Holly Attacked By Scale?

harryshoe zone6 eastern PennsylvaniaJanuary 8, 2014

Last fall, I noticed many holly leaves looking dull. Plus flying insects buzzing about. Today, I finally did a closer inspection and found what appears to be scale insects.

The top leaf surface is coated. The coating is easily rubbed off revealing a green leaf below. Probably some secretion from the insects which may attract the flys.

The plants affected are large (8'w x 6'h) but seem healthy. The infestation is widespread on both plants. I have a number of other holly nearby.

Do you have any recommendations for treatment?

Thanks

Harry

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rhizo_1 (North AL) zone 7

Cannot access your images without an account.

    Bookmark   January 8, 2014 at 4:31PM
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buckeye15(No OH)

That looks like brown soft scale that has been showing up regularly here in Ohio on Meserve hollies. I have also seen it on inkberry, boxwood, clematis, and Itea. At first I didn't think it would overwinter here in Ohio, but I was wrong. We have seen it build to damaging levels here. It has multiple overlapping generations, and by late summer the plants turn black from all the sooty mold growing on the honeydew (excrement), just like your pics show.

Here is a link that might be useful: Brown soft scale on holly

    Bookmark   January 8, 2014 at 6:18PM
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Kimmsr(4a/5b-MI)

Scale can be a problem on many plants and can be controlled by the many predators they have unless broad spectrum poisons are used that will kill off these insects.
The most common method of control for scale is the use of horticultural oils, dormant oils when the plants are dormant and superior oils when the plants are growing.

Your local office of your Penn State Cooperative Extension Service will have more information.

Here is a link that might be useful: Penn State CES

    Bookmark   January 9, 2014 at 6:35AM
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harryshoe zone6 eastern Pennsylvania

I don't know much about oil sprays. I thought they killed by smothering the pest. That seems a daunting task considering these are large bushes with thousands of small leafs.

Any advice on this operation would be appreciated.

Thanks
Harry

    Bookmark   January 10, 2014 at 2:24PM
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ken_adrian Adrian MI cold Z5

if labeled for holly.. i would use bayer tree and shrub systemic in the appropriate season ... otherwise i would find another systemic ...

one treatment.. done forever ...

presuming i though a holly worth it.. lol ...

i am not that up and personal with specimens.. to want to time out crawler hatch.. and come back a spray ad nauseum for years on end... because i am not good at it ...

ken

    Bookmark   January 10, 2014 at 4:35PM
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Kimmsr(4a/5b-MI)

Horticultural oils have been used for many years for treating scale with good results. Properly applied the oils will coat the scale and cause them to suffocate.
The systemic poisons have been found to get into the nectar that the bees and other pollinators collect and poison them and they are part of the problem with pollinator die off.

    Bookmark   January 11, 2014 at 6:26AM
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rhizo_1 (North AL) zone 7

Kimmsr is correct. It really is important to have knowledge of the ramifications of using a systemic pesticide.

Here's my thought process, for what it's worth.....it has been proved that systemics can be collected in the pollen, nectar, and fruit of treated plants. Therefore, one should assume that anything that consumes those plant products may be ingesting the toxins.

Holliy flowers are hugely attractive to insect pollinators....not just honeybees but an amazing assortment of insects. Anyone who isn't aware of that does not visit their yard very often in the spring! Hollies will be covered with busy and buzzy insects.

Their red berries are an important winter food source for a wide variety of birds and other animals. My overwintering robins, for example, go crazy over ripe holly berries, as do most of the other winter birds.

When a successful alternative to systemic pesticides (horticultural oils) exists, it is irresponsible to use the poisons. I suggest that anyone still wanting to kill scale at all costs consider removing their hollies and replacing them with something less attractive to pollinators and other wildlife.

    Bookmark   January 11, 2014 at 8:07AM
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harryshoe zone6 eastern Pennsylvania

There's no question that these holly bushes are regularly visited by bees and birds. I would prefer to spray with oil.

It would seem to be necessary to coat the underside of every leaf. These bushes have crowded together with their bed mates and are part of my foundation planting. I would likely need to crawl around on hands and knees to get the spray wand where it needs to be.

Best timing for spray cycle?

How damaging is the oil to me? This will be a close range job and hard to avoid inhaling and skin contact.

    Bookmark   January 11, 2014 at 12:53PM
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rhizo_1 (North AL) zone 7

My sprayers have a nozzle attachment that deflects the spray upwards. Perfect for sticking in the middle of thick shrubs and getting the stuff to the underside.

Hort. Oils should not be applied to broad leaf evergreens when temperatures approach freezing or above a hot weather limit on the label. I'd spray a couple of times in the spring before full flower and into the summer and fall.

Oils are considered minimally toxic, but I wouldn't breathe it in or get it in my eyes. It's my habit to wear disposable gloves no matter what I'm spraying, as well as a good mask (not a respirator) . Your lungs are very sensitive organs....don't inhale stuff that can harm them. Even chemically benign horticultural oils should not be inhaled.

Every product is different. Be sure to read and follow the label instructions on whatever you end up purchasing. Temperature restrictions as well as a list of sensitive plants should be reviewed each time you use it. And follow the dilution rates. More is not better!

I've been using assorted oils with success and safety for many years, on evergreens such as hollies as well as a long list of deciduous trees and shrubs.

Regarding the "flying insects " you mentioned. If they were the size of gnats, I'd be very tempted to guess that they might have been beneficial parasitic wasps. They pierce the scale insects in order to lay eggs; their larvae will then feed on the scale from the inside. Once they've developed, the wasps will drill a little exit hole and fly away.

Parasitic wasps do a great job of controlling scale insects and other pests. I've seen swarms of them working my camellias, which often have a smattering of tea scale.

    Bookmark   January 11, 2014 at 3:56PM
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harryshoe zone6 eastern Pennsylvania

I found a small bottle of Bonide oil spray. Mineral oil is the active ingredient. They call it an organic insecticide.

I do have a sprayer with a 30" spray arm.

The flies were pretty large. Almost house fly size. I think they were attracted to the secretion.

Thanks
Harry

    Bookmark   January 13, 2014 at 10:28AM
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EdgewaterForest

Prepare a mixture of used coffee or espresso grounds by weight 1:4 coffee to water. Mix and let it sit in your refrigerator for 12 hours. (Any longer and it will start to turn into liquor.) Strain it and let it come to room temperature before use.

Spray this directly onto your entire plant, every three days for one month. Get a nice pressurized nozzle that will knock off that sooty mold and any dead scale but will still leave the leaves intact.

Keep the plant away from other clean plants.

Also, mulch the soil 6" around the base of the plant, especially around the trunk, with more used grounds. Every time you water the plant, more alkaloids will seep into the root system and kill any dormant or hiding scale insects.

This method saved me from throwing away a 4ft tall bay tree and a 6 year old Ceylon cinnamon tree which was infested by the bay tree being too close.

Make sure you are using organic grounds. Starbucks gives grounds away for free, but they are not certified organic as far as I am aware.

    Bookmark   January 17, 2014 at 5:12PM
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harryshoe zone6 eastern Pennsylvania

Upon further inspection, it appears that a much colder than normal winter has provided a setback for these little devils. Lightly rubbing the leafs removes the insects. They appear to have dried up.

Winter low temps in 2013 were in the teens a few days and warmer most of the time. This year we have seen many nights below zero and many more in single digits. I think this weather has taken its toll.

I will still spray the dormant oil.

    Bookmark   March 11, 2014 at 11:28AM
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ken_adrian Adrian MI cold Z5

i though momma always dies ...

its the eggs under her dead carcass that are the issue ...

did you get out the jewelers loop and see any???

also.. isnt it imperative.. that you hit the wigglers after they hatch.. rather than just oiling down the plant???

any reason you dont want to use bayer systemic??? [i didnt read all the replies above]

ken

    Bookmark   March 11, 2014 at 11:58AM
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