Fungi colonizing roots of zucchini (Cucurbita pepo L. var. giromontina) plants and pathogenicity of Fusarium spp. to zucchini seedlings

Zucchini is a very valuable vegetable, easy to grow both in the field and under covers but it is often attacked by soil-borne fungi. The investigations were carried out in a farm near Lublin where three zucchini cultivars: Astra, Atena and Soraya, were grown in a tunnel and in the field in 2008-2009. Plants with stem and root rot were collected for laboratory tests. Mycological analysis showed that the predominant fungi were F. culmorum, F. equiseti and F. oxysporum. More Fusarium colonies were isolated from the roots of zucchini grown in the tunnel. In the pathogenicity test, all tested isolates of F. culmorum, F. equiseti and F. oxysporum proved to be pathogenic to zucchini seedlings, causing stunting, stem and root rot. The highest disease index was noticed in the combination with F. culmorum isolate fck61.