Big scale infestation - please help

[memememe]

I recently left my plants alone for ~ 1 month since I had to go somewhere, and I came back to almost 1/3 of my collection covered in scale bugs and mealies. Can anyone give me a way to get rid of a lot of scale at once? There's about 40 affected plants .
I think they were there before, just in smaller numbers so I didn't notice before I left. I have isolated all the plants with evidence of infestations now (I believe)

[anttisepp]

I'd spray with some systemic insecticide x2 within 2 weeks and also give it as solution in substrate once.
E.g. Provado/Acetamiprid.

[memememe]

Thanks, will try.

[zpeckler]

OH NO! That sounds like a nightmare! I'm dealing with a mild root mealy outbreak amongst my collection at the moment and even that's a PITA.

[memememe]

Definitely is. I've had scale outbreaks before, just never this bad.

[Steve Johnson]

Definitely is. I've had scale outbreaks before, just never this bad.

If you live in the US, I highly recommend an Imidacloprid soil soak. This is a systemic effect -- the Imidacloprid is taken up by the roots into the plant, making the plant's juices toxic to mealies and armored scale. Unfortunately you can't do it until your cacti start growing in spring, but when you do, you'll be good for at least 3 months of the growing season. For more information, go here and scroll down to the section called "Long-term solution for all types of scale insect":

https://www.cactiguide.com/forum/viewtopic.php?t=42129

Be sure to read everything in that section. While you're at it, please see this:

https://www.cactiguide.com/forum/viewtopic.php?t=43819

[Steve Johnson]

Another thought for all members who have been plagued by sucking pests (mealies, armored scale, and pest mites) -- they really do suck both figuratively and literally!

From hydrobuilder.com (https://hydrobuilder.com/learn/npk-rati ... t-balance/):

• "Magnesium and calcium go hand in hand, and are often an area where plants become deficient. Magnesium helps aid in the uptake and utilization of other nutrients, along with producing carbs and sugars to help during flower."

• "Calcium has a similar role in plants as in humans, helping produce strong cells and root walls. This leads to stronger plants. We've recently come to understand that calcium is actually the dominant nutrient in most plants." [My emphasis]

Just a theory, but I think that strong cells make it harder for sucking pests to break through the skin (and strong root walls keep root mealies from being a problem). If the theory is correct, y'all might want to consider the possibility that you're not giving your cacti enough calcium. There are several ways to increase it:

• A nitrogen-free CalMag product to supplement your fertilizer.

• Ca and Mg provided by acidifying tap water.

• Limestone granules for desert species adapted to growing in native limestone soils, gypsum granules for everything else. If you don't know whether your cacti are or aren't limestone growers, you won't go wrong with gypsum. Add a small amount of limestone and/or gypsum granules to your pots. They're slow-release forms of Ca, so be sure to add them at the start of each growing season.

Once again if the theory is correct, an ounce of prevention will be worth a pound of cure.

[memememe]

Thanks for that long answer! Will try.