Which leaf disease does my kaki plant have?

Garden Experts
Hello, do you have a specialist for questions regarding leaf diseases? I have attached a picture of a kaki plant that I have grown myself from seed. You can see what is happening with the leaves; I have already taken off four or five leaves as they had fully succumbed to the disease. Could you tell me what the problem is? Thank you very much!

The GARDENA gardening expert

Dear Mr. H., I have had a good look at the photo you attached; by "this disease", I assume you mean the brown edges of the leaves that are shown. 

In this context, brown leaf edges are usually the result of problems in the area of the root tips. The exact cause needs to be investigated in each case. Soil wetness or providing the plant with too much water can be a reason, as the roots then do not get enough oxygen. Over-fertilization may be another reason, as this burns the tips of the roots. Moreover, there are certain nutritional deficiencies that also cause such necrotic leaf edges.