Botrytis blight (Botrytis cinerea)

Botrytis blight: biology

Also known as grey mould, Botrytis blight typically affects wild blueberries during bloom and can cause harvested fruit to rot, resulting in yield loss.

Blueberry plants are infected with Botrytis during mid- to late bloom, particularly after a wet period. The fungus overwinters in the soil or on old plant material and then infects new growth the following spring. Blueberry flowers or entire clusters can become infected.

Infected berries cannot be used for fresh eating or processing. Spores on infected fruit can spread to healthy berries and cause rotting post-harvest.

Botrytis blight: damage description

Botrytis blight in blueberries

Tips of infected shoots will die back and turn brown to black. Infected blossoms appear water soaked and turn brown, and the discolouration can spread down the twig. This blossom blight stage causes the most loss. Infected flowers will turn brown in colour but not fall to the ground. Blighted blossoms often cling to clusters. Immature fruits shrivel and turn a bluish purple, whereas ripe, mature fruits become tan. In damp weather, all infected plant parts become covered with the characteristic "grey mould" of the fungus.

Botrytis blight: management

Follow these management strategies for Botrytis:

• Scout by inspecting the flowers of the earliest blooming clones for wilting or discolouration.
• If Botrytis blight is detected and wet weather is forecast, a spray program for Botrytis control may be required. Fungicides for Botrytis blight control should be applied prior to the commencement of any wet periods.
• Cultural practices that improve air movement, such as pruning, aid in the control of blight and fruit rot.
• Avoid excessive use of nitrogen fertilizer in the spring because rapidly growing tips are more susceptible.
• To prevent Botrytis rot of harvested fruit, pre-cool and store at 0° ° C to 2° ° C.

• Ellis, M. and Nita, M. Integrated Management of Blueberry Diseases. Ohio Agricultural Research and Development Center.
• Annis, S. 219-Disease Control Guide for Wild Blueberries. The University of Maine. Revised February 2014.
• Wild Blueberry Factsheet C.3.2.0. Government of New Brunswick. Revised 2009.
• Rieger, M. Introduction to Fruit Crops. Haworth Press Inc. 2006.
• https://extension.psu.edu/botrytis-blight-and-fruit-rot-of-blueberry
• http://www2.gnb.ca/content/dam/gnb/Departments/10/pdf/Agriculture/WildBlueberries-BleuetsSauvages/0171100028-e.pdf