is sulfur powder ok to apply to roots when repotting?

[BassetsforBrown]

I'm repotting my large columnar cactus because up until now it's soil has been entirely composed of loam, which holds a huge amount of water. I have bags of perlite and a soil meant for cacti that I'm going to mix.

When I (carefully) dig out the cactus, should I brush off whatever loam is still stuck around the roots, so as to have entirely new soil? Also, I know sulfur powder is used on cuttings to prevent rot/fungus, would it be beneficial to add some to the cactus's root base before potting, just incase?

Thank you!

[Steve Johnson]

I'm repotting my large columnar cactus because up until now it's soil has been entirely composed of loam, which holds a huge amount of water. I have bags of perlite and a soil meant for cacti that I'm going to mix.

When I (carefully) dig out the cactus, should I brush off whatever loam is still stuck around the roots, so as to have entirely new soil? Also, I know sulfur powder is used on cuttings to prevent rot/fungus, would it be beneficial to add some to the cactus's root base before potting, just incase?

Thank you!

Any remnants of old soil can spell potential trouble when repotting cacti, so -- always get the roots as squeaky-clean as possible. IMO sulfur powder doesn't do much re. the application you have in mind. Instead, soak the roots in 1% Hydrogen peroxide for 15 minutes. You can get 3% peroxide at any grocery store or pharmacy. 1 part peroxide solution to 2 parts water gives you the 1%. (This effectively kills any pathogens which could be hiding in there, plus it promotes faster healing.) Then rinse the roots in running water and let them dry out before you repot. Depending on how extensive the root system is, a few hours to a day or so before they're ready for transplanting. Be sure to repot in dry cactus mix, and let the plant settle in for 1-2 weeks. At that point, the roots are sufficiently healed, so you can start watering.

Everything I'm describing here should be considered as standard practice for hobbyist cactus growers. Why the peroxide treatment hasn't caught on more in the hobbyist community is something of a mystery.

[DaveW]

Sulphur has been used in gardening for generations to dust plant cut surfaces, so in itself will do no harm. The only time you should not use it, or Hydrogen Peroxide and similar disinfectants or fungicides is on the roots is if you are using some of the "Root Grow" or similar mycorrhizal rooting materials since they are of course fungi themselves, therefore to kill them would be counter productive.

http://www.rootgrow.co.uk/mycorrhizal-fungi.html" onclick="window.open(this.href);return false;

It is interesting to speculate whether in disinfecting the roots when you re-pot you are in fact destroying beneficial mycorrhizal fungi as well as harmful ones? But that same speculation applies to sterilising soil, unless the fungi are introduced afterwards on the plants roots? I suppose it has to be a balance where you weigh up whether it is necessary to cure an infected plant or are simply using it as a prophylactic treatment when it's side effects may be to kill off desirable mycorrhiza which may take some time to re-establish, if at all?

One of the problems with modern living is we are now "too clean" with our over use of disinfectants and so are not building up natural immunity or resistance to diseases, also this is even claimed as being responsible for the steep rise in allergies in children. Also the over use of antibiotics and insecticides is leading to resistant strains, therefore unnecessary prophylactic use of chemicals such as insecticides etc can often be counter productive so it's unwise to use them if you don't need to.

Quotes from the following link:-

"Only use chemical pesticides as a last resort and then do a spot treatment. Do not spray everything in the area “just in case”. Do not use the same pesticide repeatedly against the same pest."

"If you must use chemical pesticides alternate between two or three different classes of pesticide. The class is determined by the method the pesticide uses to kill an insect. You want to alternate between different methods of killing pests so they do not develop pesticide resistance."

"When you mix pesticides, read the label first. Use the rate on the label and apply it to the area indicated on the label. If a label says to use two teaspoons per gallon of water use two teaspoons not one or three."

http://polkmastergardener.ifas.ufl.edu/ ... es%202.pdf" onclick="window.open(this.href);return false;

[BassetsforBrown]

Sorry, but two more questions:

1. Could the chlorine & chloramine in my tap water damage the roots when I'm rinsing off the residual soil?
2. After it's clean, could I put the root base in front of my dehumidifier to speed up the drying time before planting, or would that over-dry/damage something?

Thanks again, everyone's help is much appreciated!

[Steve Johnson]

Sorry, but two more questions:

1. Could the chlorine & chloramine in my tap water damage the roots when I'm rinsing off the residual soil?
2. After it's clean, could I put the root base in front of my dehumidifier to speed up the drying time before planting, or would that over-dry/damage something?

Thanks again, everyone's help is much appreciated!

Both are good questions -- here are my answers:

1. No. I understand your concern about chlorine, etc., but I haven't seen any problems in the 3 years I've been using tap water for my cacti. The only thing I do is acidify it with 5% white vinegar to neutralize the Calcium bicarbonate that definitely is a problem when we're using hard water. I use a solid carbon block filter, but that's only water for human consumption. Should I be using it for my cacti too? Seems a bit overboard, although I could be convinced otherwise if someone shows me solid evidence that long-term exposure to chlorine/chloramines has a negative effect on the health of cacti over time. Or you can just use rainwater if you're able to store enough of it for your growing season.

2. I can't imagine that a dehumidifier would be a problem at all -- think about how dry the climate is for cacti living in the desert. Sounds like you may have "worrier's syndrome". As a recovering worrier myself, I know where you're coming from. Such being the case, I do applaud the care you have for your cacti.

By the way -- although I haven't been keeping up on the latest trends in container culture, perhaps this mycorrhizal inoculant thing is a fairly recent invention for cactus growers. Big difference between cacti in the wide open ground and growing them in pots, so color me skeptical. Maybe this is something you'd like to investigate, but personally I wouldn't bother. Once again, I could be convinced otherwise, although I'd need solid evidence to show that potted cacti grow better when they're inoculated with mycorrhiza than they would without it.

[DaveW]

It's a subject that does not seem to have had much research done for cacti Steve. Obviously sterilising soil kills off both good and bad mycorrhiza and probably other beneficial organisms too. The question is whether when re-potting plants you transfer useful mycorrhiza with them on or in their roots and whether sterilising the roots will destroy these? I must admit I have never sterilised soil for cacti, even for seed growing, and just used something like Chinosol on seedlings if mould has appeared.

For what it's worth these are what I found on the Web:-

http://tribes.tribe.net/sanpedrocactus/ ... 1e21077288" onclick="window.open(this.href);return false;

"Many common desert plants, including cacti, are heavily mycorrhizal (Fig. 3) indicating that mycorrhizas have a particularly important role in water relations in dry ecosystems and in soils with poor water retention."

http://www.davidmoore.org.uk/assets/mos ... ffects.htm" onclick="window.open(this.href);return false;

One for Carl!

Interesting is the remark in the link below about inoculating your new potting soil with a handful of the old to pass on the useful bacteria/mycorrhiza.

http://www.mattslandscape.com/bacteria/" onclick="window.open(this.href);return false;

a quote from the another web page.

"Over 95% of the world’s plant species form with mycorrhizae and require the association for maximum performance in the field."

This is the only experiment I can find using mycorrhiza on something similar to Succulent plants. In this case mycorrhiza came out worst, but they speak of watering them on and the only form I know in the UK is "Root Grow" where the granules have to be placed in contact with the roots since root exudations trigger the mycorrhizal germination. What is also interesting in the experiment is most examples that were given regular fertilisation did not perform that much better than the control that was not:-

http://www.socalplumeriasociety.com/jerk ... riment.pdf" onclick="window.open(this.href);return false;

http://www.ucpress.edu/content/pages/9139/9139.ch3.pdf" onclick="window.open(this.href);return false;

The point too is whether the mycorrhiza found in these products are those naturally found in association with cacti or Other Succulents in habitat?

It would have been interesting if they had finally knocked the plants out of the pot to show root growth. As one of my earlier links on the formation of tuberous roots in some cacti showed, soils with a high humus content form more above ground growth but less tuberous root growth than in mineral soils which produce better root systems but less above ground growth.

It is interesting to speculate then if plants in regularly fertilised mineral soils behave more like those in humus rich ones than plants in mineral soils which are only infrequently fertilised? Presumably the less nutrients in the soil the more extensive the plants root system needs to be to find them and the greater availability of nutrients the less need to form tuberous roots to store what is available?