This photo shows the symptoms of crown and root rot in curly parsley, which is a fungal disease known as Fusarium wilt. Similar fungal problems can also occur in winter and are caused by the water moulds, Pithium and Phytopthora primulae. Both flat leaf Italian parsley and curly parsley are susceptible to this disease. Part of the reason it occurs is that parsley grows with a long tap root which often reaches down into poorly drained soil which may have become waterlogged after heavy rain. The advantage of the strong tap root is that parsley is often able to find a space and force its way down to grow between rocks or cracks in pavers, though it may never reach maturity when eking out a living in these conditions. While it is possible to get a good second crop out of flat leaf parsley when it self sows in a garden bed, curly parsley is best started off from fresh seeds or seedlings planted when the days start to become cooler and shorter. For the next six weeks or so I will be lucky to be able to even pick a leaf of it.