Understanding Pesticide Resistance Fred Fishel and J.A. Ferrell, UF/IFAS Dept. of Agronomy P.G. Koehler and J.L. Castner, UF/IFAS Doc. SP121

When Pesticides Don’t Work Improper pest identification Incorrect pesticide dosage Improper application timing Pesticide doesn’t reach target pest Unfavorable environmental conditions State of poor pesticide conditions Pesticide resistance F.A. Johnson, D.E. Short, and J.L. Castner, UF/IFAS Doc. SP93

When Pesticides Don’t Work Improper pest identification F.M. Fishel, UF/IFAS Pesticide Information Office Crabgrass Bermudagrass

When Pesticides Don’t Work Improper pest identification F.A. Johnson, D.E. Short, and J.L. Castner, UF/IFAS Doc. SP93

When Pesticides Don’t Work Incorrect pesticide dosage F.M. Fishel, UF/IFAS Pesticide Information Office

When Pesticides Don’t Work Improper application timing CDMS

When Pesticides Don’t Work Pesticide doesn’t reach target pest F.A. Johnson, D.E. Short, and J.L. Castner, UF/IFAS Doc. SP91

When Pesticides Don’t Work Unfavorable environmental conditions CDMS

When Pesticides Don’t Work State of poor pesticide conditions F.M. Fishel, UF/IFAS Pesticide Information Office

Pesticide Resistance F.M. Fishel, UF/IFAS Pesticide Information Office

Definitions: Resistance An inheritable change in the sensitivity of a pest population that is reflected in the repeated failure of a product to achieve the expected level of control when used according to the label recommendation for that pest species. F.M. Fishel, UF/IFAS Pesticide Information Office

Definitions: Tolerance The inherent ability of a species to survive following a pesticide treatment. F.M. Fishel, UF/IFAS Pesticide Information Office

Definitions: Cross vs. Multiple Resistance Cross resistance: resistance to 2 or more pesticides that share the same mode of action. Multiple resistance: resistance to 2 or more pesticides with different modes of action. F.M. Fishel, UF/IFAS Pesticide Information Office

Resistance in General Kills susceptible pests, leaves resistant members of the population Resistant populations are usually resistant to all members of a chemical family Favored by continual use of a pesticide D.E. Short and J.L. Castner, UF/IFAS Doc. SP 126

Resistance in General C.R. Rainbolt et.al., UF/IFAS Doc. SS-AGR-243

“The Pesticide Treadmill” 1.Pest population rises 2.Apply pesticides 3.Pests become resistant 4.Apply more pesticides 5.Resistance becomes more prevalent 6.Switch to new pesticide

Resistance Action Committees IRAC – FRAC – HRAC –

Resistance: History Insecticides F.A. Johnson, D.E. Short, and J.L. Castner, UF/IFAS Doc. SP93

Insecticide Resistance is Costly Colorado potato beetle Budworm/bollworm complex R.L. Jacques and T.R. Fasulo, UF/IFAS Doc. EENY146 J.L. Capinera, UF/IFAS Doc. EENY219

Causes of Insecticide Resistance Natural detoxification Binding site has become genetically modified Slower absorption by the insect Behavioral resistance E.A. Buss, UF/IFAS Doc. EENY326

Causes of Insecticide Resistance Natural detoxification (metabolic resistance) J.F. Butler, UF/IFAS Doc. EENY222

Causes of Insecticide Resistance Altered target-site resistance Colorado Potato Beetle Larva Colorado Potato Beetle Adult J.L. Jacques and T.R. Fasulo, UF/IFAS Doc. EENY146

Causes of Insecticide Resistance Penetration resistance J.F. Butler, UF/IFAS Doc. EENY48

Causes of Insecticide Resistance Behavioral resistance J.L. Castner, UF/IFAS Doc. EENY25

Practical Insecticide Resistance Management Consult a professional Select early-maturing varieties Select insecticides with care S.E. Webb, UF/IFAS Doc. EENY802

Practical Insecticide Resistance Management Monitor the population Remove crop residues S.E. Webb, UF/IFAS Doc. EENY802

Practical Insecticide Resistance Management Prevention IPM, IPM, IPM S.E. Webb, UF/IFAS Doc. EENY802

Resistance: History Fungicides F.M. Fishel, UF/IFAS Pesticide Information Office

Fungicide Resistance P.F. Harmon, UF/IFAS Doc. PP198

Fungicide Resistance Types Single gene Polygenic Cross- vs. multiple-resistance P.F. Harmon, UF/IFAS Doc. PP203

Fungicide Resistance Factors Type of fungicide Frequency of use If used or alone or in combination Pathogen Viability of resistant biotypes P.D. Roberts, UF/IFAS Doc. PP236

Fungicide Resistance Strategies Resistant varieties Crop rotation Dispose/destroy crop debris Soil sterilization Alternate fungicide groups A.J. Gevens, UF/IFAS Doc. SP159

Resistance: History Herbicides F.M. Fishel, UF/IFAS Pesticide Information Office

Herbicide Resistance >300 resistant biotypes 183 species –110 dicots –73 monocots >270,000 field sites F.M. Fishel, UF/IFAS Pesticide Information Office

I. Heap, International Survey of Herbicide Resistant Weeds

Herbicide Factors for Resistance Act on a single site of action Applied multiple times during a growing season Have long residual Used for several consecutive seasons Used as “stand-alones” A.C. York, N.C. State University

Mechanism of Herbicide Resistance Exclusionary resistance –Differential uptake –Differential translocation –Compartmentalization –Metabolic detoxification Site of action resistance –Altered site F.M. Fishel, UF/IFAS Pesticide Information Office

Weed Factors for Resistance Weed reproductive capability Weed seed dispersal mechanisms F.M. Fishel, UF/IFAS Pesticide Information Office

Management Strategies Use herbicides only when necessary Rotate herbicides Use tank-mix or sequential mixtures Rotate crops Use caution if planting herbicide resistant crop varieties F.M. Fishel, UF/IFAS Pesticide Information Office

Management Strategies Combine with mechanical control Where soil erosion is minimal, use primary tillage as a management component Scout fields regularly Clean equipment before moving F.M. Fishel, UF/IFAS Pesticide Information Office

Glyphosate Technologies Glyphosate-resistant crops in-season glyphosate use Benefits Broad spectrum weed control Crop safety Rotational crop flexibility Environmentally favorable University of Wisconsin

Most Heavily Applied Pesticides Atrazine (H): 75 – 82 million pounds Metolachlor (H): 63 – 69 Metam sodium (F, H, I, N, Fm): 53 – 58 Methyl bromide (Fm): 38 – 45 Glyphosate (H): 34 – 38 Dichloropropene (N, Fm): 32 – 37 Acetochlor (H): 31 – 36 2,4-D (H): 29 – 33 Pendimethalin (H): 24 – 28 Trifluralin (H):

Most Heavily Applied Pesticides Atrazine (H): 74 – 80 million pounds Glyphosate (H): 67 – 73 Metam sodium (F, H, I, N, Fm): 60 – 64 Acetochor (H): 3 – 35 Methyl bromide (Fm): 28 – 33 2,4-D (H): 28 – 33 Malathion (I): 28 – 32 Metolachlor (H): 26 – 30 Trifluralin (H): 18 – 23 Pendimethalin (H):

Confirmed Glyphosate Resistant Weeds in the U.S. (2006) Palmer Amaranth Common Waterhemp Giant Ragweed Hairy Fleabane University of Wisconsin Horseweed (Marestail) Common Ragweed Italian Ryegrass Rigid Ryegrass

Glyphosate Resistant Weeds: U.S. Rigid ryegrass Horseweed Italian ryegrass Common ragweed Waterhemp Palmer amaranth Giant ragweed University of Wisconsin

Herbicide Costs Needed To Manage Palmer Amaranth in Georgia and North Carolina Cotton Soybean Corn Sensitive Palmer $18 $8 $10 Resistant Palmer $42 $24 $14 University of Georgia

"Stupidity is doing the same thing over and over again expecting different results" ~ A. Einstein

Resources

Photo/Diagram Credits University of Florida/IFAS University of Georgia N.C. State University University of Tennessee University of Wisconsin CDMS Fred Fishel, Ph.D. Department of Agronomy University of Florida/IFAS Copyright 2008 University of Florida Mention of trade names in this presentation is solely for providing specific information. It is not a guarantee or warranty of the products named, and does not signify that they are approved to the exclusion of others of suitable composition. Use pesticides safely. Read and follow directions on the manufacturer’s label.