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LI 700, Spray pH and its Effect on Pesticide Performance
Have you ever used a pesticide, or had someone apply one for you and it did not control the pest? You may have attributed the poor control to weather conditions, the chemical itself, applicator error, pest resistance, or maybe you bought the wrong material. But have you ever thought to check the pH of the water used to mix the pesticide? The pH of the water that goes into your spray tank makes a difference in how effectively the pesticide works. The characteristics of water used in a spray mix influence the effectiveness of some pesticides. One of the most important is the pH of the water, it’s relative acidity or alkalinity. Water with a pH higher than 7 is alkaline. Many pesticides undergo a chemical reaction in the presence of alkaline water that reduces their effectiveness. The more alkaline the water, the more rapidly the pesticide breaks down. The severity of the reaction is determined by: ● the susceptibility of the pesticide, ● the amount of time the pesticide is in contact with the alkaline water, ● the temperature of the diluted pesticide mixture, and ● the level of alkalinity (pH) of the water. How will I know if a spray should be buffered? Pesticides can break down very fast when the pH of the water is greater than 8 or 9. Some pesticides begin to break down as soon as they are combined with alkaline water in the tank. As a consequence, the active ingredients start to change to inactive ingredients before the pesticide ever leaves the tank. The degree of pest control may be somewhat to greatly decreased or even lost completely. LI 700 pH Adjuster is a buffering-acidifying agent that changes the pH of a spray solution and keeps it there. LI 700 also acts as a penetrating surfactant, deposition aid and drift reduction agent. How much LI 700 should be used? That depends on the pH of the water and the volume of water of the mixture. First determine the pH of the water. Then add LI 700 to the spray water before adding the pesticide. ● For highly alkaline water, pH 8 or higher, use 625 mL to 1.25 L LI 700 in 1000 L spray mixture. ● For mildly alkaline water, pH 6.5 to 8, use 300 to 625 mL LI 700 per 1000 L spray mixture. Adding LI 700 to the spray mixture is an easy and economical way to guarantee maximum results from your pesticide application. For further information see the attached “Product Response to Spray Solution pH” handout. Always read the complete label before using any chemical. PRODUCT RESPONSE TO SPRAY SOLUTION pH
SPRAY SOLUTION MAY BE ACIDIFIED WITH LI 700
Comments / Rate of Hydrolysis Time for 50% I. Insecticides, Nematicides, Acaricides, and Miticides
Acephate
pH 5 = 17.3 days, pH 7 = 10 days, pH 9 = 12 hrs Stable at pH 4 and 7; unstable in pH above 8. pH 7 = 12 days, pH 9 = 3.2 hrs. Do not use in water with pH over 8 pH 6 = 200 days, pH 7 = 40 days, pH 8 = 5 days, pH 9 = 78 hrs, pH 4.7 = 63 days, pH 6.9 = 35 days, pH 8.1 = 22 days, pH 10 = 7 days, hydrolyzes by strong alkalies, stable in neutral and in weak acidic solutions. Avoid alkaline materials. pH 9.2 = 4.8 hrs, pH 7 - 34 hr, pH 5 - 248 hr pH 9 = 35 hrs, easily hydrolyzes but more stable in acid than in alkaline solutions. Optimum stability = pH 4 pH 5 = 31 days, pH 7.5 = 185 days, pH 9 = 136 days, more stable near neutral, avoid extreme acid conditions Compatible with all but highly alkaline pesticides. No degradation in 20 days at pH 5. pH 7 = 5 days, pH 10 - 15 min pH 2 = 21 hrs, pH 6 = 12 hrs, pH 9 = 48 min, presence of iron Undergoes some degree of alkaline, 70% loss after 7 days at pH 7.3 pH 5 = 4 days, pH 7 = 14 hrs, pH 9 = 3 hrs Hydrolyzes rapidly in water above pH 7 and below pH 5. Iron will catalyze decomposition. pH 6 = 7.8 days, pH 7 = 3 days, pH 8 = 19 hrs, pH 10 - 2.4 hrs pH 9.1 = loss of 5% in 6 hrs, stable in slightly acidic solutions. Do not use in highly alkaline mixtures. pH 6 = 54 wks, pH 7 = 38 wks, pH 8 = 20 wks Over 90% hydrolyzes in 48 hrs in alkaline aqueous solutions. Stable 1, 16 below pH 7. Stable at pH 4.7, 3% loss in 24 hrs at pH 6.9, 45% loss in 24 hrs at Hydrolyzes rapidly in alkaline medium, stable at pH 5 to 7, pH 9 = 9 pH 4.5 = 13 days, pH 7= 12 hrs, pH 8.3 = 4 hrs, pH 10 = 1 min. Activity may be reduced when pH is above 7. Correct pH with buffering or acidifying agent.
PRODUCT RESPONSE TO SPRAY SOLUTION pH
SPRAY SOLUTION MAY BE ACIDIFIED WITH LI 700

Comments / Rate of Hydrolysis Time for 50% II. Fungicides
Fosetyl-Al
Stable in neutral or slightly acid solutions. Not compatible with lime or chlorobenzilate Chemical breakdown may occur in water with high pH (pH 7 = 1-7 pH 9 = 88 days; stable at pH 7 and below. Most effective in pH 5 to 9; use within 12 to 16 hours. Do not combine with high alkaline materials; pH 4.5 to 7.5 for III. Plant Growth Regulators
Chlormequat Chloride
Very stable at pH 3 or less, incompatible with alkaline salt Hydrolyzes slowly by water, should not be combined with alkaline A buffered wetting agent should be used, final spray should not IV. Herbicides
Decomposes slowly in alkaline solution and more rapidly if lime is Not stable to extremes of pH; pH 6 to 8 for optimum effectiveness. Stable at a low pH, alkaline conditions cause precipitation Stable in neutral or acid solutions, but decomposes in alkaline
PRODUCT RESPONSE TO SPRAY SOLUTION pH
SPRAY SOLUTION MAY BE ACIDIFIED WITH LI 700

Comments / Rate of Hydrolysis Time for 50% IV. Herbicides
Reported to have an optimum pH of 2.5, alkaline conditions Decomposes rapidly under alkaline conditions. Most effective 16 at pH 7. Avoid pH less than 3; apply within 24 hours to avoid Hydrolyzes in solutions with a pH greater than 9.5 Apply within 24 hours to avoid degradation; agitate thoroughly if left Stable in acid or neutral conditions, readily hydrolyzed in alkaline Undergoes hydrolysis under alkaline conditions, pH 7 = 5 hrs, Most effective in pH 4 to 9; avoid pH less than 4. Decomposes slowly in alkaline solution and more rapidly if lime is V. Antibiotics
Streptomycin Sulfate
Avoid use with alkaline materials. For high alkaline water sources, use of an acceptable acidifying agent may be advisable to bring tank solution to a normal or slightly acid pH. THE INFORMATION IN THIS TECHNICAL BULLETIN HAS BEEN COLLECTED AND
COMPILED FROM SEVERAL SOURCES.
THE ACCURACY OF THE INFORMATION HAS NOT BEEN VERIFIED BY LOVELAND PRODUCTS, INC. Always read the complete label before using any chemical. 1. Organophosphorus Pesticides: Organic & Biological Chemistry, Eto, M., CRC Press, 1974. 2. Farm Chemicals Handbook, Meister Publishing Company. 3. Plant Growth Regulator Handbook, 1st edition, Plant Growth Regulator Working Group, 1977. 4. "pH Effect on Pesticides", article #3004 R, Leffingwell Chemical Company, 1976. 5. North Dakota Insect Control Guide, North Dakota State University, Cooperative Extension Service. 6. "pH Effect on Pesticides", Miller Chemical & Fertilizer. 7. "The Effect of pH on Pesticides", Diad Agricultural Services, Ltd. 8. Technical Information, Carzol, Morton Chemical Company. 9. Crop Protection Chemicals References, 5th Edition, Chemical & Pharmaceutical Press, 1989. 11. "Pest-Asides", No. 3, Western Australia Department of Agriculture, February 1987. 12. "Preventing Decomposition of Agriculture Chemicals by Alkaline Hydrolysis in the Spray Tank", A.J. and H.Riedl, New York Food and Life Sciences Bulletin. 13. The Pesticide Manual, A World Compendium, 7th Edition, British Crop Protection Council. 14. The Pesticide Manual, A World Compendium, 9th Edition, British Crop Protection Council. 15. The Pesticide Manual, A World Compendium, 10th Edition, British Crop Protection Council. 16. Custom Chemicides’ Quick Guide to Buffering; 1989, 1994, Custom Chemicides.

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