Ivo T. Yanashkov and Tzenko D. Vatchev
Agricultural Academy, Institute of Soil Science, Agrotechnologies and Plant Protection (ISSAPP), 2230 Sofia, Bulgaria
Yanashkov, I. T. & Vatchev, T. D. (2021). First report of Fusarium oxysporum Schlecht. emend. Snyder and Hansen causing wilt of lettuce in Bulgaria. Bulg. J. Agric. Sci., 27 (1), 135–136
Lettuce plants (Lactuca sativa L.) showing symptoms of yellowing and wilting of folliage, stunting and death of the plants were observed in a commercial greenhouses situated near Sadovo (Sauth Central Bulgaria) in April, 2019. Roots, stems and leaves of the symptomatic plants decayed and turned reddish brown. All isolates obtained from symptomatic plants were identified as Fusarium oxysporum Schlecht. emend. Snyder and Hansen by microscopic observation of their morphological characteristics (3-4-septate macroconidia – 25.2-30.5 μm x 3.1-4.6 µm, 1-2-septate microconidia – 6.2-9.0 µm х 2.8-4.5 μm and abundant chlamydospore formation). Pathogenicity of all isolates was confirmed on lettuce cultivar Grand Rapids in pot experiments with artificially inoculated soils. Seedlings grown in inoculated soils showed wilting and root rot symptoms, identical to those observed on naturally infected plants. The inoculated pathogens were consistently reisolated from symptomatic tissues. To the best of our knowledge, this is the first report of F. oxysporum infecting lettuce in Bulgaria.