physan, MSU fertilizer and demineralized water

[vyltan]

Hi all. Well am in the process of loosing my phal collection to root rot (40 of them). They are potted in thoroughly washed many times coconut husk mixed with coarse perlite 50/50, in slotted clear plastic pots. So LOTS of aeration. BUT since I wanted tremendous root system I decided to use demineralized water with proper MSU fertilizer; problem is that direct watering would take a lot of that water so I decided to soak each orchid in a pale with water/fertilizer. That still take 5 gal of water for my whole collection but it also transferred microorganisms causing root rot from one pot to another. Since I can't afford to double my water use (or triple it) by direct watering to avoid cross contamination, am thinking of adding physan to each watering. But will those quartely ammonium chemicals change pH or mineral concentration and impede fertilizer? Feel free to suggest another solution if u have one

[WhiteRabbit]

The root rot may be a result of over-watering -
I have skewers in all my pots to help determine when to water - Phals I allow to become just about nearly dry before watering. Chc retains moisture longer than bark, so it may be you need to allow it to dry more. I use tap water with no problems - flushing thoroughly about once a month.

[dounoharm]

plain tap water works for me too....under lights, and watering weeklyby pouring water thru...it drains thru to the pebble tray and out the drain...and is discarded.....physan will stop the rot...i would think putting physan in the watering water for a short period wouldnt hurt....just a supposition....gl

[RosieC]

I'm sure I read on another thread somewhere that Ray said Physan in every watering would poisen the plants. It's fine for ocasional use but not for every watering.

Can't find where I read it though.

I use plain tap water here on Phals with no problems. I use rain water on some of the more sensetive orchids but Phals seem fine with tap water.

[tucker85]

At Norman's Orchids (orchids.com) they said that they use physan once a month. I also use it once a month during the hot humid summers here in South Florida. I agree with WhiteRabbit, I've had better luck with my phals since I started letting them dry out almost completely. They've been growing very well for me in coconut husk. Good luck.

[BikerDoc5968]

I've got a collection of well more than 40 plants and more than 40 Phals. Since I live in Michigan and it was near impossible for me to run water supply into my greenhouse, I had to resort to using a 3 gal. sprayer. I fill it with ordinary tap water and the prescribed amount of food and water ALL the Phals. Then I repeat but significantly decrease the food for the Paphs/Phrags. It takes 2 to 3 hrs to complete the job but it works for me. Sure there's lots of run-off and waste but I don't water the stuff under the benches because of the run-off. I understand your situation may not lend itself to this style of watering, if you grow under lights/windowsill in a situation where you can't have pots dripping all over the place. If that is the case, you may want to invest in some plastic large trays. Drill a small hole in the front lower corner and attach a piece of plastic tubing to run into a bucket to catch the excess water. I agree the Phals need some time to dry... not completely. I only use Physan/SA 20 monthly during the winter and maybe a little more frequently during the summer. These disinfectants are preventative measures not necessarily curative. I do spray EVERYTHING in the greenhouse with SA 20 when I spray... helps with the algae on the walls. I definitely would stop the "dip and soak" route because it may be spreading disease as well as over-watering.

[Ray]

Physan poisoning is a matter of how much, not necessarily just how often it is used. I know of one person who adds a tiny bit to his RO tank and two people who add it to their fertilizer concentrate tank. The end result is application with every watering, but at dosages less than 0.01 teaspoon per gallon. The thread in which I suspected Physan poisoning was "S/H Ultimately Not for me" in which there was apparently a much larger dose every couple of weeks. I think that in order to get the purifying effect vyltan needs, a much stronger, probably eventually toxic does would be necessary.

Doc is right that it is a preventive, because it is a topical disinfectant, not systemic. I would suggest Cleary's 3336WP or maybe Phyton (which I have no experience with) for curing the issue, as they are systemic fungicides.

I would also suggest thinking of a better way to water; dunking in the same bucket will just lead to the same again.

[BikerDoc5968]

Just an addition to Ray's comments... Phyton - 27 is: Copper Sulfate pentahydrate (CuSO4·5H2O), the most commonly encountered salt; it occurs in other forms depending on the level of hydration of the salt. This is the label for Phyton - 27: http://www.phytoncorp.com/EPA%20Labe...3USSpecLab.pdf

As you can see it is a 21% solution of Copper Sulfate with the balance inert ingredients. It is the copper ion that gives the product its bacterial/fungicidal properties. One must exercise caution when using this product as too much will kill your plant! It can also be purchased at big box stores in the crystal form to be mixed as desired. In this form it is used to break up tree roots that invade plumbing pipes. Of course one could calculate how much to add to water to make a 21% solution.

[RosieC]

Originally Posted by Ray

Physan poisoning is a matter of how much, not necessarily just how often it is used.

Thanks for the clarification Ray

[vyltan]

Thxs all for your input and suggestions. Still no one has answered my main query: does physan modify the MSU fertilizer absorbtion? Pretty please?