Virulence of Fusarium species to alfalfa seedlings

Abstract

In in vitro conditions, virulence of 91 isolates of species Fusarium genus (F. oxysporum, F. solani, F. acuminatum, F. equiseti, F. arthrosporioides, F. prolifera- tum, F. avenaceum, F. semitectum, F. tricinctum, F. sporotrichioides and F. graminearum) towards alfalfa seedlings was investigated. Isolates of investigated species originated from diseased alfalfa plants collected at four locations in Serbia based on symptoms of wilting caused by Fusarium and root rotting. Pathogenicity and virulence of investigated isolates of Fusarium spp. were determined by visual evaluation of inoculated seedlings of cultivar K28 in laboratory conditions. All isolated of investigated species had pathogenic effect on alfalfa seedlings which expressed symptoms such as necrosis of root, moist rotting and "melting of seedlings". Colour of necrotic root tissue varied from light brown, brown lipstick red to explicit black, depending on the Fusarium species. Strong virulence was established in 48 isolates, medium virulence in 31 and weak virulence in 12 isolates.

U in vitro uslovima proučena je virulentnost 91-og izolata vrsta roda Fusarium (F. oxysporum, F. solani, F. acuminatum. F. equiseti, F. arthrosporioides, F. proliferatum, F. avenaceum, F. semitectum. F. tricinctum, F. sporotrichioides i F. graminearum) prema klijancima lucerke. Izolati ispitivanih vrsta poreklom su iz obolelih biljaka lucerke koje su prikupljene iz četiri lokaliteta u Srbiji na osnovu simptoma fuzarioznog uvenuća i truleži korena. Patogenost i virulentnost ispitivanih izolata Fusarium spp. utvrđeni su vizuelnim ocenjivanjem inokulisanih klijanaca sorte K28 u laboratorijskim uslovima. Svi izolati ispitivanih vrsta patogeni su prema klijancima lucerke, koji su ispoljili simptome u vidu nekroze korena vlažne truleži i "topljenja klijanaca". Boja nekrotiranog tkiva korena varira od svetlo smeđe, smeđe, crveno-smeđe, karmin-crvene do izrazito crne, zavisno od vrste roda Fusarium. Jaku virulentnost ispoljilo je 48 izolata, srednju 31 izolat, a slabu 12 izolata.