1. Pest Management Decisions

2. IPM decision staircase
Some basic information is essential
Information must be obtained from bottom to top
Missing information will lead to incorrect decisions
Each step interacts with the other in some way

3. Major steps in the decision-making process
Pest Identification
Pest species must be correctly identified
Tells us about biology, life cycle, control strategies, etc.
Population Determination
Monitoring to determine pest population size, pest distribution, stage of development, presence and distribution of beneficials
Damage and Economic Loss
Evaluate potential damage to crop relative to pest density
Consider action, economic and/or damage thresholds

4. Major steps in the decision-making process
Available Control Tactics
Review what tactics are available and their efficacy
Cost of implementing control vs. economic returns expected
Current and projected market value
Interactions
Consider interactions among target pest and other pests and beneficials in the system
Environmental and legal constraints
Consider local, regional environmental and societal regulatory restrictions

5. Major steps in the decision-making process
Make a decision
No action
Damage caused by pest doesn’t warrant action
Reduce crop susceptibility to damage
Change some aspect of the system to limit damage to an acceptable level
Reduce pest population size
Recommended action that will reduce pest population
Combination of b. and c.

6. Monitoring
Process by which number and life stage of pests present in a location are established (aka scouting)
Key objectives are to determine:
Pest stages present in the crop
Phenology of pest
Growth stages through which the pest passes in relation to time
Density of pests in the crop
Number of pests per unit area
2,000 seeds/m2
Number of pests per plant part
5 aphids/plant
Number of pests per unit of sampling effort
10 beetles per 5 sweeps of a sweep net

7. Steps in Monitoring
Record type of plant being monitored, its size, location, condition, and date and time inspection took place
Monitor the crops for insects (using methods described above) on a regular or weekly basis, and note number of pests, their stage of growth, and distribution
Identify any beneficial insects
Take representative plant samples in the field
Assess the growth status and general health of the crop
Record the findings on field data sheets

8. Techniques for Assessing Pest Populations
There is no single monitoring technique that works for all categories of pests
Overall considerations
Data required
Actual pest numbers, presence/absence, phenology
Time of day when samples are collected
Weather conditions
Windy, cool/hot, or rainy conditions can alter pest visibility
Soil conditions
Phenological development of organism
Weed seeds vs. seedlings, 1st vs 5th instar larvae differ in size
Pest location
Soil/plant host, in-crop/field edges

9. Common Monitoring Techniques
Direct Pest Observation/Counting
Quadrats
Organisms present within an area
Weeds
Plant Samples
Samples of plant parts
Egg and larval counts, estimating leaf/root damage

10. Common Monitoring Techniques
Direct Pest Observation/Counting
Knockdown
Pests are dislodged from host onto a collecting surface/container
Larvae and non-flying insects
Sweep Nets
Nets are strong, usually about 15 inches in diameter at opening
Insects only
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11. Common Monitoring Techniques
Damage Evaluation
Sometimes looking at symptoms or injury is the only way to determine pest presence
Signs or symptoms
Pushed up soil
Frass
Slime trails
Spores, sclerotia, mycelium
Physical injury
Remote sensing

12. Common Monitoring Techniques
Trapping
Primarily used for insects
Can detect a presence but not usually reliable for population size
Will help monitor population activity and frequency of insect vectors
Visual
Sticky traps
Bait traps
Pitfall traps
Pheromone traps
Blacklight

13. Common Monitoring Techniques
Soil Sampling
Soil-borne pests
Can be time consuming, laborious
Shovels, scoops, cores
Water submersed, sieved

14. What do we need to consider when we are taking samples in the field?
Field size
Economic value of the crop
Sample location
Pest density
Sample size
Sampling patterns
Goals of manager
Mobility of the pest
Timing of sampling
Frequency of sampling

15. Assignment Choose two weeds, two insects and two diseases.
List which technique is used to monitor each.

16. Economic Thresholds

17. Damage Concept Injury Damage
The physical harm or destruction to a valued commodity caused by the presence or activities of a pest
consuming leaves, tunnelling in wood, feeding on blood, etc.
Damage
The monetary value lost to the commodity as a result of injury by the pest
spoilage, reduction in yield, loss of quality, etc.
Any level of pest infestation causes injury, but not all levels of injury cause damage

18. Just how much damage can we tolerate?
At some point, a pest begins to cause enough damage to justify the time and expense of control measures
But how does one know when this point is reached?
How much financial loss is the pest causing?
How much will it cost to control the pest?
Economic Injury Level
The pest density where economic value of the crop loss prevented by the control action is equal to the cost of that control action
Determined through extensive research

19. Economic Injury Level P=C/(V x I x D x K)
P=Pest population expressed as a density (e.g., number of pests per plant)
Point where damage equals cost of control (EIL)
C=Management costs (i.e., costs of control)
V=Market value per unit of production
I=Injury per pest equivalent
D=Damage per unit injury
K=Proportion of damage that must be tolerated

20. Economic Threshold Threshold Economic Threshold
Stimulus has reached a sufficient level to provoke a response
Must be qualified further
Economic Threshold
Pest density at which control action must be taken to prevent the population from increasing to the EIL
ET occurs at a lower population that the EIL…why?
In weed science, the ET is equal to the EIL

21. Examples of thresholds??
What are some of the thresholds written in our insect fact sheets?

22. Limitations of Thresholds
Environmental conditions can alter thresholds
Some pathogen populations are impossible to count accurately
There may not be any available controls for a pest once it reaches a detectable stage
Some pests cannot be cured
Multiple pests may attack a given crop
Not enough data available to establish the thresholds

23. Other factors that affect pest management
Cropping History
Field Location and Size
Weather Monitoring