Consideration of Surfactants in Noxious Weed Control: Adjuvants Activator Adjuvants Utility Adjuvants Sticker Penetrator Water Wetter Humectant Defoamer Conditioner Spreader surfactants oils glycerin COC’s MSO’s methoAMS polysiloxane Acids Free down load Goggle “PPP-115.pdf” Activities of a Good Adjuvant Reduces surface tension Improves Mixing Improves Retention Good Activities Improved Activity Prevents Crystallization Improves Absorption A little information on different surfactant types more commonly used • • • • NIS Silicone surfactants Oils High surfactant oil concentrates Nonionic surfactants (NIS) • • • • NIS mainly increase spray retention, and may help with herbicide absorption. Use at 0.25 to 0.5% v/v (1 to 4 pt/100 gal of spray solution) regardless of spray volume. NIS rate depends on the amount of active ingredient in the formulation, plant species and herbicides used. (see label) High rate is for use with low herbicide rates, drought stress and tolerant weeds, or when the surfactant contains less than 90% active ingredient. Silicone surfactants • • • • Reduce spray droplet surface tension, which allow the liquid to run into leaf stomata (“stomatal flooding”). Too high concentration – runoff May or may not increase efficacy Silicone surfactants are weed and herbicide specific just like other adjuvants. Oils - two types Oil adjuvants enhance post-emergent activity of most herbicides more than NIS • Petroleum oils (Crop oil concentrates COC) – COC is usually a petroleum, not a crop vegetable oil • Methylated vegetable or seed oils (MSO) – Effective with all post-emergent herbicides, except Liberty and Cobra, and will antagonize Roundup – MSO enhances post-emergent herbicides > COC >NIS – MSO adjuvants are more aggressive in dissolving leaf wax and cuticle, resulting in faster and greater herbicide absorption – The greater herbicide enhancement from MSO adjuvants may occur more in low humidity/low rainfall environments where weeds develop a thicker cuticle – MSO adjuvants are more $ than NIS and COC Most herbicides give greater weed control when used with MSO-type adjuvants. • Especially when there are: • Low humidity, hot weather, lack of rain, and drought-stressed weeds • Weeds not actively growing due to some stress condition • Weeds larger than recommended on the label • Herbicides used at reduced rates • Target weeds that are somewhat tolerant to the herbicide (buckwheat, lambsquarters, ragweed to Pursuit or Raptor, or yellow foxtail to Accent) Oil adjuvant applied on a volume or area basis • • • The optimum rate of a COC/MSO is 2 pt/A Many labels recommend oil adjuvants at 1% v/v But this spray volume dependent: 1% @ 17 GPA = 1.4 pt/A – barely ok 1% @ 8.5 gpa = 0.68 pt/A – too low Some herbicide labels contain information on adjuvant rates for different spray volumes. To ensure sufficient adjuvant concentration, add oil adjuvant at 1% v/v but no less than 1.25 pt/A at all spray volumes This is in contrast to NIS Surfactant at 0.25 to 0.5% v/v water is sufficient across all water volumes • What do you do when you have lipophilic and hydrophilic herbicides in a tank mix? – Lipophilic herbicides (Select, Banvel, Laudis, others) – Hydrophilic herbicides (Glyphosate ) Do I even need an adjuvant? • POST-emergent herbicide effectiveness depends on spray droplet retention, deposition, and herbicide absorption by weed foliage. Adjuvants and spray water quality influence POST herbicide efficacy. • Adjuvants are not needed with PRE-emergent herbicides unless weeds have emerged and labels include POST emergent application. What to use with what – follow the label! Is there that much difference in efficacy between surfactants? Depends on lot of variables Aquatic weed control - Spartina control Effect of surfactant on the efficacy of imazapyr* Syl-tac 1% Dyn-Amic 1% Kinetic 0.5% Hasten 1% Agri-Dex 2% Agri-Dex 1% 0 20 40 60 80 % control No significant difference between treatments * 6 pt/ac, 10 gpa, >6 hrs dry time Long dry time – no surfactant effect 100 100 %Control 80 60 40 A rs en al +A gr id R ex od eo + K in et R ic od eo + R Li od 70 oe 0 + D yn am R ic od eo + S yl ta c R od eo R od eo 0 +R 11 20 Rodeo applied @ 7.5 qt/ac using 1% v/v surfactant @ 10 gpa, 8 hrs dry time Low herbicide rate, short dry time gr i A d ex gr id 0 .4 A ex q gr id 0 .8 t / a c ex q ( L i 1 t / a 1% 7 0 .6 c ) L i 0 0 q t / a ( 2% 70 . 4 c ) q L i 0 0 t/ a ( 4 % K 70 . 8 c ) in q ( e t 0 1 . t/ a 1 % ic 6 c ) K 0 q t (2 in .1 et q / ac % ) K ic t/ a (4 D in e 0 .2 c ( % ) y n t ic q . 2 a m 0 t /a 5 % . c D y n i c 4 q (.5 ) 0 . t/ a % a 2 m D y n i c q t c (1 ) a m 0 . /a c % i c 4 q (.5 ) 0 . t/a % 8 c ) q t (1 /a % c ) (2 % ) A % Spartina control 14 mat Efficacy as a function of surfactant & rate 90 80 70 60 50 40 30 20 10 0 Rodeo @ 2 gallons/ac applied at 10 gpa spray volume Anti-drift agents • Reduced driftable fines (<105 microns) • Invert emulsion or polymers (polyacrylamide) which increase shear strength of water – (makes them large) • Can change GPA (calibrate again if using) • Can make a spray ‘goop’ – be careful on rate • Common to have more tip clogging • Follow mixing instructions Also reduced drift by • Spraying closer to target • Lower pressure • AI nozzles Water condition – i.e. spray carrier water quality • Minerals, clay, and organic matter • Hard water cations or micronutrients such as calcium, magnesium, manganese, sodium, and iron • Glyphosate, ACCase inhibitors, ALS inhibitors, HPPD inhibitors, and Ignite all affected by water quality . Glyphosate, ACCase inhibitors, ALS inhibitors, HPPD inhibitors, and Ignite all affected by water quality . AMS may contain contaminants and plugged nozzles – use spray grade AMS The amount of AMS needed to overcome antagonistic ions can be determined as follows: Lbs AMS/100 gal = (0.002 X ppm K) + (0.005 X ppm Na) + (0.009 X ppm Ca) + (0.014 X ppm Mg) + (0.042 X ppm Fe). Options to AMS for water conditioning: • 28% UAN fertilizer • Water conditioner adjuvants w/o AMS • Acidic AMS replacement (AAR) adjuvants Ammonium sulfate - Add before herbicide – why? - Very corrosive to sprayer parts Turbid water effects (dirty water) Sorption coefficients of several commonly used herbicides, and their responsiveness to water turbidity. Herbicide Koc (mg/L) Turbidity effect Glyphosate 24,000 Yes Sethoxydim 100 No 34 No No 2,4-D amine 100 No 2,4-D ester 24 No 2 1,000,000 No Yes Clethodim Bentazon Dicamba Paraquat Dirty leaf effects glyphosate uptake (d15N) Effect of leaf sediment on glyphosate uptake 500 400 300 clean 200 muddy 100 0 0 0.5 1 [glyphosate] (% ) 1.5 2 What can you do about turbid water? • • • • • AMS? Acidify? Deformer? Detergent? Buffering agent? What can you do about turbid water if you are using glyphosate or diquat or paraquat? • AMS? • Acidify? This type of antagonism cannot be corrected by • Deformer? adding AMS or buffering solutions. • Detergent? • Buffering agent? Instead • Choose a water source that is free of soil, grit, and organic matter. or • Switch herbicides to ones that are not affect by turbidity (low Koc) Spray tank pH • May effect herbicide activity • May effect herbicide longevity in spray tank • Weak acid herbicides such as glyphosate, 2,4-D, dicamba, and many other herbicides remain neutral at acidic pH (< 7.0) and become negatively charged at alkaline pH (> 7.0) – The leaf cuticle and cell membrane can create barriers to the absorption of negatively charged herbicide – At pH>7 the negative charge on the herbicide can attract positively charged ions in the water that can form complexes with the herbicide, ultimately reducing its absorption into the plant • Basic herbicides such as some ALS herbicides (Accent) remain neutral at alkaline pH levels – Less effective as the spray solution pH becomes acidic Extreme pH values (< 5.0 and > 8.0) also affect herbicide stability (half life) Important to know your carrier water pH Want to target the mid-range for everything Avoid using with high alkaline water (consider using water acidifier) Atrazine Atrazine, Aatrex Bromoxynil Badge, Bromotril, Clodinafop Horizon Diclofop Hoegrass Difenzoquat Avenge Diquat Reglone, Reward Glyphosate Glyfos,Roundup, Imazapyr Arsenal Naptalam Alanap Paraquat Gramoxone Trifluralin Bonanza, Treflan. Rival Phenmedipham Prowl Simazine Princep Diphenyether Cobra Resource Valor N_phenylphthalimid Fairly stable ( best mid pH range) Clopyralid + Curtail M MCPA Dicamba Oracle, Banvel , Metribuzin Sencor Oxyfluorfen Goal Pendimethalin Prowl Sethoxydim Poast Clomazone Command Diuron Diurex, Karmex Not stable at very low pH (7 reduces activity (weak acids are dissociates and poorly absorbed) – add water acidifier 2,4-D Amine • Sensitive to hard water – reduces efficacy (test water and replace if >500 ppm alkalinity and/or hardness >600 ppm)) How toxic are adjuvants? How careful do we have to be? >3000 journal articles in past 3 years related to subject One of the major issues on surfactants toxicity during aquatic uses (frogs, fish, aquatic insects) – Estrogenic and acute toxicity effects • “glyphosate formulations containing the POEA surfactant have the same potential to cause substantial amphibian mortality at environmentally expected concentrations.” Estrogenic effects on tails in Frogs Name LC50 96 hour mg/l RAINBOW TROUT Mon 0818 X77 R11 Li700 Hasten Agridex Data from – C Grue, UW, & others 2 2 6 17 74 271 NPE’s DOSE RESPONSE CURVES FOR TROUT R-11 100 HASTEN LI 700 AGRI-DEX 80 60 40 20 0 0 50 100 150 200 250 300 Concentration (ppm) Slide courtesy of C Grue, UW 350 400 450 500 DOSE RESPONSE CURVES FOR TROUT Rodeo, Arsenal AH and Arsenal AC Dose Response 100 50 Rodeo 40 Arsenal AH 60 Arsenal AC LI-700 70 Hasten R-11 Mortality (%) Mortality (%) 80 Agridex 90 30 20 10 0 1 10 100 1000 10000 Concentration (ppm)(ppm) Concentration Slide courtesy of C Grue, UW (Arsenal = Habitat / imazapyr) 100000 1000000 What about synergy or additive effects - we spray a tank mix, not single ingredients. Name LC50 96 hour mg/l RAINBOW TROUT Mon 0818 X77 R11 Li700 Hasten Agridex Roundup Rodeo Habitat Rodeo + R11 Rodeo + Li700 Hatitat + Hasten Habitat + Agridex Data from – C Grue, UW, & others Conclusion: Surfactant – makes the poison! 2 2 6 17 74 271 8 786 77716 5 22 113 479 NPE’s Should you use an ‘Aquatic Approved Surfactant’ for all your spraying? 6 page list of approved surfactants WSDA list of approved aquatic surfactants Product Name Agri-Dex Chempro Fast Break Cut-Rate Fraction Spray-Rite Sinker Class Act NG Bronc Plus Dry Bronc Plus Dry-EDT One-AP XL Hasten-EA Trail Blazer Tronic Bond LI 700 Avor Brandt Magnify Breeze Bronc Max Droplex InterLock Level 7 Pro AMS Plus Tactic Acute Acute Toxicity Toxicity Rainbow Daphnids Trout 1000 1000 1000 100 1000 100 782 223 782 225 782 223 750 1000 447 377 382 223 382 223 382 223 375 84 200 29 200 28 190 614 130 190 100 121 100 7 100 100 100 100 100 100 100 100 100 100 100 7 100 310 Product Name Competitor NIS-EA Rainier-EA Cide-Kick II M Cygnet Plus Superb HC Syl-Tac-EA Renegade-EA AgriSolutions Inergy Turbulence Winfield Solutions Inergy MSO Concentrate MSO Concentrate with Leci-Tech Forge Sphere 7 Dyne-Amic Destiny HC Atmos Spreader 90 Liberate Kinetic Denali-EA Acute Acute Toxicity Toxicity Rainbow Daphnids Trout 95 100 82 218 82 218 45 6 45 6 45 100 45 137 42 25 37 127 37 127 37 127 35 18 35 34 34 23 22 21 18 17 14 11 17 14 14 60 28 28 9 9 61 9 Alkylphenol ethoxylate vs. nonyl phenol ethoxylate Bio-degradability Concern about acute toxicity to fish Breakdown products more toxic than parent compounds Predicted chronic no effect concentration Endocrine disruptor AE NPE or POEA Readily Not readily No Yes No Yes 110 Ug/L 0.33 Ug/L No Yes

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