Rainfastness of Fungicides

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Fungicide efficacy often depends upon rainfast properties, or the ability of a fungicide to remain in place during and after rain. This presentation discusses major differences between contact fungicides, surfactants, and systemic fungicide properties.

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Rainfastness of Fungicides

  1. 1. FUNGICIDE RAINFASTNESS NICOLE WARD GAUTHIER, UK PLANT PATHOLOGY
  2. 2. FUNGICIDES & RAIN • Contact fungicides – wash off in rain • Adhesive properties – lightly stick or bind • Locally Systemic absorb • Systemic Activity – enter vascular system Won’t Wash Off Not Rainfast
  3. 3. CONTACT FUNGICIDES • Contact Fungicides are not rainfast • Surfactants can aid in adhesion • M-class fungicides are contact fungicides • • • • • • Captan Mancozeb Polyram Sulfur Syllit Ziram
  4. 4. ADHESION DEPENDS UPON… • Formulation – wettable powder, granules, etc • Particle size – small particles “stick” better • Fillers – talc, clay, etc • Soluble particles adhere better than larger particles
  5. 5. ADHESION ASSISTANCE Surfactants – “surface” spreader stickers • Reduce surface tension and improve spreadability • Alter ionic charge - retention • May encourage permeation • Included in formulation or incorporate • Buffers regulate pH of alkaline water • Reduce weathering and UV degradation • Reduction of active ingredients
  6. 6. ADHESION • Surfactants – “surface” spreader stickers • Persistence and retention, up to 1” rainfall • Dodine • Mancozeb
  7. 7. REDISTRIBUTION Surfactants prevent redistribution • Surface redistribution and retention (blue arrows) • Vapor movement (purple arrows) • Binds to waxy cuticle (yellow arrows) Paul Vincelli, University of Kentucky.
  8. 8. REDISTRIBUTION • Surface redistribution – products solubilize and redistribute under light rain. (blue and purple arrows) • Not rainfast, per se… • Fungicides with redistribution properties: • Copper • Captan • Flint Paul Vincelli, University of Kentucky.
  9. 9. TRANSLAMINAR MOVEMENT • Locally systemic – movement from one side of leaf to another (red arrow) • Localized penetration, limited movement, translaminar mobility • Locally systemic fungicides: • • • • • • Iprodione Cabrio Flint Luna series Pristine Sovran Paul Vincelli, University of Kentucky.
  10. 10. SYSTEMIC ACTIVITY • Xylem movement – upward from point of absorption • Upwardly systemic fungicides: • • • • • • Topsin M Idoprione Rally Topguard Scala Streptomycin Janna Beckerman, Purdue University.
  11. 11. SYSTEMIC ACTIVITY • Fully systemic – upward and downward movement through xylem and phloem • Fully systemic fungicides • Phosphorus acids Nature Chemical Biology Hélène S Robert & Jií Friml
  12. 12. FUNGICIDES & RAIN • Contact fungicides – wash off in rain • Adhesive properties – lightly stick or bind • Locally Systemic absorb • Systemic Activity – enter vascular system Won’t Wash Off Not Rainfast
  13. 13. QUESTIONS? WWW.SLIDESHARE.NET/NICOLEWARDUK
  14. 14. WE NEED YOUR HELP Testimonials – • Our funding (results in free services to growers) depends upon impact reports • 1 to 5 short sentences describing how our program (plant pathologist, diagnostic lab, educational program) helped you and/or your orchard • Use numbers whenever possible – acres, gallons, dollars, spray applications
  15. 15. Nicole Ward Gauthier, Extension Specialist Department of Plant Pathology www.ca.uky.edu/agcollege/plantpathology/people/ward.htm nicole.ward@uky.edu Facebook: www.KYPlantDisease.com UK - Diseases of Fruit Crops, Ornamentals, & Forest Trees Twitter: @Nicole_WardUK Blogger: nicolewarduk.blogspot.com

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