subject: Signs, Symptoms and Treatment of Botrytis Blight, Botrytis Cinerea and Botrytis Fabae [print this page] Signs, Symptoms and Treatment of Botrytis Blight, Botrytis Cinerea and Botrytis Fabae
Botrytis Blight is a fungal disease that can affect both types of herbaceous plants, annual and perennial. There are several species of Botrytis, the most common being Botrytis Cinerea.
Usually contracted and spread in springtime, Botrytis Blight thrives in cool, wet weather. It is especially damaging after several days of rain. The disease can and will survive on crop stubble over the winter and then spread the following season.
Commonly Affected Plants
Begonias, geraniums, marigolds, pansies, petunias, dogwood, calendulas and hydrangeas are all plants that are susceptible to Botrytis Blight.
Fruit and vegetable plants that can contract the disease include beans, carrots, onions, peppers, grapes, lettuce, turnips, raspberries, strawberries and tomatoes.
Botrytis Cinerea afflicts wine grapes, and Botrytis Fabae is often seen in various varieties of bean plants.
Signs and Symptoms
Botrytis Blight is sometimes evidenced by brown spots on plant material.
Botrytis Fabae appears as reddish-brown spots on leaves, stems and flowers, which is why it is often dubbed the "Chocolate Spot" Disease. It quickly infects, grows and produces spores and thrives in warmer, wetter conditions. Once "chocolate spots" appear on leaves, stems and flowers they enlarge and develop dead, gray centres. Eventually the disease can kill these plants.
The necrotrophic fungus Botrytis Cinerea materializes as gray mold. Masses of spores can cling to dead or dying tissue. When liberated, they appear as dust coming off the plants. Occasionally, tiny black structures form later in the summer.
In wine grapes, Cinerea can have different results depending on the weather conditions. In humid conditions, it will develop into gray rot. In dry periods following wet weather, it will form noble rot. The resulting bunch rot can cause major losses for the wine making industry.
Disease Management
Careful inspection of at-risk crops and thorough sanitation are two essential actions for controlling Botrytis Cinerea and Botrytis Fabae.
Infection may be prevented by avoiding overhead watering and misting plants. It is important to ensure plants are given enough room for air circulation and can dry quickly.
If crops have been stricken with blight it is important to remove infected flowers, leaves or entire plants as necessary. Avoid removal when crops are wet as it is easier to accidentally spread the spores that way.
Use of a fungicide spray such as OxiDate is highly recommended for both prevention and treatment. Apply it in spring when the weather is cool and wet, and also if blight was a problem in the previous year.
Crop rotation and regular weeding are also very good ways to prevent and "treat" Botrytis.
