# Foliar feeding...



## dodidoki (Dec 3, 2014)

Inretesting question. I have no idea about in practice. Does anyone use this for paph? Way of fertilizing, solution ( TDS, ratio of elements?)?
I ask it because followings: I use "traditional" fertilizing with watering, modified K-lite ( I reduced Ca and raised K), and I saw few incredible plants....most of them from Sam and Fischers. Huge plants with many very nice big( not big, HUGE!), dark green leaves, and almost no roots....in contrast I have many plants with nice big root system, but plants are half in size than Sam's ( I talk about same species). Another thing I ask about foliar feeding, that if I water my plants I carefully remove all of water from leaves ( in spite of continous air moving, few rots accour time by time, latest lost is my very nice and expensive sanderianum....just after watering days) Many thanks for your advice: Istvan


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## gonewild (Dec 3, 2014)

dodidoki said:


> Inretesting question. I have no idea about in practice. Does anyone use this for paph? Way of fertilizing, solution ( TDS, ratio of elements?)?
> I ask it because followings: I use "traditional" fertilizing with watering, modified K-lite ( I reduced Ca and raised K), and I saw few incredible plants....most of them from Sam and Fischers. Huge plants with many very nice big( not big, HUGE!), dark green leaves, and almost no roots....in contrast I have many plants with nice big root system, but plants are half in size than Sam's ( I talk about same species). Another thing I ask about foliar feeding, that if I water my plants I carefully remove all of water from leaves ( in spite of continous air moving, few rots accour time by time, latest lost is my very nice and expensive sanderianum....just after watering days) Many thanks for your advice: Istvan



I foliar feed everytime I water because I drench the foliage when I water and water always with nutrients. I never remove the water from the leaves.

Concerning the rot... do you notice the rot appears soon after you water with nutrients? Such as you would suspect the water caused the rot to happen?
Do you know the K content of your media?


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## dodidoki (Dec 3, 2014)

gonewild said:


> I foliar feed everytime I water because I drench the foliage when I water and water always with nutrients. I never remove the water from the leaves.
> 
> Concerning the rot... do you notice the rot appears soon after you water with nutrients? Such as you would suspect the water caused the rot to happen?
> Do you know the K content of your media?



Bark+ akadama, neutral, if I flush out with RO water, there is no TDS increasing.


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## dodidoki (Dec 3, 2014)

Yes, I suscepct that water is the causing agent, maybe water is infected. I know well, Cl is toxic so I try now with H2O2. Best way would be to water with freshly collected rain water but it is impossible to do in practice.


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## gonewild (Dec 3, 2014)

dodidoki said:


> Yes, I suscepct that water is the causing agent, maybe water is infected. I know well, Cl is toxic so I try now with H2O2. Best way would be to water with freshly collected rain water but it is impossible to do in practice.



But do you know the potassium mineral content of the growing media including what may be in the media naturally and also what potassium may be bound to the media?

Phal growers install Cl injectors to sterilize the water so i don't think you need to worry about it being toxic.

I don't suspect the water is the problem because of carrying disease pathogens. I suspect your media is saturated with some element and when you apply more of that element with fertilizer it triggers a reaction of a "rot" outbreak. I focus on K because I have been experimenting with a similar issue.


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## gonewild (Dec 3, 2014)

I found this, what in it might be a problem when combined with your fertilizer?...

Chemical analysis of Akadama & Akadama mud
Composition of Akadama
Percentage
SiO2-51.30%
Al2O3-38.05%
MgO-1.94%
MnO-0.26%
CaO-0.78%
Fe2O3-7.67%
pHpzca-6.9


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## gonewild (Dec 3, 2014)

OK I'm going to give you a theory...

Akadama is a clay product with a very high CEC. 

The clay has attached a high amount of K and is holding it in the media.
When you water with fertilizer containing K you experience a "rot" outbreak. The media in saturated with K your plants are saturated with K and the rot is a result of K toxicity.

Try removing all K from your fertilizer and see if you see less rot after watering.


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## dodidoki (Dec 3, 2014)

gonewild said:


> But do you know the potassium mineral content of the growing media including what may be in the media naturally and also what potassium may be bound to the media?
> 
> Phal growers install Cl injectors to sterilize the water so i don't think you need to worry about it being toxic.
> 
> I don't suspect the water is the problem because of carrying disease pathogens. I suspect your media is saturated with some element and when you apply more of that element with fertilizer it triggers a reaction of a "rot" outbreak. I focus on K because I have been experimenting with a similar issue.



Total cc is around 70 ppm. N is about 10 ppm, K ratio is about 1/10 of total. Do you advice me to flush all of pots with RO water?( to wash out accumulated salts).


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## gonewild (Dec 3, 2014)

dodidoki said:


> Total cc is around 70 ppm. N is about 10 ppm, K ratio is about 1/10 of total. Do you advice me to flush all of pots with RO water?( to wash out accumulated salts).



Yes I would flush out as much as possible. But most important is to remove K from your fertilizer.... to see if there is less rot as a result. 
I'm not saying never use K or that K is the problem but you can go a long time without providing K without any ill effect to the plants so nothing to loose by trying this idea.

What I'm suggesting is that the clay has bound K that won't flush out but that becomes available to the plant roots. Each time you add more K in the fertilizer you add to the problem. If the Akadama has been able to bind a high amount of K and you apply more in the fertilizer you may be subjecting the plants to toxic levels each time you water. That could explain why you notice rot or rot like symptoms after you water.

Akadama clay has extremely high capacity to absorb chemicals so that is why I would look at it as a potential problem source.


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## Ozpaph (Dec 3, 2014)

gonewild said:


> I foliar feed everytime I water because I drench the foliage when I water and water always with nutrients. I never remove the water from the leaves.



Same for me.
Remember, plants die sometimes for what appears to be no good reason. Its just 'harder' when its a sandie or something prized.


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## orcoholic (Dec 3, 2014)

This is just a stab in the dark, but are the plants repotted regularly, and when you do, do you pot in a pot size based on the root ball size. If you are getting no roots on "huge plants", the huge plants with no roots should still be potted in small pots. Potting in large pots will prevent root growth - and sandies hate overpotting

Also, by drying the leaves off after watering, you're preventing any foliar feeding. Foliar feeding is good for micronutrient absorption. Macronutrients can only be absorbed by the roots.


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## Stone (Dec 3, 2014)

gonewild said:


> OK I'm going to give you a theory...
> 
> Akadama is a clay product with a very high CEC.
> 
> ...



I don't know what to say to this except perhaps.......Utter nonsense. Show me one tiny little piece of evidence that shows potassium leads to rot. Just one!!!


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## Ray (Dec 3, 2014)

gonewild said:


> Akadama is a clay product with a very high CEC.




Is that a natural, mined-, or fired product?


Ray Barkalow
firstrays.com


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## Stone (Dec 3, 2014)

dodidoki said:


> Inretesting question. I have no idea about in practice. Does anyone use this for paph? Way of fertilizing, solution ( TDS, ratio of elements?)?
> I ask it because followings: I use "traditional" fertilizing with watering, modified K-lite ( I reduced Ca and raised K), and I saw few incredible plants....most of them from Sam and Fischers. Huge plants with many very nice big( not big, HUGE!), dark green leaves, and almost no roots....in contrast I have many plants with nice big root system, but plants are half in size than Sam's ( I talk about same species). Another thing I ask about foliar feeding, that if I water my plants I carefully remove all of water from leaves ( in spite of continous air moving, few rots accour time by time, latest lost is my very nice and expensive sanderianum....just after watering days) Many thanks for your advice: Istvan



Istvan, If you experience rot, The first thing to look at is temperature and air. ( and also mites and mealy bugs should be destroyed) If you dont have a lot of both and long hours of light, you must let the plant sleep. You should not give any fertilizer (especially N) and just enough water to keep the roots a little damp. 
If you grow under lights and have min temp of 20 and good air movement 24/7 then the Indonesian Paphs can continue to grow all year.
The rot has nothing to do with potassium. Akadama should be ok if it is the hard kind.


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## Stone (Dec 3, 2014)

Ray said:


> Is that a natural, mined-, or fired product?
> 
> 
> Ray Barkalow
> firstrays.com



Yes natural mined subsoil sometimes fired sometimes not. The Japanese use it as a standard P/medium but not too often for orchids. Chinese Cyms are grown in it and it is used as part of a Paph mix by some.
CEC is moderate from memory.


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## Stone (Dec 3, 2014)

gonewild said:


> Show proof for this statement please.



Well if I really need to again.....I have used plenty of K for years on all kinds of flora and don't get root rot fro it. = proof. ( if I get root rot it is for another reason. ( probably a watering issue...not enough..too much)

Ozpaph just said the best Paph grower he knows uses Aquasol. Plenty of K......Proof.

I don't understand your need to continue with this crazy theory??

Now you show me proof of K causing rot please.


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## Stone (Dec 3, 2014)

gonewild said:


> > > It's a shame you don't have insight and only want to rely on the old standard written rule. Loosen up, have a beer, have two and try something new.
> >
> >
> >
> > ...


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## gonewild (Dec 3, 2014)

Stone said:


> Now you show me proof of K causing rot please.



At the moment the proof that K contributes to rot like symptoms is the overwhelming number of observations by K-lite users that they immediately notice a reduction in rot after reducing the K amounts.


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## Stone (Dec 3, 2014)

gonewild said:


> > None of what you say is proof that potassium in excess does not cause toxicity or rot or rot like symptoms.
> 
> 
> 
> ...


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## AdamD (Dec 3, 2014)

Sigh. Hijacked again. Hands up don't shoot. 

Getting back to the question at hand, yes, I use a foliar feed. I dilute a quarter tsp/gal of a 20-20-20 with 1/3 Nitrogen from urea, 1/3 from ammonia, 1/3 from nitrate. I spray once every two weeks or so, it has helped my plants tremendously, in addition to the dilute K-lite I use at almost every watering. Things have really greened up. Give it a try. See what it does for you. I can't give specific em or pH readings, sorry. I'm just a modest carpenter with a high school diploma and a passion for growing orchids...


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## gonewild (Dec 3, 2014)

AdamD said:


> Sigh. Hijacked again. Hands up don't shoot.
> 
> Getting back to the question at hand, yes, I use a foliar feed. I dilute a quarter tsp/gal of a 20-20-20 with 1/3 Nitrogen from urea, 1/3 from ammonia, 1/3 from nitrate. I spray once every two weeks or so, it has helped my plants tremendously, in addition to the dilute K-lite I use at almost every watering. Things have really greened up. Give it a try. See what it does for you. I can't give specific em or pH readings, sorry. I'm just a modest carpenter with a high school diploma and a passion for growing orchids...



To the point of the thread.... since you are foliar feeding I assume you dont dry off your foliage. When you water with K-lite do you wet the foliage?


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## AdamD (Dec 3, 2014)

gonewild said:


> To the point of the thread.... since you are foliar feeding I assume you dont dry off your foliage. When you water with K-lite do you wet the foliage?



I try to avoid getting water in crowns when watering, but I don't get anal about it. Since I water early in the morning before work (about 2 hours before lights on/sunrise), if water does happen to accumulate in crowns I'll try to tip the pot and persuade it out. If there's some left, oh well. Haven't lost a plant to rot in a long while. (Knock on wood)


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## AdamD (Dec 3, 2014)

When I do foliar feed, I do it on days off, after the "sun" has been up for a while.


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## gonewild (Dec 3, 2014)

AdamD said:


> I try to avoid getting water in crowns when watering, but I don't get anal about it. Since I water early in the morning before work (about 2 hours before lights on/sunrise), if water does happen to accumulate in crowns I'll try to tip the pot and persuade it out. If there's some left, oh well. Haven't lost a plant to rot in a long while. (Knock on wood)



You and Istvan both use K-lite but he modified his and increased K.
You sort of modified yours as well by foliar feeding.
He has rot problems.
You have not had rot problems in a long while... would that have any relationship to when you started using K-lite?

I suspect his problems may be related to the clay in his media trapping excessive amounts of K. Or some other mineral factor in it. What type of media do you use? 

I realize that there are other environmental factors that could be wrong but I'm assuming Istvan has created a correct environment. And the rot he experiences is directly related to when he waters so environment is less likely and that leaves media and nutrient as prime suspects.


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## AdamD (Dec 3, 2014)

I would say the rot went away around the same time K-lite came in to play. Also switched from CHC based mix to Orchiata/ sphag mix around the same time. I still have some plants in CHC but they are doing well since the switch to K-lite. I have only been foliar feeding for a few months now. It was an experiment gone right


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## Bjorn (Dec 4, 2014)

Mike, AdamD, Istvan, Lance: what is your water source? And the quality of it?
By quality I mean particularly if it is hard and contains calcium or magnesium.
I would not use plain RO water on my plants. RO water should always be mixed with a certain amount of salts before use. Using plain RO water on plants can give them osmotic shocks which may cause big problems later on. If flushing is needed, I would have done it with a diluted calcium nitrate or magnesium sulphate solution.


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## dodidoki (Dec 4, 2014)

Thanks for advices. I use RO water ( TDS around 5-8 ppm) diluted with K-lite up to 70 ppm. Cause of MOD was yellowing leaves, I think it was because of too much Ca ( relative Mg deficiecy). I had only one rot problem within one year ( knock,knock!), but it killed one of my most expensive slipper (saderianum Red Petal). I asked about this way of fertilizing, because I saw Sam's plants with very few roots ad very huge green crown. Same as wild collected plants, they have relatively few short roots and big crown. In culture, they shoot may new roots but despite of this crown begins to be smaller. I just look for the "Why?".


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## naoki (Dec 4, 2014)

Bjorn said:


> I would not use plain RO water on my plants. RO water should always be mixed with a certain amount of salts before use. Using plain RO water on plants can give them osmotic shocks which may cause big problems later on.



I saw this on Xavier's article, but it seems to be far fetched. Does anyone know if there is any scientific support to this statement (osmotic shock)? Biologically, it seems unlikely (but my understanding of plant physiology isn't so great). Basic college plant biology books (there is always a chapter describing how water moves from root to leaves) would say that the plants have the easiest time to absorb RO water. Absorption of water through root is mostly passive process. The cell (plasma) membrane is basically a semipermeable membrane (water can go through it, but solutes usually don't). Water usually flows from low concentration region to high concentration region across the membrane (this is explained by something called "water potential"). So roots (which usually have higher solute concentration than irrigation water) can easily absorb water if it is surrounded by pure water. But if it is surrounded by high concentration fertilizer, the water moves from root cells to outside (this causes dehydration of the root cells, which is the so-called "fertilizer barn"). Additionally the root skin (epidermis) cells shouldn't be that wimpy (i.e. cells are unlikely to explode with the maximum flow rate of water into the cells). We have issues if we take bath in RO water, do we? 

Shoot:root ratio adjustment system of plants is a highly tuned mechanism. Lots of water and nutrients means less root and more shoot (leaves). This is general for most plants, and it has been shown in orchids, too. Do you think this is related to your question, Istvan? For the wildly collected plants, are you saying that they don't grow roots under the cultivation or that they don't have lots of roots after the collection? If later, the collectors are probably not digging up all the roots. Also, when they are associated with mycorrhizae, orchids can get away with smaller root mass.


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## Bjorn (Dec 4, 2014)

I partially agree naoki, but could it be that there are some, more hidden connection to why plain RO is not advised? Personally, I have seen that very pure water tends to dissolve copper, could eg, Heavy metal dissolution cause these problems? Just a suggestion....
Btw. placing a copper rod into a container with pure water prevents algae. Could this have some significance here?


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## Bjorn (Dec 4, 2014)

Another thing, sometimes we see reported "lesion-like" patches on slipper leaves that traditionally have been attributed to "overwatering". Could such kind of oedemea be induced by alternating use of too pure water and fertiliser? By creating a too high osmotic pressure in the plant?
And this happens to the roots and wouldn't it possibly destroy or at least influence their fuctionality?


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## gonewild (Dec 4, 2014)

I have deleted and edited several of my posts in this thread. if you want to know why send me a PM.


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## gonewild (Dec 4, 2014)

AdamD said:


> I would say the rot went away around the same time K-lite came in to play. Also switched from CHC based mix to Orchiata/ sphag mix around the same time. I still have some plants in CHC but they are doing well since the switch to K-lite. I have only been foliar feeding for a few months now. It was an experiment gone right



Thanks for that input.Your observation of a rot problem going away after switching to K-lite and changing from CHC media is in line with what I am looking at. CHC may be a trap for K much the same as Akadama may be and adding to an accumulated K excess problem.

Foliar feeding works. Here in the tropical area we live most farmers have not traditionally fertilized and they don't have very productive farms (small family farms). Now there are many stores selling nutrient products that are all foliar feed based. Almost no farmer fertilizes by adding chemical nutrients to the soil. The stores literally have dozens and dozens of bottles and bags of foliar nutrient combos. The interesting observation is when they apply a foliar feed that is say a complete 30-10-10 formula their crop improves and looks pretty good. All the additional nutrients are from foliar feed including NPK and the plants respond to the NPK as well as the micros. Foliar feeding is effective.


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## Ray (Dec 4, 2014)

Bjorn said:


> I partially agree naoki, but could it be that there are some, more hidden connection to why plain RO is not advised? Personally, I have seen that very pure water tends to dissolve copper, could eg, Heavy metal dissolution cause these problems? Just a suggestion....
> 
> Btw. placing a copper rod into a container with pure water prevents algae. Could this have some significance here?




I have been using RO on my plants for at least 25 years. I even went almost a year adding no fertilizer (broken metering pump on an automated schedule while I was traveling a lot), and the plants were relatively OK - some black leaf tips due to no calcium, and generally slowed growth and reduced blooming, but there was no "osmotic shock or imbalance".

Sure, pure water is considered to be chemically aggressive, but so what? Vascular fluids are solutions, and in all cases, the solvent is pure water. Once it's within the plant, that "pure" status vanishes.

Let's also consider that 1) orchid vascular fluids are roughly 4x the dilution of that in most terrestrial plants (more of that solvent), and 2) after that initial canopy wash-down, epiphytes in nature only get pure water most of the time.


Ray Barkalow
firstrays.com


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## Ray (Dec 4, 2014)

Concerning foliar feeding, not all plants are created equal in that respect. The fact that farmers do it is not particularly relevant.

Alan Koch (Gold Country Orchids) once mentioned that the macros are taken up by the roots, and trace elements by the leaves. I don't know that I buy that 100%, but as was mentioned earlier, when watering, my plants get soaked - leaves and roots - so how can I argue either way?


Ray Barkalow
firstrays.com


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## gonewild (Dec 4, 2014)

naoki said:


> Also, when they are associated with mycorrhizae, orchids can get away with smaller root mass.



Any plant that is wild collected brings it's associated mycorrhizae with it. And all divisions of that plant in the future also bring along the mycorrhizae.... unless the mycorrhizae have been killed off by excess fertilizers.


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## gonewild (Dec 4, 2014)

Ray said:


> Concerning foliar feeding, not all plants are created equal in that respect. The fact that farmers do it is not particularly relevant.
> 
> Alan Koch (Gold Country Orchids) once mentioned that the macros are taken up by the roots, and trace elements by the leaves. I don't know that I buy that 100%, but as was mentioned earlier, when watering, my plants get soaked - leaves and roots - so how can I argue either way?
> 
> ...



Can't really argue either way. But it is known that Phals take in N from UREA through their leaves so I guess that contradicts Alan Koch's statement.
In reality all nutrients that are applied as foliar feed either are absorbed through the foliage or they migrate down to the root zone and are picked up by the roots later. So foliar feeding works.


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## dodidoki (Dec 4, 2014)

Dear Bjorn!
I think you fight with same problems as me. I opened a thread about "overhydration" symptoms few month ago. My experience was following , especially with phrags: just after waterings, within few hours(!!!) oily spots appeared on leaves , but randomized, not at base. These spots disappeared within one or two days if I stand my plants just in front of fan. So I did that after: I never waited for spots, I water my phrags and stand them just in front of fans for a day. Symptoms disappeared. Another problem is not so simply. When an orange, smelling spot appears at the base of paph...it is ( I think ) Erwinia, my theory is that bacteria is in water, furthermore, in STANDING water. In nature if there is a heavy rain, water flushs out pathogenes from plants. ( rain water is about 4-10 ppm). But if there is heavy rain, there is heavy wind, too!!!
I will try with diluted H202 avoiding pathogenes ( 0,5 % CC) once per month.

Original question was about foliar feeding. Rot is "just" a side problem, I had only one this year ( but hard....600 USD plant).

I think that 12 N : 5 Ca: 2 K : 3 Mg is not too big K to accuse with rot. Regular fertilizers contains macros 3:1:1 N/P/K ratios...


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## Bjorn (Dec 4, 2014)

Dear Istvan,
Thak you for that input. i think it is strange things going on when a leaf gets wet patches from watering. Remeber at least the polantas are more or less soaked year round in their natural habitat, so this thing cannot be natural. But it is good that just by drying out you can get rid of it. i hardly ever see it btw, just a couple of times during all my time growing paphs. Could it be caused by swings in fertiliser and water supply? 
B


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## TyroneGenade (Dec 4, 2014)

I don't have time to read through this entire thread. I am assuming no one has yet presented research data correlating K with rot, so here is one paper it took me 2 minutes to find:
http://www.apsnet.org/publications/...uments/1982Articles/PlantDisease66n08_728.pdf
I suspect there are others...

BUT I do not think the issue is K toxicity but instead Ca/Mg deficiency. See http://www.apsnet.org/publications/...Phyto74n10_1250.pdf?origin=publication_detail (another paper it took 1 minute to find) Again, I suspect there are others showing the same thing.

I see no point in back-and-forth arguing unless we are going to actually do the experiment to find out what is really going on in the substrate. Similarly, sending samples to a plant pathologist would determine the cause of the infection (Mg deficiency?). 

If your plants have a Mg deficiency, then all foliar feeding is going to do is supply the bacteria with the nutrients they need to cause more trouble.


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## Stone (Dec 4, 2014)

TyroneGenade said:


> > I don't have time to read through this entire thread. I am assuming no one has yet presented research data correlating K with rot, so here is one paper it took me 2 minutes to find:
> > [/QUOTE]
> > That is a scientific pape...wiley.com/doi/10.1002/jpln.200420485/abstract


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## Rick (Dec 4, 2014)

Stone said:


> I don't know what to say to this except perhaps.......Utter nonsense. Show me one tiny little piece of evidence that shows potassium leads to rot. Just one!!!



In the original arguments for low K (probably in posts 2 years old) I linked research from the Fluid Fertilizer Institute that demonstrated that plants with high K low Ca tissues are considerably more susceptible to Erwinia (basal rot) than plants with high Ca low K tissues.

http://fluidfertilizer.com/pastart/pdf/36P16-19.pdf

Similar results for Botritus. 

I believe rots in potatoes have been linked to calcium deficiency.

And reduced calcium in plants has been linked to elevated K.


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## Stone (Dec 5, 2014)

Rick said:


> In the original arguments for low K (probably in posts 2 years old) I linked research from the Fluid Fertilizer Institute that demonstrated that plants with high K low Ca tissues are considerably more susceptible to Erwinia (basal rot) than plants with high Ca low K tissues.
> 
> http://fluidfertilizer.com/pastart/pdf/36P16-19.pdf
> 
> ...



The calcium content in the leaves in some of the severe botritis cases are well below what is considered normal. At the same time K is in the very high range. If you apply tremedous amounts of K and/or do not supplement Ca you get these kind of figures. OK that's a given and I never argued with that.

However, let's look again at optimum hydroponic ratios as there is no interference from cation exchage in the media and we can observe optimum growth response (including Ca utilization) freely and efficiently.
Here we typically see otpimum Ca additions of about half that of K.
( but even so I have not seen any evidence of the kind of extreme reduction of K you seem to think is necessary anywhere on earth. You would think if K was such a problem in horticulture they would have discovered that by now)


As an example (you used beans, I'll use Chrysanthemum. These are the most EC sensitve crop I have in the table in front of me)

Optimum nutrient composition- mg/L or ppm:
NO3..147
NH4..14
P.......31
K.....196
S....32
Ca...110
Mg...24

This tells me that reducing K is not the way to go (in most common situations) providing sufficent Ca is important.

Very high levels of K can reduce uptake of Ca which MAY lead to increased disease in some plants.

There is no problem with reduction of Ca from the use of ''regular fertilizers'' if some form of Ca is provided.

The kinds of extreme dumping of potassium on crops without sufficient Ca is only seen in agriculture not horticulture (greenhouse plants)


My conclusion: K is not causing the ''rot''


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## Brabantia (Dec 5, 2014)

gonewild said:


> What I'm suggesting is that the clay has bound K that won't flush out but that becomes available to the plant roots.


How do you explain this? If Potassium can be picked up by roots inevitably it exists a period of time during which it is in liquid phase. Or:is it at the points of contacts between roots and substrate which has absorbed (or adsorbed) Potassium that the roots pick up potassium. The same process by which Paphiopedilum roots take Ca when they are growing on calcareous stones.


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## gonewild (Dec 5, 2014)

Brabantia said:


> How do you explain this? If Potassium can be picked up by roots inevitably it exists a period of time during which it is in liquid phase. Or:is it at the points of contacts between roots and substrate which has absorbed (or adsorbed) Potassium that the roots pick up potassium. The same process by which Paphiopedilum roots take Ca when they are growing on calcareous stones.



There exists both of your possibilities at the same time.
Potassium exists in media in 3 states...
1. Dissolved in water.
2. Ionically bound. (CEC)
3. As part of the chemical composition of the solid materials.

Substrates like the Akadama clay have a high CEC compared to most other media used for growing orchids. That means the clay has the ability to bond and retain a large amount of potassium that enters the media in irrigation water. The clay also has a reputation (bonsai) as being high in potassium so I assume in has a potassium content that dissolves into water as the clay decomposes.

When I said "the clay has bound K that won't flush out but that becomes available to the plant roots" I was referring to #2 and #3 above. The CEC of the clay combined with the potassium mineral content that gets leached out has the potential to create a lot of ppms of K in the media water so there exists an unknown amount of K available to the plant. Far more than you may think. Combine this with a "full dose' of K in the fertilizer water and do you really know how much K you are exposing the plant to? 

Then with the case of the Akadama clay there is a high aluminum content that has the potential to mess things up under certain conditions.

It's not just a matter of how many ppms you apply in fertilizer it is the total plant environment over a period of time that needs to be considered. 

Here is a fairly easy to understand document on CEC and how the nutrient exchange works. http://www.ctahr.hawaii.edu/mauisoil/c_relationship.aspx


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## Stone (Dec 5, 2014)

gonewild said:


> > When I said "the clay has bound K that won't flush out but that becomes available to the plant roots" I was referring to #2 and #3 above.
> 
> 
> 
> ...


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## gonewild (Dec 5, 2014)

Stone said:


> You would think if K was such a problem in horticulture they would have discovered that by now)



Mike, We have yet to see any research that looks at the effects of long term culture in a high K environment. If they had done such trials maybe they would have discovered it by now. 

Also we are not "Horticulture" we are "Orchid culture", whats good for a Mum has nothing to do with whats bad for a Paph.


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## gonewild (Dec 5, 2014)

Stone said:


> gonewild said:
> 
> 
> > Lance, how do you reconcile this with the last sentence of thesecond last paragragh of your link?
> ...


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## myxodex (Dec 6, 2014)

I've had root rot problems which have been largely eliminated by adding some tap water to my rain water. I would recommend checking media pH. Also sulphate, like calcium, is a major nutrient as far as pathogen resistance is concerned. In fact low pH issues can be made worse by low sulphate, because at low pH the micros (Cu, Zn, Mn, Fe; in decreasing order of toxicity) become more available partly because more are released from CEC media and sulphur biochemistry is critical for oxidative damage repair (glutathione) and metal ion chelation (phytochelatins). I only add 5% tap water because my tap water has an alkalinity of 264 ppm (as HCO3) and also has 55 ppm sulphate which tops up what my medium supplies. My advice then is get a tap water analysis from your water provider, and work out how much to supplement with. I agree with Bjorn about RO water, not because of osmolarity issues, but because of HCO3 and/or sulphate.


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## Rick (Dec 6, 2014)

myxodex said:


> because at low pH the micros (Cu, Zn, Mn, Fe; in decreasing order of toxicity) become more available partly because more are released from CEC media and sulphur biochemistry is critical for oxidative damage repair (glutathione) and metal ion chelation (phytochelatins).



I agree the role of trace metals is overlooked in problems with our plants.

Back in the day, the micros weren't part of most fertilizers, and just came in as "impurities" with our tap water, natural compost, potting mix materials.......

As a toxicologist the micros can be very toxic to aquatic animal and plant species.

Copper is a very potent algacide.

The toxicity of these metals is mediated by not only pH, but hardness, TOC, TDS.

Models have been developed to predict the toxicity of metals to sensitive organisms.

The influential factors include:
pH
Hardness (i.e. Ca and Mg concentration)
Humic acid content
sulfur
chloride

Also to consider are the deficiencies of these micros in plants due to antagonism by ammonia and potassium.

You could be doomed in either direction, which may make it worthwhile to check metals in potting mixes to see if you are in accumulation mode.


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## Stone (Dec 7, 2014)

Bjorn said:


> Mike, AdamD, Istvan, Lance: what is your water source? And the quality of it?
> By quality I mean particularly if it is hard and contains calcium or magnesium.
> I would not use plain RO water on my plants. RO water should always be mixed with a certain amount of salts before use. Using plain RO water on plants can give them osmotic shocks which may cause big problems later on. If flushing is needed, I would have done it with a diluted calcium nitrate or magnesium sulphate solution.



Lately I am trying to use rainwater for the smaller plants (which is most of them by far) I'm trying to avoid Cl and Fl mainly. For the rest of the collection water straight from the hose. I think the cal carbonate level varies from time to time but its not very high. pH is around 7.
Concerning flushing. (and I don't know if it would work but in theory it should) is to use a strong dose of zeolite clay (you can get it anywhere these days) mixed in your flushing water a couple of times and then flush with plain water to remove what is left of the clay. Again theoretically, this should remove many of your favorite cations quickly and easily as its CEC is through the roof compared to say peat or CHC. I did it once to get rid of a moldy kind of smell in the p/mix I did not like and it seemed to work for that too!
Probably not necessary to do unless you over fertilize in the first place. 
Just a thought.


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## dodidoki (Dec 7, 2014)

Reading your comments it is very interesting, that some of you talkad about root rot, because I mentioned erwinia, what killed my 600 USD sandy.. :-( R.I.P.!
Erwinia does not hurt roots at all, I think. All of my plants declined by root insuff., killed by fungi. Erwinia is more problematic, because it kills not the root, but the base of crown, and spreads vertically, inwards to the center. All of plants killed by erwinia were otherwise healthy plants and died suddenly, day by day ( I couldn"t see anything at night, there were orange ( and smelling) wet spot at base in morning, plants died within 2-3 days. After K-lite diet this disease reduced at about 1/10, so I think this way helps to prevent it, indeed.


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## gonewild (Dec 7, 2014)

dodidoki said:


> Reading your comments it is very interesting, that some of you talkad about root rot, because I mentioned erwinia, what killed my 600 USD sandy.. :-( R.I.P.!
> Erwinia does not hurt roots at all, I think. All of my plants declined by root insuff., killed by fungi. Erwinia is more problematic, because it kills not the root, but the base of crown, and spreads vertically, inwards to the center. All of plants killed by erwinia were otherwise healthy plants and died suddenly, day by day ( I couldn"t see anything at night, there were orange ( and smelling) wet spot at base in morning, plants died within 2-3 days. After K-lite diet this disease reduced at about 1/10, so I think this way helps to prevent it, indeed.



All of my comments about rot were about foliage and not roots. Actually what I see with "excess" K is really good root growth. The root system becomes too efficient at gathering nutrients and the plant stores unused potassium in the foliage and just keeps storing more until it creates a foliage problem. How that causes rot is the unanswered question and I have an idea about it, so I ask questions when someone has a related issue. Does not seem my ideas are too popular however.


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## Stone (Dec 7, 2014)

gonewild said:


> > The root system becomes too efficient at gathering nutrients and the plant stores unused potassium in the foliage and just keeps storing more until it creates a foliage problem. How that causes rot is the unanswered question
> 
> 
> 
> ...


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## gonewild (Dec 7, 2014)

Stone said:


> gonewild said:
> 
> 
> > As far as I have observed, I have not seen evidence to suggest that ''standard'' accumulation of K causes an increase in disease problems in the leaf.
> ...


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## Ray (Dec 8, 2014)

While my gut tells me that reduced K is a plus, I really believe that plant nutrition is such a complex subject that we are like the pack of blind men being asked to describe the elephant.

I'm just glad I didn't get the scrotum...

(Sorry...just bored, sitting here waiting for jury duty.)


Ray Barkalow
firstrays.com


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## gonewild (Dec 8, 2014)

Ray said:


> While my gut tells me that reduced K is a plus, I really believe that plant nutrition is such a complex subject that we are like the pack of blind men being asked to describe the elephant.
> 
> I'm just glad I didn't get the scrotum...
> 
> ...



:rollhappy:
I agree completely Ray. Plant nutrition is very complex. So complex that is humorous to continue to believe it is as simple as it is written now. 
Give a blind man time to experiment and feel his way around and he can describe an elephant in far more detail than a man with sight. And a blind woman can make the description just by talking with the elephant. And, the moral is that reality is not always visible to those that only look at the obvious.


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## Stone (Dec 8, 2014)

gonewild said:


> > So the simple solution is to use less K
> 
> 
> .
> ...


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## gonewild (Dec 8, 2014)

Stone said:


> gonewild said:
> 
> 
> > .
> ...


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