Tag Archives: Fusarium oxysporum

175–186 D. Kyselov and S. Kalenska
Species composition and population structure of phytopathogenic fungi in sugar beet agrocenoses of short-rotation crop rotations in the western forest-steppe of Ukraine
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Species composition and population structure of phytopathogenic fungi in sugar beet agrocenoses of short-rotation crop rotations in the western forest-steppe of Ukraine

D. Kyselov¹* and S. Kalenska²

¹Private Enterprise “Zakhidnyi Buh”, 39 Yunosti Avenue, Pavliv village, Sheptytskyi District, UA80250 Lviv Region, Ukraine
²National University of Life and Environmental Sciences of Ukraine, Ministry of Education and Science of Ukraine, 15 Heroiv Oborony street, UA03041 Kyiv, Ukraine
*Correspondence: dmytro.kyselov@zahbug.com.ua

Abstract:

This study analyzed the species composition and population structure of phytopathogenic fungi in short-rotation sugar beet agrocenoses of the Western Forest-Steppe of Ukraine. Based on 150 samples (90 roots and 60 rhizosphere soil samples) collected from fields of PE “Zakhidnyi Buh”, a total of 240 fungal isolates were identified. The dominant taxa included Fusarium oxysporum, F. solani, Phoma betae, Rhizoctonia solani, and Botrytis cinerea, accounting for more than 90% of the rhizosphere mycobiota. The genus Fusarium was the most abundant (48 ± 3.5%), forming a stable infectious core of the agroecosystem. Short-rotation crop sequences (wheat-soybean-beet and maize-soybean-beet) were found to increase the isolation frequency of F. oxysporum by 25–30% and Phoma betae by 18–22% compared with other systems, while the share of Rhizoctonia solani in rotations with maize reached 16%. Soil type significantly influenced the species profile: F. oxysporum predominated in calcareous sandy soils (≈35%), whereas F. solani and P. betae were dominant in chernozems. Morphological variability of Fusarium isolates (pigmentation and sporulation level of 2.5×10⁵–1.8×10⁶ spores mL⁻¹) indicated high adaptability and potential for the formation of virulent races. Ecological analysis revealed a low alpha-diversity level (H′ = 1.13–1.32) and a high dominance index (D = 0.42–0.51), indicating structural simplification and increased pathogen specialization. Three functional fungal groups were distinguished – primary pathogens (Fusarium spp.), opportunists (Phoma betae), and necrotrophs (Rhizoctonia, Botrytis) – which form a hierarchical model of the parasitic complex. The results confirm the cumulative effect of short crop rotations and demonstrate the necessity of integrating biocontrol agents (Trichoderma, Gliocladium) and ecological soil sanitation measures to restore microbial balance and reduce infection pressure in short-rotation systems of the Western Forest-Steppe.

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1854-1861 S. Salazar, F. Bayas-Morejón, Z. Niño, J. Guevara, M. Ruilova, O. Merino, W. Donato and J. Guamán
Morphological and biochemical indicators of Fusarium oxysporum f sp. fragariae in strawberry crops (Fragaria x ananassa Duch) in the province of Pichincha, Ecuador
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Morphological and biochemical indicators of Fusarium oxysporum f sp. fragariae in strawberry crops (Fragaria x ananassa Duch) in the province of Pichincha, Ecuador

S. Salazar¹, F. Bayas-Morejón¹*, Z. Niño², J. Guevara¹, M. Ruilova¹, O. Merino¹, W. Donato² and J. Guamán¹

¹Estatal de Bolívar, Facultad de Ciencias Agropecuarias Recursos Naturales y del Ambiente, Departamento de Investigación. Centro de Investigación y Desarrollo Biotecnológico, EC020150 Guaranda, Ecuador
²Universidad Estatal de Bolívar, Facultad de Ciencias Agropecuarias Recursos Naturales y del Ambiente, Departamento de Investigación. Centro de Investigación del Ambiente, EC020150 Guaranda, Ecuador
*Correspondence: isba@doctor.upv.es; fbayas@ueb.edu.ec

Abstract:

Fusarium oxysporum f. sp. fragariae is a fungal pathogen, transmitted by soil in crops of strawberry (Fragaria x ananassa Duch.), which causes wilt disease that, kill the strawberry cultivars. The disease caused by Fusarium oxysporum f. sp., fragariae is hard to detect as the of the symptoms are similar with other soil-borne diseases. In spite of detection methods targeted F. oxysporum using molecular criteria have been developed, they have not been shown to successfully identity the unique identity of F. oxysporum strain that causes this disease. In Ecuador, the cultivation of strawberry has acquired great importance for the consumption, promoting the increase of its production. However, the process of importing plant material from producing countries for the purpose of improving production has contributed to the spread of the fungus. The objective of this study was to identify the presence of the Fusarium oxysporum f. sp fragariae by means of morphometric identification and the application of biochemical methods (BIOLOG) in the province of Pichincha. Fifty-two diseased strawberry plants and 52 asymptomatic plants were analyzed. Of these, 13 isolates were identified by morphometry as F. oxysporum. However, through BIOLOG four strains were identified as F. oxysporum, 5 as Fusarium sp., 2 F. lateritium, 1 F. udum and 1 strain as F. sacchari. The results obtained through the identification and evaluation confirmed the presence of F. oxysporum f. sp., fragariae in evaluated strawberry cultivars, thus determining the high risk to exist if the pathogen spreads in new plantations in Ecuador.

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461-464 A. Wagner, W. Michalek and A. Jamiolkowska
Chlorophyll fluorescence measurements as indicators of fusariosis severity in tomato plants
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Chlorophyll fluorescence measurements as indicators of fusariosis severity in tomato plants

A. Wagner¹, W. Michalek² and A. Jamiolkowska¹

¹Department of Plant Protection and Quarantine, Agricultural University,Leszczynskiego 7, 20-069 Lublin, Poland; e-mail: annawagner@poczta.onet.pl
²Department of Plant Physiology, Agricultural University, Akademicka 15,20-950 Lublin, Poland; e-mail: wladyslaw.michalek@ar.lublin.pl

Abstract:

In these experiments the pathogenicity of Fusarium oxysporum populations was investigated. Disease index for inoculated plants was compared to chlorophyll fluorescence parameters measured with the fluorometer PAM. For most of the isolates of higher pathogenicity, the disease index was correlated with the decrease of photosynthetic activity of plants. However, in some cases the damage to the photosystem was more severe than external disease symptoms indicated, suggesting that chlorophyll fluorescence measurements might be helpful in early evaluation of the severity of F. oxysporum.

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