Sterilize Cactus soil

[darth1211]

Hello, I bought Espoma cactus soil, and once I opened it, I saw a few fungus gnats. How.do I sterilize the cactus soil in the oven?

[Tom in Tucson]

Hello, I bought Espoma cactus soil, and once I opened it, I saw a few fungus gnats. How.do I sterilize the cactus soil in the oven?

This product touts that it contains fungus on the label, and the gnats help to prove that. If you sterilize the soil, it most likely will kill the fungi, which defeats the purpose of using it.

[darth1211]

Hello, I bought Espoma cactus soil, and once I opened it, I saw a few fungus gnats. How.do I sterilize the cactus soil in the oven?

This product touts that it contains fungus on the label, and the gnats help to prove that. If you sterilize the soil, it most likely will kill the fungi, which defeats the purpose of using it.

Wait, why did they put fungus in the soil? aren't fungus gnats gonna mess up the cactuses?

[ohugal]

As far as I know fungus gnats need moist soil in order to survive. Since the soil will mostly be dry, I don't think they pose a significant threat.

[darth1211]

As far as I know fungus gnats need moist soil in order to survive. Since the soil will mostly be dry, I don't think they pose a significant threat.

Inside the bag is pretty moist. Should I just let it air out?

[jerrytheplater]

Espoma sells a wide range of organic products. I bought their cactus fertilizer solely for the added microorganisms. Various soil bacteria and soil fungi. These are naturally found in our soils. What is found in the desert remains to be seen. I wish I knew.

Fungus gnats: open the bag and let it dry out. Or you could water with a solution made from the mosquito bits sold in big box stores. That is a variety of Bacillus thuringiensis that will kill the fungus gnat larvae.

[Steve Johnson]

Espoma sells a wide range of organic products. I bought their cactus fertilizer solely for the added microorganisms. Various soil bacteria and soil fungi. These are naturally found in our soils. What is found in the desert remains to be seen. I wish I knew.

Then you might be interested in reading this:

https://askabiologist.asu.edu/explore/desert-microbes

A question -- does Microcoleus in desert soils provide any benefit to the roots systems of cacti? This wasn't addressed in the article, although just going by intuition, I sorta kinda think it doesn't. Here's a related question -- do the Ectomycorrhizal and Endomycorrhizal fungi in the Espoma organic cactus mix provide any benefit to the roots systems of cacti? If so, what is it? An explanation would be helpful.

[C And D]

Repeated wet dry cycles will kill most fungi added to the soil mix
If you still have problems, try a Physan 20 soil soak
I use it sterilize seed beds that are made of soil containing added micro-organisms

This doesn't eliminate fungus gnats though, you need to treat those differently if you have a bad case

[greenknight]

Bacillus thuringiensis israelensis (Bti) is a bacterium which used to kill the larvae of mosquitoes and fungus gnats. It's available in mosquito dunks, granules, liquid and powder. I would get the powder - mix a little into that cactus mix and seal it up. It will kill the larvae, not the adults - but they only live about 8 days.

I don't think you should worry about the fungi, which have nothing to do with the gnats. I did a small trial with mycorrhizal inoculant on cactus cuttings and there did appear to be a benefit, with stronger growth from the treated ones. Too small of a test to be definitive, but it certainly didn't hurt. One species of mycorrhizal fungus, Trichoderma harzianum, is poven effective as a biological fungicide - it will kill other fungi that attack the roots of a plant which it colonizes. Espoma includes this species in their fertilizer, not sure if it's in the planting mix.

[MikeInOz]

The best way to treat the media is to solarize it. If you are still getting hot sunny days, put the mix into a clear plastic bag and lay it on it's side in full sun. Try to flatten it out to make it about 4 inches deep and fold over the opening of the bag to hold in the heat. The mix must be moist but not very wet. On a really hot day it will heat up to at least 60 or more degrees (hot to the touch) This will kill of all insects and their eggs (very quickly) and most pathogens but will not harm beneficial microbes as long as it does not get too hot. The cooler and cloudier the weather, the longer you need to leave it. You can then use it with confidence after that as soon as it cools off (providing the quality is good to begin with). Be careful if the mix contains controlled release fertilizers because they will quickly release their contents if the temp in the bag gets really high.

[jerrytheplater]

Espoma sells a wide range of organic products. I bought their cactus fertilizer solely for the added microorganisms. Various soil bacteria and soil fungi. These are naturally found in our soils. What is found in the desert remains to be seen. I wish I knew.

Then you might be interested in reading this:

https://askabiologist.asu.edu/explore/desert-microbes

A question -- does Microcoleus in desert soils provide any benefit to the roots systems of cacti? This wasn't addressed in the article, although just going by intuition, I sorta kinda think it doesn't. Here's a related question -- do the Ectomycorrhizal and Endomycorrhizal fungi in the Espoma organic cactus mix provide any benefit to the roots systems of cacti? If so, what is it? An explanation would be helpful.

Thanks for the link Steve.

Regarding your question: The Cyanobacteria, Microcoleus forms/helps to form the desert crust on the soil, as the link said (or one of the others I followed). This crust helps to keep the soil from blowing away in the wind. I'd say that's a huge benefit to the root systems of cacti. The soil does not blow away and keeps the roots buried. Plants are not sandblasted by the blowing soil.

I'd say the crust also traps in some moisture in the soil as the water/moisture would have a hard time wicking up through the crust layer. There is a big physical textural difference between the soil and the crust. Kind of like putting gravel in the bottom of a pot, but in reverse. You end up with a perched water table in the pot. The water can't pass through the difference in texture in the layers. The crust does the same at the top.

Take a look at areas in the desert damaged by off road vehicles, what does the plant life look like there compared to areas with an intact crust? I don't know if you'd see a difference first hand, but I suspect there is a big difference. I'd be curious if any of our members have seen areas like what I'm imagining/describing.

Those are not direct benefits to the roots like when the Mycorrhizae penetrate and live within roots or around the roots. But it is an indirect benefit.

Your related question is the same question that I have. I just figured it can't hurt the cacti. It is not my primary fertilizer.

I do see a very big difference in a bog plant growing in fully saturated substrate since using the Espoma Cactus fertilizer there. The plant has really grown huge. The substrate is more open. I'm really pleased with what I see there.

[Steve Johnson]

Regarding your question: The Cyanobacteria, Microcoleus forms/helps to form the desert crust on the soil, as the link said (or one of the others I followed). This crust helps to keep the soil from blowing away in the wind. I'd say that's a huge benefit to the root systems of cacti. The soil does not blow away and keeps the roots buried. Plants are not sandblasted by the blowing soil.

I'd say the crust also traps in some moisture in the soil as the water/moisture would have a hard time wicking up through the crust layer. There is a big physical textural difference between the soil and the crust. Kind of like putting gravel in the bottom of a pot, but in reverse. You end up with a perched water table in the pot. The water can't pass through the difference in texture in the layers. The crust does the same at the top.

Take a look at areas in the desert damaged by off road vehicles, what does the plant life look like there compared to areas with an intact crust? I don't know if you'd see a difference first hand, but I suspect there is a big difference. I'd be curious if any of our members have seen areas like what I'm imagining/describing.

Those are not direct benefits to the roots like when the Mycorrhizae penetrate and live within roots or around the roots. But it is an indirect benefit.

Your related question is the same question that I have. I just figured it can't hurt the cacti. It is not my primary fertilizer.

I do see a very big difference in a bog plant growing in fully saturated substrate since using the Espoma Cactus fertilizer there. The plant has really grown huge. The substrate is more open. I'm really pleased with what I see there.

Regarding what you just said about Mycorrhizae, here's some food for thought:

https://www2.nau.edu/~gaud/bio300/mycorrhizae.htm

Useful or not? Let me know what you think.

[Minnesota]

Regarding your question: The Cyanobacteria, Microcoleus forms/helps to form the desert crust on the soil, as the link said (or one of the others I followed). This crust helps to keep the soil from blowing away in the wind. I'd say that's a huge benefit to the root systems of cacti. The soil does not blow away and keeps the roots buried. Plants are not sandblasted by the blowing soil.

I'd say the crust also traps in some moisture in the soil as the water/moisture would have a hard time wicking up through the crust layer. There is a big physical textural difference between the soil and the crust. Kind of like putting gravel in the bottom of a pot, but in reverse. You end up with a perched water table in the pot. The water can't pass through the difference in texture in the layers. The crust does the same at the top.

Take a look at areas in the desert damaged by off road vehicles, what does the plant life look like there compared to areas with an intact crust? I don't know if you'd see a difference first hand, but I suspect there is a big difference. I'd be curious if any of our members have seen areas like what I'm imagining/describing.

Those are not direct benefits to the roots like when the Mycorrhizae penetrate and live within roots or around the roots. But it is an indirect benefit.

Your related question is the same question that I have. I just figured it can't hurt the cacti. It is not my primary fertilizer.

I do see a very big difference in a bog plant growing in fully saturated substrate since using the Espoma Cactus fertilizer there. The plant has really grown huge. The substrate is more open. I'm really pleased with what I see there.

Regarding what you just said about Mycorrhizae, here's some food for thought:

https://www2.nau.edu/~gaud/bio300/mycorrhizae.htm

Useful or not? Let me know what you think.

Hello, Steve & Jerry,

The combination of Jerry's thought and premises with the confirmations of the mycorrhizal article seem to be the foundation of a microenvironment's basic priniciples.

The looming question, if these are two essential components of a functional microenvironment favorable to optimal growth, is this: what are the encompassing principles of a healthy microenvironment? If we see two here, and two others are addressed in provision of nutrients and soil content/management, what are the other primary factors in replication of this environment? Light, temperature, water, and ... ? If anyone has ideas on the 'bigger picture,' it would be useful and educational to codify in one place, briefly and succinctly. I know I would really appreciate seeing this for consideration and application. And Steve, you're always coming up with terrific research. Jerry, your concepts and experience are very solid and thoughtful.

Just tossing around some thoughts.

Bret

[MikeInOz]

You end up with a perched water table in the pot. The water can't pass through the difference in texture in the layers. .

In theory, that might be the case Jerry but in practice it rarely happens. Especially with the coarse materials we use. Even if or when it does, it just moves the ''saturated'' layer higher up in the profile but does not make a difference to the total moisture content of the pot. I go into it more here...https://cactiguide.com/forum/viewtopic. ... er#p379733

[Steve Johnson]

I sent a PM with a few questions on mycorrhizae to Mike, and his answer says it all:

Hi Steve
Although mycorrhizae have been found in some cactus species' roots I think we can pretty much ignore them in cultivation. They can help plants deal with very poor soil fertility and heat and water deficit but those in cultivation don't experience these problems. In fact we can generally say that cultivated plants usually do better than they do in the habitat.
The other points are that Myc is destroyed or inhibited with even low levels of P in the soil, and that you may need to use a specific species of Myc to have it even work. I never have worried about them and don't intend to. I do grow other kinds of plants though and I go out of my way to inoculate propagations of those that I know need it.
Cheers
Mike