Pest identification help

Trouble shoot problems you are having with your cactus.
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loyall
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Pest identification help

Post by loyall »

When I water two of my cacti I see microscopic specks floating on the surface of the water that collects in the saucer beneath the pot. I only observe these specks when I go to empty the saucer after watering. I can't take a photo because they are so small. They appears as ten to fifteen floating and moving specks that are the size of the point of a straight pin. Some stop moving and I wonder if perhaps they drown. On the other hand, something that small probably cannot break the surface tension of the water, so cannot drown. I can't be sure. I have a small hand held magnifying glass but it doesn't really provide me a better view. I don't observe anything on the plant stems, but anything the size of the specks in the water would be almost impossible to see. Thoughts, suggestions, web links?
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Steve Johnson
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Re: Pest identification help

Post by Steve Johnson »

See this:

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

Call it "everything you wanted to know about cactus and succulent pests, but were afraid to ask". I know more about these pests than I ever wanted to, but at least I was able to share what I've learned since all growers encounter them at one time or another.
If you just want photos without all the blather, please visit my Flickr gallery.
My location: Los Angeles, CA (Zone 10b)
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loyall
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Re: Pest identification help

Post by loyall »

Thanks Steve. I am aware that you are our resident pest expert. That is why I have reviewed many of your posts since I first joined this terrific forum, including this link that you posted here. I just don't identify my experience in your photos and descriptions. Perhaps I am being excessively vigilant, and see a problem where there is none.
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BryanT
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Re: Pest identification help

Post by BryanT »

Is it possible what you saw just some white crystallized mineral and fertilizer salt deposits (a white, chalky residue)?
Bryan
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loyall
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Re: Pest identification help

Post by loyall »

That occurred also to me Bryan, but the specks in question are more dark than white, and did appear to me to move. Possibly it was only Brownian motion of inanimate specks. I will be paying closer attention. Thank you.
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Steve Johnson
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Re: Pest identification help

Post by Steve Johnson »

loyall wrote: Sun Oct 23, 2022 12:06 pm Thanks Steve. I am aware that you are our resident pest expert. That is why I have reviewed many of your posts since I first joined this terrific forum, including this link that you posted here. I just don't identify my experience in your photos and descriptions. Perhaps I am being excessively vigilant, and see a problem where there is none.
I try not to make any assumptions about whether members have or haven't seen my presentation on pests, so I'm glad that you made some use out of it already. Microscopic specks collecting in the water of your saucer could be nothing, or they could be root mealy eggs being flushed out of the drain hole. I sorta kinda doubt that possibility, but I firmly believe in taking the "better safe than sorry" approach -- unpot the plants and see if you have the beginning stages of a root mealy infestation. If you do, it'll be obvious going by the photographic examples you see in my presentation. Since the roots of your cacti are going dormant, an Imidacloprid soil soak won't do any good, so give them a good soak in warm soapy water to kill the root mealies and their eggs. If you don't have a root mealy problem, at least you'll know that you had nothing to worry about there. In both cases let the roots dry out and repot the plants. Root mealies really are the worst, and if I was in your situation, I don't think that the vigilance would be excessive at all.
If you just want photos without all the blather, please visit my Flickr gallery.
My location: Los Angeles, CA (Zone 10b)
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loyall
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Re: Pest identification help

Post by loyall »

Thank you Steve. Your last tailored post was kind of what I was hoping for when I posted. Sorry I didn't mention that I had read through your excellent overview. So your long-shot speculation is that my specks might possibly be mealy eggs. I wouldn't have thought of that. I find many photos of mealies on the internet, but no photos of mealy eggs, so I can't compare. But mealy eggs shouldn't move, correct? Unless they are small enough to be affected by Brownian motion in a liquid. But a hatched mealy must also be extremely small.
BTW, what's your opinion of Bonide 0.22% Imidacloprid granules? I put that on my dozen windowsill cacti early in the summer.
Contrary to your recommendation, I think I will take a wait and see approach.
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Steve Johnson
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Re: Pest identification help

Post by Steve Johnson »

loyall wrote: Sun Oct 23, 2022 9:24 pm Thank you Steve. Your last tailored post was kind of what I was hoping for when I posted. Sorry I didn't mention that I had read through your excellent overview. So your long-shot speculation is that my specks might possibly be mealy eggs. I wouldn't have thought of that. I find many photos of mealies on the internet, but no photos of mealy eggs, so I can't compare. But mealy eggs shouldn't move, correct? Unless they are small enough to be affected by Brownian motion in a liquid. But a hatched mealy must also be extremely small.
BTW, what's your opinion of Bonide 0.22% Imidacloprid granules? I put that on my dozen windowsill cacti early in the summer.
Contrary to your recommendation, I think I will take a wait and see approach.
Mealy eggs in water would move only with Brownian motion, although I don't think they hatch on a microscopic level. Truth be told, my experience with root mealy infestations is confined to looking for the telltale signs in affected cacti showing unhealthy skin color and failure to plump up when I give them regular watering in the growing season. Since I keep the collection outdoors 365 days a year, I don't worry about the possibility of root mealies unless and until I see those signs (thankfully none this year). Wait-and-see is fine, so just keep an eye out for anything that doesn't look normal based on your experience. If you don't see an obvious cause, time to look at what's happening below-ground.

Question about the Bonide -- are you putting the granules directly into the pot, or are you diluting them with water for a soil soak? Should be a soil soak, and off the top of my head, 3/4 cup of the granules diluted in a quart of water is sufficient to soak your dozen windowsill cacti when they start growing next year.
If you just want photos without all the blather, please visit my Flickr gallery.
My location: Los Angeles, CA (Zone 10b)
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loyall
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Re: Pest identification help

Post by loyall »

Actually I followed the directions, and mixed one and a half tablespoons of granules into the top soil layer of a five inch pot. That should create a systemic poison against sucking pests. I know it won't kill eggs.
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loyall
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Re: Pest identification help

Post by loyall »

I have some further observations regarding my unidentified pests. Today I checked the saucers of the two affected cacti without watering them, and I observed about ten specks in each saucer. Using a ruler, I judged these tiny brown specks to be approx ¼mm in diameter. To me this seems rather small for your typical houseplant pests. They definitely move albeit slowly, and since there was no water, it is not brownian motion. IsopropyI alcohol seemed to kill them, and then I rinsed out the saucers. I am wondering if these could possibly have arrived in my commercial cactus mix. I also wonder if these are necessarily injurious to cacti. I have used the systemic pesticide imidacloprid on these plants, but if these pests do not suck, then they will not be affected by the systemic poison. Is there a non-systemic insecticide that can be safely used on the soil of potted house plants?
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jerrytheplater
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Re: Pest identification help

Post by jerrytheplater »

Insecticidal soap can work. I've used a 2% by volume Ivory Liquid Soap as a drench without any harm to the cacti I used it on. I searched for Ivory Soap and found it on Amazon, but it is bar soap. You'll have to cut it up and dissolve it. But now the question is do you use 2% weight to weight- which is 0.02 x 8.33 lbs/gal = 0.167 lb soap dissolved in a gallon of water or 2 2/3 ounces. Might be easier to buy the Insecticidal Soap.

Ivory Soap bars: https://www.amazon.com/Ivory-Soap-Origi ... DYUDG?th=1

Insecticidal soap: https://www.saferbrand.com/articles/wha ... cidal-soap
Jerry Smith
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45 inches (114 cm) rain equivalent per year, approx. evenly spread per month
2012 USDA Hardiness Zone 6b: -5F to OF (-20C to -18C) min.
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