[Dave Coulier]

I am posting this on behalf of a buddy. Its for you all to read and discuss amongst yourselves. I can not answer for Gojo, so if you have any questions, consulting the references would be best.

Phosphite: What companies aren't telling you.
What phosphites will and will not do for a plant; the good and bad.
by gojo

I wrote this after I heard a buddy uses Pure Flowers (phosphite) as a phosphorus (P) fertilizer for pre-flowering because of claims by Pure Flower company; and I know a few people on Icmag who use it, so I thought this could help them and others. This is in no way meant to be an insult or upset anyone who uses phosphite as a P fertilizer, I just hope to help explain and sort out truth from fiction from claims made by sellers/makers of phosphite fertilizers. This is not meant to be conclusive, it's only my take on what I have learned.

Phosphites (Phi) are formed using phosphorous acid (H3PO3) that is neutralized to form salts and becomes phosphonate ions (H2PO3), also called phosphite. Often Phi is sold in the form of potassium phosphite (K2H2PO3). Normally P is supplied with fertilizers containing phosphoricacid (H3PO4), which is a form of phosphate (Pi) available to plants.


What does phosphite do for plants?


It is a systemic fungicide active against a few soil fungal pathogens and a few foliar fungal pathogens when used as a foliar spray additive (ex., PM). Phosphites are sold as fungicides by most of the AG companies yet some companies are being unethical when they label Phi as a P fertilizer.

Foliar application of Phi has been shown to act as an 'inducer' for SAR (Systemic Acquired Resistance). SAR is a natural red-alarm mode for plants which can make grow bigger, faster and can increase yields and resistance to biotic attacks and environmental stress. Other products at the hydro store such as chitosan (as Chi), harpin protein (as Messenger and now Employ), salicylic acid (as Scorpion Juice) also activate the salicylic pathway acting as inducers for SAR.

Even from just a single foliar application of Phi it has been shown that in many plants and trees “...it increases floral intensity, yield, fruit size, total soluble solids, and anthocyanin concentrations [ex., a source of color for purple buds], usually in response to a single application.” (Lovatt and Mikkelsen; 2006). Those responses could be due in part to induction of SAR by Phi.

Phi has been found to supply P to P-deficient plants when Phi is applied as a foliar spray. Once taken in by the plant the mode of action is a bit surprising and not very well understood. Phi can't be used as a P source by the plant directly, even though Phi was absorbed into the leaf. There is some disengagement in the academic world whether or not plants can convert Phi into Pi; one side thinks it is possible but they can not prove it because they can not identify a potential enzyme or reaction for the conversion. The other side thinks it is not possible because no one can show what enzyme or reaction could convert Phi into Pi. The latter group makes the point that Phi, even after a single application, has been found to remain in plant tissue for over a year. The latter group claims plant usage of Phi once it is absorbed is low which is why Phi can become phytoxotoxic in concentration. That point is sound because Phi is systemic and stable once in the plant tissue.

Microbes in the media (ex., rhizosphere) and the and on leafs (phyllosphere) can convert Phi into Pi and then the plant can use the Pi as a P source, this is how Phi is thought to benefit plants in terms of P; however that conversion is a slow process. Most microbes do better consuming Pi for energy than Phi.

Plants given only Phi as a P source (in hydro or soilless) will become P-deficient in a short time. What this means is that Phi is not an adequate source for P. Phosphite can not replace Pi as a plant nutrient source for P; the P attained by plants from application of Phi to P-sufficient plants is very low.

What does phosphite not do for plants?

Phi is not a replacement for Pi as a source of P in bloom boosters, that means products like Pure Flowers, if only using phosphite as the P source, will not preform as well as bloom booster with phosphoric acid or other Pi source for boosting P. Applying Phi during pre-flowering when the plant can use extra P (and N, K, Ca, Mg, etc) is probably the best time because plants can tolerate and can benefit from higher levels of P and K (more of the latter than the former).

Phi can not replace Pi to provide P to plants even though the Phi and phosphorous acid contain higher levels of P (~39%) than Pi and phosphoric acid (~32% P). Phi is more water soluble than Pi and is absorbed faster into the respiration tissue (roots) or photosynthesis tissue (leafs). However, once inside the plant Phi does not provide P for the plant in sufficient quantity and can inhibit growth and health of the plant if overused.

Phi is not a broad range system fungicide with a wide range of fungi it will inhibit. I for one am interested in using it as a pre-flowering bloom booster as foliar spray which might also help prevent occurrence of PM.

Phi has been found to inhibit Pi uptake, probably because both Phi and Pi taken up by plants using Pi transports. Considering Phi is absorbed faster than Pi, it is possible Phi effects the Pi transporters ability to uptake Pi.

Phi interferes and can inhibit with Pi starvation responses in plants, such as increased roots growth and increased root to shoot ratio, etc.

How can phosphite hurt plants?

Phi can cause phytotoxic conditions in plants when used in high concentration or used often. Using levels (ppm) of Phi that are the same as commonly used levels of Pi is suggested as the max concentration to prevent phytotoxicity, and not to apply often. However, applying Phi at rates (ppm) lower than Pi, especially as a foliar spray, seems the safest route. I think this is why usage rates for Pure Flowers and other Phi products is so low, excess Phi will cause phytotoxicity and sufficient Phi will not boost P like bloom booster with Pi.

Plants can self-regulate uptake of some ions such as nitrate nitrogen, P, Ca, Mg, etc. It is thought at least in the case of nitrate N and P that the level of certain amino acids in the xylem trigger the plant to stop or greatly reduce uptake of specific ions. This means the plant controls the uptake of some ions from the rhizosphere. I think this is good because a plant's nutritional needs changes over time and it would be hard (or impossible) to try and give a plant a “perfect” hydro fertilizer in terms of ppm of ions at all stages of growth each day. Letting the plant take care of it takes the work out it for us. However, if the ionic solution (fert water) is too rich I believe osmotic factors can bypass plant self-regulated uptake and cause phytotoxicity.

An example of one cation which plants can not self-regulated uptake is ammonicial nitrogen (often sold as ammonium). Because plants can not limit up take of ammonicial nitrogen and because ammonicial nitrogen is taken into roots efficiently ammonicial nitrogen can cause phytotoxic conditions in the roots if the plant can't move enough sugars into the roots to keep up with conversion of ammonicial N for plant usage. It's possible that Phi acts in a similar fashion to ammonicial nitrogen bypassing the plants ability to limit P uptake, and because Phi isn't converted within the plant and has low usage rate by the plant it can become too concentrated and then cause phytotoxicity.

Use of Phi could injure beneficial fungi in the media and phyllosphere. However, it was found Phi does not have a strong fungicidal effect on a broad array of fungi species in soil.

How should phosphite probably be used?

Phi should be used as a foliar spray in my opinion, only during pre-flowering. Spraying at most two times using weak solution at week 2 and then week 3 (before buds start forming), or spraying once at week 2 or 3 with a stronger solution might be the best option.

Phi is readily absorbed though the cuticle layer into leafs, but use of a good non-ionic surfactant and 2.5-5 ml of CalMag+ per gallon of water will assist in cuticle hydration and swelling which increases absorption of other ions and organic substances into the leaf. Adding humic acid in folair spray is good because it prolongs the time the water droplets survive on the leaf (humic acid reduces rate of evaporation) and humic acid benefits the leaf in other ways too.

If using Phi as a root drench (soilless, hydro, etc) including Pi will help mitigate some antagonistic effects of Phi upon Pi and Pi transport.

How should phosphite probably not be used?

Phi should not be used to replace Pi as the sole source of P in bloom boosters. Phi will not provide the level of P that Pi provides in terms of the P available to the plant. This is why plants given only Phi as the sole P source will become P-deficient and grow poorly. It is odd to me that Phi can simultaneously create P-deficient plants and plants suffering from phytoxicity. I believe if people see increased yield when using Pure Flowers it's probably from the K and not the Phi which offers little useful P to the plant. From what I have read in some forums (like here at Icmag) most people do not think Pure Flowers gives more yield than other good bloom boosters, YMMV. I for one will not be using Phi (like Pure Flowers) as a bloom booster replacement; I think I may use the potassium phosphite and potassium silicate product Green Speed Si (0% N- 2% P – 5% K - 5% Si) as a folair spray during per-flowering.

Phi should probably not be used on a regular basis at concentrations equaling that used for Pi; application once every few weeks if used as a fungicide or as a SAR inducer; or one (max twice) during pre-flowing if using as a bloom booster. This in only my opinion after never using Phi (yet), so YMMV.


References:

Phosphite Fertilizers: What Are They? Can You Use Them? What Can They Do?
C.J. Lovatt and R.L. Mikkelsen
Better Crops/Vol. 90 (2006, No. 4)




Phosphorous and phosphoric acid: When all P sources are not equal
Asha M. Brunings, Lawrence E. Datnoff and Eric H. Simonne
Horticultural Sciences Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida; doc document is HS1010, April 2005




Attenuation of Phosphate Starvation Responses by Phosphite in Arabidopsis
Carla A. Ticconi, Carla A. Delatorre, and Steffen Abel
Plant Physiol, November 2001, Vol. 127, pp. 963-972




Phosphite, an Analog of Phosphate, Suppresses the Coordinated Expression of Genes under Phosphate Starvation1
Deepa K. Varadarajan, Athikkattuvalasu S. Karthikeyan, Paino Durzo Matilda, and Kashchandra G. Raghothama
Plant Physiol, July 2002, Vol. 129, pp. 1232-1240




Effect of phosphite fertilization on growth, yield and fruit composition of strawberries
Ulvi Moor, Priit Põldmaa, Tõnu Tõnutarea, Kadri Karpa, Marge Starasta and Ele Vool
Scientia Horticulturae Volume 119, Issue 3, 3 February 2009, Pages 264-269




Transport and compartmentation of phosphite in higher plant cells--kinetic and P nuclear magnetic resonance studies.
Danova, Dijkema C, DE Waard P, Köck M
Plant Cell Environ. 2008 Oct;31(10):1510-21. Epub 2008 Jul 24.




Phosphite Treatment: Treating Your Plants with Phosphite
Dieback Working Group




Bleeding Trees
Annette Stark
Ventura County Reporter




Phosphites and Phosphates:When Distributors and Growers alike could get confused!
New AG Internatlation, September 2007
(indudsty publsion)




A brief note about potassium phosphite on phytophthora
Dr. Ilangovan Ramasamy
Chief Scientist, Arborjet
(written by a coorpate sitcints but good info regless with refences to boot)



Benefits of Tru-Foliar™ Fertilizers Containing Phosphite (HPO3-)
Grigg Bothers Foliar Fortilzers
(written with good info and some reces but ti's a brodcouhre for their prouct but has good pics of Phi vs Pi vs control as a fertlizer)


A critical assessment of the suitability of phosphite as a source of phosphorus
Arne M. Ratjen1, Jóska Gerendás
Journal of Plant Nutrition and Soil Science, Volume 172, Issue 6, pages 821–828, December, 2009


Effect of phosphite phosphorus on alfalfa growth
K. L. Wellsa, J. E. Dollarhidea, R. E. Mundell Jr.
Communications in Soil Science and Plant Analysis, Volume 31, Issue 15 & 16 September 2000 , pages 2707 - 2715


Phosphate foliar fertlization as a source of phosphite residues
L. Tosi, M. Malusà
ISHS Acta Horticulturae 594: International Symposium on Foliar Nutrition of Perennial Fruit Plants

[PoopyTeaBags]

Very good read may have to use my PK booster as well and the pure flowers sparyingly

even though this round did excellent with no other pk booster some plants did not react as well so maybe that is the reason....

[swordfish]

thanks, do you reccomend not using scorpion juice if I were to use pure flowers foliar?

[PoopyTeaBags]

Originally Posted by swordfish

thanks, do you reccomend not using scorpion juice if I were to use pure flowers foliar?

too different products mean to do kind of the same thing... i would test it on one plant first but i do not think it would hurt it... however do use a pk booster with it

[Admiral Canna]

Interesting read. Thanks.

[gashouswidow]

Thanks for the info.

[grapeman]

these scientists only know what we farmers teach them. Never the other way around.

[spurr]

@ all,

I am "gojo", the author of the article Dave was kind enough to post for me. One thing I forgot to mention in my article is that phosphites will hinder and prevent AM fungi (and other endomycorrhzial fungi) from forming mycorrhzia (symbiotic infection) to host roots because phosphites are systemic fungicides. This is yet another reason to not use phosphites (ex. Pure Flowers) as a P source, phosphites should only be used as a fungicide...

[spurr]

Originally Posted by swordfish

thanks, do you reccomend not using scorpion juice if I were to use pure flowers foliar?

Scorpion juice is salicylic acid, it is a SAR (Systemic Acquired Resistance) inducer. SAR is when a plant goes into defense 'mode', and often the plant grows faster, is more stress resistant and yields better. However, and this is a BIG however, salicylic acid reduces glandular trichome density (over X leaf area) and development!

A good SAR inducer is methylated jasmoic acid (apply as foliar spray from 25-100 ppm), it not only induces SAR, but it also increases glandular trichome density and number! Plants naturally use methylated jasmoic acid to form tirchs, along with GA3 too.

[spurr]

Originally Posted by grapeman

these scientists only know what we farmers teach them. Never the other way around.

...I had to lol at that one bro, but not in a mean way You and I are [edit: were] friendly , but you know me as a different nic. I once told you why tensiometers are (most probably) the best way to quantify soil-water status, ex., for your grapes...