of Ozone Exposure on Phytopathogenic Microorganisms on Stored Apples

    The aim of our study was to clarify the effect of ozone exposure on several phytopathogenic fungi on stored apple fruits under different storage conditions. The study was conducted at Bistrita, Romania, in the storehouse of an experimental apple orchard in 2002 and 2003. Two widely grown apple cultivars (‘Jonathan’ and ‘Golden Delicious’) were used. General microbial examination of the fruits was made during storage in order to identify the most important storage pathogens. Efficacy of six ozone treatments was evaluted on fruit decay caused by phytopathogenic fungi. Monthly observations (January, February, March and April) were made of the degree of decay and three measurements were assessed (disease frequency, disease intensity and degree of attack). Our results showed that the most important phytopathogenic fungi during storage was blue mold, caused by species of Penicillium. Disease frequency of apple fruits was very high on cv. ‘Jonathan’, much higher than on cv. ‘Golden delicious’. Ozone treatments (25 ppm ozone for 0.5 and 1.5 hours in November) caused significantly lower disease incidence on stored apple than all other ozone treatments. For longer storage, it seems that additional ozone treatments in February increased treatment efficacy. Cv. ‘Golden delicious’ seemed to be more resistant to storage diseases than cv. ‘Jonathan’ both on the untreated and treated fruits. The effect of the ozone treatments was also the most effective when 25 ppm ozone was applied for 0.5 and 1.5 hours in November.