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Plant Diseases/shrub/star jasmine/gardenia


QUESTION: I am in new homeowner and for the first time I have noticed problems with the leaves on my plants yard. When is my star jasmine the other is a shrub, I  don't know the proper name for, last I think is a gardinia. I tried fertilizer and waiting about a month and still not improving. I wondering if there is a disease infecting them all. I will attach pictures. I just want to save them.

ANSWER: Dear Jennifer, Sorry for the delay in getting back with you.  Unfortunately, you didn't attach the pictures to your question, but not to worry.  I will describe the most common problems with gardenias and jasmines and you can see which problem you think you have.  The first thing about gardenias/jasmines is that they are very acid loving.  They require a lot of iron, and when it runs low, the leaves will look more yellow with green veins running through them.  If your leaves are green on the veins and lighter or yellow on the rest of the leaf, then you have a condition called chlorosis which requires adding iron to the plant.  Get some Ironite and apply according to directions.  If the leaves are brown or dry around the edges, this is caused by either freeze burn or the plant is too dry.  In this case, maybe water more and it will stop freezing soon, if it hasn't already.  If you have brown/black circular spots in the leaves, then you have a fungus, probably Cercospora.  In this case, get the best fungicide you can, and as a fellow Texas, I would look for a product containing the active ingredient Proprioconozole.  Lastly, you could have bumpy spots on the leaves and stems, or perhaps cottony areas.  In this case you have scale (or for the cottony stuff, that would be mealybugs, which is actually a moving form of scale).  To get rid of this, spray with a lightweight horticultural oil to smother these bugs which can't be killed by other insecticides.  You will have to spray several times about a week apart, and you will know they are dead when a moderate stream of water will knock them off.  Oh, you could also have blackened sooty leaves, which could be caused by either scale or aphids, and the horticultural oil will work on them too.  This is pretty much all that can go wrong with this type of plant.  I hope I have addressed your question, but please write back if you have further questions.  Good luck, Melissa

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QUESTION: Thank you so much for your reply. I will find the fungicide and the iron supplement.  I believe that is what is happening to the gardenia and the jasmine.  I was trying to use an android device to send the last message. So I hope this time the pics attach.  One is the jasmine, is the iron deficiency the reason for the red color too?  Also, is the iron problem why the gardenia, has the bald spot on one side of the plant?
Thanks Again!

Dear Jennifer, Yes, the jasmine definitely has a touch of Cercospora, which is the red color you see, although it is very minor.  You could probably just pull off the affected leaves, since there don't seem to be too many, and spray with fungicide once and it will be fine.  As for the gardenia, I think you have a drainage problem.  That is almost always the case when they get bald like that.  You might try to improve the drainage in the area a bit by digging around the plant to get some excess water away from it, move it to another spot, or possibly raise the plant up higher.  You can prune the plant back as well.  It should be in a pretty sunny spot and not be in a wet place in the garden. The only other real reason for them to go bald would be splits and breaks around the stems from some external damage (like a pet jumping on it).  I hope this information helps.  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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