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Plant Diseases/Green film on Crown of Thorns


My Crown of Thorns plant have branches that have turned green. There are also some branches that are green at the bottom but have not reached the top. You can also see where the green appears to be spreading up the plant in the thorns. Does my plant have a Fungus, Mold, and how should I correct this issue.
Thank you for your time.

Dear Ellen, Sorry for the delay in answering your question.  You do seem to have a bit of fungus or moss growing on your crown of thorns, but you can probably correct the situation without sprays.  This condition is caused by keeping your plant too wet.  Even though these plants have leaves, they are still considered succulents.  Keep your plant in poor soil, such as a sand-like mixture without much organic material in it.  A soil designed for palms and cacti is ideal.  Water only when the soil is completely dry, and if you have a saucer underneath the plant, be sure to keep this drained and dry at all times.  Fertilize lightly and infrequently, at 1/2 to 1/4 strength, and only when the plant is actively growing.  In addition, this plant should have full sun at least an hour a day.  If you are limited to indoor light, then make sure the plant is in the brightest possible light.  The green moss should dry up quickly on its own, but if you want to remove it more quickly, you could spray the plant with Neem.  Neem is organic and is very handy for small home gardeners and houseplant enthusiasts because it will control insects, spider mites, and fungal conditions.  Your plant should perk up quickly just by drying it out, but if you have more questions, please write back.  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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