Trees in Tooting Common have become infested with a highly contagious disease which can cause a bleeding bark as well as branches becoming disfigured and fall.
Wandsworth Council officers have identified that about 20 horse chestnuts lining Chestnut Avenue have been infected with bleeding canker disease, although there are fears all of the trees along the road could be infected.
Further assessments are taking place and the council has said pruning has taken place to avoid potential dangers.
The disease has been in the UK for decades, but there has been a dramatic increase in cases in recent years.
According to the forestry commission in 2000 there were only four reported cases; in 2006 that rose to 110; one year later half the horse chestnuts in Britain were thought to be showing symptoms.
The disease is less likely to spread to other species of tree, but it is still a concern. It is possible for the trees to survive the disease, but the council spokesman said that because the trees in the common are old, which reduces their chances.