Silver torch cactus discolouration at top problem help!!

[MadridPeter]

Hello everyone! I just wanted to ask for some advice...last week I bought a pair of silver torch cacti and the taller column has brown discolouration at the back of the top point plus the hair does not grow on the spot and the stem surface seems to be a bit broken but the rest of the cactus column and its shorter pot partner look perfectly healthy...please can anyone suggest a cause or what I can do? Photo attached

[george76904]

Is it squishy? Because it looks like your cactus may have rot. You said the stem appeared to be broken? Like fattened and split? If so it may be over watering.
Sorry your cactus is sick,
Will

[MadridPeter]

I touched it with a pen and it's not squishy also touched with finger and small spines pricked me...I added a new photo

[george76904]

That picture looks like there may be white fuzzy stuff on the cactus in the problem area. Have you looked into mealy bugs? the white fluff is pretty characteristic.

[greenknight]

There is also dry rot that makes black, dead patches that aren't squishy - the good news is it spreads very slowly if at all. Still would be a good idea to cut that off and get rid of it.

I'd be more worried about the possibility of mealies.

[MadridPeter]

Problem is I don't know if it's mealy bug because the old man cactus has white hair coming from all areola plus one long spine normally ..I think this may be a case of overwatering and not enough light in place I bought it from last week...I probably should use insecticide as a precaution right? I don't think there is rot as the brown hair is the hair that was attached to the part of the stem that burst open I think

[greenknight]

If it's not mushy you can just watch and wait for now, see how it does. No hurry about cutting it off if it is black rot, I've seen cacti that lived for many years with patches of it.

You could try squishing some of those little white tufts with tweezers to see if there's a bug inside. Still, if there's any doubt, a treatment with a systemic insecticide as a precaution is not a bad idea. See this article - http://www.cactiguide.com/cactipests/#mealybugs" onclick="window.open(this.href);return false;

[george76904]

I am behind greenlight, as he is the more experienced cacti owner. I hope that your cactus gets better though!

[Rod Smith]

This appears to be a Cleistocactus strausii and it looks as though the top of the main stem has died. This happened to two of my C. strausii stems last winter and can be due to insufficient water in the dormant season. They don't like their roots to be completely dry. In my case the top third of the stem withered and I eventually cut it off just above the bottom of the dead part. If yours is firm to the touch and not squishy this is probably what has happened. It looks unsightly but new stems will grow, either from the top of the stem or the base of the plant.

[MadridPeter]

I will try that thanks green knight and George..I'd like to avoid any cutting of stems for now

Rod thanks very much for identifying the cactus and from just a top down photo angle! ..I assumed it was cephalocereus sinilis because of its column style stem and white hair ..would you advise me to water it with liquid fertiliser? I reported it after I bought it and touching its soil and roots noticed no moisture

[Rod Smith]

Give it some water without fertiliser till you see signs of growth from somewhere on the plant or from the base. Then give fertiliser in every second or third watering.

[MadridPeter]

Hello Rod! I think after examination of the taller column that it's worse off than I thought because it's spines are brown and have not developed on the top half plus some areola have brown fur ..not many but still ...the top is thinner too with less hair..now it's partner in the pot is a good bit shorter with yellow spines all along its stem and a healthy whack of hair ..I am thinking separation of the too and maybe the taller one is a lost cause...any opinions?

[Rod Smith]

If they are definitely two separate plants I agree you should pot them separately. If the second stem is growing on the same rootstock, you could be drastic and chop down the "dodgy" stem, leaving the "good" stem to continue growing. If you do the latter of the two suggestions, you will almost certainly get some fresh growths appearing from the base. I've had to take drastic action on two occasions with mine. See first photo below, taken in March 2014. I lopped off the two dead sections once they had withered away and am getting good growth now from several other stems. The second & third photos were taken today.

Cleistocactus strausii withering 30 March 2014.jpg (52.8 KiB) Viewed 3991 times

Cleistocactus strausii 18 March 2015 (1).JPG (37.99 KiB) Viewed 3991 times

Cleistocactus strausii 18 March 2015 (2).JPG (37.43 KiB) Viewed 3991 times

[MadridPeter]

Thanks very much you've been a great help and so have others on here..looks like straussi sprout pups from the base like yours all in the same pot..mine are most probably the same plant..so chopping required!