Need help identifying what is eating my summersweet shrub

8 years ago

Early this spring my wife pruned our summersweet shrub almost to the ground, mistakenly thinking it was a different kind of plant. I was going to throw it out but planted the remains in a pot and kept it watered all summer. After a month or two it started showing signs of life and produced two stems which grew leaves. When the weather turned cold I decided to bring it indoors and have it in a laundry room sitting next to a south facing window. Lately though, I've noticed that some of the leaves seem to be brown and curled up on the edges and others appear to have been chewed up. I've mixed together an insecticidal soap solution of Dawn, canola oil and water and have sprayed it a couple of times within the past two weeks. I'm not sure if this did anything as there doesn't seem to be a change at all. Anyone have any ideas what I am dealing with and how to go about correcting it? Thanks

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rhizo_1 (North AL) zone 7

8 years ago

A thorough search will inform you that dish detergents are infamous for causing injury to plants. Dawn detergent, advertised as a super-duper grease buster is one of the worst.

These products can destroy the cuticle, the protective waxy coating of the epidermal cells. The cuticle is a plant's first defense against the world, and has the task of keeping the good stuff in.

Commercially manufactured insecticidal soaps are superior at killing soft bodied pests without harming the plant's protective layer. The next time that you have properly identified a plant pest such as spider mites, aphids, scale nymphs, etc., a real insecticidal soap might be the way to go. ID of the pest is important, though.

I agree with others who have opined that the problems shown appear to be environmental. Watering with a cup of water every two or three days seems extremely excessive. We measure watering requirements by frequency not volume because a containerized plant should be drenched fully on each watering day. The frequency is dependent upon numerous factors. I have plants that are watered once every month or so in the winter, determined by what the potting medium feels like, for example.

That this is a hardy, deciduous plant makes it extra susceptible to issues when brought inside. That was also faulty advice, absolutely. I think that I might have left it in the ground. Most plants do very well when cut back to the ground, bursting with new growth in the spring.

Alternatively, since you did dig it up, it would probably have wintered nicely in an unheated garage with very infrequent watering. By the way, though summersweet does okay in moist outdoor soil, one always needs to be extremely careful when growing in containers.

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Comments (11)

Dave in NoVA • N. Virginia • zone 7A
8 years ago
maybe lack of humidity
gardengal48 (PNW Z8/9)
8 years ago
last modified: 8 years ago
Not an insect problem :-) Likely some sort of watering issue. Also, this plant really wants to be dormant at this time of year and preventing it from entering a natural period of dormancy can shorten its lifespan and will definitely affect any flowering.

You don't say where you are located but is there any reason this can't be outside? It is extremely cold tolerant. Or at the very least in a very cool (40F) location? Having it in a warm house on a window sill is NOT doing it any good!
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Dave Sal
Original Author
8 years ago
Thanks both of you for your comments. The humidity is fine, but I read somewhere that it was OK to bring it in for the winter since it was barely alive. I wanted it to have the best chance of survival. I'm in the Chicago area and it's about 10 degrees outside right now and don't want to kill it. Should I take it outside when it gets a bit warmer? I've also read that it likes moist soil, but not too moist so I water it with about a cup or two every three days or so.
User
8 years ago
What's the humidity at? If it's 10° outside you have the heat running, and unless you are actively providing humidity your air is going to dry out..

What type of potting soil is it in? Are you checking manually to see how dry the soil is before watering, or are you just watering regardless?
ken_adrian Adrian MI cold Z5
8 years ago
dawn is a detergent not a horticultural soap ..

canola oil is not a horticultural oil ...

you did not make a 'horticultural soap solution' imo ...

you started loving it to death.. when you brought it inside ... the best you can do.. is hope you can squeak thru indoors.. treating it as a houseplant ... even if you can.. i would not expect it to look really good by then.. but i wouldnt care.. as long as it shows some life ...

you can not throw it outside without proper hardening off .... and i dont know how you would do that in your part of the world ... this time of year ...

you might do better if you had it under lights for about 16 hours per day ... to ir 3 inches from the light .... winter days are real short.. with weak sun.. and modern windows stop some of the good stuff leaves need ..

water properly.. and hope for the best ... it should be dormant or in winter slow down.. imo.. fert is not an option ...

ken
Dave Sal
Original Author
8 years ago
I have a whole house humidifier (Aprilaire 600M) and the indoor humidity is about 40 at the moment. The insecticidal soap that I made was from a recipe that was suggested online as a cheap alternative that works. I guess I will only water when the potting soil is dry (Miracle Grow brand potting soil) and try to give it as much light as possible. I regret bringing it inside now, but again, I checked before I did and read that it would be good since it might not survive outside in the state that it was in. Thanks for all the responses.
Dave Sal
Original Author
8 years ago
Thanks rhizo_1, for the excellent, informative post. I guess I read some incorrect information and have been dealing with this plant all wrong. Since it's still very cold here (-1 Fahrenheit) I don't think putting it in the detached, unheated garage would be beneficial. It will be warming up into the 20's next week and I'm wondering if it might be OK to move it out there at that time. I'll also cut back on watering and check the soil before I do.
Dave in NoVA • N. Virginia • zone 7A
8 years ago
last modified: 8 years ago
Since it's not dormant, I would think exposing it to outside sub-freezing temps might kill it. Not sure. I would keep it as cool as possible -- just above freezing to maybe 55 degrees, if you can. Perhaps you can induce dormancy.
gardengal48 (PNW Z8/9)
8 years ago
I'd be inclined to follow Dave's advice.......attempting to move outside now would likely be too much of a shock to the plant. But it will not thrive under normal indoor conditions either. Keep as cool as you possibly can and with luck it will enter a short dormant period. Doesn't really matter too much about light if you can induce dormancy, as photosynthesis will halt for that period. Cold basement closet or root cellar available? Attic?
Dave Sal
Original Author
8 years ago
Unfortunately I don't have any place like an attic or basement that is at the appropriate temperature. Since I insulated the rim joists in my crawlspace it stays around 63 degrees all year round. Attic is basically at the same temps as outside air. I guess I'll just have to cross my fingers and hope it survives until spring when I can move it back outside and replant it. I assume this is not a plant to keep in a large pot all year round. Thanks again for the replies.