I came by on Saturday to ask about my sick cactus. Here are some pictures I took for you to better diagnose the problem. I’m very attached to the cactus so what ever I can do to cure it please let me know.
I only water the cactus once every three months and the last watering beginning of October I fed it a little of the cactus food. I first discovered the discoloration about 3 weeks ago.
Please feel free to email me or call me xxx-xxxx, if you have any questions or need more pictures.
Thank you for your help,
If your plant was by a window I would have said it had a bad sunburn from being turned so the shaded side was suddenly facing the full sun glare and UV…. But since it looks like it is back in the room, it looks like your Euphorbia has caught a virus or fungus. It may have been brought on by water stress, we usually recommend watering plants like yours once a month during the summer months and every six to eight weeks during the winter. Although other than the infection you plant looks like it was doing fine with your water schedule, but being stressed may have made it more susceptible to an infection.
If it is a fungus, it may be treatable with a Neem Oil spray (Neem Oil is a natural, but usually effective treatment for both fungus and insect problems, that will not make your house toxic). I recommend spraying the plant with a 1% Neem Oil Solution to the point of run-off and even watering it in to the potting soil. Retreating two or three times once every ten days. If Neem doesn’t stop the fungus you could use a more aggressive chemical fungicide, but since we only use organic products I can’t recommend a product.
If it is a viral infection unfortunately all you can do is water and fertilize it with Kelp, which is sort of like a multi-vitamin for plants and hope the plant can fight it off. Plant viralcides are not for houseplants as you do not want chemical warfare in your living room.