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INTERACTIONS BETWEEN RACES OF FUSARIUM OXYSPORUM F.SP. DIANTHI AND CULTIVARS OF CARNATION
The results show cultivar x race interactions, but also some differentiation between isolates of a race.
Isolates of race 2 induced regular Fusarium wilt symptoms in most cultivars.
At the end of the test period, only the cultivars Revada and Novada remained externally symptomless.
Histopathological investigations of some cultivars showed a heavy degradation of cell walls and xylem parenchyma cells, with dark brown discoloration of the surrounding tissue.
Isolates of race 4 induced similar, but less aggressive symptoms.
However, some interactions were found: Lena was less susceptible to race 4 than to race 2, but Pallas, Alice and Sam’s Pride showed severe or complete wilting.
The pathogenesis of race 4 isolates was similar to that of race 2, with less vascular browning.
Race 1 induced atypical Fusarium symptoms in some cultivars.
Most of them remained resistant, but Niky, Elsy and Sam’s Pride showed a rapid necrosis of leaves, followed by wilting.
The vessels of these cultivars had assumed a pale brown colour and were colonized heavily.
However, no degradation of cell walls was observed.