Fungal characteristics and varietal reactions of powdery mildew species on cucurbits in the steppes of Ukraine
¹Department of Selection and Seed Production, Dnepropetrovsk State Agrarian University,Voroshilov 25, 49600 Dnepropetrovsk, Ukraine; e-mail: firstname.lastname@example.org
² Department of Plant, Soil and Agriculture Systems, Southern Illinois University, 62901,Carbondale, IL, USA; e-mail: email@example.com
Powdery mildew caused by fungal species Sphaerotheca fuliginea (Schlect ex. Fr.) Poll. [syn. Podosphaera xanthii (sect. Sphaerotheca) xanthii (Castag.) U. Braun & N. Shish. Comb. nov.] and Erysiphe cichoracearum D.C. [syn. Golovinomyces cichoracearum (D.C.) Huleta] is the most frequent cucurbit (Cucurbitaceae) crop disease in the northern steppes of Ukraine. Species commonly cultivated in Ukraine (melon, watermelon, squash) were colonized by both species. Ash gourd (Benincasa hispida Cogn.) and bottle gourd (Lagenaria siceraria Standl.) were colonized only by E. cichoracearum. Sponge gourd (Luffa cylindrica M.J. Roem) and fig-leaved gourd (Cucurbita ficifolia L.) were not colonized by either of these fungi. Varieties within species varied from resistant to highly susceptible. Four melon varieties were agronomically elite and had resistance to both species. Those two species were consistently differentiated by the location on the conidia where germination occurred, and by the ratio of conidial length to width. Indicator host species and varieties can provide a tentative identification of which powdery mildew species are present in the field.Varietal differentials suggested that races 1 & 2 of S. fuliginea were present onwatermelon, and that race 1 and at least one other race were present on melon.