Presentation on theme: "Agricultural Spray Adjuvant Technology -Sorting Out the Adjuvant Puzzle- Activator Adjuvants Spray Modifier Adjuvants Utility Modifier Adjuvants Utility."— Presentation transcript:
Agricultural Spray Adjuvant Technology -Sorting Out the Adjuvant Puzzle- Activator Adjuvants Spray Modifier Adjuvants Utility Modifier Adjuvants Utility Products Steve Barnhart – Agriliance Regional Agronomist ?
Adjuvant Confusion! Compendium of Herbicide Adjuvants (Southern Illinois University – 1/02) –Lists 36 different companies selling various types of adjuvants. There are more! –Lists 440 different adjuvants. There are many more!
What is an Adjuvant? An adjuvant is any additive used in conjunction with a pesticide to increase biological activity and/or to modify various physical properties of a spray solution.
Importance of Adjuvants Pesticide Stability Solubility Compatibility Foaming Suspension Surface Tension Droplet Size Drift Volatilization Coverage Adherence Penetration Adjuvants play a key role in controlling these variables Spray applications are affected by many physical variables
Adjuvants Are Classified Into Four Categories Activator Adjuvants –Enhance Pesticide Performance Surfactants, Crop Oil Concentrates, Methylated Seed Oils, Fertilizer Solutions, Penetrants Spray Modifier Adjuvants –Affects Physical Properties Of Spray Solutions Stickers, Deposition Aids, Drift Retardants, Evaporation Aids Utility Modifier Adjuvants –Minimize Handling and Application Problems Compatibility Agents, Buffering Agents, Defoamers, Anti-foams Utility Products –Minimize Application Problems Foam Markers, Tank Cleaners
Adjuvants Types Surfactants (also called spreaders or wetting agents) –An adjuvant that reduces surface surface tension between the spray solution droplets and the pest target’s surface, thus providing greater coverage. Crop Oil Concentrates –A combination of oil (petroleum or vegetable) and surfactants/emulsifiers. Crop oil concentrates act as penetrants, stickers, spreaders (limited), humectants, etc. Methylated or Ethylated Seed Oils –An emulsified methylated or ethylated seed oil. Act as penetrants, spreaders (limited), humectants, etc.
Adjuvants Types - cont. Penetrators –Enhance uptake of pesticides through target pests surfaces. Spreader/Stickers/Extenders –Combine spreading and adhesive qualities to improve coverage and retention of pesticide. Water Conditioning Agents –Reduce the antagonistic affects of impurities (Ca, Mg, Mn, Fe, etc.) found in water carrier. Potentially greater pesticide efficacy results.
Adjuvants Types - cont. Humectants –Increase the drying time of spray solutions which provides greater time for the pesticide to enter the targets surface. Used during high temperature, low humidity and low spray volume situations. Deposition Aid –Reduces the amount of fine spray particles that carry pesticide out of target areas. (polyacrylimides, encapsulators, others) –Reduces evaporation of the spray droplet; Used during high temperature, low humidity and low spray volume situations. Drift Control Agents –Reduces the amount of fine spray particles that carry pesticide out of target areas. (polyacrylimides, encapsulators, others)
Adjuvants Types - cont. Compatibility Agents –Compounds that aid in stability and dispersion of various pesticide formulations and spray carrier mixtures. Buffer Agents/Acidifiers –Generally lower the pH of the spray solution and reduce rapid changes in pH either higher or lower. Reduces the degradation of pesticides by chemical hydrolysis. –Dimate, Malathion, Sevin, etc. –Some buffers are used to raise the solution pH for greater herbicide solubility (Example: micro-rate herbicide applications of Betamix + Upbeet + Stinger on sugar beets) Colorants –Used to alter the color of spray solutions.
Adjuvants Types - cont. Suspension Agents –Extend the period of time a pesticide will remain in suspension and if agitation is stopped for a time, upon agitation they aid in re-suspension of the mixture Defoaming Agents –Suppresses foam of various pesticide solutions, aids in filling tanks Foaming Agents –Used for marking swath width.
Who Regulates Adjuvants? Basically the industry is self-regulated Formulations are considered “trade secrets” –not disclosed to the public
Quality Issues Lack of consistent regulation Confusion and Opportunity “Yes, there is a difference among adjuvants - All adjuvants are NOT created equal.” (Dr. Richard K. Zollinger-NDSU)
Value of Spray Additives What value does the adjuvant bring? Without adjuvants many herbicides would not perform!
Value of Spray Additives (Accent, Pursuit, Spirit, etc.)
Activator Adjuvants Nitrogen Fertilizers N-Pa-K AMS Liquid N-Pa-K 28%N AMS AMS Substitute AG3018 Non-Ionic Surfactants Preference Activate Plus Spreader/Stickers Complex Transfix Crop Oil Concentrates Prime Oil Superb HC Hi-Per-Oil Seed Oil Concentrates Prime Oil EV Methylated Seed Oil Destiny Nitrogen+Surfactant Blends Class Act Next Generation Newtone Organosilicone Surfactants Silkin Methylated Seed Oil + Organosilicone Blend Rivet Conditioner+AMS+Antifoam Alliance Level 7 Nitrogen+Drift Control Corral AMS Dry Placement ProPak Nitrogen+Surfactant+Drift Control AG1040 Nitrogen+Conditioner+Drift C. Arrow four
Activator Adjuvants are Specific Why More Than One Activator Adjuvant? Herbicide Specific –Work well with some herbicides, but not all! Non-ionic surfactants work well with Roundup while oil based surfactants inhibit Roundup performance. –Herbicides Differ Water soluble versus oil soluble Contact versus Systemic
Activator Adjuvants are Specific Why More Than One Activator Adjuvant? Weed Specific –Work well with some, but not all weeds! Oil based surfactants are generally more effective for annual grasses and lambsquarters which have waxy cuticles. –Cuticle (wax type and thickness) –Leaf Surface (hairiness) –Leaf Angle (vertical or flat)
Activator Adjuvants are Specific Why More Than One Activator Adjuvant? Environmentally Specific –Soil moisture, temperature, humidity Non-ionic surfactants provide better crop tolerance during high humidity conditions than do oil based adjuvants. Meanwhile, methylated seed oil based adjuvants provide better control during very dry conditions compared to non-ionic surfactants or conventional crop oil concentrates.
Adjuvant vs. Surfactant The terms Adjuvant and Surfactant are often used interchangeably in our daily spray discussions. Surfactants are actually a specific type of adjuvant. All surfactants are adjuvants, but not all adjuvants are surfactants.
Surfactants Form a “bridge” between unlike chemicals that don’t readily mix –water and oil –water and the wax on a leaf surface Lower the surface tension of spray droplets Allow for more complete spray coverage and sticking on plant surfaces May contain fatty acids to further improve herbicide retention and penetration
Surfactants Complex long chain polar molecules Composed of alcohols and fatty acids Lipophilic “tail” and hydrophilic “head” Three general groups –Non-ionic, anionic, cationic
Surfactant Activity Structure Activity Hydrophilic Lipophilic Water Oil droplet
Charged Surfactants (Anionic, Cationic and Amphoteric) Anionic surfactants have a negative charge and have limited compatibility with pesticides. Cationic surfactants have a positive charge and have limited compatibility with pesticides. Amphoteric surfactants have both charges and may vary their charge with changes in pH. Charged adjuvants may be more effective with salts (glyphosate, 2,4-D amine, etc.)
Uncharged Surfactants (Non-Ionic) Uncharged or non-ionic surfactants are compatible with most pesticides There is a wide variety of non-ionic chemistry Some inert chemicals are considered to be adjuvants as they reduce surface tension. These chemicals (butanol, diethylene glycol, etc.) have little or no biological activity.
Surfactants Typical ingredients of surfactants –Surfactant active ingredient –Fatty acids –Alcohols –Water –Polyethylene glycols
Common Active Ingredients of Nonionic Surfactants Alcohol Ethoxylates - best biologically, very expensive Nonyl Phenol Ethoxylates - good biologically, in 95% of today’s surfactants, being looked at by EPA as a endocrine disrupter. Alkyl Octylphenol Ethoxylates - good biologically, expensive Alkyl Polysaccharides - good biologically, new chemistry, corn starch base, mixes well with AMS Urea Clathrates - good biologically, dry alcohol ethoxylate, expensive Fatty Acid Ethoxylates - good biologically, soybean base, may replace phenol ethoxylates
Common Active Ingredients of Nonionic Surfactants - cont. Tallow Amine Ethoxyalates - good biologically, used in Roundup Ultra, partially ties up free ions that can be antagonistic to the glyphosate molecule. Phosphate Esters - good biologically, also used in Roundup Ultra, partially ties up free ions that can be antagonistic to the glyphosate molecule. Fatty Acids - usually tree oils, biologically active EO/PO Block Copolymers (organosilicones) - expensive Siloxanes (organosilicones) - expensive
Other Ingredients Found In Surfactants Water Alcohols (IPA-isopropyl alcohol) – for storageability Polyethylene Glycol –used mainly as a filler, no biological activity Diethylene Glycol –used mainly as a filler, no biological activity Diols
Adjuvant Labels Can Be Confusing Nonyl phenol ethoxylate Alkyl phenol ethoxylate Poly ethoxylates Alkyl aryl polyethoxylates Alkyl polyoxyethylene Polyethoxylated derivatives These terms can all mean the same thing and may refer to the same constituent.
Physical Properties Used To Compare and Measure Surfactants Surfactant Load HLB - Hydrophilic:Lipophilic Balance Contact Angle Draves Wetting Surface Tension
Surfactant Load Is a measure of the exact content of true non-ionic surfactants in a particular product. Expressed as percentage. A product with a true surfactant load of < 50% may not meet the requirement for an adjuvant as specified by some pesticide manufacturers.
Comparison Of Active Ingredients In Typical Surfactants - Performance Will Not Always Be The Same- 60% Alkyl Aryl Ethoxylate 20% Fatty Acids 3% IPA 7% Polyethylene Glycol 10% Water 50% Alkyl Aryl Ethoxylate 20% Phosphate Ester 10% Diol 5% IPA 15% Water 90/10 Surfactant ? (80/10) 80/20 Surfactant ? (70/30)
Comparison Of Active Ingredients In Typical Surfactants - Performance Will Not Always Be The Same 82% Nonyl phenol Ethoxylate 7.9% Fatty Acids 0.1% IPA 10% Water 45% Nonyl phenol Ethoxylate 10% Fatty acid esters 30% Glycols 5% IPA 10% Water 90/10 Surfactant ? (89.9/10.1) 90/10 Surfactant ? (55/45)
HLB (Hydrophilic:Lipophilic Balance) HLB is the relationship between the nature of the hydrophilic and lipophilic portions of the surfactant molecule. The range of HLB is 1-20. The higher the value the more hydrophilic the surfactant. Most effective surfactants have a value between 10-18. The HLB is not measured, it is calculated. Research has shown that there is significant herbicide/HLB/weed interactions
HLB and Herbicide/Surfactant Solubility 10120 Oil Soluble (Lipophilic) Water Soluble (Hydrophilic) Prime Oil Destiny Superb HC Preference Activate Plus Silkin Accent, Assure II, Atrazine,Beacon, Classic, Fusilade DX, Harmony GT, Poast, etc. Sterling/Banvel, Blazer, Galaxy, Gramoxone, Liberty, Pursuit, Reflex, Cornerstone/Roundup/Touchdown, etc. Herbicides Surfactants
Effect of HLB on Giant Foxtail Control with Accent
Contact Angle This is a profile measurement of a drop of water in contact with a solid surface. When a surfactant is added to water the surface tension of the solution is reduced and the spreads out over a greater area. This flatter droplet has a lower contact angle reading. A water droplet has a contact angle of 93 degrees. A superior wetter will have a contact angle of 45 degrees or less.
CONTACT ANGLE “Contact angle” (CA) is a profile measurement of a drop of water in contact with a solid surface. When a surfactant (wetting agent) is introduced into the solution, the surface tension is reduced and the water droplet becomes flatter. The lower the CA produced by the surfactant, the greater the spreading and coverage properties of that spray solution. Water has a CA of 93 degrees. A typical surfactant influences the contact angle 30-45 degrees, and a “super wetter” surfactant can reduce contact angles to 15 degrees or less.
Contact Angle - cont. Water 94 0 Water + Preference (NIS)38 0 Water + Activate Plus (NIS) 35 0 Water + Silkin (silicone NIS)24 0 Water + Prime Oil (COC)58 0 Water + Destiny (MSO)59 0 Crop Oil Concentrates and Methylated Seed Oils have surfactants in their formulation, but do not as effectively reduce contact angles like true surfactants.
Draves Wetting This is a test to measure the time in seconds it takes to completely wet a woven cotton skein. A superior wetter will require less than 20 seconds for wetting to occur. The lower the score in this test the better wetting characteristics the product has.
DRAVES WETTING TEST t Draves wetting correlates to how well a pesticide solution will wet and spread on a solid surface (i.e.: plant, weed, etc.). This standard method test measures the time (seconds) it take to wet a woven cotton thread. t A superior wetting agent at a 0.25% v/v concentration will require less than 20 seconds for wetting to occur. (Water measures at >300 seconds.) t The lower the score on this test the better wetting characteristics the product has.
Draves Wetting - cont. Water >300 Water + Preference (NIS) 16 Water + Activate Plus (NIS) 11 Water + Silkin (silicone NIS) 2 Water + Prime Oil (COC)>300 Water + Destiny (MSO)>180 Crop Oil Concentrates and Methylated Seed Oils have surfactants in their formulation, but do not have the wetting characteristics of true surfactants. Seconds
Surface Tension Surface tension is a condition that exists at the free surface of a liquid. The surface tension test measures the force required to pull a floating ring off of the surface of a liquid. This force is measured in dynes/cm. Water has a value of 74 while typical spreaders will have a value of 30-50. Super wetters will be 10-30.
SURFACE TENSION “Surface tension” is a condition that exists at the free surface of a solution. The dynes per centimeter (dynes/cm) measurement in the test determines the amount of “force” required to pull a floating ring off the surface of the solution. The higher the dynes/cm, the more force is applied. Since surfactants affect tension, the lower the dynes/cm the better the coverage. Conversely, the higher the dynes/cm of the solution, the greater the impact on coverage. The surface tension of water is approximately 74 dynes/cm. Typical wetting agents will reduce surface tension to 30-50 dynes/cm, while super wetters reduce this figure to 10-30 dynes/cm.
Surface Tension - cont. Water 73 Water + Preference (NIS)35 Water + Activate Plus (NIS)32 Water + Silkin (silicone NIS)27 Water + Prime Oil (COC)36 Water + Destiny (MSO)52 Dynes/Cm
–Reduce antagonism from hard water cations (Ca ++, Mg ++, Fe ++, K +, Na +, ZN ++ ) Free salts in water attach to sulfate ions –In some cases can help overcome antagonism between certain herbicides –Can lower pH and buffer spray solution Reduces breakdown of certain pesticides due a process called “Alkaline Hydrolysis”. –Increase penetration of herbicide into plant cell membranes through “Ion-trapping”
Nitrogen Fertilizer’s Role as a Water Conditioner
Nitrogen Fertilizers (NH4) Weeds which respond to the addition of UAN solutions or AMS. –Foxtails, johnsongrass, quackgrass, woolly cupgrass, velvetleaf, cocklebur, sunflower, P. smartweed, v. mallow, devilsclaw, lambsquarters and w. mustard. Herbicides which are enhanced by nitrogen 2,4-D Amine MCPA Amine
Nitrogen Fertilizers (NH4) Herbicides where antagonism from mineral salts in the water can affect their performance: –Roundup, Cornerstone, etc. (glyphostate) –Liberty, Liberty ATZ (glufosinate) –Banvel, Clarity, Distinct, Sterling (dicamba) –2-4-D amine –MCPA amine Herbicides where UAN does NOT overcome the antagonism of mineral salts in the water; AMS must be used: –Roundup, Cornerstone, etc. (glyphostate) –Liberty, Liberty ATZ (glufosinate)
Nitrogen Fertilizers (NH4) Even in the absence of mineral salt impurities in the water, weed control of certain weeds is enhanced by the addition of UAN solutions or AMS.
Concerns with AMS/Polyglycolether Products Ammoniated Salt Adjuvants –Advertised as AMS substitutes –Do not meet label recommendations for NIS or AMS –Generally NOT approved
Value of Spray Additives v SPRAY GRADE AMMONIUM SULFATE. v AMMONIUM SULFATE SOLUTION v PREMIXES
Roundup/Adjuvant/AMS Trial % Barnyardgrass Control (17 DAT) Adjuvant Roundup Original Rate = 16 oz/a; LSD (.10) = 2; Adjuvants rates varied by product
Roundup/Adjuvant/AMS Trial % Waterhemp Control (17 DAT) Adjuvant Roundup Original Rate = 16 oz/a; LSD (.10) = 13.8; Adjuvants rates varied by product
Roundup/Adjuvant/AMS Trial % Velvetleaf Control (17 DAT) Adjuvant Roundup Original Rate = 16 oz/a; LSD (.10) = 11; Adjuvants rates varied by product
Roundup/Adjuvant/AMS Trial % Foxtail Control (17 DAT) Adjuvant Roundup Original Rate = 16 oz/a; LSD (.10) = 2; Adjuvants rates varied by product
Crop Oil Concentrates Non-phytotoxic oils + emulsifiers (surfactants) –Generally 80-95% oil and 5-20% emulsifier –Petroleum based or vegetable in origin Surfactant portion aids in spreading/wetting Increase spray retention/prolong drying time Increase penetration through the leaf cuticle More effective than NIS adjuvants in low humidity, and on drought stressed or larger weeds
Accent/Beacon Adjuvant Trial Kansas State University % Shattercane Control (87 DAT) Accent Rate = 0.168oz/a; Beacon Rate = 0.19 oz/a; LSD (.05) = 14
Methylated Seed Oils Activity is similar to greater than crop oil concentrates Additional properties include: –Very low evaporation rate enhances spray retention and uptake –Oily liquid more easily penetrates plant cuticle –May protect against UV degradation –Most active adjuvant chemistry –Perform well under dry stress conditions
Beacon/Accent Adjuvant Trial % Velvetleaf Control (19 DAT) Beacon/Accent Rate = 0.38 oz/a + 0.33 oz/a; Activate Plus = 0.25% v/v; Prime Oil and Destiny = 2 pt/a; UAN = 2 qt/a LSD (.10) = 5
Best Spray Management Practices To Minimize Spray Drift Issues Use good judgement –Consider wind speed and direction –Consider climatic conditions Select the proper equipment –Manage spray droplet size Nozzle type, size & pressure –Keep boom height low Use a drift control/deposition agent –Maximize spray deposition –Reduce spray drift It is necessary to consider all of the above in order to do the best you can to reduce drift and maximize herbicide performance.
Drift Control Agents “Encapsulators” –Suspends small capsules(150-180 Micron size) of pesticide in the spray solution significantly reducing the amount of pesticide contained in drift susceptible fines. –Placement & Placement Pro Pak Do not affect spray droplet size “Thickeners or Viscosity Modifiers” –Increases the viscosity of spray solutions which in turn increases droplet size and reduces the amount of drift susceptible fines. –Corral Poly, Corral AMS Dry, Arrow four, AG1040 Do enlarge spray droplet size Neither a “Thickener” or an “Encapsulator” –InterLock
Can Drift Control / Deposition Aids Improve Pesticide Efficacy? Yes !
Can Drift Control / Deposition Aids Improve Pesticide Efficacy? Yes ! European Corn Borer Damage as Influenced by Adjuvants Treatment Rate% Visual Damage% Damaged Stalks None ----7367 Pounce 4 oz/a3733 Pounce + Preference 4 oz/a 2 pt/100 g 3023 Pounce + Placement 4 oz/a 2723 Pounce + Placement + Preference 4 oz/a 2 pt/100 g 2317 Pounce + Rivet 4 oz/a 2 qt/100 g 3023 LSD P=(0.05) 7.69.5 Source: Plant Research Service – Bethel, Missouri
Cotton Defoliation: 8/30/02 Dropp.2 + Finish 16 0z/Ac + Class Act Next Gen. 2.5 Gal/200 + 4 0z/Ac Placement
While the previous pictures show defoliation of cotton. Could this same canopy penetration enhancement carry- over to better control of such soybean insects as soybean aphids or spider mites which tend to colonize under leaves and down in the crop canopy? How about improved soybean rust control? Probably!
InterLock for Soybean Rust 2004 I Brink,South Africa InterLock = deposition aid at 4 oz/a Activate Plus = non-ionic surfactant at 1 pt/100 g.
Interactions Which Affect Postemergence Performance Adjuvants Environment PlantsHerbicide
Selecting the Best Adjuvant or Adjuvant Combinations Oils and Fertilizers Methylated Seed Oils Crop Oil Concentrates Surfactants and Fertilizers Nitrogen Fertilizers Silicone Surfactants Non-Ionic Surfactants Spray Conditions Good Adverse Weed Control and/or Crop Injury High Low