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

[Steve Johnson]

No worries, Wayne! I didn't take any offense at what you said -- the problem with humor being expressed online is that it can be taken seriously (which I did), but you're a good friend, so please don't feel bad about it.

Re. alcohol -- before I discovered Avid and TetraSan, I used IPA spray on any cacti that had flat mites rearing their ugly little heads. Spraying at night was never a problem. As I think about it some more, it's possible that your IPA/denatured alcohol mixture was fine, and for you spraying at night was the problem. I apologize if I gave you a bum steer on that one, but at least the lesson gives us a "rule of thumb" for people who use it:

• 70% IPA -- spraying at night is preferable if your plants could be exposed to direct sunlight before the IPA application evaporates.

• 100% alcohol -- spray only during the day, but make sure that your plants are away from direct sunlight when you do it.

[Edwindwianto]

Hi everyone

Just found this dedicated page for mealubugs identification

The author is
Lance S. Osborne
Professor of Entomology
University of Florida

=======================

Another interesting reading, is this page
It says that mealybug life cycle is greatly effected by the high Nitrogen consentration on the plant

I quote

The results of this study show that the citrus mealybug life history parameters were influenced by the applied nitrogen concentrations (ppm), leaf nitrogen concentration (%), and total moisture content (g). Citrus mealybugs feeding on both green and red-variegated coleus, receiving the high nitrogen fertilizer concentrations (200 and 400 ppm) had the greatest egg loads, were larger in size, and had the shortest developmental times.

......

Thus, higher nitrogen concentrations, in the form of supplemental fertilizers used in greenhouse production systems, leads to an increase in the performance of citrus mealybugs as defined by increased egg loads, larger mature females, and shorter developmental times 

I know that mealybug is most active during the warmest months (spring) and typically, you would use fertilizer during this months to boost your cacti growth...well, i guess that explains the heavy outbreak during those months...
Ao be careful when applying your N fertilizer...

=======================

The last one is this post

This study tells us that peat based medium (represented by Metro Mix 360) supports the outbreak of mealybug...shown by the much higher number of individual when the outbreak occurs...
When that peat based medium is subtituted by a percentage of other medium, the amount of individual drops significantly

=======================

Conclusion

What do all this scientifique studies tell us?

We might have to rethink about the type of medium we used and our fertilization regime...

It is better to prevent than a long talk about "what insecticide is better?", "how to kill it effectively?" etc

The keys
Warm months
High Nitrogen content in plant tissue
Peat based medium

Equals super outbreak

Edwin

[samreu]

Steve, quick question. In your recommended dilution for 3 in 1, just to confirm you are using the "ready to spray" product with hose attachmentVersus the concentrate that is available? I am assuming Bio-advanced is the new label for the old Bayer product. There are 3 versions, a ready to spray for hose attachment, a ready to use in a spray bottle and a concentrate.

There is also a Bio-advanced Complete Insect Killer formula with .72% Imidacloprid with .36% beta-cyfluthrin - seems to be more readily available?

[Steve Johnson]

I am assuming Bio-advanced is the new label for the old Bayer product. There are 3 versions, a ready to spray for hose attachment, a ready to use in a spray bottle and a concentrate.

Correct, Bayer Advanced is now BioAdvanced. The version I use is in the bottle with the ready-to-spray hose attachment, although we just need the liquid to dilute in water for soil soaks. Not difficult to take the hose attachment top off for this, but the concentrate bottle does make it a bit easier.

There is also a Bio-advanced Complete Insect Killer formula with .72% Imidacloprid with .36% beta-cyfluthrin - seems to be more readily available?

I can find it in the US, so check Amazon and find out if you can get it in Canada. If you can, the dilution rate should be 1/2 cup of the liquid concentrate per gallon of water, or 2 tablespoons per quart. As to the beta-cyfluthrin, I don't think it does anything against cactus pests, but it certainly won't do any harm.

Since spring is less than 3 weeks away, you should be close to the time when you're ready for soil soaks. Keep an eye out for signs of new growth on your cacti -- when you see it, then soak away. However, please be sure that you capture the runoff and dispose of it properly through your local home hazardous waste center.

[samreu]

Thanks Steve. I am going to go with the insect 3 in 1 , ready to spray or concentrate - they seem to be the same % and active ingredient - .01 lbs of active imadocloprid..
Label says 2.67 ounces/gallon - so at your recommended 3/4 cup or 6 ounces, you're doubling up the dosage, correct? and that has worked no problem.
Was there a reason for the doubling up?
Thanks again.

[Steve Johnson]

Thanks Steve. I am going to go with the insect 3 in 1 , ready to spray or concentrate - they seem to be the same % and active ingredient - .01 lbs of active imadocloprid..
Label says 2.67 ounces/gallon - so at your recommended 3/4 cup or 6 ounces, you're doubling up the dosage, correct? and that has worked no problem.
Was there a reason for the doubling up?

The bottle of 3-in-1 I got a couple of years ago contains 0.47% Imidacloprid, and that's the 3/4 cup-per-gallon dilution I'm using. Take a look at the percentage on yours -- if it's 0.71%, 1/2 cup per gallon is fine. I've been working with Imidacloprid for 8 years, and I can tell you that doubling up poses no problems for cacti or succulents. Do the soil soaks once in the spring, then you'll be set for the rest of the growing season.

Thanks again.

You're welcome, and happy growing!

[keith]

What do all this scientifique studies tell us?
We might have to rethink about the type of medium we used and our fertilization regime...
It is better to prevent than a long talk about "what insecticide is better?", "how to kill it effectively?" etc
The keys
Warm months
High Nitrogen content in plant tissue
Peat based medium
Equals super outbreak

yea i've been noticing that for 20 plus years its why I went to a diatomaceous earth mixture which is a powder and not popular but I don't like root mealie bugs.. I didn't know about the N2 though interesting. Imidacloprid also works BUT last year I did a through soak and lost at least 10 plants to rot and a few got sun burned. Maybe just too much water and my new mostly pumice mix got too wet IDK. Or my Imidacloprid is old ? its over 20 years old. It did get rid of the scale outbreak on my Stenocactus.

[Steve Johnson]

Imidacloprid also works BUT last year I did a through soak and lost at least 10 plants to rot and a few got sun burned. Maybe just too much water and my new mostly pumice mix got too wet IDK. Or my Imidacloprid is old ? its over 20 years old. It did get rid of the scale outbreak on my Stenocactus.

Pesticides generally have a shelf life of 5 years. After that, their chemical composition starts to break down and become unstable. Taking a chance on 20-year-old Imidacloprid wasn't the best idea, and I have a feeling that's why you lost plants after you did the soil soak. As to the sunburn -- if the skin of our plants is exposed to Imidacloprid in direct sunlight, it causes a phototoxic reaction AKA "chemical sunburn". That's why I always do my soil soaks at night.

[Edwindwianto]

I didn't know about the N2 though interesting.

Another scientific paper that might interest you Keith

I quote

For adult males, the estimated optimum and maximum temperature thresholds were 28.7 and 31.9 degrees C; and for adult females, they were 28.4 and 32.1 degrees C, respectively.

It means for a male, at 28.7degC it loses it's fertility
And at 31.9degC it dies

I notice, when i put my pot under the fullsun until 10AM, my mineral mixture is quite heated up...and i mean it is quite warm...like i would make my coffee warm...
Sadly...i dont have a thermometer and am not willing to invest on one (just for 1 use and then it will never be used again)...

So if anybody could do this experiment and shared us the result...it would be very nice...
Just use your mineral soil (doesnt need a plant in it)...put it under the sun from sunrise until 10 o'clock...and measure the temp...
Of course...you should have a climate that is (give or take) similar to the one of thailand or Chihuahuan desert...

I know that surface temperature could be higher than the air temperature...so although Bkk's average low temp is only 25 degC...my substrate could very well reach those mealy's threshoods above...
I suspect...the heat of the mineral soil everyday...is enough to repel those root mealy bug...

If it were so, then this would be another benefit of using pure mineral soil
I mean, there is no root mealy in calcareous desert soil

EDWIN

[wildfire070]

I'm a fairly new succulent grower and have been having mealybug issues for the past few months. I've tried IPA and topical solutions to try and kill them but still find them at the bottom of my pots and in saucers. I'm afraid they're in the soil and roots and making it hard to get rid of them.

I managed to find Bioadvanced Tree & Shrub Feed & Protect at the store. Ingredients are Imidacloprid 0.74%, Clothianidin 0.37%, plus fertilizer 2-1-1. Directions say for containerized plants mix 1 tsp with 1 gal of water.

Would that be an effective concentration of Imidacloprid to kill mealybugs? Is that amount of fertilizer harmful to succulents? I have a variety of jade plants, echeverias, and aloes.

Any advice would be greatly appreciated!

[Steve Johnson]

I managed to find Bioadvanced Tree & Shrub Feed & Protect at the store. Ingredients are Imidacloprid 0.74%, Clothianidin 0.37%, plus fertilizer 2-1-1. Directions say for containerized plants mix 1 tsp with 1 gal of water.

Would that be an effective concentration of Imidacloprid to kill mealybugs? Is that amount of fertilizer harmful to succulents? I have a variety of jade plants, echeverias, and aloes.

Any advice would be greatly appreciated!

1 tsp. per gallon of water isn't nearly enough for an Imidacloprid soil soak to be effective against mealies. With the Tree & Shrub, the correct dilution should be 1/2 cup per gallon, but that's way too much fertilizer for all plants, not just cacti or succulents. It's best to avoid insecticides with premixed fert anyway, so I'll recommend my Imidacloprid product of choice, which is the BioAdvanced 3-in-1 Insect Disease & Mite Control concentrate:

https://www.amazon.com/BioAdvanced-7012 ... r=8-1&th=1

The amount of Imidacloprid is 0.47%, and the proper dilution will be 3/4 cup per gallon. Adding fertilizer is a good idea, but not required. If you'd like to do that, I highly recommend the following:

https://www.amazon.com/Dyna-Gro-Orchid- ... 218&sr=8-3

Dilute 1/2 tsp. per gallon of water.

[wildfire070]

For a soil soak, would I just mix up the solution and use that to water my succulents like I normally would? Or do I actually soak the plants in it? And if so, for how long do I leave it in the solution?

[Steve Johnson]

For a soil soak, would I just mix up the solution and use that to water my succulents like I normally would? Or do I actually soak the plants in it? And if so, for how long do I leave it in the solution?

A soil soak is just that -- saturate the mix, not the plant. Imidacloprid taken up through the roots makes our plants' juices toxic to mealies, and this systemic effect lasts throughout the growing season. Truth be told, I grow only desert cacti, so my season runs March-October, and I do my annual soil soaks every May. There may be succulent species that do most or all of their growing in fall and winter, so make sure that your succulents are in growth when you do the soil soak. If you have any questions about that, post them on the Succulent Growing Help forum, and someone should be able to guide you further.

[wildfire070]

I looked at the BioAdvanced 3-in-1 but it seems that they have eliminated the Imidacloprid in formulations in certain US states that have restrictions on Imidacloprid. My local store says they noticed the change in formulation within the last 6 months. I looked on Amazon as well and a few of the recent reviews said they also didn't have Imidacloprid in the newer bottles although it is still labelled as a 3-in-1.

The only other bottle I could find with a good percentage of Imidacloprid is the BioAdvanced Complete Insect Killer for Soil & Turf.

It has 0.72% Imidacloprid and 0.36% B-Cyfluthrin. And the recommended dilution I've read is 2oz per gallon of water. Is there any harm to the plants with the Cyfluthrin?

[Steve Johnson]

I looked at the BioAdvanced 3-in-1 but it seems that they have eliminated the Imidacloprid in formulations in certain US states that have restrictions on Imidacloprid. My local store says they noticed the change in formulation within the last 6 months. I looked on Amazon as well and a few of the recent reviews said they also didn't have Imidacloprid in the newer bottles although it is still labelled as a 3-in-1.

The only other bottle I could find with a good percentage of Imidacloprid is the BioAdvanced Complete Insect Killer for Soil & Turf.

It has 0.72% Imidacloprid and 0.36% B-Cyfluthrin. And the recommended dilution I've read is 2oz per gallon of water. Is there any harm to the plants with the Cyfluthrin?

First of all, I recommend that you do the following:

http://www.cactiguide.com/forum/viewtop ... 24&t=43819

I just went on Amazon, and I saw a review from January 2020 which said that the BioAdvanced 3-in-1 should really be called 2-in-1 since it no longer includes Imidacloprid. Glad you gave me the heads-up -- if this is a state-by-state restriction, I may not be able to get it here in California anymore. Luckily I can still buy the Insect Killer for Soil & Turf, so at least I'm not out of luck with the Imidacloprid I need. Thanks for letting me know about it!

According to the Extension Toxicology Network (Cornell University, Michigan State University, Oregon State University, and University of California at Davis), Cyfluthrin is not a systemic, so it won't have any effect on cacti or succulents. You should be fine with the soil soak, although I'd go with a dilution of 1/2 cup (4 oz.) per gallon of water. It's awfully hard to overdose cacti and succulents on Imidacloprid, so if you go with what I'm suggesting, you'll be set for a good long time.