Most fungal infections are devastating to the bulbs, usually resulting in the death by “rotting off”.
If when growth commences the leaves are stunted and “too” green, this may indicate basal plate rot, caused by either damage to the basal plate or a fungal disease. The bulb will not have rooted and is using its stored energy resources to try and grow. Discard bulb and immediate soil if possible.
If the flowers have tiny brown spots on them after rain this could be an early indication of stagonospora curtisii. The leaves may also have brown/orange lesions or the tips may be dry and withered. If the infected bulbs cannot be lifted immediately then remove the infected leaf parts to avoid the disease spreading, which it does by spores forming in the lesions and being shed by rain. On lifting the plant the bulb will appear to be slightly shrunken, the tunic will be flaky and fall off without assistance, the bulb will feel sticky and the outer scales will have patches of a yellowish-brownish stain. Ideally, discard all infected bulbs and surrounding soil. If the bulbs are lifted in summer, any that do not show the symptoms may be soaked in a weak bleach solution (2%); this sometimes is enough to kill off any dormant spores on the bulbs. Bulbs can be stripped of the damaged scales, until a perfect white bulb is left, then potted up and placed under cover to grow on. Next year will tell if that has worked!!
Over the last few years I and other people who grow snowdrops seem to have suffered from a fungal disease that shows no symptoms on the plant when in growth, but on lifting an orange stain is found on the outer scale. If left this orange stain becomes soft until a hole appears in the scale. The “hole” then spreads throughout the scale, then the bulb. I have sent samples of these bulbs away to laboratories for analysis with the results being a form of botrytis. Regular lifting of the bulbs, discarding all suspect material and soil appears to be the best way to deal with this disease. Increasing the drainage of the soil by the addition of perlite seems to have helped. Stripping the bulbs and chipping them seems to be successful up to the formation of the bulblets stage, but I have yet to grow on the bulbs to see if healthy stock can be achieved.
I have only had one occurrence of botrytis which shows itself as a grey furry mould and that was on a stem that had broken off during a heavy gale. The plant was discarded.
I personally do not believe in spraying the plants with fungicide, just as a precautionary measure. It may help the plants or it may not, but most fungicides that are bought over the counter will be too weak to tackle the real “nasties”. Good garden hygiene, good cultivation techniques and luck are a better approach.
Galanthus leaves showing the symptoms of stagonospora