Berkshire, United Kingdom

I've had my tree fern for many years now and each year it has looked better, healthier and has given me more fronds - this year I got 13. However, I have noticed that it has developed a disease/pest problem in the past month. It has black marks up the stem of many of the fronds, two of which have broken off halfway. There are waht look like burn marks and many of the gree leaf edges are disappearing.

On plant Dicksonia antarctica

• 29 May, 2010