If you're checking for any nasties in your greenhouse or cold frame over the winter months, one of the most common diseases which needs to be eradicated is grey mould, otherwise known as Botrytis.

It appears on chrysanthemum petals, causes the core of gladiolus to rot, leads to ghost spot on tomatoes where a pale green ring appears on the skin, and other symptoms on onions, geraniums and a host of other plants.

The damage spreads rapidly and can cause whole fruits to collapse. Botrytis is common on apples, grapes, strawberries, raspberries and currants, while vegetables affected include beans, brassicas, cucumbers, lettuce, peas, potatoes and celery and carrots in store.

The grey mould fungi can attack virtually any flower, vegetable or fruit in your garden, although soft-leaved plants are the most vulnerable. It covers stems, foliage and fruit with a soft grey fluff and can seriously damage crops.

Snowdrops can also be affected and whole clumps may need to be removed and burned to avoid the mould spreading to other plants.

Grey mould can be extremely active in the greenhouse, destroying whole trays of seedlings, and is encouraged by cold, wet conditions, playing havoc with dead and rotting vegetation and weak plants.

Once the fuzzy grey fungal growth appears on the foliage, causing it to discolour and rapidly deteriorate, the disease may then spread into the main body of the plant.

Fungal spores are spread on air currents or by rain splash, and infection is most likely where the plants are damaged, perhaps by a slug attack or frost crack.

Once an infection occurs on a vulnerable plant, the fungus will spread into living cells, causing them to die. At the same time the mould, which comprises spore-bearing growths called conidiophores, appears on the surface.

Woody plants including gooseberries, raspberries and even roses may suffer from dieback after their leaves wilt and shrivel, changing to brown. Bark cracks and in humid conditions the mould appears.

If conditions are not suited to the germination of the spores, maybe because of low temperatures or low humidity, they will lie dormant until the right conditions emerge.

Indeed, grey mould spores are present all over the garden and because the fungus can live in so many places on so many plants, it's pretty hard to avoid them.

While outdoor attacks are most common during wet weather in summer, when high temperatures and humidity prevail, in winter grey mould is most likely to happen under glass, when plants are at the lowest point of their annual growth cycle, producing a mass of vulnerable decaying foliage.

The first way to stop it is to stem the conditions in which it thrives, so you need to sweep dead leaves off the garden, ventilate the greenhouse to try to reduce the humidity and burn all affected material. Under glass you also need to reduce the amount of watering you do and increase the heat a little. It's worth pruning an affected plant by cutting out the infected area at a point well below the last point of damage.

Ensure that all plants are adequately spaced because damp and overcrowded outdoor crops can also become a haven for grey mould. Also, make sure you check that any crops stored are adequately dried before being placed in store and are inspected on a regular basis. Any showing signs of disease should be removed immediately to avoid the spread of infection. Deadhead all flowers which look to have signs of grey mould.