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Scale not going away on Crepe Myrtle
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Author:  charmon711 [ Sat Jun 26, 2010 12:35 pm ]
Post subject:  Scale not going away on Crepe Myrtle

We have sprayed (saturated) our Crepe Myrtle twice in the last two weeks with Garrett Juice, after blasting the scale off with the hose first, just to have the scale come back the next day. From what we've read, scale appears to actually be an insect, not a fungus. Is this correct? We understand there are many different types of scale and we were reading about an Elm, so maybe it's completely different for a Crepe Myrtle. Please note, we have root flare. Do we need to move on to the sick tree treatment?

Thanks for all your expertise.

Author:  sandih [ Sat Jun 26, 2010 4:05 pm ]
Post subject:  Re: Scale not going away on Crepe Myrtle

Mine has scale too, and yes it is an insect. I used horticulture oil on mine a few years ago and it killed (suffocated them) but they are back now. Does your plant seem stressed in any other way? Mine is small and is in a pot, so mine may be stressed because of that. Happy, healthy plants don't normally have that problem. If you navigate up top..click on Learn, Articles, the S for scale you can read add'l info on how to get rid of it.

Author:  sandih [ Sun Jun 27, 2010 8:05 am ]
Post subject:  Re: Scale not going away on Crepe Myrtle

Female scale insects lay their eggs under their bodies or scale covers. When they first hatch, young scales have legs and are quite active. At this stage, they are called crawlers. Crawlers disperse, locate new feeding sites, and then transform into immobile adults.

Scale hits plants that are in stress. The high-nitrogen fertilizers are the primary culprits. Being planted too low is the next most common with too wet or too dry coming in third. The scale insects can be killed with horticultural oil, Bioganics, Eco-EXEMPT and even with the organic mound drench products in most cases. However, the pests will be back if the cause of the plant stress is not eliminated.


Common name: Scale

Scientific name: Order Homoptera. Soft Scale--family Coccidae, Armored Scale--family Diaspididae

Size: Adult--1/10" to 1/5"

Identification: Adult scales attach themselves to bark, shoots, or foliage. If they are hollow and flake off easily, they are dead. Live ones range in color from white to dark brown.

Biology and life cycle: Soft scales like garden and ornamental plants. Armored scales prefer orchard crops. All have incomplete metamorphosis. Soft scales are covered with a secreted waxy or cottony material. Males may have a single pair of wings. Females can give birth to live scales as crawlers. Nymphs have legs and brown antennae. Armored scales secrete and build a stronger coating. Young are born alive or hatch from eggs and are active until after the first molt. Males have wings, well-developed antennae, and simple eyes--females don't.

Habitat: Garden, farm, and landscape plants.

Feeding habits: Scales suck plant sap through piercing, sucking mouthparts. Will attack many ornamental and food crops.

Economic importance: Can do severe damage by reducing vigor and stressing plants. Serious citrus pest.

Natural control: Twicestabbed, lindorus, and vedalia lady beetles; parasitic aphids; parasitic wasps. Healthy plants.

Organic control: Horticultural oil year round has been the recommendation in the past. A better plan is to spray with plant oil products in the growing season. A mixture of Bio Wash and 2 oz of orange oil per gallon of water has shown great results. Adding a cup of natural diatomaceous earth per gallon of water will also help.

Insight: Mealybugs are closely related to scale and controlled with the same methods. San Jose scale, a tiny species of scale related to the fruit tree pest, is used to make shellac. Scale insects only attach stressed and unhealthy plants. Make sure the plants are not being over-watered or under-watered first. Then apply the Sick Tree Treatment to the root zone of the plants.

Author:  charmon711 [ Sun Jun 27, 2010 12:27 pm ]
Post subject:  Re: Scale not going away on Crepe Myrtle

Thank you Sandi for all the great tips. We saw the young scale crawling yesterday, so now we understand they are an insect (and gross at that). We will try the horticulture oil, although I'm wondering if this kills the good microbes.

Author:  sandih [ Mon Jun 28, 2010 6:44 am ]
Post subject:  Re: Scale not going away on Crepe Myrtle

It will cover and smother whatever it's sprayed on. Look for any other cause of your tree being stressed. How much do you water it? When was it planted?

Author:  charmon711 [ Thu Jul 01, 2010 7:17 pm ]
Post subject:  Re: Scale not going away on Crepe Myrtle

We sprayed with the horticulture oil, and that hasn't worked. The tree is about six years old. I guess we will try the sick tree treatment.

Author:  sandih [ Fri Jul 02, 2010 5:43 am ]
Post subject:  Re: Scale not going away on Crepe Myrtle

It's not immediate.

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