Browsing by Author "Polat, Z."

Now showing 1 - 2 of 2

Comparative Aggressiveness and Fungicide Sensitivity of Phytopythium Vexans and P. Litorale Associated With Kiwifruit Vine Decline in Türkiye
(John Wiley and Sons Ltd, 2025) Polat, Z.; Gültekin, M.A.; Özer, G.; Türkkan, M.; Derviş, S.
BACKGROUND: Kiwifruit vine decline syndrome (KVDS) is an economically critical disease threatening production in Türkiye. The oomycetes Phytopythium vexans and P. litorale are increasingly implicated, but their comparative roles and effective management remain poorly understood, creating an urgent need for sustainable control strategies. This study aimed to (i) compare the virulence of these two species and (ii) evaluate the in vitro versus in vivo efficacy of key fungicides to identify reliable control strategies. RESULTS: Pathogenicity assays revealed that P. litorale was significantly more aggressive, causing severe disease (Disease Severity Index, DSI > 70%), whereas P. vexans induced only moderate symptoms (DSI < 42%). A critical disconnect was observed between laboratory and greenhouse fungicide performance. For instance, oxathiapiprolin, which was highly potent in vitro (EC50 = 0.001169–0.006158 μg mL−1), provided only moderate disease control in vivo. Conversely, pyraclostrobin-based fungicides delivered superior protection against the highly aggressive P. litorale, reducing the DSI to a range of 20.83–21.88% and significantly enhancing root biomass. CONCLUSION: This study establishes P. litorale as a highly aggressive pathogen in KVDS etiology and demonstrates that in vitro data alone are misleading for predicting fungicide field performance. Pyraclostrobin-based fungicides are identified as the most effective candidates for managing KVDS caused by P. litorale. These findings underscore the necessity of integrating in vivo validation in screening protocols and adopting species-specific management approaches, providing a critical roadmap for developing sustainable solutions against this devastating disease. © 2025 Society of Chemical Industry. © 2025 Elsevier B.V., All rights reserved.
Emergence of Severe Stemphylium Leaf Blight on Leek (Allium Porrum) During Seed Production in Türkiye
(John Wiley and Sons Inc, 2026) Polat, Z.; Beşirli, G.; Gültekin, M.A.; Derviş, S.; Özer, G.
A severe leaf blight epidemic caused by Stemphylium vesicarium was observed on cultivated leek (Allium porrum L.) in a commercial seed production field in Türkiye. The disease occurred in early summer 2025 during the second year of a biennial seed production cycle, where incidence reached 50%–75%. The extended cultivation period characteristic of seed production (12–18 months) likely served as a key epidemiological driver, enabling pathogen overwintering and extensive inoculum accumulation, in contrast to the shorter cropping period of annual vegetable production systems. The pathogen was identified as S. vesicarium based on morphological features and confirmed by maximum likelihood phylogenetic analysis of combined internal transcribed spacer (ITS) and glyceraldehyde-3-phosphate dehydrogenase (gapdh) gene sequences. Pathogenicity was verified through fulfilment of Koch's postulates using two representative isolates on healthy leek plants. This report constitutes the first confirmed occurrence of S. vesicarium on leek in Türkiye and demonstrates a shift in its epidemiological importance from a minor foliar pathogen in annual systems to the causal agent of a severe epidemic under biennial seed production conditions, highlighting the need for targeted surveillance and management strategies to mitigate disease risk in both seed and commercial leek production. © 2026 Wiley-VCH GmbH. Published by John Wiley & Sons Ltd.