How to recognise it
In spring narcissus (daffodil) shoots appear covered with a grey mould. Spores (conidia) are produced by this mould and spread to other plants. The foliage of newly infected plants turns brown at the base, then yellows/browns and wilts at the tip. Eventually they will also become coated with the same grey mould.
Within the bulbs of infected plants black sclerotia (hardened, dormant fungal masses) may be produced which pass into the soil ready to infect plants the following year. It should be noted, however, that other fungal infections will also produce black sclerotia, so these alone shouldn’t be taken as an indicator of smoulder.
Why it’s a problem
Affected plants may fail to grow or result in distorted, weak growth.
Where you are likely to find it
This diease affects narcissi and most commonly occurs in cold, wet conditions. It may also infect snowdrops.
How to prevent it
Ensure that you obtain bulbs from reliable sources so you don’t run the risk of introducing the disease into your garden. The removal of weeds and wider spacing of bulbs can improve air flow and reduce the moist conditions which this fungus prefers. You can also plant bulbs on a rotation basis in different areas so the disease doesn’t accumulate in the soil.
How to get rid of it
Lift the bulbs in the summer and, before replanting in the autumn, rub off the papery tunic around the bulbs to remove any sclerotia. Spraying with a bordeaux mix can also help. This should be sufficient to control the diease so only the occasional plant is affected. To be rid of the disease completely any infected plants should be destroyed.
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