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Monday - April 27, 2015

From: Austin, TX
Region: Southwest
Topic: Diseases and Disorders, Pests, Trees
Title: Carolina buckthorn and Neem Oil Spray Damage
Answered by: Anne Van Nest

QUESTION:

It's April, I have a Carolina buckthorn that seemed to be doing well, about 8 feet tall, about 2 years old in part shade. It was putting out new leaves about a month ago and seemed to have infestation of aphids on the new leaves. I sprayed some diluted neem oil on the leaves and after a while all of the new growth turned black and now it has no leaves. I am concerned that it is dying and I am not sure what happened to it. Any insights?

ANSWER:

Sometimes plants do have a bad reaction to neem oil.

Here's what bonnie L. Grant says on the Gardening Know How Website:

How to Apply Neem Oil Foliar Spray

Some plants can be killed by neem oil, especially if it is applied heavily. Before spraying a an entire plant, test a small area on the plant and wait 24 hours to check to see if the leaf has any damage. If there is no damage, then the plant will not be harmed by the neem oil.

Apply neem oil only in indirect light or in the evening to avoid the product burning foliage and allow the preparation to seep into the plant. Also, do not use neem oil in extreme temperatures, either too hot or too cold. Avoid application to plants that are stressed due to drought or over watering.

The good news is that the aphids are probably gone from your Carolina buckthorn, the bad news is that you will have to be patient to see if the tree sends out new leaves (it probably will). Sending out another set of leaves will stress the plant so some TLC will be necessary with some extra water during drought this summer.

From the Image Gallery

Carolina buckthorn
Frangula caroliniana