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Hi. For 13 years, my flowering shrubs had no issues. Then suddenly in 2017, one of them came up with a lot of scale with white honeydew. The undersides of the branches looked like popcorn. By 2018, many of the branches died despite my efforts (picture 4, with now bare center). The scale has now moved to the neighboring flowering shrub (picture 3). It is infested badly (pics 1 and 2). All the white specs are scale (disregard the white gloved finger, lol) They come back every spring now. I don't know why they suddenly arrived in 2017, but they are not going away. I soaked the shrub 3 times with Ortho. My procedure has been to soak with Ortho and then hose the scale off the plant after a rain. Often, the damage is already done.

I need to stop them! What can I do to prevent them from attacking my flowering shrubs every spring? Rather than trying to attack them when they are already bound to the branches, I'd prefer to prevent them from getting to the branches to begin with. Any ideas are appreciated. Thank you!

My answer may or may not help your situation, but within my organically gardening paradigm, my perception of scale is mostly as indoor pest that can appear on overwintering plants — and along with mites which are also difficult to control when heavily infested, my solution has been to keep the plant alive until warm enough for the plant to survive outdoors in spring, then put them out where the first blooms attract beneficial parasitic insects.

I don’t always know exactly what the beneficial organisms are present — predatory wasps and flies, and spiders earlier in the season, possibly joined by ladybugs, green lacewings, praying mantises, assassin bugs, etc. later when it’s warmer — but I know they are out there among my Garden Patrol because the plants usually recover.

Due to the same natural guardianship, my outdoor garden plants generally are not hard hit by things like scale. Shrubs and trees are also visited by birds like chickadees, titmouses (titmice?), nuthatches, that definitely appear to be pecking and scraping things from the bark, and possibly finches and wrens and passing kinglets and warblers although they might only be dining on softer bodied aphids and such.

...so from my perspective, by constantly treating your plants — and thereby the surrounding area and vegetation — with strong -cides like Ortho (whichever one you are using), the beneficial insects and organisms that probably gather to the infestation are killed along with the pests, and then usually it’s some the pests are the ones that survive or come back faster and re-infest without predators to control them. Depending on chemicals being used, they maybe harmful to predators on higher levels like birds as well.


There are some reference to beneficial and parasitic wasps and other insects here:

Scale Insects | Horticulture and Home Pest News
https://hortnews.extension.iastate.edu/scale-insects

Hi Applestar. The link to that article was extremely helpful, especially in that it focuses on the exact scale pest that I'm encountering. I could only wish that the natural predators could control the infestation. But as the article references, if the natural predators can't keep up and the plant is suffering, more drastic measures must be taken. It seems my approach was on track...a combination of chemical sprays and mechanical control.

But the article also answers my question, which is what to do to prevent the scale from getting to the branches in the first place...starting with dormant oil in early spring by treating the entire plant with horticultural oil. I am already using a natural horticultural oil to control ninebark fungus. Maybe the same mixture can be used next spring on the ornamental shrubs. I'll research that, as I prefer natural means when possible. Then I need to use the Ortho PRIOR to actually seeing the honeydew, in order to kill the crawlers BEFORE they set up shop and put up the protective cover that shields them from treatments so that they can feed and lay their eggs.

So I can do more next spring rather than simply inspecting and hoping that I don't see more "popcorn". And I WILL do more. What I have to realize is that whether it's fungus on my ninebarks, or borers attacking my dogwoods, or now scale infesting my ornamental shrubs...the problem never goes away on it's own no matter how much I wish for it. I need to be more proactive, especially early spring.

Thanks for your help! Much appreciated.

Glad the article helped I wondered if the hort oil spray could be the missing step in your regimen, but since I don’t spray, I wasn’t confident in voicing my opinion.

As Apple noted, I have also not had problems with scale outside - only on my indoor potted plants, mainly starting on my curry tree. Everything went two years without scale, after being repotted, and I put some DE in the mix, plus I brushed some tanglefoot on the trunks, which I figured would help keep the ants out - when I would see scale, I would see ants, which farm them, like aphids, for that honeydew.

The thing that I found that helped kill them best is orange oil, which was more effective than plain horticultural oil, or neem oil. However, the orange oil left brown spots on the leaves of the curry tree, though it didn't bother the lime trees or bay laurel. The scale would die quickly, then wash off fairly easily. This year I used half orange oil and half neem oil, which worked well, though still spotted the curry leaves.

I do have scale problems. I have a different species of scale called a peach scale and the papaya mealy bug. Both of these are very difficult to control. I the papaya mealy bug on the papaya. The entire underside of the leaves were covered in white mealy bugs and the trunk was also covered. When it gets that bad, the only thing to do is bag and trash. I have a hard scale (peach scale) that likes to go on the roses, peppers, papaya, hibiscus and other plants. It is extremely resistant to chemicals and even merit could not kill it. I have had to severely cut back the heavily infested plants or I have had to just get rid of the plants because I also had root mealybugs which are opportunistic and difficult to kill especially if the plant is already weak.

I have stopped treating anything specifically for this type of scale or mealybug. I do treat the roses for blackspot and the hibiscus for erineum mites with Bayer Rose care (imidicloprid + fungicide). Actually, I usually get the 2 in 1 rose care without the fertilizer since I fertilize the roses with something else so it is not needed. I only use this April-July when the pests are especially active and these ornamentals are on the other side of the house away from the vegetables. I use rose care for disease control on the roses and controlling erineum mites on the hibiscus. For resistant pests like white flies, hard scale, and root mealybugs I don't spray and protect the natural predators. Root mealybugs are especially hard to control so in the end, I usually have to get ruthless and pull out the plants when they get too weak. The predators are not enough. I primarily use water to control white flies and jet spray water under the leaves of the plants. I usually look under the leaves of my plants when I water and when I see something, I blast it off. It does not kill adult whiteflies but if you knock off the eggs and instars, they can't come back by themselves. Eventually the whiteflies will go somewhere else if they are not allowed to reproduce. I don't have aphids, but if I see ants, I will put out ant bait since the ants will protect aphids from their predators.

Also in my arsenal is 70% rubbing alcohol. Spray it on the pest under the leaves, just don't do it in the middle of the day.

For the peach scale, I have given up on eradication, I will use a brush and some soapy water to brush off the scale from the stems of my plants. It keeps their numbers down and as long as the plant is able to keep its leaves and is fed enough, it will tolerate the problem. This is what I do with the roses, since my other option will be to pull all of the roses out and wait for awhile before I replant anything that scales like. If there is peach scahle on peppers, I just discard them. It is not that hard to grow another one.

I do like corn. It is not the most practical plant for a small garden since the yield is so small. However, the aphids that are attracted to the corn, attracts the purple ladybug aka mealy bug destroyer. The mealybug destroyer eats a lot of white flies.

Keeping plants healthy, getting rid of the sickest ones, attracting predators, and using mostly water to control pests and cultural controls makes it possible to grow things fairly well although they won't be problem free.

Adult scale has a hard waxy covering that makes it hard to kill them with pesticides. If you are using oils, you should be aiming them at the crawlers. Even when the adult scales are killed, their shells remain so it is hard to tell if they are dead or not. On small plants and small infestations, alcohol dipped cotton swab works, so does a fingernail.
On larger infestations, cut back the plants if they can take it. On what is left, you will have to brush or scrape them off. It will probably take multiple attempts. You will need to continue to use oils, on the crawlers every couple of weeks and continue to scrape off the scale to kill and keep them from breeding.

https://aggie-horticulture.tamu.edu/gal ... troyer.htm

7https://www.bioadvanced.com/products/rose-flowe ... oncentrate

https://www.bioadvanced.com/products/ro ... oncentrate
https://entnemdept.ufl.edu/creatures/orn ... _scale.htm
https://hdoa.hawaii.gov/pi/files/2018/0 ... 3-2018.pdf
https://entnemdept.ufl.edu/creatures/fru ... alybug.htm