Plasma wrote:I'm new to the forums, but I have had these cacti for years. However, two of my oldest have developed strange problems. I have no idea what species these are, so I have included full plant photos as well. If anybody could tell me what may be wrong, I would be very grateful. I don't know a whole lot about plants, but I like them too much to just let them die.
Don't know the species on your first cactus, but the corkscrewing is a sign of stress from lack of water. Fanaticactus alerted the forum to a great and very thorough article that deals with the effects of stress on cacti and succulents. If you'd like to read it here's the link:
http://davesgarden.com/guides/articles/view/3030/" onclick="window.open(this.href);return false;
You'll have to scroll down quite a bit before you get to the section on shriveling, but you can see some examples of cacti corkscrewing as a result of dehydration. If you don't want to bother scrolling, here's a salient quote from the article's author:
"I don't know if these 'twisting' of Ferocacti is always a sign of 'shriveling' in dehydration and this plant is not mine so I am not sure what it normally looks like. But I have had several large Ferocacti with almost no roots that were ornamentally tightly spiraled and somehow still alive (sadly that was before I started photographing plants so I don't have examples of these two in their corkscrew shape). When planted and slowly rewatered the roots came back and the corkscrew shape I liked so much, completely unscrewed itself until the plants fattened up and had perfectly straight up and down rows of spines... healthy plants! But no longer so cool looking. The Melocactus on the right has also showed signs of corkscrewing or shriveling in response to a particularly long, dry period. And the Cereus cactus below was being offered at a nusery for sale. In this case, the stress of dehydration has an appeal and may allow this plant to be sold as a 'spiral' form, when in all liklihood, it will unspiral as soon as it gets some water. I hope this isn't being sold as a rare monstrose form."
I concur with the sunburn problem on #1. Not much you can do about the existing damage, so the best thing is to gradually acclimate the plant to stronger sun, and it should outgrow the damage once it gets proper watering and fertilizing. Don't know where you live, but if it's somewhere north of the equator, your cacti shouldn't be getting any water until spring. Once the growing season kicks in, your plants should start responding to water.
By the way, I may not be getting a good look at the potting mix in your photos, but it appears to be way too heavy on soil. I'd strongly suggest adding a mineral component for better drainage. Heavy soils tend to retard healthy root growth -- even though you've had your cacti for years, I think they could be doing a lot better in the right mix with proper watering and feeding.
#2 looks like a Cleistocactus with some normal base corking.