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Effect of Phosphorous Acid Fungicide Timing on Potato Foliage for Pink Rot Control. Trent Taysom. Thank You!. What is Phosphorous Acid?. NOT Phosphoric acid (H 3 PO 4 ) or Phosphate (P 2 O 5 ) or Phosphorus (P) ! NOT true acid; (pH is 6 to 7) Phosphorous Acid is H 3 PO 3
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Effect of Phosphorous Acid Fungicide Timing on Potato Foliage for Pink Rot Control Trent Taysom
What is Phosphorous Acid? • NOT Phosphoric acid (H3PO4) or Phosphate (P2O5) or Phosphorus (P) ! • NOT true acid; (pH is 6 to 7) • Phosphorous Acid is H3PO3 • Also referred to as Phosphite, Phosphonate • FRAC group 33 (low risk of resistance) • Mono- and di-basic Na, K, and ammonium salts of phosphite
Phosphorous Acid Mode of Action • Fungicide • Relatively weak • Active against mefenoxam-resistant organisms • Systemic properties • Induces systemic acquired resistance • Relatively safe • LD50 > 5,000 mg/kg (absorption/ingestion) • Signal word = Caution
How important is the time between application and irrigation? Time between Resist 57 (10 pt/acre) application and irrigation (center pivot)
How important is the timing when the program starts? Stage when the Resist 57 program (10 pt/acre, 3X, every 14 days) was started
Other Considerations • Environment can effect phosphite uptake • P. cinnamomi, Shearer et al., 2012 • Phytotoxicity • MSO made phyto worse (greenhouse, NSDU) • Higher humidity = higher chance of phyto?