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Lettuce Grey Mould


Lettuce Grey Mould

Usually appear in

All Year

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Caused By:-     The Fungus The Fungus Botrytis cinerea


Lettuce Grey mould is caused by the fungus Botrytis cinerea which is a very common, quick-spreading disease and its airborne spores are always present. B. cinerea is also a cause of damping off in seedlings. It thrives as a saprophyte (a micro-organism living on dead organic material), but can also infect living plants under the right humid conditions. It causes the growth of a fuzzy grey mould. This fungus infects many plants, especially those grown under glass wherever there are humid conditions. It is also a common disease of soft fruit, such as apples, grapes, strawberries, blackberries, raspberries, gooseberries, beans, cucumber, courgettes, lettuce, tomatoes and many more where it affects leaves, buds fruits and soft herbaceous stems.
Grey mould normally enters through a wound or infects plants under stress, but will infect healthy plants as well, especially in the right humid conditions. Masses of grey mould are produced at the point of infection. It can be expected at any time of year.
Affected leaves are inedible and should not composted. The worst case is when the lettuce is attacked at the base and a slimy, yellowish red-brown rot forms, which can the kill the entire plant.
Masses of grey mould are produced at the point of infection.
The fungus forms black, seed-like resting structures (sclerotia) in dead plant tissue which can carry the fungus through periods when host plants are scarce.
There are anumber of closely related Botrytis species which attack specific plants such as Snowdrop (B. galanthina), Peony (B. peoniae) and Broad bean (B. fabae).
See these other Grey Moulds and Botrytis fungi Bean Chocolate Spot, Botrytis, Grey Mould, Lily Disease, Onion Neck Rot, Peony Wilt, Rose Grey Mould, Snowdrop Grey Mould, Strawberry Grey Mould.


Although there aren't any specific chemicals available to treat grey mould, sulphur dust will reduce the problem. Hygiene is very important, especially under glass. Promptly remove any infected parts of the lettuce. Try to reduce the risk of damage to lettuce leaves by especially by Slug and Snails. Reduce humidity by improving ventilation and space plants out to ensure good air circulation, and water early enough in the day to allow the leaves to dry out before the evening. Also remove any garden debris that might harbour the fungus and control weeds. Crop rotation should always be practiced where possible. In the organic world products containing plant and fish oil blends may be used, but are not recommended by the manufacturers for grey mould control and are unlikely to have much impact.

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