Mode of Action in Plant –
Potassium Phosphonates are systematically absorbed by the plant and are mobile, within the plant, trans-locating to the new growth, via both the phloem element and the xylem. They are a highly soluble form of Phosphorus and Potassium, which is beneficial to plant growth, rooting and root development, accelerating foliar uptake of other cations such as potassium, calcium, magnesium, and most micro elements. Not only does phosphite help roots, but is actually beneficial to the regeneration of mycorrhizae on the roots of trees. Phosphorus and Potassium, are rapidly absorbed by the leaf tissue and roots for maximum and efficient plant use by moving systemically upward and downward in the plants vascular system, phloem and including the root system.
Once applied and rapidly absorbed, by the plant, phosphites undergo an oxidation or conversion process resulting in the continual release of soluble phosphorus. The phosphonates have been observed to activate defense mechanisms that kick into gear when attached by disease or insects. This product has fungistatic activity against major fungal pathogens and has shown to promote the trees natural defense systems capable of stimulating host defenses through induced systemic resistance. The mode of action of phosphorous acid is twofold, by acting first within the fungus, inhibiting fungus growth, and also by changing the nature of the fungal cell walls by activating the plants own immune defense response through rapid cytological action, and triggering other cellular phytoalexin accumulations and metabolic changes and other resistance inducers. Phosphonates are highly selective, non-toxic fungicides against numerous fungal pathogens, and provide both protective and curative responses against such plant diseases. It is a highly systemic sterol inhibitor that penetrates and Trans-locates, preventing fungal cell development, by interfering with cell wall formation and growth throughout the plant by inhibiting sterol biosynthesis. Once the phosphite moves up the tree and enters the leaves, it stimulates the production of infection-fighting chemicals within a layer known as the cambium.
Phosphites are quickly absorbed by plants; therefore, they present a high degree of solubility and mobility. The systemic character (ascending and descending) and quick absorption by the roots, stems and leaves, allow various methods of application in accordance with the type of plant and characteristics of the pathogen to be controlled. The Phosphite is highly mobile in trees and moves bi-directional in the phloem and upward to the leaves in the vascular systems. Because Phosphite has one less oxygen molecule than phosphate, a higher degree of solubility and mobility, within the plant is achieved. This unique characteristic permits phosphites to be rapidly absorbed or taken up across the membranes of plant foliage and/or roots, in both their nutritive and plant protective roles, with immediate activity on contact.
The efficiency of phosphite application in certain pathosystems is due to the fact that the plant presents better assimilation in the presence of phosphorus, making it capable of activating defense.
Potassium phosphite moves through the plant fast, both by basipetal and acropetal transport. It stops mycelium growth and indirectly stimulates the resistance of plants because phosphite encourages the production ofelicitin, which increases immunity.