How to keep phals alive and well while I'm away?

[sangenuer]

I rescued 20 phals back in February. They were all in rough shape - root rot, crown rot, mealybugs, scale, you name it. Five died, but the remaining 15 are all doing pretty well with new leaves, roots, and/or spikes depending on the plant. The infestations are pretty well controlled with frequent visual checks and wiping down with alcohol. I only see a scale insect on one or two of them once in a while. The mealybugs are a bit more persistent. They had mostly disappeared until the last week, when I started seeing more of them. I'm inspecting closely every day or two and continuing to remove anything I see with alcohol wipes. For watering, I had just been generously spraying the top of the planting medium (bark) every day or two until recently when they've seemed to need more. So I gave them a good soak a few days ago and have been continuing the spraying as they've started to dry out a little.

That's all just background info, though. My real question is what to do when I go away for most of July. I'll be gone from the 4th-27th. There will be friends staying in my house from the 22nd until we get back and I can ask them to water for me. But what about the 2 1/2 weeks before that?

I had thought that maybe giving them a good soak right before I leave would hold them over until our friends arrive, then I'd ask them to spray daily. But in the last few weeks humidity levels have dropped and they're drying out much more quickly than before. Will they survive if they go that long with no water? And with the increased mealybugs I'm afraid they'll take over, and I kind of hate to ask our friends to deal with inspecting and removing pests.

Is there some treatment I can do that would help hold off the mealies for a bit? And do you think they'll survive without water for a couple of weeks if they're well soaked right before? I'm trying to find someone who can at least come in and spray them but I haven't had any luck so far. Should I fertilize before I go or would it be better not to? Any other advice for me?

[estación seca]

What are the temperatures?

You need to eliminate the bugs. That's long enough for them to reemerge and kill plants.

[sangenuer]

Temps are around 75F / 24C. Summer, no air conditioning, but stays fairly cool.

How can I get rid of the bugs? I've already repotted all, multiple times for a few.

[jcec1]

I'd stick them in the bathtub with a couple of centimetres of water (or ideally systemic insecticide).

[Dalachin]

I don’t know what is available where you are, but I have used imidacloprid in the past. Either the granules or the 1.47 concentrate diluted as a drench. It takes awhile and multiple treatments to be effective, it is a systemic. While I’m waiting for the systemic to kick in, I spray affected plants with isopropyl alcohol. I’ve used this effectively in the past, and I just got some plants from a grower infected with mealies so I’m in the battle right now!

[estación seca]

I agree with jcec1. To get rid of scale and mealy bugs I completely submerge plants in a pitcher or bucket of water with a tiny amount of dish soap added - just enough for a few bubbles. Leaving the plant submerged for 4-6 hours should be adequate; if any remain after you get back you can dunk again for a little longer time.

The benefit of this is drowning the eggs. Soap and alcohol sprays don't get all the eggs.

I invert most plants into the pitcher or bucket so the media don't float out of the pot. I usually need to put something on the inverted pot to keep everything submerged.

I think your plants would do better with a periodic complete wetting of the media rather than spraying the surface so often. This also means less time spent watering. Let your Phals get almost completely dry before rewatering. You can tell how dry they are by lifting them after a good wetting, then again every few days. Merely spraying the surface will not get the roots deep in the pot wet.

[sangenuer]

By "completely submerge" do you mean leaves and all, or just the pot? What about flower stalks? If you're inverting them in a bucket it seems like you must mean leaves too, but I'm having a hard time picturing how to do this without damaging the plants.

Imidacloprid is banned in the EU, so hopefully a long soak in slightly soapy water and spraying with alcohol will help. 70% isopropyl, right?

---------- Post added at 12:06 PM ---------- Previous post was at 11:12 AM ----------

So I've been reading and it seems like mealybugs are pretty hard to drown. One YouTuber posted video of soaking a succulent for 48 hours and still finding live bugs on it. But I read on a few sites that hot water will kill them pretty quickly, if the plant can tolerate it. Instructions I've read say to soak the roots in 120F/49C water until the center of the root ball reaches 115F/46C. What I can't find is whether orchid roots can take water that hot.

Thoughts?

[estación seca]

Soaking kills mealy bugs on succulents. I've done it. The soap is necessary to reduce surface tension and wet the mealybugs. Without it they might live due to air trapped in their waxy covering.

Yes, I mean submerge the entire plant and pot. If anything remains above water bugs will survive.

They crawled far away from your plants to lay eggs, which may remain viable for 2 years, so you can expect more.

[sangenuer]

I have the first batch soaking in water with a little dish soap now. I’m planning to leave them for 4-5 hours. I cleaned the outer pots, trays, clips, stakes, etc by soaking in 50C soapy water for 20 minutes and will wash the areas around where they live with soapy water as well.

What’s the best way to avoid crown rot once I take them out? They’re all still potted so I can’t tip them upside down to drain.

Thanks so much for all the guidance!

[estación seca]

Blow the water out with your breath.