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Plant Diseases/NEEM alternate


QUESTION: Dear Melissa
I have four young Alstonia trees (6-7 feet height) in my garden and 70%-80% leaves of these plants have nipple galls. Should i remove all affected leaves? Wouldn't plants die ? NEEM is not available in my city. What is the other insecticide i can use.

ANSWER: Dear Zuber, I'm sorry to hear that you are not able to get NEEM in your city.  It is a bit ironic, since the Neem tree is native to India.  However, in this case, I don't think NEEM would help with the galls.  By the time the gall forms on the tree, there is pretty much nothing that you can do to get rid of it.  These are caused by small insects which develop in the galls.  The abnormal leaf tissue will usually protect them from any insecticide.  Often even if the insect dies, the gall will continue to grow.  The good news is that the gall doesn't hurt the tree in any way - they are just irritating to look at.  The best way to get rid of these is by prevention, but you will have to wait until next year.  During the winter when the trees are dormant, and then later when the tree has just leafed out and the leaves on the tree are formed, you can spray with a horticultural oil.  Spray the leaves thoroughly and it will smother any pests who have come to make new galls.  Another solution might be to spray the dormant tree and then the new leaves with Spinosad - another organic ingredient.  I'm not sure how easy the Spinosad would be for you to find, and the horticultural oil would be more economical.  I'm sorry there isn't a good way to get rid of the gall, but I hope this information helps you.  Good luck, Melissa

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QUESTION: Dear Melissa
Thanks a lot
I have purchased Neem online. Many online shopping sites are selling it. Should I spray it on unaffected leaves to prevent galls to develop on them or wait till winter.


Dear Zuber, I'm glad you were able to locate NEEM as it is a very useful organic pesticide.  I would probably go ahead and spray the leaves when you get it.  It may not change anything, but if the insects are still making the galls, then you will very likely stop them.  However, if the insects have already passed this stage in their life cycle, then your spraying won't make any difference.  Still, it won't hurt, so I would probably spray.  Then later you can spray in the winter, and again when the leaves have just formed on the trees.  One additional tip that might help - when the trees drop their leaves, I would remove and burn or discard them.  Don't use them for compost and don't leave them lying around, as they may harbor more insects that will have a head start for next year.  Good luck, and I hope next year finds your trees without galls.  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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