Corynebacterium fascians andBotrytis cinerea inPelargonium zonale an aspect from the many factors causing the wilting of pelargonium

The investigations on the cause of the “Lent disease” of mother plants as well as cuttings ofPelargonium zonale have indicated, that these troubles are due to faulty cultural methodes combined with an infection byCorynebacterium fascians and “weakness parasites”. The bacteria cause the axillary buds to develop leafy galls on the stem under the soil level and small tumorous growths on the cortex of the stem above, the socalled corky spots. The infected plants may not wither, but galls and spots are more easily infected by pathogens than healthy plants. FrequentlyBotrytis cinerea infects these tissues and causes the black base rot. Spraying the mother plants with streptomycin (Fytostrep 60: 2.5 ml/l) and thiram (0.2%) decreased the base rot, but markedly inhibited the rooting of the cuttings. Moreover, the inocula of bothC. fascians andB. cinerea are present in such a large quantity, that full control is impossible. Reduction of losses may be achieved by improvement of cultural methods and soil disinfection.