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

[Glorioustache]

By methylated spirits, do you mean denatured alcohol? I have used isopropyl alcohol for mites before, but I hadn't heard of using methylated spirits. I made the mistake of spraying some echinopsis with isopropyl alcohol once while they were out in the sunlight. They were horribly burned and unsalvageable.

Methylated spirits = denatured alcohol. Alcohol is alcohol, so it doesn't matter which kind we use. As I said in my presentation, spraying should be done away from direct sunlight, or better yet -- at night.

Good afternoon Steve! I had understood that only isopropyl alcohol killed pests. Are you saying that ethyl alcohol will work too? I would like to control an aphid outbreak I have on an Echeveria and some mealybugs on a couple of cacti, but I am having trouble finding isopropyl...

[Steve Johnson]

Good afternoon Steve! I had understood that only isopropyl alcohol killed pests. Are you saying that ethyl alcohol will work too? I would like to control an aphid outbreak I have on an Echeveria and some mealybugs on a couple of cacti, but I am having trouble finding isopropyl...

Like I just said -- alcohol is alcohol, so it doesn't matter which kind we use.

[Dodi Russell]

I just read something about the use of mothballs and camphor .is it safe to use and has anyone tried it.

[Steve Johnson]

I just read something about the use of mothballs and camphor .is it safe to use and has anyone tried it.

Can't recommend what I haven't tried myself, so I'll defer to other members who may be able to give you the answer.

[nachtkrabb]

How would you apply them, great goodness..?!
Camphor is rather hot, nothing I would bring close to my plants.
N.

[WayneByerly]

Methylated spirits = denatured alcohol. Alcohol is alcohol, so it doesn't matter which kind we use. As I said in my presentation, spraying should be done away from direct sunlight, or better yet -- at night.

I don't think that's quite right Steve ... about alcohol being alcohol. I believe that IPA and denatured alcohol have different chemical formula's ... I've used IPA for minor infestations of mealy bugs ... quite successfully. And then once (OMG, I will NEVER do that again, I swear), because I didn't have enough IPA I mixed it (about half and half) with denatured alcohol thinking "alcohol is alcohol". And THIS is what it did to my Myrtillocactus geometrizans.

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I cannot even show you the WORST part of the damage as I have already cut the worst damaged stems down, cut the tops off, discarded the most damaged pieces, and placed them on top of some dirt, hoping they would root. One WHOLE side of my M. geometrizans looked like what you can see above. I almost cried.

----- on the other hand ...
OK ... this was a GREAT post ... as good, if not better than your fertilization posts. I'll have to copy the text and paste it in a notepad file so I can read it thoroughly ... later.

----- on the other hand ...
Where do you live Steve?!?!?!?!?! What state? I only ask so that I'll know where to NEVER, not as long as I live, willingly move to. Based on some of what you wrote, and some of the infestations that you have seen, I think you have some of the worst luck I have ever seen. It sounds something like the seven plagues of Egypt.

In something like ten years of collecting cacti, I've had ONE mealy bug infestation, and a couple of minor occurances ... and MAYBE some spider mites once, although I'm not sure...

(slow, sad shaking of the head) ... there but for the grace of God go I ...


----- on the other hand ...
Nice to hear from you again ... it's been a while since i've been to the forum. Thanks for this post.

Wayne ...

[Steve Johnson]

Hi Wayne,

Good to hear from you again too. Your cautionary tale about denatured alcohol (AKA methylated spirit) is worth noting, although I know people who use it without any problems. There are 2 possibilities regarding what happened to you:

1. If you mixed 100% denatured alcohol with the 70% IPA we get at the store, the mix might've been too strong, in which case diluting it with water would've prevented the problem.
2. You sprayed your Myrtillocactus when it was in direct sunlight. If you didn't do that, we're back to possibility #1.

I live in the Baldwin Hills area of Los Angeles CA. L.A. has something like 7 different microclimates, and mine is coastal Mediterranean, which is more humid than the inland areas. Doesn't matter -- my pest problems have been by no means unique, and they can happen to anyone at anytime anywhere. By the way, the photos in my presentation that are labeled with CactiGuide.com come from other sources, so they're from other folks' plants. The infestations you see in those pics are way worse than anything I've ever had to contend with.

[Dodi Russell]

Steve Johnson how long do you let the plant sit in the imidacloprid solution. My melocactus got infected with severe root mealy bug mealy bug infestation.Here are the pictures of what I am going to use and the picture of the infestation.

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What should I do.
Is the plant worth saving.
Will I be able to use the soil if I heat it up at a very high temperature to kill the root mealy bug.
Should I check the other plants have a infestation also because I didn't notice this for a long time.

[Steve Johnson]

Hi Dodi,

I can guide you on what to do, although unfortunately I won't have enough time for it tonight. I'll be able to give you the proper attention tomorrow night, so don't do anything yet.

[Dodi Russell]

Ok, I will isolate this plant from the others.I couldn't find the imidacloprid content present but the imidacloprid is in a 50 ml bottle. It is a product of Bayer. There is another insecticide called ACTARA.

[Steve Johnson]

Ok, I will isolate this plant from the others.I couldn't find the imidacloprid content present but the imidacloprid is in a 50 ml bottle. It is a product of Bayer. There is another insecticide called ACTARA.

The Bayer product and Actara are both neonicotinoids, so either one should be an effective soil soak on all types of scale insect including mealies. The Bayer product's label states 200 grams per liter, which is .2% Imidacloprid, so I'll have to do some math and figure out the dilution rate for your soil soak. I'll get back to you tomorrow night with instructions on what to do.

[Steve Johnson]

Hi Dodi,

Did some research on the Bayer website, and instructions for your Admire Imidacloprid indicate a dilution of 35 ml per 5 liters of water. It's awfully hard to overdose cacti on Imidacloprid, so you should be fine if you up the amount to 10ml per liter. Your Melocactus is definitely worth saving, so here's what to do...

Pot the Melo in fresh, dry cactus mix. Let it settle in for 1-2 weeks before you water it. The term "soil soak" means exactly what it says -- saturate the mix with the Imidacloprid-water solution. Water the plant with plain water 7-10 days after that, and the roots will continue to take up any residual Imidacloprid. If you're concerned about the possibility that root mealies have spread to your other pots, you may want to give the rest of your cacti a preventative soil soak as well.

The downside to Imidacloprid is the fact that it's harmful to bees, so we need to be responsible about disposing of Imidacloprid-laced runoff. When you do soil soaks, capture the runoff in a pan or bucket, then pour it into an empty bottle or jug for disposal. Home hazardous waste centers are easy to find here in the US, although I don't know if it's a problem for you in Sri Lanka. If it is, you may have to steer clear of the Imidacloprid and kill the root mealies with warm soapy water before you pot your Melo.

[Dodi Russell]

Hi Dodi,

Did some research on the Bayer website, and instructions for your Admire Imidacloprid indicate a dilution of 35 ml per 5 liters of water. It's awfully hard to overdose cacti on Imidacloprid, so you should be fine if you up the amount to 10ml per liter. Your Melocactus is definitely worth saving, so here's what to do...

Pot the Melo in fresh, dry cactus mix. Let it settle in for 1-2 weeks before you water it. The term "soil soak" means exactly what it says -- saturate the mix with the Imidacloprid-water solution. Water the plant with plain water 7-10 days after that, and the roots will continue to take up any residual Imidacloprid. If you're concerned about the possibility that root mealies have spread to your other pots, you may want to give the rest of your cacti a preventative soil soak as well.

The downside to Imidacloprid is the fact that it's harmful to bees, so we need to be responsible about disposing of Imidacloprid-laced runoff. When you do soil soaks, capture the runoff in a pan or bucket, then pour it into an empty bottle or jug for disposal. Home hazardous waste centers are easy to find here in the US, although I don't know if it's a problem for you in Sri Lanka. If it is, you may have to steer clear of the Imidacloprid and kill the root mealies with warm soapy water before you pot your Melo.

Thanks
I am going to use the soap water bath to treat the mealy bugs. I don't want to damage the surrounding ecosystems using Imidacloprid just to save my plant. ImidaclopridI is sold here as a pesticide and is just sprayed on plants. I never knew the impact it had on other ecosystems. Thanks for informing about the impacts of ImidaclopridI.

Edit: here's the melocactus in the soap water bath

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I am going to heat up the potting mix the melocactus was in, that will clean the mix.

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I washed the roots and put it in a Hydrogen peroxide solution( the H2O2 I get is 6% so in another topic I was told to dilute it with 4 parts water and 1 H2O2 )

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Bubbles forming on the root of the plant. After this I am going to pot it after 2 or 3 days

[Steve Johnson]

Hi Dodi,

Looks like you're doing the right thing, and I think your Melo should do well with the steps you've taken. While I do recommend Imidacloprid, proper disposal is an absolute requirement, so I won't recommend it for people who are unwilling or unable to deal with Imidacloprid-laced runoff responsibly through a home hazardous waste center.

[WayneByerly]

Hi Wayne, Good to hear from you again too.

Your posts, while very varied in their subject matter, are always very detailed and very didactic. As such, they have always been extremely welcome to me. So I'm very glad that I ran into this post. My experiences with parasites have been very limited, but I'm extremely glad to see accumulated in one place the information that would be required to deal with almost any pest. I've always had a great deal of respect for your knowledge base and have always been very appreciative of the very detailed knowledge that you always manage to present.

***************

Hi Wayne, Good to hear from you again too. Your cautionary tale about denatured alcohol (AKA methylated spirit) is worth noting, although I know people who use it without any problems. There are 2 possibilities regarding what happened to you:

1. If you mixed 100% denatured alcohol with the 70% IPA we get at the store, the mix might've been too strong, in which case diluting it with water would've prevented the problem.
2. You sprayed your Myrtillocactus when it was in direct sunlight. If you didn't do that, we're back to possibility #1

1. Dern ... when you say it like this it seems so simple. Why did I not think of this at the time? Isopropyl alcohol is not 100% alcohol. It's diluted. WHY wouldn't I think to dilute the denatured alcohol? Heavy sigh! Sometimes I feel roughly equivalent, intellectually speaking, to a burlap bag full of marbles! (Not very sharp)
2. This consideration did occur to me. So I sprayed it at night. Now, in retrospect, I have to wonder about the brilliance of that move. As I am absolutely certain that you are aware of, cacti reverse their food production cycle from that of other plants. Their stomata open up at night, inhaling carbon dioxide, storing it until sunrise for use in food production. So it seems to me now that it would have been best[/<<i] to do the spraying in the daytime when they're stomata were closed (to prevent ingestion of foreign materials), while shielding them from direct sunlight.

***************

I live in the Baldwin Hills area of Los Angeles CA. L.A. has something like 7 different microclimates, and mine is coastal Mediterranean, which is more humid than the inland areas. Doesn't matter -- my pest problems have been by no means unique, and they can happen to anyone at anytime anywhere. By the way, the photos in my presentation that are labeled with CactiGuide.com come from other sources, so they're from other folks' plants. The infestations you see in those pics are way worse than anything I've ever had to contend with.

Have you ever said anything that you just immediately didn’t wish you could take back? Or at least alter the method of delivery? Well I've managed yet once again.

It has always been something of a desire on my part be able to make people smile, or even laugh. So I make these attempts at being funny. They generally fail miserably. I should give it up. I guess I’m a slow learner. And I say that yet once again as I find my most recent attempt (which was supposed to be funny) … was a miserably failed attempt at humor… as is apparent to me now. My apologies … no criticism or denigration whatsoever was intended. I did indeed figure that some (if not most) of your images of pest infestations were from sources other than your own personal experience. Again, it was just a foolish attempt at being funny. There was no real intent whatsoever in casting aspersions, affront, insult, slight, slur, or imputation on you OR the place where you live.