Narcissus Basal Rot
Basal rot is a soft brown rot that starts in the basal plate of the bulb and gradually spreads to the top it.
The problem is more prevalent in the damp and warm conditions of spring, and is caused by a fungus that only affects Narcissus species.
It is a relatively common soil contaminant and may live harmlessly on the bulb surface, but on occasions it will invade bulb roots that are dying back naturally.
Signs of infestation in planted out bulbs may manifest itself in premature die back in the foliage, and or the bulb may develop neck rot.
Suspect bulbs should be removed and destroyed and it is advisable not to replant any Narcissus species in same soil.
Bulbs left in the ground rot and fail to grow the following season.
If lifted and stored, infected bulbs may not die completely over winter, but will fail to thrive in the following season.
To check for infestation in stored bulbs, gently squeeze bulbs to find any that feel soft.
This in itself might not show if a bulb is infected as other things can cause bulbs to soften.
For example: A pinkish-white fungus may be visible on the basal plate.
To confirm if basal rot is present, select a suspect bulb and cut it into two parts.
If the bulb is contaminated you will see one or more partial or complete brown rings (rotted scales).
Mummified bulbs can be another sign that the bulb/s is contaminated.
All bulbs affected in these ways should be destroyed.
To control the disease;
Handle bulbs carefully to avoid bruising, discard suspiciously soft bulbs, and dust stored bulbs with sulphur.