The MGS Forum
Gardening in mediterranean climates => Pests and diseases => Topic started by: saldemain on January 27, 2015, 12:22:12 PM
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Has anybody witnessed a fungal/bacterial problem with the Leaves on Aloe arborescens ? It does look like Frost damage where the lower leaves turn black and eventually the whole plant shrivels ? It does take some time though. It isn't frost damage as it happens throughout summer also, and one plant can be fine standing next to a contaminated plant . I cant look up on the internet as the only hits I get is Aloe ...................cure for cancer :( I am in the Algarve / Portugal.
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I also experience some 'diseases' with Aloe arborescens and one of it's hybrids ANZAC. I have watched my plants and several large banks of them in old plantations in parks and gardens on the Adelaide Plains for some years now. My conclusions are that the plants are susceptible to cold and excessive damp in Winter as well as frost. Sometimes the leaves develop large black spots but sometimes whole plants die. This can take a very long time to happen and by the time I've noticed the severity of the damage it is too late to save the plant. I think the stem gets damaged to the point of rotting through but as it is comparatively woody it doesn't collapse and an observer is easily led to think things are OK. But gradually the leaves begin to show signs of die-back, blackening spots and eventually complete 'death'. I live approx. 350m above Adelaide and the altitude seems to make the difference as it is colder and much damper here in Winter; not just rain and hail but endless days of fog and deep cloud cover which I think are probably alien to the natural conditions in which this aloe grows. There are aloes that grow at high altitudes in Sth Africa and get regular Winter snows but they are not the 'arborescent' tree-form species, rather compact, ground hugging rosettes such as Aloe polyphylla. Hope this helps.
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Me too, I'm afraid. Lost one potted plant this summer - so not cold or dampness. Started to rot at soil level. Cutting the healthy stems off and leaving them to dry hoping to plant them on was largely a failure. Only one stem out of about 9 or 10 has survived and I haven't planted that one yet. Fingers crossed that when I do plant it the whole process of rotting from the bottom up doesn't start again.
By the way, all the other succulents which are around it, different species but including other Aloe species, have not suffered at all. ???
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I was hoping for a pathogen ............... a treatable one as opposed to environmental problems !! I was suspecting a fungal problem, although no spores have been spotted ( scuse the pun ), well I was hoping only because it could have been treated. then I thought bacterial because of the blackening leaves. I haven't looked at the bases of the stems to see any rot, will check and maybe some photos ............. I just hate not knowing !!
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To re-root big Aloe cuttings: first make sure the cut face of the stem shows ABSOLUTELY no tell-tale patches of rot infected tissue; the usual colour is pale greenish-cream-white. Infected tissue looks brownish and sometimes translucent-ish. Second, make absolutely certain the cut face is completely dry with no signs of weeping sap. Third, plant the cutting/ trunk upright. Fourth, plant the cutting in DRY sand (Builders sand) Fifth - NO WATERING, NO FEEDING. Sixth, WAIT. It make take 6 months or longer so make certain it is in bright light, dry atmospheric conditions and safe from rats and mice and 100% protected from frost and freezing. ::)