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[New Wisdom]

Hello folks. 

I have a pretty bad problem right now.  There is a nasty mealybug infestation on my indoor dormant plants.  I cannot give them systemic treatments because they are not in-taking water/nutrients at the moment since they are dormant.   

I am thinking of getting them with some insecticidal soap and then applying neem after killing the the planted suckers.  Any thoughts?


Have any of you had to deal with mealybugs on dormant indoor cacti?

Thanks!!
New Wisdom

[plantlight]

 . I hate that.  Will you post a picture of the damage?

[nobody]

I had a problem with this last year with some dormant cutings I bought. I removed everything I could see with a toothbrush dipped in alcohol and then applied DE to everything in the immediate area. I would suggest covering the area they are in with a bed sheet and wear a mask before applying DE.

What is the ambient humidity where you have the cacti?

nobody

[doublebenno]

best treatment would depend on which cacti you are talking about.

[misplant]

insecticide soap spray & a toothbrush, forget about the neem & get some continuous air circulation going in the area

[LSoares]

Tricky. Contact insecticides won't get to the buried/hidden bugs. Best to go the individual bug elimination route, hoping to keep the mealies number down until spring. Weather allowing (unlikely in your climate zone), some ladybugs might do the trick. Don't you have a friend in warmer climates willing to catch (or buy) and ship some your way?
Another possibility is to drop the temps below mealybug activity threshold and put everything on hold until spring (if by "indoors" you mean "greenhouse").

Here in Portugal cacti rarely go properly dormant...

[trichocereus]

http://www.naturalinsectcontrol.com/subcat.php?cat=5&subcat=19

[Sunshine]

Exposing cuttings and even whole plants to low temperatures helps drastically reduce mealybug survival in our experience. Several subtropical plant species can tolerate “chilling” for short periods — we use more than 36 hours at 36° F — with no damage and superior mealybug control. Unfortunately, not all plant species can withstand this. In contrast, university research groups in Maryland and Hawaii have achieved mealybug control with hot water (120° F) baths.

http://www.gpnmag.com/targeting-white-menace-mealybugs

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[New Wisdom]

There are literally hundreds of cacti. Aztekium ariocarpus lophophora trichocereus sulcorebutia, echinopsis, echinocereus, blah blah blah blah.  It's pretty dry here around like 10-30% humidity max.  It's going to be a lot of work.

By indoors I mean inside the house on shelves unfortunately.

Thanks for all the advice. There's a lot to ponder, but I'm going to start by squishing the ones I can find and using alcohol on them. This should only take me like 48 hours of work.  Then I might put some DE on each pot.  I threw away the really bad ones out into the snowy compost pile so those are done for.   

[plantlight]

So sorry for your misfortune.   I wish you well New Wisdom!
Cheers 

From yucca do nursery:
http://www.yuccado.com/article_winter_containers
Even with proper air circulation and optimal irrigation insect infestations occur.  . . To control all of the soft bodied insects in the winter we use a variation of the following formula sprayed on with a pump up sprayer. On occasion we will change up the formula and substitute or add Neem Oil and or a small amount of Orange Oil to the Ultra Fine Horticultural oil base so the formula is not always the same.

Per Gallon of Water

1 oz of Ultra Fine Horticultural Oil
2 oz of Spinodad
1 oz of Pyrethrum

[Toxicodendron]

Using insecticidal soaps, oils, or anything that has a lipid soluble quality will damage the skin of the cacti.

IME, soaps & oils of any kind with the aerial cacti is asking for disaster.

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[plantlight]

Using insecticidal soaps, oils, or anything that has a lipid soluble quality will damage the skin of the cacti.

IME, soaps & oils of any kind with the aerial cacti is asking for disaster.

Yep, Missouri Botanical Garden warns against soaps and recommends the cotton swab/alcohol method but also has a caveat about alcohol:

4. Remove mealybugs and scale using cotton swabs dipped in alcohol. Spraying the plant with a dilute alcohol solution (1:3) may help control pests that are not easily visible but the solution may damage the epidermis of sensitive cacti and succulents. Test a small area before spraying the entire plant.

6. Use insecticidal soap but be aware that it may damage some plants. Cacti have oils and waxes that may make them susceptible to damage from the soap. Be sure to read the product’s label to see if it is safe for your plant. It is a good idea to test a small area of the plant before spraying the entire plant.

The entire article is very informative:
http://www.missouribotanicalgarden.org/gardens-gardening/your-garden/help-for-the-home-gardener/advice-tips-resources/pests-and-problems/insects/mealybugs/insect-pests-of-cacti-and-succulents.aspx

I don't know any of this first hand, have only a few cactus and have consider myself a cactus newbie.  I defer to you guys that have battled this first hand.  All the best to you.