Oklahoma No ‐ Till Conference, 2016 Managing Insects on a Budget Tom A. Royer, Extension Entomologist 1
Should Pesticides be used in an IPM Program? “ Utilizes all suitable pest management tactics…………..” • Biological • Cultural • Host Plant Resistance • Mechanical/Physical • Host Plant Resistance • Pesticides • Regulatory 2
Chemical Control ( Using an Insecticide Economically ) • Follow LABEL recommendations for: • Rate • Frequency • Coverage • Use properly calibrated equipment designed to deliver thorough coverage • Spot treat only infested areas if possible • Protect beneficial insects and limit run ‐ off 3
Pest Management: Decision Thresholds! • Economic Injury Level (EIL) • The break ‐ even point between the cost of control and the loss in yield without control • This must be measured in some way • Not feasible for all pests 4
Injury vs. Damage • Injury: the effect of pest activities on host physiology that is usually deleterious • Centered on pest activities • Damage: the measurable loss of host value (yield, quality, aesthetics). • Centered on crop and its response to injury 5
Calculating an Economic Injury Level • Calculating Loss per Insect • Not as easy as it might first seem • Different insects, different types of injury • Difference in crop susceptibility (variety, growth stage) • Can be obtained by: • Crude field observations • Simulated damage 6 • Experimentation with various insect numbers at various crop growth stages
How is an EIL Developed? • Value of Crop is known •Absolute pest numbers are related to injury • Injury is related to yield loss •Effectiveness of control is measured 7
The Economic Injury Level (EIL) • Economic Injury Level – defines the break ‐ even point at which the cost of control ($) equals the loss in yield ($) if the pest is not controlled EIL =__C__ VIDK C = Cost of control V = Value of commodity I = Physical injury/pest unit D = Loss/unit of physical injury K = Loss prevented by control 8
Pest Management: Decision Thresholds! • Economic (Treatment)Threshold (ET) • The pest density at which management action should be taken to prevent an increasing pest population from reaching the economic ‐ injury level • Not feasible for all pests (plant diseases, weeds) 9
Economic Threshold (ET) • Is also called the ”action threshold”; it is a pest population level or a damage threshold that allows a grower to control the pest before it exceeds the EIL. • It can be fixed, or calculated: • ET=EIL*C where C = a factor of population increase over unit of time 10
How is an ET Developed? •Sampling method is selected for accurately estimating pest numbers or injury level (index) • Sample method is related to absolute pest levels • ET is set below the EIL, used as a prediction, or trigger • ET = EIL x Time Factor (fixed or predictive) • Fixed = x % below threshold to provide time to treat • Descriptive = EIL x C ‐ x where C = factor of increase per unit time 11
How is an ET Set? • Thresholds are set for efficient (economic) application of corrective pesticide applications • They can be adjusted based on insect biology (change in temperature, crop stage) • Example: Greenbug thresholds are different for January vs October, because greenbugs can multiply much faster in Oct. 12
Using an Economic Threshold 40 35 Aphids Untreated Aphids per Tiller 30 EIL ET 25 20 Spray 15 Decide 10 5 0 0 1 4 7 10 13 16 20 23 26 29 Days 13
Using an Economic Threshold 40 35 Aphids Treated Aphids per Tiller EIL 30 ET 25 20 Spray 15 Decide 10 5 0 0 1 4 7 10 13 16 20 23 26 29 Days 14
Using an Economic Threshold Pest resurgence 40 35 Aphids Treated Aphids per Tiller EIL 30 ET 25 20 Spray Spray 15 Decide Decide 10 5 0 0 1 4 7 10 13 16 20 23 26 29 Days 15
Using an Economic Threshold Pest resurgence 40 35 Aphids Treated Aphids per Tiller EIL 30 ET 25 20 Spray Spray 15 Decide Decide 10 5 0 0 1 4 7 10 13 16 20 23 26 29 Days 16
Updated Expert Systems Cereal Aphid and Sorghum Headworm http://entoplp.okstate.edu/gbweb/index3.htm 17 http://entoplp.okstate.edu/shwweb/index.htm
Updated Expert Systems Cereal Aphid and Sorghum Headworm • Cereal Aphid Expert System: • A computer program located at http://www.pswcrl.ars.usda.gov/gbweb/index.htm • Developed by USDA ARS, SST Development Group and OSU. • Includes a calculator for determining economic thresholds for greenbug infestations • Sorghum Headworm Decision Support System • A computer program located at http://entoplp.okstate.edu/shwweb/index.htm • Developed jointly by USDA, Oklahoma State, Texas A&M and West Texas A&M University • Includes a calculator for determining economic thresholds for 18 headworm infestations
How does “Glance ‘n Go” Sampling for Greenbugs Work? • Record counts of infested tillers, i.e. that have one or more greenbugs and or mummies on a Glance ‘n Go form, which is based on the time of year, and the pre ‐ determined economic threshold. 19
Sorghum Headworm Sampling • Record counts of medium and large headworms collected in a shake bucket which is based on a pre ‐ determined economic threshold 20
myFields Economics Oklahoma State University 21
Managing Insects on a Budget • Thanks! • Kris Giles, Norm Elliott, Ali Zarrabi, Jason Warren • Oklahoma Wheat Commission • Great Plains Oilseed Association • Oklahoma Canola Commission • Oklahoma Cooperative Extension Service and the Agricultural Experiment Station 22
Should Pesticides be used in an IPM Program? • Pesticides can to be used in an IPM program, however only as a last resort and of course in a manner that is legal. • Pesticides are to be used when there is no risk of environmental damage or when benefits outweigh the risks. Use pesticides only when other control practices aren’t available, economical or practical. • Must monitor pest populations in the field. • Identify the pest • Compare pest population and the economic threshold • Life stage susceptible to pesticide? • Crop stage and preventable loss. 23
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