This disease is caused by various strains of botrytis cinerea, an organism that can either parasitize or survive on dead organic matter, relying on a susceptible host for sustenance. Botrytis primarily affects rose blooms and infrequently affects leaves. In the European Market, which serves as a major destination for Kenyan Flowers, head botrytis is recognized as a significant destructive disease. The disease thrives in conditions of high humidity, making it most prevalent during cool and wet weather and in high-altitude growing areas. The disease initially develops in the farm and can continue to progress even during storage or transportation of the flowers. This disease greatly diminishes the vase life of the flowers as it leads to complete decay.
The first signs of an attack are the appearance of red/pink spots on the tips and edges of the flower petals. This discoloration is a reaction to the fungal infection. Flower buds may fail to open and instead form compact balls. The flower heads can also decay over time. In severe cases, the stems themselves may be targeted, leading to the complete dieback of the plant.
INSIGHT: The fungus remains dormant in plant debris or soil during unfavorable conditions and only attacks the plant when favorable conditions are present.
To prevent the growth of the fungus, it is important to keep the plant canopies dry. Ensuring proper airflow within the plants is also crucial in inhibiting fungal development. Maintaining good hygiene practices, such as removing plant debris from the beds and sanitizing harvesting tools, is recommended. Additionally, spraying with fungicides like Iprode, Chariot, Nature Gold, Sporeguard, Megaprode Lock, and Pilote, as well as using dip treatments like Botristop, Botriguard, Fastruno, and Biosure, can be effective.
Tip: It is advisable to alternate between different fungicides since the fungus has demonstrated resistance to certain treatments.