STUDIES ON FUSARIUM WILT RESISTANCE IN CARNATION

According to the methods of contamination, the resistance of the Carnation varieties to the Fusarium wilt proved to be completely different. Pallas, one of the most resistant, becomes susceptible after contamination of the rooted cuttings by dipping in a dilute suspension of microconidia (20 000/ml) whereas it resists to a natural inoculum concentration higher than 20 000 propagules/g in dry soil.

The resistance levels also varies with decreasing the light intensity : Pallas becomes susceptible, Champagne remains resistant.

As a result of screening on artificially infested soils, 26 varieties were compared in glasshouses in which Carnation cultivation was no longer economically feasable. Only six proved as resistant as Pallas : Duca, Elsy, Sarah, Clair Avril, Diano, Lanathena, Lanakino. We found an average tolerance in several of them similar to Sacha : Londesty, Valero, Londernal, Sarinah, Praline, Etna, Teddy.

A large variation in the degree of wilting was observed probably due to the heterogeneity of the inoculum. A special experimental arrangements would be necessary to increase the effectiveness of the resistant tests done in practical conditions.