BROWN MARKING ON CACTI

[Philip Greswell]

I would be interested to know if anyone has taken the time to examine this topic in any detail.i have just started looking having accepted the marking for some years. in fact not observing the plant too closely until now when for some reason i have decided to look at it more closely.

we know brown marking can be caused by too low temperatures in the winter.also by red spider and pathogens such as bacteria.is there anything else ? over watering? sun too hot.old age.poor health.

we also know that some plants are not affected but others are more prone to marking such as gymnocalyciums and thelocactus, but there are others. for example, some lobivias,denmosa,melocactus( the latter which are kept warm for the winter so it isn't the cold that is doing it)

a badly marked gymnocalycium has a corky layer under the spines which can be levered off with a pen knife, areole spines and all.

the marks can be a single patch, marking along the ribs, marking between the ribs.spots and lines, marking on the end of tubercles,marking on one side and not the other side.lines between the ribs of a denmosa which appeared last year are getting thicker,perhaps as the girth expands when new flesh is growing?

i have ordered a pocket jewellers lens to check all the marked plants to see if there is any red spider in any of these marks,although my experience of red spider is it quickly turn a green cactus in to brown one very quickly, which is then not worth keeping, the plant having been ruined.

it is the bacteria or the funghi i am interested in as the possible causes!.for example, i have some small brown blobs/circular marks appearing in the past couple of weeks or so on trichocereus crest and a baby matucana as well if they are a bacteria are they air born or from the rain water from the water butts .

i am told such marks will eventually grow out? but if it is a bacteria, will it? and is i worth the wait

any thoughts on what might be the causes, how it happens and spreads and how to control it or prevent it from happening would be of interest. my greenhouses are well ventilated.although the number of plants is small when compared to the total collection, it nevertheless is annoying when for some unknown reason brown marks appear such as with the trichocereus and matucana i mentioned.

[Aiko]

Your caps lock was stuck, it seems...
I will not strain my eyes trying to read through that.

[rodsmith]

Your caps lock was stuck, it seems...
I will not strain my eyes trying to read through that.

Ditto.

[daniel82]

From my own experience I personally find brown marks are usually caused by too low temperatures in winter and natural corking due to age. Both look different, cold producing distinct areas whereas corking is usually uniform from the base up and isn't always disfiguring. Marking from mites is nearly always at the top of the plant and almost looks like a dysting of rust on the plant, very different to other marking. Random dots or circles can quite often be traced back to plants being pricked by the spines of a neighbour, sometimes in transport, sometimes due to pots being crammed closely together.

Also while mite damage is unsightly, they usually grow through it really well and (depending on the species) within a season or two it can almost unnoticeable.

[MikeT]

There are lots of different kinds of brown marks. Most damaged tissue will end up some shade of brown, if it scars rather than rotting. The brown may be damage, in which case the pattern/distribution may help to indicate the cause; but brown marks can also be normal, especially on older tissue in some species. Without a picture of the plant in question, it's difficult to narrow down the many ways a plant can be damaged.

[Philip Greswell]

Caps lock no longer there so, if you have anything to add, I look forward to hearing from you.

Thank you Daniel and Mike for your responses.

[MikeT]

We really need a picture to make any meaningful comments

[Peter]

I reckon that the reasons for brown marking can be complex. In my experience, simply turning, moving or repotting a plant can cause distress leading to such disfigurement.

[Philip Greswell]

Thank you Peter. That is interesting.

Philip

[Philip Greswell]

Thank you Mike for suggesting I provide pictures of the marking.I have just asked Bill how I go about doing this.There will be many pictures to illustrate the problem, but as you say, for more meaningful comment, pictures are required.

I am grateful for the comments received.It must be an issue that affects everybody but asking around, few people know what the causes are or, if as it seems, they are so many, it is just not possible to say what they are in a brief conversation.

So far, the question of damage being caused by bacteria or fungi has not been mentioned so if anyone can comment on this aspect, I would be very pleased to hear from you.For example,

How to avoid or prevent it ....spray vulnerable species with systemic fungicides...albeit there is only one I have seen for sale.

The conditions required for it to get hold....high humidity, a more delicate epidermis

The times of year it can happen,but this may depend on the type of bacteria.

Whether bacteria can survive in water butts and if water born bacteria would survive on a cactus.

Thanks again.