Mealies and flat mites and scale -- oh, my! (Updated 6/11/2022)

Trouble shoot problems you are having with your cactus.
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jerrytheplater
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Re: Mealies and flat mites and scale -- oh, my! (Updated 6/11/2022)

Post by jerrytheplater »

I had Root Mealy bugs in my cacti discovered in January, the heart of my winter. I took them all out to their pots and washed off all of the potting mix. I then soaked them in a 2% soap solution to which I added Malathion according to the label directions. In the US a sprayable formulation is sold by Spectracide. I don't remember which brand I used, but it was a sprayable formulation.

After soaking them, I drained them on newspapers to speed up the drying. I remember I stored the plants in a cool low light room bare root. What I don't remember is if I treated them again to get newly hatched Mealy bugs. Whatever I did worked.
Jerry Smith
Bloomingdale, NJ
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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Steve Johnson
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Re: Mealies and flat mites and scale -- oh, my! (Updated 6/11/2022)

Post by Steve Johnson »

Holunder wrote: Sat Nov 05, 2022 5:25 pmIf I do the same in winter while they are dormant in a cool place I probably would risk rot and I am just guessing that the systemic insecticide will not be absorbed by dormant plants. How is the best way to deal with that?
You're correct on both counts -- soil soaks are effective only while the roots are in growth during the spring and summer, doing it in the fall and winter guarantees rot. If you see stem and/or spine mealies, you have 2 options:
  • Gently remove them with tweezers. This option can be a bit "labor-intensive" if you find a lot of them.
  • Spray the affected plant(s) with Isopropyl alcohol or methylated spirits.
Stem and spine mealies won't tolerate persistently cool conditions, so I don't think you'll see them at all in the winter. Root mealies are another matter -- you've already seen my presentation (thank you for that, by the way! :D ), so the following quote from Cactus Nursery in the UK is for people who haven't:

"Root mealybugs (Rhizoecus falcifer) are among the worst pests of cacti and other succulents. They live almost exclusively on roots and the parts of the stem that are below the surface. They are similar to stem and spine mealybugs in that they also secrete whitish, woolly, or powdery wax. Root mealybugs prefer dry substrates. They multiply particularly rapidly during the dry winter dormancy period. Affected plants look pale, become sickly, and gradually die. Plants damaged and weakened by root mealybugs are especially susceptible to fungal diseases."

Cacti undergo a certain amount of shriveling in winter, and that's normal. The tricky part is knowing the difference between shriveled skin colors that are normal vs. abnormally pale and/or sickly. Unfortunately you haven't been with your new cacti long enough to know what they should normally look like over the course of their winter shriveling. However, if your gut intuition tells you that things may not look right, unpot the plant and do a thorough root inspection. If you do see a root mealy infestation, soak the roots in warm soapy water to kill the mealies, let the roots dry out completely, and repot the plant in clean, dry potting medium. (For new growers out there -- as much as you may be tempted into doing it during the winter, don't even think about watering until the next growing season begins.) Regular dish soap is fine, although insecticidal soap wouldn't be a bad idea.
jerrytheplater wrote: Sun Nov 06, 2022 1:13 am I had Root Mealy bugs in my cacti discovered in January, the heart of my winter. I took them all out to their pots and washed off all of the potting mix. I then soaked them in a 2% soap solution to which I added Malathion according to the label directions. In the US a sprayable formulation is sold by Spectracide. I don't remember which brand I used, but it was a sprayable formulation.

After soaking them, I drained them on newspapers to speed up the drying. I remember I stored the plants in a cool low light room bare root. What I don't remember is if I treated them again to get newly hatched Mealy bugs. Whatever I did worked.
This brings up an interesting question -- if we soak the roots with nothing more than soapy water, will it kill root mealy eggs too? My only encounter with root mealies took place at a time when the growing season allowed me to do Imidacloprid soil soaks, killing the mealies and their eggs in one shot. I've been around my cacti long enough to know what looks normal and what doesn't when they go through the fall/winter shriveling process, so if I see the telltale signs of a root mealy infestation this winter, it'll be time to unpot cacti and knock the infestation down before it goes too far. Such being the case, it's possible that soapy water won't be enough to kill root mealy eggs. When I had my first collection way back in the 1970s, Malathion was the only game in town, and I did soil soaks with it every spring (I still remember that nasty smell). Will it kill root mealy eggs? Certainly, but I'd rather stay away from Malathion, and now that I think about it, I'm leaning toward either insecticidal soap or a solution of water, dish soap, and Imidacloprid. Your 2% soap solution sounds good, Imidacloprid does kill root mealy eggs, so all we need to know is how much Imidacloprid we should add. Here's the recipe I have in mind:
  • Per quart of water -- 4 teaspoons dish soap (a little more than 2%, but that's fine), and 1 tablespoon of 1.47% Imidacloprid.
A couple of questions for you, Jerry. #1 -- does the water have to be warm when we soak the roots of infested cacti? #2 -- after you soaked the roots, did you rinse them in running water before you let them dry out? My guess is that rinsing would be counterproductive, although I didn't want to make any assumptions here.
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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Holunder
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Re: Mealies and flat mites and scale -- oh, my! (Updated 6/11/2022)

Post by Holunder »

Thank you Steve and Jerry for your experience and thoroughly answer. As I just started this year having cacti I hope I will see early enough if they get mealybugs this winter. I will be extra careful with the plants I bought the last weeks, inspecting their roots and putting them in new dry mineral substrate an then keeping them in a different place away from my other plants until next spring.

Holunder
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Re: Mealies and flat mites and scale -- oh, my! (Updated 6/11/2022)

Post by C And D »

The Cyzmic CS has really worked well for me on root mealies and their eggs
I had a real problem, especially plants with deep tuberous roots
and I had regular mealies on some Mesembs and other sensitive plants

They are all gone now, can't find a single live bug.

If you have them, I suggest a deep soil soak no matter what time of year it is.
Check out our plant and seed lists
http://www.CandDplants.com

Craig and Denise Fry
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Re: Mealies and flat mites and scale -- oh, my! (Updated 6/11/2022)

Post by jerrytheplater »

Steve Johnson wrote: Sun Nov 06, 2022 5:42 am A couple of questions for you, Jerry. #1 -- does the water have to be warm when we soak the roots of infested cacti? #2 -- after you soaked the roots, did you rinse them in running water before you let them dry out? My guess is that rinsing would be counterproductive, although I didn't want to make any assumptions here.
1) I am thinking I had this infestation way back in the early 2000's, so as far as the temperature of the water, I'm going to guess that I used tepid water like I would for most of my house plants. At least room temperature. I do water with a hose in summer, but my summer water is warmer than winter water since it comes from a Reservoir and is significantly warmer in summer.

2) I know I did not rinse them. I wanted as much contact as possible. Newspapers to get the bulk of the water ASAP. Plus, I was hoping for residual benefit from the Malathion.
Jerry Smith
Bloomingdale, NJ
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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Steve Johnson
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Re: Mealies and flat mites and scale -- oh, my! (Updated 6/11/2022)

Post by Steve Johnson »

jerrytheplater wrote: Mon Nov 07, 2022 9:16 pmI know I did not rinse them. I wanted as much contact as possible. Newspapers to get the bulk of the water ASAP. Plus, I was hoping for residual benefit from the Malathion.
Makes sense, so thanks for confirming my belief that rinsing after a root mealy soak would indeed be counterproductive. :)
If you just want photos without all the blather, please visit my Flickr gallery.
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Holunder
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Re: Mealies and flat mites and scale -- oh, my! (Updated 6/11/2022)

Post by Holunder »

C and D, good to hear that CYZMIC CS did the job. I can get the same lambda-cyhalothrin ingredient in Bi 58 N here in Germany. I've read a lot of mixed comments about it, but I would give it a try if I'm desperate.
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Re: Mealies and flat mites and scale -- oh, my! (Updated 6/11/2022)

Post by keith »

For really bad infestations during the growing season Imidacloprid will work IF the roots are alive. But in Winter I would depot the cactus and cut off most of the infected roots, use a contact poison on whats left and let the cactus stay bare root for the rest of the Winter. Pot it up in the Spring.
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Re: Mealies and flat mites and scale -- oh, my! (Updated 6/11/2022)

Post by jerrytheplater »

keith wrote: Tue Nov 08, 2022 4:19 pm For really bad infestations during the growing season Imidacloprid will work IF the roots are alive. But in Winter I would depot the cactus and cut off most of the infected roots, use a contact poison on whats left and let the cactus stay bare root for the rest of the Winter. Pot it up in the Spring.
So now I have a question for any and all: If I treat the plants like I described-depot, soak in contact poison, dry, leave bare root till spring, repot. The only difference between what I said and what Keith says is that he cuts most of the infected roots off.

My question: does the cactus totally discard the old roots by letting them dry out and decompose and make entirely new roots from the base of the plant? Or do new roots form from the larger roots dangling from the cactus body?

If the plants make entirely new roots after suffering the trauma of depotting, then it makes sense to always cut off all of the roots before soaking with the contact poison.
Jerry Smith
Bloomingdale, NJ
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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Re: Mealies and flat mites and scale -- oh, my! (Updated 6/11/2022)

Post by keith »

hi Jerry its root mealie bugs that can kill roots you'll notice it after they dry out . new Roots will grow from healthy roots . I do trim roots a little when transplanting but different than root mealie bug trimming which cuts off dead infected roots. Bad mealie bug infection I've cut ALL the small roots off but not fat tap roots.
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Re: Mealies and flat mites and scale -- oh, my! (Updated 6/11/2022)

Post by jerrytheplater »

keith wrote: Thu Nov 10, 2022 1:00 am hi Jerry its root mealie bugs that can kill roots you'll notice it after they dry out . new Roots will grow from healthy roots . I do trim roots a little when transplanting but different than root mealie bug trimming which cuts off dead infected roots. Bad mealie bug infection I've cut ALL the small roots off but not fat tap roots.
Thanks Keith.
Jerry Smith
Bloomingdale, NJ
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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Re: Mealies and flat mites and scale -- oh, my! (Updated 6/11/2022)

Post by Cactimaniac »

I have tried hot bath method with soap and so far 4 month later no sign of root mealies. I did remove all soil on some lophophora and left only tap root, let it callous and repeat hot soak and soap. They had aldready new roots before being potted. I have them potted in a transparent pot so if any mealies return i will spot them.

I also did soil soak with acetamiprid with a repeat after 4 weeks on all my other plants just in case.

This was all summer. Let se which method is best.

From now on i will not buy plants. I will only grow from seed and use sterilised sand as substrate which works great in my humid location.
Sweden, Stockholm
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Re: Mealies and flat mites and scale -- oh, my! (Updated 6/11/2022)

Post by keith »

Predatory Spider Mite on a Astrophytum not the best picture but they run fast ,
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Re: Mealies and flat mites and scale -- oh, my! (Updated 6/11/2022)

Post by ohugal »

Beneficial insect? They also attack other pests or just spider mite? I use it when I don’t have time to spray my plants. Is it expensive where you get them? Often they require specific conditions in terms of temperature and humidity.
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Re: Mealies and flat mites and scale -- oh, my! (Updated 6/11/2022)

Post by keith »

These spider mites are present in the environment which means the other species that eat plants are too. Usually every year I have spider mite after the predatory types fade away by late summer. Just have to keep a sharp eye on the plants.
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