carolyn

rose of sharon tree

:roll:
When blooming season arrives my rose of sharon flower buds barely open only to turn yellow and die. What would a solution be for this problem?

The Helpful Gardener
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Hibiscus syriacus (Rose of Sharon) is a voracious feeder and may be dropping the buds to retain energy. Try some heavy feeding in spring and early summer, and then back off as flowering approaches (The foliage would be getting sparse and a touch yellowy if I'm right here...)

Scott

Newt
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Hi Carolyn,
Bud drop can be caused by too much water, not enough water or too much fertilizer. If your ROS is planted in or near a lawn that gets fertilized regularly, that could be the cause. Take a look here.

There is also a flower blight that affects ROS. It's called Botrytis cinerea.
https://members.tripod.com/~h_syriacus/diseases.htm

The site I recommended above recommends using Benomyl as a fungicide. I DO NOT recommend it's use. Take a look here as to why.
https://www.pan-uk.org/pestnews/actives/benomyl.htm

Take a look here for an environmentally friendly solution.
https://gardensalive.com/item_display.asp?ProductNumber=2313

Newt

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Thanks Newt!

Newt
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Scott, you're welcome! :D
Newt

Carolyn

Rjose of Sharron

Newt wrote:Hi Carolyn,
Bud drop can be caused by too much water, not enough water or too much fertilizer. If your ROS is planted in or near a lawn that gets fertilized regularly, that could be the cause. Take a look here.

There is also a flower blight that affects ROS. It's called Botrytis cinerea.
https://members.tripod.com/~h_syriacus/diseases.htm

The site I recommended above recommends using Benomyl as a fungicide. I DO NOT recommend it's use. Take a look here as to why.
https://www.pan-uk.org/pestnews/actives/benomyl.htm

Take a look here for an environmentally friendly solution.
https://gardensalive.com/item_display.asp?ProductNumber=2313

Newt


Thanks for your information. It was really helpful. Do you think it would help to prune this fall. The tree was planted last year. Thanks

Newt
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Joined: Wed May 26, 2004 2:44 am
Location: Maryland zone 7

Carolyn,
You're very welcome. I'm glad you found the information helpful, but you haven't shared with us what is wrong with your ROS, so I can't say if pruning would help. Scott and I gave you a few possibilities. Besides, what are you pruning for - to remove damaged wood, to shape, to remove diseased wood? If wood is diseased, the pruners should be dipped in a solution of one part bleach to 9 parts water after each cut.

You said it was planted last year. I'm wondering if you have the receipt as many nurseries give a one year guarantee. Also, was it rootbound when it was planted? If so, that could be the problem.
https://msucares.com/lawn/tree_diseases/images/rootball.gif


Pruning a ROS is best done in late winter - February. You don't want to prune and possibly cause a flush of growth that won't have time to harden off before frost. If a shrub blooms in spring, best to prune after blooming and if it blooms in summer or fall, prune in late winter.

Newt

Carolyn

Rose of Sharron-Buds won't open

Sorry I wasn't quite clear. What happens is my rose of Sharron Tree looks great during the summer green leaves and all. In late fall the flower buds appear look healthy but do not open or blossom into flowers they stay as large buds but eventually turn yellow ,dry out and fall off. We have had an unually wet summer in south western Ontario. I should add that I planted the ROS in late fall of last year. Maybe that has had an affect on the flowering this year but the buds didn't open last year either, They were formed when we planted but never blossomed. I hope this makes some sense to you because I'm getting very frustrated with this ROS.

Newt
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Carolyn, no problem! Been there. With your description, it sure sounds like blight, and it came with it! Try one of the first three here.

https://www.dirtdoctor.com/view_question.php?id=204

Hope this helps,
Newt

The Helpful Gardener
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Carolyn, you're in good hands...

Scott

Newt
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Scott,
Thank you!! :oops:

Newt

bentonstreet
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Joined: Wed Apr 27, 2005 12:29 pm

Rose of Sharon buds not opening

I have 12 different Althea (Rose of Sharon). Mostly tree form. For the last several years one of them has produced tons of buds but no flowers and last year a second one has shown the same problem. These affected plants are over 200 feet apart with 10 unaffected plants between them. Every body gets the same sun, water and fertility dance. Whatever is on them is sucking the buds dry and not affecting the leaves, stems or branches. It looks like little white fuzzy balls on the tips of the buds only. The white stuff does not move around. Every other part of the plant looks healthy. Nothing on the leaves, nodes, crotches, etc.. The buds do not turn yellow and drop off. The just stay there until late fall. I have dissected the buds and can find no evidence of any insect. Nothing is in the bud. I have tried every version of alcohol, soap concoction known to man. That gets rid of some but not all of the white stuff and 2 days later it is back. I have tried fungus sprays. I have tried insect sprays. I have sprayed the plant. I have sprayed the ground. I have not done a snake dance yet..... I can send you photos. I have talked to all of the garden centers in my area and shown them photos. They have been of no help. My county extension office after seeing photos says that their "BEST GUESS" is that it is a viral thing and I should remove the 7' tall affected plants.... "BEST GUESS!!!!!"... My guess is that they should not quit their day job. I know it is NOT mealy bugs. I am in zone 5b. I find it hard to believe that I can be the only person experiencing this problem.

Ron
rvb103@comcast.net[/img]

The Helpful Gardener
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The fact that infects only two trees after all this time makes me think they are probably right about the virus, and then the solution is as they say. You can drive virus out of a plant by holding the temperature over 85 degrees for two weeks, but labs are the only place I've seen them pull that one off. Could just try to increase the vigor of those plants with micorrhizae, potash and the like but I don't think you will get rid of it. The lack of other infections, futility of fungicides (I think the white at the bud tip was likely fungal, but suspect it is secondary, and not the primary pathogen) really do point to virus. All ANY nurseryman, biologist or stock jockey at the big box store CAN do is guess; without testing at the lab level it's ALL a guess. More education makes for better guesses, but I'm guessing too! :roll:

Cut some infected material, bag and seal it, and send it to your state Agricultural experiment station. You pay their salaries and that's what you pay them for. If you are looking for a definitive answer that's your best (free) bet...

Scott

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