Browsing by Person "Scheer, Christian"

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Assessment of a postharvest treatment with pyrimethanil via thermo-nebulization in controlling storage rots of apples
(2021) Büchele, Felix; Neuwald, Daniel A.; Scheer, Christian; Wood, Rachael M.; Vögele, Ralf T.; Wünsche, Jens N.
Apples are very susceptible to infections from various fungal pathogens during the growing season due to prolonged exposure to environmental influences in the field. Therefore, a strict and targeted fungicide strategy is essential to protect fruit and trees. Increased environmental and health concerns and pathogen resistance have resulted in a rising demand to reduce fungicide usage and residues on marketed fruit. Thus, producers must develop new plant protection strategies to conform to the legal and social demands while still offering high-quality apples. This study assessed the efficacy of a post-harvest fungicide treatment with pyrimethanil via thermo-nebulization for controlling storage rots and compared the results to those of standard pre-harvest fungicide strategies. The results showed that a single post-harvest application of pyrimethanil successfully controlled storage rots and is comparable to strategies using multiple pre-harvest fungicide applications. The control of fungal rot was sustained even after 5 months of storage and 2 weeks of shelf life. Thermo-nebulization into the storage facility allowed for a lower dosage of fungicide to be used compared to pre-harvest applications, while still maintaining optimal rot control. Residue analyses showed that the post-harvest fungicide treatment did not exceed legal or retailer’s standards.
Extensive efficacy tests of non-antibiotic fire blight control agents
(2020) Bantleon, Georg; Scheer, Christian; Hartung, Karin; Vögele, Ralf
Application of control agents to prevent new infections is an integral part of disease management for fire blight on pome trees caused by Erwinia amylovora (Burrill) Winslow et al.. Due to resistance development and human health concerns when using antibiotics, non-antibiotic control agents with high efficacy are urgently needed. In this study extensive efficacy tests with some classical antibiotic and relatively new non-antibiotic control agents for the prevention of bloom and shoot blight as well as phytotoxicity tests based on fruit russeting were carried out using young apple trees. Furthermore an experimental design for testing control agents preventing fire blight following hail injury was developed. The high efficacy of streptomycin (> 90%) and streptomycin containing spray strategies (> 80%) was confirmed. Non-antibiotic agents with high efficacy are LMA (85%), a potassium aluminum sulfate, and Juglon (80%). LMA is already in use in practice in Austria and Germany with a temporal and restricted permission and the administrative process to gain the legal status of a pesticide is ongoing whilst already admitted in Switzerland. Juglon, an organic compound from walnut, did show a high efficacy, but no consistent results (80.0 and 69.5%). Myco-Sin showed good results to prevent infection after artificial hail simulation. Antinfek showed high efficacy (90%) in preventing bloom blight, but could be tested only once so further research is needed to confirm this result. The design of the presented study enabled an extensive evaluation of the potential control agents and the aggregation and comparison of results and can be advised for other evaluations.
Impact of plastic rain shields and exclusion netting on pest dynamics and implications for pesticide use in apples
(2025) Bischoff, Robert; Piepho, Hans-Peter; Scheer, Christian; Petschenka, Georg
Apple production is among the most pesticide-intensive cultures. Recently, plastic rain shields and pest exclusion netting have emerged as potential measures to reduce the heavy reliance on chemical pesticides in apple, due to their inhibitory effect on pathogen and pest infestations. In a field trial, we compared yields, pest, and pathogen abundance in an orchard consisting of four plots, where two plots were covered with anti-hail net covers, one with plastic rain shields only, and one with plastic rain shields and exclusion netting. Pests and pathogens were assessed visually, and beating tray samples were collected to compare overall arthropod diversity between plots. We observed virtually no scab infections in both plastic rain shield plots, despite a more than 70% reduction of fungicides applied, when compared to anti-hail plots. Although no codling moth insecticides were sprayed in the plot with exclusion netting we found significantly reduced damage here, when compared to the anti-hail plots. However, likely due to microclimatic changes, we observed an increase of powdery mildew, woolly apple aphids, and spider mites under plastic rain shields. Modeling of metabolic rates of arthropod herbivores and predators revealed that there is an increased potential of herbivory under plastic rain shields. However, in terms of plant protection, the net effect of plastic rain shields and exclusion netting was a substantial reduction in chemical pesticide use, demonstrating that they represent a promising approach to minimize the use of chemical pesticides in apple production.