mystery ailment

[salan]

We have a beloved cactus, (Colin), who is around 25 years old and 6 feet tall...he has outlived all of my partners previous relationships, though he has been nurtured since he came to live with me. He has pride of place in a bright spot in the kitchen french windows, and was re-potted last year into a larger pot, with fancy specialist compost and given a good feed. All of a sudden,this year, he has developed small black spots, and has begun looking 'withery'. He also feels rather spongey, towards the top rather than the bottom; which still looks strong.Your thoughts would be much appreciated, as my partner has stated that if he does die, I will be booking a coffin which can fit both of them in (not that he is being dramatic of course!) We have attached a selection of pictures which may help to diagnose the problem.. Many thanks and best wishes Sally and a deeply distressed Alan (Nottingham)

[hegar]

I am a little bit worried about the lesions on your plant, because there is a visible chlorosis present. This is generally an indication of an infection. In case of a fungus, there should after some time form fungal fruit bodies and sometimes also visible mycelium. The fruit bodies, which contain fungal spores, are either rather small roundish bumps, cushion-shaped structures sticking out of the leaf epidermis or fuzzy structures.
In case you do have several of these stems, it may be best to cut the infected one off and discard it. That way you will prevent it from infecting the others. If it is the only stem you do have of this plant, the least you should do is to physically separate it from the other ones in order to find out, if the lesions multiply or become larger. Both of these occurrences would be an indication of an infection.

Harald

[greenknight]

I agree with Harald. By the way, it's a Euphorbia, not a cactus - the milky sap is toxic, and a strong irritant, be careful not to get any in contact with your eyes or mucous membranes. Very painful if you get it in your eyes.