COMPARISON OF 5 STEM INOCULATION METHODS WITH RESPECT TO PHYTOALEXIN ACCUMULATION AND FUSARIUM-WILT DEVELOPMENT IN CARNATION

Five methods of stem inoculation of carnations with conidial suspensions of Fusarium oxysporum f. sp. dianthi were compared for uptake of the suspension, induction of phytoalexin accumulation and wilt development. Inoculation was performed by incision of the stem across droplets of inoculum placed on leaves, or by injection of droplets into the stem. With both methods, higher inoculum dosages led to higher wilting rates and higher phytoalexin concentrations. Injection was more effective than incision since a lower inoculum dosage was required to obtain the same phytoalexin levels. Injection therefore appears the most promising technique for the development of routine screening methods for resistance based on phytoalexin accumulation.