Are my knockout roses ruined?

waggie450May 8, 2010

Help! Something has eaten the leaves on all 7 of my knockout rose bushes. Some of the leaves just have holes in them. However, at the base and in the middle of the bush, it looks like the leaves were literally put through a shredder. It all happened before I knew it. There is also something white on some of the leaves. I'm in Kentucky and it's not all that warm yet, and I had no clue I'd have a problem so early in the year.

I have since sprayed the bushes really well with a product for bugs. I've also removed as many leaf stems as I can at the base of the branch. My question is will the leaves grow back any time soon? The bushes look so bad I am half tempted to dig them all out and purchase new, but if the leaves will start coming back within the month, I'll simply wait it out.

I had a problem with bugs getting one of the bushes last year but only one of them and not this early in the season. I'm wondering if the mulch we brought in had something in it.

Can someone please tell me if and when the leaves will grow back in and if I should get out there and remove the rest of them. I removed quite a few but it's very time consuming. Also, will doing so compromise the bush?

Oh, by the way, the bushes ARE blooming nicely. Just look awful...

Many thanks!

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dan_keil_cr Keil(Illinois z5)

Hold on and don't dig them out yet. Knockout roses are very hardy and carefree. Meaning they will grow without our help. Have you fed them yet? The stems have buds that new leaves will come out on. Just be pantient with the bushes and in a few weeks you will have new leaves.

    Bookmark   May 8, 2010 at 1:45PM
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jim1961 Zone 6a Central Pa.

Taking out your knockouts and replacing them with new KO's
will NOT solve you problem.
You will need to figure out what pest is shredding your roses, then figure out what needs done to help the problem.
New KO's will have the same insect problem.

    Bookmark   May 8, 2010 at 2:35PM
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york_rose

Can you post pictures of the damaged roses? Different critters eat roses in different ways. Posting images of the damage will help us figure out what your likely pest is.

    Bookmark   May 8, 2010 at 2:44PM
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lovemyenglishroses(6)

The same exact thing has happened to all 5 of my knockout roses, and a few of my english roses. I have found small green catepillars all over the bottoms of the leaves. They start out really small, and then get big enough to finally see. I just picked off about 50 or so of them and killed them. I purchased my knockouts last year and they were tiny, and eventually grew to about 4 feet in one season, so I am not too worried about them not growing back. I hope you are able to control your insect problem. It's not fun seeing all of those beautiful roses with completely devoured leaves. If you spray, make sure to spray the bottom of the leaves.

    Bookmark   May 8, 2010 at 3:28PM
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greenhaven(SW MI z6)

lovemyenglishroses, you have sawfly larvae. The OP might, too, but we have no real way of knowing. The best control for sawfly larvae is hand-squishing, even though it can be a painstaking task. if you avoid spraying insecticides the wasps can come in and do their job hunting the larvae. The are very efficient, and fascinating to watch!

    Bookmark   May 8, 2010 at 4:13PM
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karl_bapst_rosenut(5a, NW Indiana)

Spraying insecticides just increases the problem as it kills any natural predatory insects along with the bad guys. It takes awhile to build up a large good guy population and everytime you spray anything toxic, you have to start over from scratch. I've yet to have insect damage kill a rosebush. They've made them look pretty bad in the past but after 7 years I seem to have enough good guys around to handle things. Aside from a few aphids which disappear quickly, I've had no problems with bugs so far this season. If I do see a problem, I'll just look the other way.

    Bookmark   May 8, 2010 at 8:40PM
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zack_lau

I lost a Double Delight to insect damage--not sure what sort of caterpillar looking insect it was--but it was defoliated and never recovered. I was new to rose growing and didn't realize that I needed to do something when I saw those leaves being eaten.

    Bookmark   May 8, 2010 at 9:10PM
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waggie450

Thanks for all your comments and suggestions! When I was outside planting other flowers yesterday, I encountered a few white larvae. Is that the sawfly larvae Greenhaven mentioned? In any case, I got rid of them. I haven't seen any bugs on our roses, which is why I'm not totally sure what's getting them. As everyone suggested, I'll keep an eye on them, remove the affected leaves, and hope for some new leaf growth soon. Someone mentioned posting pics of my bushes. I don't see a place on this post for doing that, so where do you do it?

    Bookmark   May 9, 2010 at 9:29AM
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jim1961 Zone 6a Central Pa.

Posting pics on the forum. You would have to sign -up on photobucket.com, it's free. You would then upload your pics to photobucket, then copy and paste the HTML code (link) provided for each pic into your posts or threads.

    Bookmark   May 9, 2010 at 9:21PM
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melissag

I am having the same problem as waggie450. I have no clue I can see nothing on the leaves. I will try to post a link.

Here is a link that might be useful:

    Bookmark   May 24, 2010 at 10:34PM
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olga_6b

Melissa, your picture suggests damage from sawfly larvae. Don't know what part of the country you are in. In my MD garden by now sawfly larvae is gone, but the damage is here. You can look undersides of leaves. If you see green worms looking like caterpillars, they are sawfly larve. But as I already mentioned, it could be that there are already no larve, it was eaten by benefiicial insects, if you didn't spray any insecticides. The new leaves will grow fast if there is enough water and sun and your soil is reasonable. If you want you can give your roses a litle of fertilizer or compost to speed the growth of new leaves.
Olga

    Bookmark   May 25, 2010 at 5:55AM
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melissag

Olga,

Thanks I was doing more research last night on the forums and that is what it looks like. I live Northern KY also. I have finally treated with a different insecticide yesterday because what I used originally did not work.

    Bookmark   May 25, 2010 at 10:12AM
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olga_6b

I personally never use insecticide for sawfly larvae. When I notice first signs of damage in spring, I just use my finger to sqish them. If you catch this problem at early stage, it is very easy to take care of. And beneficial insects will help. If you start spraying insecticides, you kill everything, good and bad. In a long run there is more damage thean benfit. You need good bugs to deal with aphids, thrips, etc. You kill all your natural supporters.
Olga

    Bookmark   May 25, 2010 at 3:44PM
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wmarkw

I've noticed quite a few Jap beetles the last few days. They are eating up my leaves and blooms on my KO roses. I have been knocking them off and trying to kill them.

I also applied Bayer 2-1 rose/flower care granules a couple of weeks back and it states on the lable that it kills adult Japanese Beetles. Well I've seen plenty humping and eating away so not sure if it is working. Have any of you had any luck with this product? I also read that you can spray soap/water on your plants as well?

    Bookmark   May 25, 2010 at 4:34PM
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henry_kuska

wmarkw, this product (Bayer 2 in 1) is based on disulfoton, which (to my understanding) the EPA has banned. See the following link which states (according to my interpretation) that Bayer 2 in 1 (432-1286) can not be sold after December 31, 2010.

The EPA information is at: http://www.epa.gov/fedrgstr/EPA-PEST/2009/September/Day-23/p22921.htm

--------------------------------------------------

As to why it can no longer be sold, the following may be "eye-opening" :

"Hazard Rankings
More hazardous than most chemicals in 6 out of 7 ranking systems.
Ranked as one of the most hazardous compounds (worst 10%) to human health."

The above quote taken from:

http://scorecard.org/chemical-profiles/summary.tcl?edf_substance_id=298-04-4

------------------------------------
The summary in the following link:
http://news.agropages.com/News/NewsDetail---1739.htm
may be easier to read than the EPA page.

Here is a link that might be useful: scorecard link for above

    Bookmark   May 25, 2010 at 8:51PM
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mintboxer

At the beginning of the summer I purchased a Terminix All Clear Mister to deal with the mosquitoes in my back yard. It works very well on all flying pests. I bought the All Clear natural concentrate to use in it which is virtually chemical free and harmless to humans, pets and plants. This past weekend I noticed my knockout rose bushes were almost decimated of their leaves. Once I found out they were infested with sawfly larvae, I figured I would try the mister on the plants, since the suggestions posted here seemed very time consuming and not very effective. I placed the mister in close proximity to the rose bushes and gave them 2 five minute misting sessions. When I checked the bushes this morning, dead larvae were everywhere on the ground around the plants, and none appeared to be on the leaves anymore. Hope this helps!

    Bookmark   September 22, 2014 at 7:37PM
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michaelg(7a NC Mts)

mintboxer,

Thanks, this is interesting. The active ingredient used in the Terminix mister is geraniol, a natural ingredient that occurs in rose oil and is secreted by honeybees.

    Bookmark   September 23, 2014 at 10:17AM
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catsrose(VA 6)

Thank you, Michael, for checking the ingredients!

    Bookmark   September 24, 2014 at 9:32AM
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