Grey Mould
Botrytis cinerea

Names:

Gladiolus Leaf Blight

See Neck Rot of Allium species

Noble Rot of Grapes.

Description:

Grey, cobwebby fungal growth sometimes with tiny black spore bodies. Underlying plant tissue is usually soft.

All above ground plant parts may be attacked especially if damaged by insects, disease or mechanically.

Cyclamen

The infection usually starts near ground level.

Grapes

Berries are most commonly affected. They go soft and a grey fungal growth appears soon after. Berries damaged by insects or hail are very susceptible to infection by wind borne spores. Infection can occur at flowering. The disease may develop after picking in storage.

In wine grapes the disease may be beneficial as it imparts a particular flavour to sweet white wines, hence one of its common names "Noble Rot".

Lilies

Round to oval, yellow to reddish brown spots appear on both sides of the leaf. Their colour may fade with time and the leaf may be destroyed as the spots grow and join. Stems may be spotted and break at the lesion. Infected buds may wither and turn brown or produce distorted flowers. These symptoms may also be caused by Botrytis elliptica.

Lettuce

A soft rot that may be edged with red and have grey furry hyphal growth with black sclerotia occurs on the lower leaf stalks and may rot the base completely leading to death or stunting in less severe cases.

Pears

Dying flowers are often infected and the disease spreads to the fruit. A soft rot appears on the fruit followed by a grey, powdery growth of spores.

Pelargonium

Mainly affects flowers that fade or wither and brown. A furry growth appears on the dead petals that may be matted together. Infected petals may fall onto leaves below and infect them.

Roses

Mainly affect flowers and buds and occasionally leaves. Buds turn brown and rot and the infection may travel down to the stem. Pink rings are produced on petals. It usually lives on dead material and only attacks living material in cool and humid conditions and if these conditions persist the grey hyphal growth may be seen.

Species Affected:

Brassicas, Ornamentals, Pelargonium(Regal, Ivy and Zonal).

Brussels Sprouts, Cabbages, Chives, Garlic, Gladiolus, Grapes, Leeks, Onions, Radish, Shallots very susceptible.

Apples, Pears, Strawberries

Chickpeas

Biology:

Favoured by cool, wet, humid conditions.

Infection favoured by tissue damage due to frost, pest attack or sand blasting.

Spores spread by wind.

Survives in mainly on crop residues.

The fungus can grow on both living and dead material.

Produces sclerotia which may survive in soil or debris for many years.

Spread wind, water splash and direct contact with infected material.

Life Cycle:

Origin and History:

Distribution:

Significance:

Very damaging to Brussels Sprouts and Cabbage heads.

Management and Control:

Decrease humidity.

Reduce planting density.

Remove and destroy infected plants and parts.

Prune carefully with sharp tools to minimise damage.

Onions

Harvest onions carefully at the right stage, then cure them correctly in well ventilated areas.

Brassica crops

Dispose of crop residues by burial or burning.

Avoid damaging seedling when transplanting.

Avoid wet conditions at transplanting.

Don't use excessive nitrogen applications.

Fruit

Dip fruit in fungicides.

Grapes

Prune to increase are circulation and let in sunlight.

Remove dead or shrivelled grapes and leaves.

Pick bunches carefully to reduce the risk of the disease developing in storage.

Lettuce

Increase air circulation. Reduce planting density.

Improve drainage.

Water and fertilise regularly to maintain maximum growth.

Avoid damaging plants.

Destroy crop residues and remove infected plants.

Apply fungicides ensuring the underside of leaves are treated.

Pelargonium

Remove and destroy infected flower heads and leaves immediately.

Reduce humidity by spacing plants and improving air circulation.

Plant in sunny positions.

Apply fungicides.

Roses

Remove and destroy infected buds, flowers and stem.

Destroy prunings and leaf litter.

Apply fungicides in cool humid conditions.

Strawberry

Use plastic or other mulch to prevent soil contact with fruit.

Apply fungicides from blossom stage onwards.

Related and Similar Species:

References:

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Acknowledgments:

Collated by HerbiGuide. Phone 08 98444064 for more information.