Herbicide Resistance: Herbicide Resistance: Protecting the PPO’s Protecting the PPO’s Eric P. Prostko Eric P. Prostko Extension Weed Specialist Extension Weed Specialist Dept. of Crop & Soil Sciences Dept. of Crop & Soil Sciences The University of Georgia The University of Georgia
Herbicide Resistance Herbicide Resistance Definition Definition • WSSA definition WSSA definition • • “the “the inherited inherited ability of ability of • a plant to survive and a plant to survive and reproduce following reproduce following exposure to a dose of exposure to a dose of herbicide normally herbicide normally lethal to the wild type” lethal to the wild type” ALS-Resistant Palmer Amaranth in Peanuts
Herbicide Resistance Herbicide Resistance Why???? Why???? • Selection Pressure Selection Pressure • – Overuse of single Overuse of single – product or MOA product or MOA • Pollen Drift Pollen Drift • – Resistant trait moves Resistant trait moves – thru pollen thru pollen Palmer Amaranth Pollen Palmer Amaranth Pollen
PPO Inhibiting Herbicides PPO Inhibiting Herbicides • • PPO or Protox PPO or Protox – Protoporphyrinogen oxidase – Protoporphyrinogen oxidase – Enzyme found in chloroplast – Enzyme found in chloroplast and mitochondria needed for and mitochondria needed for formation of chlorophyll formation of chlorophyll – Cell membrane destruction Cell membrane destruction – • Many common herbicides have • Many common herbicides have this mode of action!! this mode of action!! , Ultra Blazer, Cobra, Goal , – Ultra Blazer, Cobra, Goal – Reflex, Ronstar, Resource, Reflex, Ronstar, Resource, Aim, Valor, Storm, Spartan, Aim, Valor, Storm, Spartan, ET ET
Glyphosate and ALS resistance is forcing Glyphosate and ALS resistance is forcing GA growers to rely on PPO herbicides!!! GA growers to rely on PPO herbicides!!! ALS-Palmer Amaranth GR-Palmer Amaranth
Palmer Amaranth Control in Peanuts Palmer Amaranth Control in Peanuts Macon County, GA – – 2007 (38 DAT) 2007 (38 DAT) Macon County, GA NTC Valor SX 51WG @ 3 oz/A
GR- -Palmer Amaranth Control in Palmer Amaranth Control in GR Soybean – – 2007 (83 DAT) 2007 (83 DAT) Soybean Untreated Prefix 5.29EC @ 2 pt/A SB-01-07
What the heck is Prefix??? What the heck is Prefix??? • 5.29 SC formulation • 5.29 SC formulation – 4.34 lbs Dual Magnum 4.34 lbs Dual Magnum – – 0.95 lb Reflex 0.95 lb Reflex – • Use rate is 2 pt/A ($10.50) • Use rate is 2 pt/A ($10.50) – At 2 pts/A you get the following……. At 2 pts/A you get the following……. – – 1.085 lb ai of Dual Magnum (18.2 ozs/A) 1.085 lb ai of Dual Magnum (18.2 ozs/A) – – 0.2375 lb ai of Reflex (15.2 ozs/A) 0.2375 lb ai of Reflex (15.2 ozs/A) –
High Potential to Overuse (Abuse) High Potential to Overuse (Abuse) Reflex and Valor Reflex and Valor Herbicide Peanut Corn Soybean Cotton Herbicide Peanut Corn Soybean Cotton Reflex No (?) No Yes Yes Reflex No (?) No Yes Yes Valor Yes Yes Yes Yes Valor Yes Yes Yes Yes (PPLNT) (PPLNT) (PPLNT) (PPLNT) (LAYBY) (LAYBY)
PPO Resistance Already Exists! PPO Resistance Already Exists! • Common waterhemp Common waterhemp • – 2001 (KS) 2001 (KS) – • Resistant to POST but not PRE – 2002 (IL) 2002 (IL) – – 2005 (MO) 2005 (MO) – • Common ragweed Common ragweed • – 2005 (DE) 2005 (DE) – • Wild poinsettia Wild poinsettia • – 2004 (Brazil) – 2004 (Brazil) *
Preventing PPO Resistance in GA Preventing PPO Resistance in GA • Know modes of action • Know modes of action • Should we save the PPO herbicides for our 2 most • Should we save the PPO herbicides for our 2 most important row crops (cotton, peanuts)??? important row crops (cotton, peanuts)??? – 1.7 million acres (cotton + peanuts) vs. 0.78 million acres (soy 1.7 million acres (cotton + peanuts) vs. 0.78 million acres (soybeans + corn) beans + corn) – • Rotate crops • Rotate crops – Corn (atrazine, Callisto, 2,4 Corn (atrazine, Callisto, 2,4- -D, Status) D, Status) – – Soybeans (Dual Magnum, Sencor) Soybeans (Dual Magnum, Sencor) – • Try not to use a PPO more than once per crop per year • Try not to use a PPO more than once per crop per year – i.e. Do not use Valor and Reflex on cotton in the same year i.e. Do not use Valor and Reflex on cotton in the same year – – 2 2- -1 1- -2 program??? 2 program??? – – What about peanuts???? What about peanuts???? – • Valor, Cobra, Ultra Blazer, Storm
Preventing PPO Resistance in GA Preventing PPO Resistance in GA • Include other residual herbicides with PPO’s Include other residual herbicides with PPO’s • – Dual Magnum, Intrro, Outlook Dual Magnum, Intrro, Outlook – – Treflan, Prowl, Sonalan Treflan, Prowl, Sonalan – – Boundary (Sencor + Dual Magnum) Boundary (Sencor + Dual Magnum) – – Prefix (Reflex + Dual Magnum) Prefix (Reflex + Dual Magnum) –
Preventing PPO Resistance in GA Preventing PPO Resistance in GA • Use other weed control tactics • Use other weed control tactics – Cultivation Cultivation – • No known cases of steel- resistance have been reported • Diesel fuel prices and time are major deterrents – Hand Hand- -rogueing (seed rogueing (seed- -bank bank – control) control) • Do not want to but may have • Do not want to but may have to!!! to!!!
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