SOME ASPECTS OF THE EPIDEMIOLOGY OF FUSARIUM OXYSPORUM F.SP. GLADIOLI ON FREESIA

Research on resistance of cultivars and new selections of Freesia to F.oxysporum f.sp. gladioli showed a large discrepancy between symptoms on the parts of the plants above the soil and on or in the corms.
Frequently the corms of plants, which did not show symptoms on the leaves at the time of flowering, were all infected by F.oxysporum f.sp. gladioli, although showing no symptoms on the outside.
Corms and cormlets, showing no symptoms on the outside, were planted in disinfected soil.
After 5 months only ca. 5% of the plants showed symptoms on the leaves.
After lifting however, 12% of the corms proved to be infected by F.oxysporum f.sp. gladioli. Subsequently in the same soil diseasefree cormlets of a susceptible cultivar were planted.
After 3 months 40% of the plants showed symptoms of an attack by F.oxysporum f.sp. gladioli on the leaves and 60% on or in the corms.
It was demonstrated that plants of Freesia, showing no symptoms on either the leaves or the corms, can nevertheless be contaminated by F.oxysporum f.sp. gladioli. The symptomless apparently healthy corms can act as a carrier of the pathogen.
When planted in fresh soil, they can infect this soil.
The soil then can be a serious source of infection to a following Freesia crop.

IV International Symposium on Flower Bulbs

H. Rattink

https://doi.org/10.17660/ActaHortic.1986.177.9