Wirestem normally attacks seedlings and causes the stems to fail and the seedling to topple over. This fungus is sometimes mis-diagnosed as grey mould because very soon after being infected by wirestem they may well be infected by grey mould. 

Wirestem can also affect plants well after the seedling stage. In these cases the signs are stems which are harder than normal, shrunken and brownish in colour.

Treatment of Wirestem
Once wirestem has infected plants there is no treatment other than removing and burning the infected plants. Avoiding wirestem is easier, sow seeds more thinly, avoid over-watering and keep the soil well-drained by incorporating well-rotted compost and digging deeply and thoroughly to open up the soil.