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Foliar Nutrition Sprays Containing Phosphites |
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"Based on the best information in my collection of scientific literature, all of the phosphites act primarily to elicit, or turn on, plant defenses. They are not fungicidal in the truest sense, because they do not directly poison the fungus. That's why we use the term 'elicitor'." Paul Cincelli Ph D
Plant Pathologist
University of Kentucky
There are approximately 20 different phosphite-based products on the market today. Some have EPA registration as fungicides. In addition to the phosphite-based fungicides there are also several phosphite-based turf fertilizers, nutritional supplements, and conditioners on the market.
Phosphites are phosphorus atoms combined with three oxygen atoms, PO3. Conventional phosphate fertilizers have the same phosphorous atom combined with four oxygen atoms, PO4. The biological differences between these two compounds are remarkable, even though chemically they are very similar.
Salts of phosphites, including potassium phosphite, are effective in promoting the plant's natural defense system against several diseases. Potassium phosphite application results have shown several other characteristics, such as accelerating foliar uptake of other cations including potassium, calcium, magnesium, and most micronutrients, when they are applied in combination. Phosphites have also shown that they supply more phosphorous per molecule than phosphate.
Work has been ongoing on phosphite products at Michigan State University, Rutgers University and the University of Kentucky. Grigg Brothers has been included in testing at MSU and Rutgers during 2002, 2003, and again in 2004. Results have shown that Grigg Brothers PK Plus, when combined with Gary's Green and Ultraplex, is a very effective foliar spray for summer stress of both bentgrass and annual bluegrass greens. This same research has shown that all the phosphite products, including the fungicides, are more effective when mixed with nitrogen. In 2004 Grigg Brothers will be included in the testing of phosphites at the University of Kentucky on bentgrass. In 2004, Grigg Brothers will also be looking at phosphites on summer decline of bermudagrass greens at both the University of Florida and Clemson University.
Based on current studies our recommendation remains: 6fl/oz PK Plus - 3fl/oz Ultraplex mixed with 1 to 2 gallons of water per 1000 sq/ft every 2 weeks throughout the summer season.
Attachments:
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 V02I02.pdf | | 547 Kb |
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release 1/19/2011 |
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