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| Onion White rot |
A fungal disease, that causes the bulbs of onions, garlic, shallots and chives to rot.
The disease rots the roots and attacks the bulb, the leaves wilt, turn yellow, and in some cases the plants appear loose in the soil.
On closer inspection one can see a white fluffy mould which later forms small black, seed-like structures called sclerotia.
n.b The attack is generally less severe on leeks.
The sclerotia can remain alive but dormant in the soil for at least 8 years, and are encouraged out of dormancy by chemicals produced by plants of the allium family.
These stimulated sclerotia germinate and produce a fungal mycelium that attacks the roots, eventually spreading to the bulb.
The disease is not airborne and is transmitted principally in contaminated soil, and is most severe in cool, wet summers.
There are no chemical treatments available to amateur gardeners.
Destroy affected plants immediately, do not compost them, and ensure that you remove all affected parts to prevent sclerotia from contaminating the soil.
Rotation of crops is not always successful due to the longevity of dormancy period.
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