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Plant Diseases/Diseased Euphorbia trigona


diseased cactus
diseased cactus  
I have had My cactus for about a year and as i have learned more about them i have released that she is perhaps diseased.
I got her from my sister where it had been left behind by the previous owners of her house. So i know little of how she was cared for.
I have recently re-potted her.
As you will see from the picture she is red at the top and corky brown at the bottom.
I live in Scotland where it can be cold but she is an indoor plant of course
I would really appreciate any help and advice regarding this.

Dear Eve, Your Euphorbia is beautiful, and there may only be a little bit wrong with it.  In general, when these plants get larger, the bottom of the plant will become more corky at the bottom.  The red/bronze color of new foliage is also normal.  These are relatively problem free plants, and you only have to remember a few things: they don't like to be too cold, too shady, or too wet.  So long as you take care of these three requirements your plant should last virtually forever.  If it is very cold during the winter, it may look a bit worse, but should perk back up in the springtime.  Also, keep the plant in as much sun as possible (though they generally stay next to windows).  Also, make sure you don't water the plant too often.  Once every week or two is plenty.  Don't water until the soil seems completely dry.  Your soil does look quite porous, which is good for draining water, but you want to have the soil fairly compact so the plant feels steady and rigid in the pot.  Make sure when you water, if you have a saucer underneath you should drain it after watering.  Your plant doesn't look unhealthy actually, but if you are concerned about it developing a fungus, I would just reduce the water, and cut off any part that may be rotten.  (I didn't see anything that looked bad.)  You could spray with a fungicide if concerned, but I don't think I would do that. Most problems with Euphorbia can be solved by just drying the plant out.  They tend to develop spots of 'character' as they become older, and more corkiness, but that doesn't mean there is a disease.  I hope this information helps.  I think your plant looks quite healthy and beautiful.  Please write back if you have any further questions.  If you do have any 'mushy' spots, you can simply cut these off and the plant will be fine.  If you do get a mushy spot, reduce watering.  Good luck, Melissa

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Melissa Johnston


Plant diseases, landscaping, tropical plants, roses, herbs, plant care, grafting, horticulture, plant identification, anything about plants I can likely answer.


35 years experience in various plant businesses, 1984 Certified Texas Master Gardener.

Master Gardener Association of Texas charter member

none as of yet, but I have a plant q&a book I am in process of submitting.

Magna cum laude graduate of Texas A&M, 1978

Awards and Honors
Plant growing awards, highest grade for Texas Master Gardener graduates.

Past/Present Clients
Past member of and was very highly rated. Owned landscape company in the past, Almost Paradise, and was very successful despite little equipment, no help, and no advertising. Lived well for two years until 9/11.

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