PRELIMINARY RESULTS ON BIOLOGICAL CONTROL OF BOTRYTIS CINEREA IN FORCED TULIPS
Infection of bulbs by B. cinerea takes place during cold treatment. Infection may cause discoloration of flowers, thus yielding a product of poor quality (Bergman et al., 1983; Muller and Conijn, 1978).
In practice, the severity of damage caused by B. cinerea has increased since the fungus became resistant to the fungicides benomyl and vinchlozolin, which are used as bulb disinfectants (Muller and Koster, 1987). This was one of the reasons to investigate the possibilities of biological control.
It has been observed that tulips grown in potting soil that had been used for tulip forcing before, showed less infection by B. cinerea than tulips grown in steam-sterilized soil. This effect has been attributed to the presence of antagonists in the soil (Muller and Koster, 1987).