Basics of Pesticide Resistance. Sam Markell, Ph.D. Extension Plant Pathologist

Basics of Pesticide Resistance Sam Markell, Ph.D. Extension Plant Pathologist

Outline Use of pesticides in North Dakota How does resistance occur? Risk factors

Million acres Pesticide Use in North Dakota 25 20 15 10 Herbicides Insecticides Fungicides 5 0 1984 1989 1992 1996 2000 2004 2008 Pesticide Use Surveys Zollinger et al.

Percent of acres Pesticide Use on Wheat in North Dakota 120 100 80 60 40 Herbicides Insecticides Fungicides 20 0 1984 1989 1992 1996 2000 2004 2008 Pesticide Use Surveys Zollinger et al.

Percent of acres Pesticide Use on Soybean in North Dakota 120 100 80 60 40 Herbicides Insecticides Fungicides 20 0 1984 1989 1992 1996 2000 2004 2008 Pesticide Use Surveys Zollinger et al.

Reasons for increasing use

01/02/03 05/08/03 09/11/03 01/15/04 05/20/04 09/23/04 01/27/05 06/02/05 10/06/05 02/09/06 06/15/06 10/19/06 02/22/07 06/28/07 11/01/07 03/06/08 07/10/08 11/13/08 03/19/09 07/23/09 11/26/09 04/01/10 08/05/10 12/09/10 04/14/11 08/18/11 12/22/11 04/26/12 08/30/12 01/03/13 Cents/Bushel 2000 Cash Price for Spring Wheat - Minot, ND Jan. 2, 2006 - Jan. 24, 2013 1800 Spring Wheat 1600 1400 1200 1000 800 600 400 200 0 Frayne Olson

01/02/03 05/22/03 10/09/03 02/26/04 07/15/04 12/02/04 04/21/05 09/08/05 01/26/06 06/15/06 11/02/06 03/22/07 08/09/07 12/27/07 05/15/08 10/02/08 02/19/09 07/09/09 11/26/09 04/15/10 09/02/10 01/20/11 06/09/11 10/27/11 03/15/12 08/02/12 12/20/12 Cents/Bushel 1800 1600 1400 1200 1000 800 600 400 200 0 Cash Price for Soybean - Hunter, ND Jan. 2, 2006 - Jan. 24, 2013 Soybeans Frayne Olson

Reasons for increasing use Money Wet cycle Diseases like water Plant Health Concept of yield increase in absence of New/novel pests threats Resistant weeds, invasive species, outbreaks Insurance Application vs IPM Increased rates (glyphosate)

Our current situation High crop prices High usage of pesticides Applications when they may not be needed? Limited modes of action Shift in usage heavy dependence on single mode of action

How do pathogens become resistant to fungicides? Random mutation Selection pressure Survival of the fittest

Pesticide Resistance Sensitive to fungicide Resistant to fungicide

Resistance Risk Factors - Mode of Action Pesticide Multi-site: Pesticide is active against multiple/many Pesticide in metabolic pathway. Single-site: Pesticide is active against one specific point in metabolic pathway.

Not all FRAC etc. are equal risk! QoI (strobilurins): Headline, Quadris, etc Phenylamides: Ridomil Methyl benzimidazole carbamates (MBC) Thiophanate Methyl, Topsin Dicarboximides: Rovral, Iprodione FRAC 11 FRAC 4 FRAC 1 FRAC 2 High Risk High Risk High Risk Medium-High Risk SBI (Triazoles): FRAC 3, Low-Medium

Resistance Risk Factors - Pest Fecundity Waterhemp (in excess of 100,000 seeds/plant) Dry bean (not very many) Longevity Dormancy of seeds, overwintering, extended diapause, survival of cysts Variability Pathogens with sexual and asexual reproduction Outcrossing of plants (waterhemp)

Resistance Risk Factors - Human Multiple application of the same FRAC, IRAC, HRAC Cut and/or sub-lethal rates Fluroxypyr mixes - Kochia Bad timing of application Big weeds, epidemic in progress, not at thresholds Bad technique Nozzles, etc.

FRAC, IRAC, HRAC codes Fungicide (or other) Resistance Action Committee (FRAC) Based on Mode of Action (MOA) Labels will have codes on first page

Pesticide Resistance Sensitive to fungicides Resistant to fungicide 1 Resistant to fungicide 2

Resistance Summary Many factors point to pesticide increase Random pest variability, selection pressure, survival of the fittest Risk factors in pest, host, and usage

Thank You - Questions