Botrytis (grey mould)

Botrytis spp. is one of the most common fungal diseases of fruit and vegetable crops and can affect plants at most stages of production.

Cause

The fungi Botrytis spp., mainly B. cinerea.

Symptoms

Flower petals are very susceptible to Botrytis infection. Blossom blight often leads to fruit rots. Affected fruit become water-soaked and soft. They are rapidly covered with a thick grey mould. Other plant parts such as bulbs and stems can also be affected.

Botrytis also causes secondary rots on fruit and vegetables in storage or transit and in the marketplace.

This fungal disease may also cause seedling damping-off, leaf spots and rots of vegetative plant parts.

How it spreads

Spores are dispersed in the wind. The fungus can survive from season to season on crop residue or as sclerotia (a hard 'package' of fungal hyphae that can remain dormant for some time) in the soil.

Most infections occur when the Botrytis spores come in contact with aging flower petals. Cool weather with heavy dew or fog favours infection.

Crops affected

Tomato, bean, capsicum, cucumber, brassicas, lettuce, onion, grapes, strawberry, mango and macadamia.

Control

• Destroy crop residues after harvest and remove diseased fruit from packing sheds.
• Reduce humidity in greenhouses and shadehouses.
• Apply registered fungicides as field sprays or post-harvest treatments suited to your crop and situation.

Chemical registrations and permits

Check the Australian Pesticides and Veterinary Medicines Authority database for chemicals registered or approved under permit to treat this pest on the target crop in your location. Always read the label and observe withholding periods.