Fungi colonizing tansy phacelia plants (Phacelia tanacetifolia Benth.) after fungicides treatments

Abstract

Tansy phacelia (Phacelia tanacetifolia Benth.) is considered a disease-resistant plant. The aim of the study was to determine which fungi (pathogens and saprofites) colonize phacelia plants. The greenhouse and field experiments were conducted in 2016. Phacelia plants were treated with fungicides from different chemical groups. Three combinations of products in the greenhouse experiment and 4 combinations in the field experiment were used. Plants without any protective treatments were used as a control. Parts of plants showing some disease symptoms were selected for isolation of saprotrophic and pathogenic fungi. The isolated and identified fungus species obtained from individual samples differed qualitatively and quantitatively. Among the pathogenic fungi the most important were Fusarium spp. [mainly Fusarium solani (Mart.) Sacc., Fusarium avenaceum (Fr.) Sacc., Fusarium equiseti (Corda) Sacc. and Fusarium oxysporum Schltdl.], Botrytis cinerea Pers., Sclerotinia sclerotiorum (Lib.) de Bary, Alternaria alternata (Fr.) Keissl. and Pythium irregulare Buisman. In some cases large differences in the occurrence of pathogens have been observed, depending on the site of the experiment (field and greenhouse) and on the type of fungicides.