Transcript Pest Management Tactics & Strategies • Covers chapters 8 – 17 in text • Includes all major tactics categories: – – – – – – Biological control Cultural control Pesticides Mechanical/Physical controls Behavioral-based control.

Pest Management Tactics &
Strategies
• Covers chapters 8 – 17 in text
• Includes all major tactics categories:
–
–
–
–
–
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Biological control
Cultural control
Pesticides
Mechanical/Physical controls
Behavioral-based control methods
Regulatory-based concepts
• Also includes all factors necessary for choosing/deciding
among controls
– Monitoring methods
– Decision tools
Pest Management Decision
Categories
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•
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Tactical vs Strategic
Preventative vs. Curative
In-Season vs. Intra-Season
Control vs. Non-control (i.e. monitoring)
Single Dimension vs. multidimensional
– Temporal: Single Period vs. Multiperiod
– Biological: Single spp. (pest) vs. Multiple spp. (pests,
beneficials, other non-targets)
– Economic: Immediate payback vs. multiple economic
considerations.
Who makes IPM Decisions?
• Growers who manage the pests?
• Consultants who make recommendations to
growers?
• Extension specialists who develop
educational/training materials?
• Researchers who decide which topics to
research?
• Administrators who decide which things to fund?
• Others?
Pest Management Strategic Plans
Decisions about how IPM needs to advance in a
particular cropping system. A planning tool.
• Driven by national programs
• Closely associated with Crop Profiles and
Crop Timelines
• Provide a framework for IPM decisions
• No specific format, but most include:
– Pest profiles for each important pest
– Management tactics currently used
– Additional needs in research, extension,
training
Assignment
• Split into groups of 3
• Each group finds a Pest Management Strategic
Plan
• Distribute the web site for the plan over IPM-L by
Thursday, Feb. 19.
• Each group discusses their plan in class on
Wed., Feb. 25
• Suggestion: One person discusses the pests,
one discusses the tactics, one discusses the
needs.
Most Decisions are Tactical &
Follow a Procedure
1.
2.
3.
4.
5.
Identify pest
Determine pest population density
Evaluate potential damage
Review available control tactics
Consider possible interactions with other
pests
6. Evaluate legal/environmental issues
7. Make a decision
The Decision Itself
•
•
Must rely on a priori objective criteria.
Often an economic framework.
Four possibilities
A.
B.
C.
D.
No action
Reduce Pest Population
Reduce Crop Sensitivity to Damage
B & C above
8. Follow-up to confirm expected outcome
An Alternative View to Fig. 8-1
Identification: Focuses on early
seasonality factors
•
•
•
Pathogens – Identification of conditions
leading to disease often more important
than identifying the pathogen itself.
Weeds – Seedling identification is the
main issue
Arthropods – Knowing when immatures
will be present often a key to
identification of pest problems.
Monitoring
• Synonymous with “Scouting”, “Sampling”, “Pest
Surveillance”
• Normally conducted to gather information
needed by a decision tool
• Types of decision tools that using monitoring info
include tools that:
–
–
–
–
Time preventative treatments
Determine whether curative controls are needed
Determine whether either of the above were effective
Select specific measures from several choices
Monitoring Determines:
• Crop Status (development stage, stand
density, standing crop, etc.).
• Identity of pests
• Phenology
• Age distribution
• Number or size of population
– Absolute (#/unit habitat or area)
– Relative (#/unit effort)
– Qualitative (Scaled from “low” to “high”)
Requirements of Monitoring
Methods
•
•
•
•
•
Simple to use
Fast
Inexpensive
Applicable to a broad range of pests
Reliable for decision making purposes
Decision-making reliability is crucial
• Credibility of IPM depends on decisions being
correct
• Decisions have to be made with imperfect
information & much of the imperfection is in
monitoring data
• Every decision has a risk of being wrong
• Lesson: We must understand how frequently our
decisions are incorrect and if there is a bias for
overcontrol or undercontrol in our mistakes.
Reliability for Decision Tools
Pest Population on Next Sample Date
Max Tolerable Pest Pop.
I
II
Max Tolerable Pest Pop.
III
IV
Pest Population on One Sample Date
Pest Population Density
Consider this situation
Maximum Tolerable Level
Time (Weeks)
Pest Population Density
Say we sample at weekly intervals
Maximum Tolerable Level
1
2
3
4
5
Time (Weeks)
6
7
8
You have to make
decisions at each
sampling date
I Correct decision to control
II Incorrect decision to do nothing
III Correct decision to do nothing
IV Incorrect decision to control
Pest Population Density
IV
Maximum Tolerable Level
I
II
III
III
III
III
1
2
3
4
5
Time (Weeks)
6
7
8
Construction of the decision diagram from
sampling data
I
II
III
Pest Population Density
Pest Population on Next Sample Date
Max Tolerable Pest Pop.
Max Tolerable Pest
Pop.
IV
IV
I
II
III
III
III
III
1
Pest Population on
One Sample Date
Y
X
2
3
4
5
Time (Weeks)
6
7
8
Example: Find 15 pest individuals at first
sample, 20 on the second sample
I
II
III
Pest Population Density
Pest Population on Next Sample Date
Max Tolerable Pest Pop.
Max Tolerable Pest
Pop.
IV
20
IV
I
II
III
III
III
III
1
15
Pest Population on
One Sample Date
20
15
2
3
4
5
Time (Weeks)
6
7
8
Example: Then, on the third week, we find
40 pest individuals
I
II
40
III
Max Tolerable Pest
Pop.
IV
Pest Population Density
Pest Population on Next Sample Date
Max Tolerable Pest Pop.
IV
I
II
III
III
III
III
20
Pest Population on
One Sample Date
1
40
20
2
3
4
5
Time (Weeks)
6
7
8
Not all decision points are equally susceptible to error
Pest Population Density
IV
Maximum Tolerable Level
I
II
III
III
III
III
1
2
3
4
5
Time (Weeks)
6
7
8
Reliability for Decision Tools
Pest Population on Next Sample Date
Max Tolerable Pest Pop.
I
II
Max Tolerable Pest Pop.
III
IV
Pest Population on One Sample Date
Reliability Depends on Several
Factors
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•
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Specific species being monitored
Sites (site selection is important)
Specific technique being used
Number of samples taken
– Number at each site & number of sites
• Weather
• Observer (Scout) – Scout training is emphasized
• Other minor effects:
– Field size, location, & aspect
– Time of day (pests with diurnal activity)
– Field history
Some of These are Linked
•
•
•
•
Specific species being monitored
Sites (site selection is important)
Specific technique being used
Number of samples taken
– Number at each site & number of sites
• Weather
• Observer (Scout) – Scout training is emphasized
• Other minor effects:
– Field size, location, & aspect
– Time of day (pests with diurnal activity)
– Field history
Reading for Friday
• Bring your blue books with you to class
• Before class, look through them & be able to
locate the insect, weed, and pathogen
monitoring sections of each book.
• Over the next few weeks (i.e. by the next exam),
be able to (1) describe at least one monitoring
method for each pest group in each cropping
system, (2) compare two sampling methods from
different crops, for the same pest group (e.g.
insects) and in the same generic category
(absolute, relative, qualitative).
Conclude Pest Monitoring
• Closely read the material on “Techniques
for assessing pest populations”, pp. 183 –
197.
– There will be an exam question here.
– We won’t discuss it in lecture but may refer to
the material as if you are very familiar with it.
– Be sure & apply this section to your analysis
in your term paper.
Decision Making
• Have discussed the “Maximum Tolerable Level”
but have not defined it.
• Several Points to Make:
– More than 1 “Level” is usually needed.
– There are many kinds of such levels (cf. p. 200 – 201
in text for one list).
– “Action Levels” or “Thresholds” are one general
method of decision making. We will discuss the other
one (Optimization) later.
• The leader in this field has been L. Pedigo. Be
sure & read his article in the “Reading
Assignments”
Pest Population Density
The General Problem
Maximum Tolerable Level
Time (Weeks)
Pest Population Density
We actually see this:
Maximum Tolerable Level
1
2
3
4
5
Time (Weeks)
6
7
8
One problem is that we need to allow for management
response time – The time between when a control decision
is made and when it takes effect
Pest Population Density
Assume it takes 1 week to
decide a control is needed,
apply it, and for it to work
Maximum Tolerable Level
Decision must
be made here
1
2
3
4
5
Time (Weeks)
6
7
8
Pest Population Density
The other problem is uncertainty
Maximum Tolerable Level
1
2
3
4
5
Time (Weeks)
6
7
8
Solution to both problems (mgmt response time &
uncertainty) is to create two levels
Pest Population Density
The maximum pest level that
one is willing to tolerate.
Maximum
EconomicTolerable
Injury Level
Level
Economic Threshold
The pest level at which action must be
taken in order to avoid exceeding the EIL.
1
2
3
4
5
Time (Weeks)
6
7
8
Quick Notes on EILs & ETs
• ET is always < EIL
• Units of ET & EIL are the same
– Often pest density (absolute or relative)
– Can also be injury (e.g. % defoliation)
– Can also be implicit factors (e.g. leaf wetness)
• EIL & ET are hard numbers calculated
from equations developed through field
research.
The Basic EIL Model
The basic concept is that the EIL is the point at
which the cost of a control = the value of
damage that will be avoided by the control.
Value of damage avoided is a product of:
Crop market value (V)
Pest population density (P)
Injury caused by each pest individual (I)
Damage resulting from that injury (D)
Proportion of total damage that cannot be avoided by
the control (K)
The Basic EIL Model
V  P'I  D  K  C
C
EIL  P' 
V  I  D K
Example
• Assume:
– It costs $50/A to apply a given control (C)
– A crop is worth $40/bushel (V)
– Leaf area equal to two leaves/row foot are
eaten by each pest individual/plant (I)
– The loss of two leaves/row foot results in the
loss of one bushel/A (D)
– Even if you apply the control, you will still lose
10 % of the crop (K = 0.1, no units)
Example, Continued
C
EIL  P' 
V  I  D K
50
EIL 
 6.25
40  2 1 0.10
Understanding the Units is Key
C
EIL  P' 
V  I  D K
50
EIL 
 6.25
40 1 2  0.10
$/A
EIL 
$ lv/rowft
bu/A


bu pest/plant lv/rowft
Here’s how the units balance
$/A
EIL 
$ lv/rowft
bu/A


bu pest/plant lv/rowft
EIL  1/1/(pest/plant)
Result:
 pest/plant
EIL = 6.25 pests/plant
One of the principal advantages of EILs
is their objectivity and scientific basis
C
EIL  P' 
V  I  D K
I, D, and K are determined empirically through field
& laboratory experimentation.
C is, for the most part, easily determined.
For most agricultural crops, V is commonly
available.
The principal source of subjectivity is in
“Value”: Ex: Tree Crops & Gypsy Moth
Pest Population Density
Forest Ranger
C
EIL  P ' 
V  I  D K
Municipality
Lumber Company
Resort Owner
Note that in all of these cases: C, I, D,
& K are all the same. Only V changes.
Time (Weeks)
Some examples of EILs & their
derivation.
• EIL for Mexican Bean Beetle in Soybean –
Details the development of an EIL.
• EILs for sorghum midge on sorghum –
See Table 1 in the middle of the article.
• Common stalk borer in Nebraska corn
• Sweet potato whitefly on cantaloupe
How are ETs calculated?
•
Most common method is heuristic. Most
common rule of thumb is 1/3 EIL.
• Two examples of more formal methods
are:
(1) ET = EIL/r
(2) ET = EIL/(expected rate of change in
pest population)
General notes on ETs
• ETs are the predictive part of an EIL/ET
pair – one acts on an ET in order to
prevent the EIL from being exceeded.
• ETs are one type of “Action Threshold”.
Other types were in Pedigo & your text
(pp. 201 – 202).
• Note your text’s discussion of limitations of
thresholds.
Advantages of Thresholds
• Conceptually easy to understand makes them easy to
implement/adopt. Can also be represented in many
formats: single numbers, tables, charts.
• Scientific basis to threshold criteria
• Flexibility gives broad applicability
– Can be applied to a variety of pests in many situations
– Can utilize many variables as the action variable. Climatic
variables often used for pathogens.
– Have been extended to take into account many other issues.
Examples include
•
•
•
•
Age distribution
Multiple controls (e.g. biocontrol)
Environmental Impacts (i.e. macroeconomic “C” values)
Risk
Closely read the remainder of this
chapter
• This is the only place where the following
topics are discussed:
– Use of field history
– Field location & size
– Monitoring climate
– Use of computer/mathematical models
– Aesthetic effects
– Risk Assessment
– Economics
Tactics
•
•
•
•
•
•
•
•
Cultural Tactics (Chapter 16)
Biological Control (Chapter 13)
Pesticides (Chapter 11)
Resistance, Resurgence (Chapter 12)
Host Plant Resistance (Chapter 17)
Behavioral Control (Chapter 14)
Physical & Mechanical Tactics (Chapter 15)
Legislative Prevention (Chapter 10)
Cultural Management of Pests
• Change the way the crop is grown so as to
– Make crop less suitable to pests
– Make crop more suitable to biocontrols
– Make crop better withstand pest attack
• All are preventative tactics, most target
pest complexes.
• Many individual types of tactics, each of
which has a narrow application range.
• Read Introduction on p 413 - 414
Basic Categories/Examples of
Cultural Techniques
• Prevention/Preplant
– Ex: use weed-free seed
• Field Preparation & Planting
– Ex: increase plant spacing to reduce disease
• Cropping Tactics
– Ex: use barrier crops to help exclude insects
• Harvest Tactics
– Ex: harvest early to reduce yield loss
• Sanitation
– Ex: pick up prunings to reduce pathogen inoculum
Good situations for cultural controls – Any of
these will lead to the use of cultural controls
• Multiple simultaneous pests susceptible to 1
control method
• Crop has broad flexibility with respect to specific
tactic but pest(s) does not
• Pest complex:
– Has one or more key pests vulnerable to
environmental manipulation
– Lacks pests capable of causing severe damage at
low density
– Contains one or more pests that lack better control
alternatives
Benefits of cultural controls
• Often easily incorporated into the
production system
• Predictable level of control, even if partial
• Fast acting
• As a group, relatively sustainable
Disadvantages of Cultural Controls
• Some are not environmentally benign (e.g.
conventional tillage, residue burning)
• May alter crop value or gross income
(planting date, harvesting, spacing)
• Some are labor/energy intensive (pruning,
tillage)
• Widespread adoption may be low
• Many conflicts
Conflict Illustration
Normal Planting Date
Late Planting Date
Pest Density
Crop’s Maximum
Susceptibility Period
Time
Conflict Illustration
Normal Planting Date
Late Planting Date
Pest Density
Crop’s Maximum
Susceptibility Period
Time
Often better to think of cultural
control tactics as altering the pest
complex rather than controlling it.
Conflicts Occur with:
•
•
•
•
Agronomic Traits
Other Pests
Markets
Other Cropping Practices
Begin Discussion of Cultural Control Categories
Basic Categories/Examples of
Cultural Techniques
• Prevention/Preplant
– Ex: use weed-free seed
• Field Preparation & Planting
– Ex: increase plant spacing to reduce disease
• Cropping Tactics
– Ex: use barrier crops to help exclude insects
• Harvest Tactics
– Ex: harvest early to reduce yield loss
• Sanitation
– Ex: pick up prunings to reduce pathogen inoculum
Prevention/Preplanting Tactics
• Site selection
• Preventing pest transport (equipment, soil)
• Use pest-free seed/transplants/rootstock
Field Preparation & Planting
•
•
•
•
•
Cultivation & fertility
Plant & row spacing
Planting date (early vs late)
Planting method (depth, insertion method)
Mulches – organic & synthetic
Cropping Tactics
• Trap/Barrier Crops
– Trap crops are destroyed with the pest
– Barrier crops are on field perimeter
• Intercropping – Two or more useful crops
• Cultivar mixtures – Different cultivars may
have to be planted in different fields to
create a “cultivar patchwork”. Multilines
will be discussed in HPR.
• Water Management
Cropping Tactics – Crop Rotation
• Intercropping in time
• Especially effective against soil-based
pests: Weeds, soil-borne pathogens, rootfeeding insects
• For weeds:
– Changes weed complex
– Not stand alone weed mgmt, instead used to
facilitate weed mgmt
Harvest Tactics
• Harvest timing (early vs late) -- may use
early/late varieties, dessicants, defoliants, or
other growth regulators.
– Crop matures before pests build up
– Harvesting operation itself causes extensive mortality.
• Harvest method
• Partial Harvesting -- Prevents movement to high
value crops
– Maintains young age structure
– Concentrates natural enemies (usually more mobile)
Sanitation
• Residue Removal
• Burning/Flaming
• Pruning (Removing Part of a Plant)
– Infected/Infested host tissue
– Foliage that provides pest access
– Alters canopy microclimate
• Roguing (Removing an Entire Plant)
– Crop hosts
– Alternate hosts
• Removing Other Resources (Often in Structures)
– Harborage sites
– Food/water sources
Biological Control
• One of the oldest pest management tools
• One of the most complex
• Excludes some biologically-based tools
– Use of pests own behavior, biology, ecology
– Use of crop resistance
• As a result, many definitions
Biological Control Defined
“The use of parasitoid, predator, pathogen,
antagonist, or competitor population to
suppress a pest population making it less
abundant than it would be in the absence
of the biocontrol agent
Emphasis on “population” helps exclude
microbial pesticides
Biological Control
• Natural Control vs Biological Control
– Natural Control is unmanaged, Biological
Control is managed. Definition of “managed”
can be pretty loose.
• Natural Enemy = NE = “Biological Control
Agent” & “Biocontrol Agent”
– Any non-crop species that is antagonistic to
the pest. Includes predators, parasites,
parasitoids, pathogens, competitors.
– May be managed or unmanaged.
Biocontrol Ideal
Biocontrol agent
introduced
Population Density
Pest
EIL
Biocontrol Agent
Time
Three components interact to produce
different biocontrol approaches
Emphasize effect
of cropping
system on NE
Cropping
System
Ideal
NE lacks
persistence,
emphasize
introduction
Emphasize
the NE-Pest
Interaction
Pest Complex
Natural
Enemy
Cropping System Characteristics
Conducive to Biocontrol
• Stability
• Abiotic environment supports NE’s
– Temperature, moisture & shelter are all available as
needed by NE
– Soils support soil-based NE’s
• Biotic environment supports NE’s
– Alternative food sources available
– Food for all life stages available
• Management practices compatible
• Crop should have some damage tolerance
Biocontrol usually allows some
injury and/or damage
Population Density
}
Biocontrol agent population
always lags behind the pest
population. This allows the
pest population to build up to
some extent.
EIL
ET > EIL/3
ET = EIL/3
Time
Pest complex characteristics
conducive to biocontrol
•
•
•
•
Few species in the target niche
Stable species composition
Few key pests, few direct pests
Ideally, minor pest species can act as
alternate hosts/prey
Note the benefits of biocontrol, pp 338 - 339
Costs/Disadvantages of Biocontrol
• Usually requires change in management
practice
• Increases scouting effort
• Intrinsic time delay
• Increased risk
– New NE’s may cause harm
– Uncertainty about NE requirements/reliability
– Always a potential for pest to escape control
• Fundamentally incompatible with other control
tactics
Characteristics of Effective NE’s
• Can detect pest populations at low densities
• Rapid population growth relative to pest
population
• High pest destruction rate per capita
• Synchronized phenology
• Persistence at low host density
• Persistence over cropping seasons/rotations
• Tolerant of management actions
• Willingly adopted by pest managers & growers
Common Trade-off Quesitons
• Generalists vs. specialists.
• Multiple vs. single biocontrol species
Generalists vs. Specialist NE’s
• Disadvantages of generalists:
– Usually have lower numeric response
– Kill fewer pests/unit time/NE
– May be attracted to other species
• Advantages of generalists:
– Better survival when pest population is low
– More likely present at pest establishment
– Multiple generalist species can co-exist as a
community (greater stability & reliability)
Phase Plane – Specialist NE
Population Density
Natural Enemy Population
A specific phase plane’s characteristics are determined
by (1) the biological parameters of the NE and Pest and
(2) how closely the NE and Pest population dynamics
are coupled. Specialists tend to be highly coupled.
Time
Pest Population
Elementary Implications of the
phase plane
Too Many NE’s for Pest Pop. –
NE Crash Imminent
Outcome Uncertain –
Probably Bad
Pest Min
Pest Max
Natural Enemy Population
NE Max
Stable -- Good
Too Many Pests,
Two Few NE’s
– Pests Have
Escaped Control
NE Min
Too Few Natural Enemies
-- Pest Resurgence Danger
Pest Population
Must be < EIL
The “good” area often identified in
decision guides as NE/pest ratios
Spider Mite Examples
• Predator mite/pest mite (spider mite) on
apples must be at least 1:10 in
Washington raspberries.
• In N. Carolina apples:
– 1 Predator mite/18 pest mites
– 25 Coccinellid predators/5 trees
• European red mite in W. Virginia orchards
– If mites > ET, no spray if predator/mite > 2.5
Multiple vs. Single NE Introductions
• Denoth et al. 2002 analyzed 167
biocontrol introduction projects
– Multiple introductions increased success for
weed control, decreased success for insects
– In > half, a single NE species was ultimately
responsible for almost all realized biocontrol.
– Recommend that multiple introductions
should be used with restraint when attacking
insect pests