Dormant Oil on Crepe Myrtles

9 years ago

I have a few Crepe Myrtles that tend to suffer from aphids and possibly scale. I'd like to use dormant oil on them this year to see if it improves the situation. I have a few questions:

1. What kind of oil should I use?
2. When should I apply it?
3. How many applications should I do?

Also, if aphids are bad in my garden, should I go ahead and spray all my deciduous trees with dormant oil?

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Comments (10)

ken_adrian Adrian MI cold Z5
9 years ago
dormant oils work by smothering what is actually there ... so it can not be used... prophylactically ... as a preventative ...

regardless .... no matter what you use.. you need to fully ID the problem .... and then act accordingly ... we prefer not to guess about what is going on ... else we waste product ... time.. and money ...

ken
rusty_blackhaw
9 years ago
There are lightweight oils that should be safe to spray whether or not your crepes are in active growth - check label instructions for types of pests that will be controlled.

I doubt that spraying deciduous trees (if this is even feasible) will do much for control of aphids in the rest of the garden.
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where in the world did you come up with the witches brew of soap and cooking oil ... are you a witch????? oiling leaves in the heat of summer.. can do more harm than any aphid will ever do ... i agree ... if the aphids are gone.. the black stuff will disappear.. if you dont kill the tree first ... when that happens.. only time will tell ... once it isnt being replaced or built up every day ... then every rain shower will reduce it ... my only suggestion ... is that you insure that there is no scale.. because they do the same thing.. and your witches brew will have no impact on them .. good luck... ken
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rhizo_1 (North AL) zone 7
9 years ago
Dandy, glad I saw this and can save you from ken, lol. Crape myrtles benefit greatly by horticultural oil applied during the dormant season.

Most (not all) species of aphids overwinter as eggs on the above ground parts of woody plants. There is a particular aphid that infests ONLY crape myrtles, and it just happens to be one of those egg layers, lucky for us.

Insect eggs, just like all others, are gas permeable. The oil will smother the eggs very effectively, making a big dent in the numbers of aphids we have to deal with in the spring. Dormant oil applications break the cycle.

For dormant season purposes, I'd recommend a refined petroleum product such as Volke Oil, which has been around for generations. But, you can also use any one of the commercial products that are so readily available. Read labels at the garden center to make sure that you don't purchase something with a bunch of unwanted chemicals.

Read and follow the directions carefully, as always.

It can be applied any time during the dormant season, three times over the course of the season with the last one just before the buds open in late spring. For the Crapemyrtle Aphid, be sure to spray the dormant buds and stem axils.

As far as the rest of your garden, I wouldn't spray oils unnecessarily. Save it for those plants with known aphid or scale problems, when it can be very useful.

Remember, Crapemyrtle Aphids are a big issue for crapes only. Plus, not all varieties of crapemyrtles are susceptible. It would be well worth your time and money to buy cultivars that that have been bred for resistance to such pesky problems like aphids and powdery mildew.

Here is a link that might be useful: Click me
ken_adrian Adrian MI cold Z5
9 years ago
just cant help yourself.. to answering a question.. without denigrating others.. eh rhiz ...

pshaw

your answer would have been the same without the gratuitous insult ....

ken
rhizo_1 (North AL) zone 7
9 years ago
Aw, cmon, ken. I was just kidding around....that's what the "lol" is for! I KNOW that you can take it, as often as you dish it out.

But I am sorry that your feelings were hurt. I'm not in the habit of denigrating.
oberci
Original Author
9 years ago
I have the Bonide spray that I use on my fruit trees and was thinking of using that.

I'm aware that some cultivars are more susceptible, but there is no way I'm taking these trees out and starting fresh. The problem is not huge but I would like to do my part to help the trees.

They also need a bit of pruning--just low hanging branches, crowded branches, etc. (No Crape Murder, I promise) and I was wondering if I should do this before or after I spray? Or does this matter?
brandon7 TN_zone7
9 years ago
I would spray first because, as Rhizo mentioned, the spray should be done during the dormant season. The best time for most pruning would be in late winter/very early spring. I wouldn't spray and prune at the same time, but the relative timing isn't going to be important.
rhizo_1 (North AL) zone 7
9 years ago
dandy, is the Bonide product an oil spray.....Bonide makes a lot of different products? I'm pretty sure that mine is Bonide; is yours a paraffin oil? I've been pleased with the results.

Lol....I would prune first....less surface area to spray, and fewer crannies for the aphids to hide their eggs. But as Brandon says, doesn't matter all that much.
blakrab Centex
9 years ago
The other option is like a bad NBA team tanking the season vying for lottery picks...

Crepe myrtles can be very prone to sap sucker infestations...but if you let it get bad enough...they will eventually (maybe by the end of the same season) attract a large colony of ladybugs to devour a large majority of them.

Or the other even better option is to (think outside the Big Box &) just plant something more resistant like a Texas Persimmon, Pineapple Guava or Rusty Blackhaw to begin with, instead...

This post was edited by blakrab on Sun, Jan 18, 15 at 20:46
brandon7 TN_zone7
9 years ago
You might also check with a local extension agent and see what they recommend. I imagine that dealing with crApe myrtle problems in your climate could be very different than what some of us experience in our areas. Your local extension agent should be very familiar with how to best deal with your issue in your climate.