Dr. Richard Freeman
This primer introduces the audience to a framework for understanding and practicing Integrated Pest Management (IPM). The intended audience includes horticulturists, orchardists and farmers who are interested in sustainable practices. Please see the author’s note at the end of this guide.
Introduction
Maintaining and preserving ecosystem complexity and functionality is fundamentally important to ecological horticulture. Thus, pest management must align with ecological flows and process and must avoid their disruption. Generally speaking, complex and functional ecosystems will keep pest species to a minimum, so avoiding severe chemical and mechanical disturbance takes a high priority. Fortunately, managing a container environment without aid of severe measures such as pesticide application is possible and highly advantageous.
Integrated Pest Management is a common sense framework for preventing and managing pests based on expected costs and benefits. It requires a focused awareness on the container ecosystem and applies a large variety of strategies and tactics to preventing and solving problems.
This primer briefly explains IPM and outlines the planning and management process. Section 1 gives a general overview of IPM. Section 2 outlines basic IPM practices.
Section 1. Overview of Integrated Pest Management
Integrated Pest Management (IPM) is a decision-making framework that combines strategies to limit pest damage to a level determined by the grower’s goals and objectives, while minimizing risk to people, pets, and wildlife. With IPM, the grower uses the minimal intervention necessary to meet production objectives, while favoring smart farm design, prevention and natural control mechanisms. This approach optimizes labor and material costs in the workspace and minimizes chemical impact on the plant. The grower monitors the growing space for pests and responds on a scale and intensity appropriate to the levels of damage and infestation. Low-cost, minimal-risk, and least-damaging solutions take preference.
This approach recognizes that pests will inevitably be present and combines a variety of complementary strategies and tactics to keep pest populations below a harmful threshold. Mimicking natural ecological systems, the grower must integrate these techniques and tactics into a larger, adaptive strategy that begins before catastrophic situations arise, thereby preventing most potential problems.
While IPM is the best approach to responding to infestation crises and crisis-management, its greatest advantage is in avoiding crises through planning, preparation, and prevention. Whether the horticulturist creates a complete, documented IPM plan or briefly outlines an IPM plan, a well-conceived and executed plan can preclude expensive losses to arthropod and pathogen infestation.
Further, a good IPM program will identify, make explicit and quantify the many assumptions underlying threat assessment and response – supplementing the manager’s intuition with an explicit account of the problem-solution framework. As an equally important corollary, a good IPM will allow the horticulturist to budget expected costs and benefits in detail, drastically improving short- and long-term planning.
IPM emphasizes maximizing the spread between expected benefits (income) and expected costs. When considering pesticide use – or any other cultural practice – the farmer compares the expected costs from pest-induced damage to the expected management costs for labor, equipment and materials. The farmer must also assess the risk of decreased product value, bad press, consumer dissatisfaction and possible action, regulatory action, and health hazards (to workers and community) due to pesticide contamination. Having assessed costs and benefits, the producer can avoid cultural practices that don’t show a return.
1.1. General principles guide IPM
Overall, several general principles guide IPM:
1.1.1. Uncertainty and risk.
Carrying out management treatments in an ecological setting introduce uncertainty and risk. Unintended consequences are the norm and some of them can create long-term costs much greater than their short-term benefits.
1.1.2. The Precautionary Principle
The precautionary principle states that before undertaking any action that will affect public health or the environment, in the absence of scientific knowledge on the effects, the manager should adopt full precautionary measures. This principle refines the principle, Primum non nocere, or “First, do no harm,” by obligating the formulator to prove that an action will preserve and protect public health.
1.1.3. Cost Benefit
Management treatments should make economic sense, short-term and long-term. Managers should focus treatments on the most severe problems (in terms of short-term and long-term economic outcome) on which they can have the most impact.
1.1.4. Minimal disruption
“Managers should use treatments that have the least disruption on natural controls, the least hazardous to human health, the least toxic to non-target organisms, and the least damaging to the garden and general environment.”
1.1.5. Long-term Strategy
Strategies and treatments should focus on long-term and permanent pest reductions.
1.1.6. Feasibility
Strategies should be easy and cost-effective to implement in the field.
1.1.7. Design the agriculture ecosystem
Designing pests and problems out of the agricultural system should take priority.
Section 2. IPM Management Practices
IPM includes a large set of cultural practices that fall into four groups. Ecological & Sanitation practices create a low-risk growing environment that is healthy for plants and is invulnerable to pest outbreaks. Monitoring is key to catching problems early, before serious infection or infestation. Indirect controls (also called environmental controls) involve adjusting growing environments (lighting, atmosphere and soil) to thwart pests. Direct controls follow or accompany indirect controls. Direct controls include mechanical, biological and chemical controls.
The manager/farmer employs controls in response to a perceived threat, which is based on analyzing monitoring data in light of economic damage-thresholds, which the manager will have already established (as described below). When a pest infestation reaches a threshold and triggers a response, the grower consults the prepared response strategy. (Again, see below.) If the infestation arises from a pest on the target pest list, the grower can devise a specific treatment based on the prescribed general response. If the infestation is not on a target pest list, the grower must research the specific pest and devise a response that reflects and supports management objectives.
2.1. Ecological controls, nutrition management and sanitation controls
This category of practices will prevent pests and is fundamentally important to IPM.
2.1.1. Ecological controls
Ecological controls encourage biodiversity in the growing ecology. Above ground, ecological controls involve creating biodiverse ecosystems that attract and support beneficial arthropods while blocking and confusing pests. In outdoor operations these ecosystems involve blocks, strips and corridors planted with carefully selected plants to provide the pest management functions while building healthy soil to decrease management needs of the special areas. In indoor operations (including closed greenhouses), ecological controls involve polycultures carefully designed and optimized for indoor use.
2.1.2. Nutrition management
Nutrition management is an important factor in the relative attraction of pests to plants. “The indirect effects of fertilization practices acting through changes in the nutrient composition of the crop have been reported to influence plant resistance to many insect pests. Among the nutritional factors that influence the level of arthropod damage in a crop, total nitrogen (N) has been considered critical for both plants and their consumers. Several other authors have also indicated increased aphid and mite populations from nitrogen fertilization especially herbivorous insect populations associated with Brassica crop plants known to increase in response to increased soil nitrogen levels.”
2.1.3. Sanitation controls
Sanitation controls combine cultural principles with physical, permanent growing facility features. Facility features can include exclusion tactics, for instance, building tight, slightly-depressurized changing rooms, separate quarantine rooms, and effective filtering of heating, ventilation, air-conditioning. Cultural principles can include such rules as restrictions against pets and street ware, a strict policy against importing clones and a well-established container-media procurement policy.
2.2. Monitoring
Monitoring combines observation with data-keeping. Monitoring is an on-going process that starts at a base level (no infestation) and increases in intensity when an infestation exceeds critical-thresholds and triggers a response. A response typically involves intensifying monitoring, implementing direct controls (and treatment), or both.
Monitoring effort and cost will depend upon the size of the crop and the grower’s desired sample intensity. Monitoring practices can range from casual, visual observations to systematic counts based on traps and/or filters, depending upon the grower’s goals and priorities. Managers can also monitor plant damage as an index of infestation.
2.2.1. Scouting
Scouting involves physically inspecting plants and can vary in rigor from the casual glance to systematic observations. Sample intensity can range from a representative sample to full-intensity (monitoring every plant), as often as necessary. Growers follow a specified protocol beginning with visual inspection of plant parts in whatever order the grower prefers, perhaps live-sampling branches or entire plants when necessary. Inspections can occur during light-periods or dark-periods, depending upon the target pest’s life cycles.
2.2.2. Traps and Lures
Traps and Lures can be specific to one or a few pests, but the idea is simple. Sample intensity can range depending upon the management situation (trigger response). Trap placement depends upon the sample intensity, the type of trap used, and the known life-cycles of the targeted pests.
Data-keeping formats can range from GIS-based data-bases or spreadsheets to written note-taking or “taking note” mentally.
2.3. Indirect Controls or Environmental Controls
Response strategies proceed along a path beginning with indirect control, which involve altering the growing environment to impede pest population development. Indirect controls can including disrupting habitat by cleaning, re-arranging, or redesigning the growing area or changing environmental parameters like room temperature, relative-humidity, air-movement (wind) and dust. (Some authors use the term “environmental controls” for indirect controls.)
2.4. Direct Controls
Depending upon need, plant-stage and farm objectives, farmers can proceed to using direct-control strategies. When assessing direct control alternatives, the IPM farmer heeds the precautionary principle assuring that he or she will “first do not harm.” Safely within this important constraint – and all things being the same – the farmer will prefer to err towards minimizing pest risk – a “false-positive” error (or Type I error). Within the constraint of doing no harm to society or environment, the farmer would generally “rather be safe than sorry.”
2.4.1. Mechanical controls
Direct-control strategies begin with mechanical controls like hand-picking insects or spray-hosing plants.
2.4.2. Biological controls
If mechanical methods are not adequate, the manager proceeds to employing biological controls, like introducing store-bought predators and parasitoids, as individual species or in combination – for example the spider-mite predator combination of Stethorus punctillum (a type of “lady beetle”) or Phytoseiulus persimillis (a predatory mite). Other biological solutions include using fungi and bacterial that thwart or kill pests, for example moulds in the Hyphomycetes fungal order or bacteria in the Pseudomonas genus.
2.4.3. Chemical controls
If necessary, direct controls can involve minimum damage chemical controls and application techniques. Applying chemicals can have several types of deleterious unintended consequences, so extreme care is necessary, and following label guidelines is crucial. A pesticide label is considered a legal contract, and using a pesticide outside those label restrictions is illegal. Most compounds that kill pest will also kill beneficial organisms, so managers should adapt a strategy to obtain or attract pest suppressing organisms.
Potential long-term problems and costs that can follow from chemical treatment include residue (persistent effects), resurgence (which means a pest population rebounds after a treatment because the treatment has killed that pest’s predator population), and resistance, which describes a pest strain’s proclivity to evolve resistance to commonly-used pesticides. Secondary pest infestations occur when an additional pest moves after a treatment has eliminated its competition and predation.
Thus, a manager should use the least disruptive, hazardous, generally toxic and damaging alternative that meets the objective – and only in the most severe cases when the economic benefits are clear. If feasible, spot applications are better than broad-scale applications, and they minimize impact while saving on materials costs. Managers should time treatments to match up with appropriate pest morphology stages and with an appropriate range of weather and environmental conditions – as well as social conditions.
Generally, pesticides can be divided into essential oils and their extracted volatiles, botanicals and vegetable extractions (like Allium sativum, garlic), non-organic compounds (for example, sulfur products), microbe-synthesized pesticides, insect growth regulating hormones, vegetable oils, horticultural soaps of various strength and disruptiveness, horticultural oils, and a multitude of synthetic pesticides.
If infestations persist after an initial or successive response, a triggered response may require a more expensive or intensive strategy or strategic combination, as prescribed in the response strategy. The manager should document all strategic actions for cost-tracking and for building a knowledge base.
Section 3. Assembling the IPM program
The IPM process begins with some basic planning steps. These steps make clear and explicit the grower’s priorities and guide the choice of strategies throughout a growing cycle and in the case of a pest infestation.
3.1. Farm Goals
Goals are statements of purpose that declare “what” the grower wants to accomplish. For example, a goal might be written like this one: “Our goal is to grow high-quality product with minimum-possible chemical application.” Farm goals reflect the grower’s priorities and should be explicit, no matter what they are. A farm will generally have many goals – which together make up its mission – and making these goals explicit is an important step towards agronomic success.
3.1.1. Assessment
An assessment is a structured analysis and description of the growing environment based on systematic observations. An assessment includes information on growing space basics (zones, area sizes, spacing, etc.), physical limiting factors (light, water, CO2, temperature), ventilation and airflow, soils and containers, surrounding vegetation and wildlife, chemical and biological limiting factors (nutrients and soil biological nutrient-cycling), or other pertinent items.
3.1.2. Objectives and Constraints
Objectives state how the grower intends to meet his or her farm goals. For example, “our objective is to grow healthy plants by using soil mixes and practices that yield maximum biological nutrient-cycling.” That objective is one of two or more how-to statements that will together meet the goal. Another example is an objective that could help with the minimal application goal, “…to monitor for pest infestation from beginning to end of each cycle.”
Constraints are specific restrictions on objectives, based on values, economic limits, or environmental limits. A constraint might read, “We will use no organophosphate pesticides,” or “We will use no chemical application during the budding cycle.”
3.1.3. Objectives Implementation
Implementing objectives involves creating a well-defined and explicit program that includes several components.
3.1.3.1. Management principles
Management Principles are rules that support implementation of objectives. These principles include cultural controls, which shape the general growing environment. Management principles can include items like keeping personal pets out of the grow area, entering the grow space with clean-clothes, leaving no standing water in the grow space, or maintaining the grow room within specified temperature or relative humidity ranges. These principles focus on preventing problems, but they also include measures that will affect monitoring and response practices.
3.1.3.2. List of Tasks
A List of Tasks could include such items as creating a mix recipe, filling and placing containers with a 12-inch buffer between adult crowns, and placing pest traps at designated locations. For long-term cost-tracking and budgeting, this list is a valuable resource.
3.1.3.3. Schedules
Schedules are key for planning because they help with identifying critical pathways and avoiding bottlenecks, labor-scheduling, budgeting and cost-tracking.
3.1.3.4. Cost-benefit model
A cost-benefit model of the operation is key, are are cost models of each treatment that includes labor costs is key to weighing the cost and benefit of implementing controls.
3.1.3.5. Monitoring Plan
A monitoring plan is vital to IPM. A monitoring plan specifies the types, locations, and scheduling of monitoring tactics (for example observing sticky traps) on the basis of a sample-design. A monitoring plan should target as many types of pests as possible, with special attention to known target species and types. Monitoring intensity will increase with the known presence of pests and with the intensity of the infestation. The plan should also include an estimation of the labor demands for each response – for cost-tracking and future budgeting.
3.1.3.6. Critical threshold and triggers statement
A critical threshold and triggers statement defines the level of damage that the grower is willing to suffer before responding. (A critical threshold is also known as an Economic Threshold.) Creating critical thresholds involves making decisions on economic risks before a crisis occurs. After establishing the critical thresholds, the grower defines observation-based action triggers that indicate an infestation has reached that threshold. When the trigger conditions are met, the grower responds with an appropriate response. Responses will vary with different strains, pest species (or complexes), timing, and other factors. Intensified monitoring follows a treatment and the persistence of an infestation may trigger a further response.
3.1.3.7. Strategic Response Statement
A strategic response statement is a list of responses to triggers. Responses can include any combination of increased monitoring, indirect controls and direct controls. Responses will often be sequential (one control following another). Intensive monitoring should follow any treatment.
If a treatment fails to suppress the pest satisfactorily below the critical threshold, the grower may need to redefine thresholds and/or escalate to more intensive responses. The Response Statement includes each successive strategy and associated responses that the grower intends to use in a triggered response.
The response strategy should include an estimation of the costs (including labor) for each IPM control involved in any response – for cost-tracking, budgeting, and assigning additional labor during an outbreak. This estimation should be integrated into the cost-model.
3.1.3.8. Materials inventory and sourcing guide
A materials inventory and sourcing guide is key for quick response on all treatments not requiring fresh beneficial organisms, especially for target pests. In addition, being aware of all commercial sources of biologicals for quick procurement is key, since these organisms must be fresh (so storage is not feasible). This guide is useful for ordering-efficiency and cost tracking.
Map-based Designs are highly-useful guides for implementing objectives, and we encourage the grower to make one or have one made. A map on a geographical information system is very handy because one can try several designs while analyzing growing-space area – per plant or per zone – or other parameters such as the volume of individual growing spaces.
Conclusion
IPM is a risk-management approach to pest management that requires knowledge of an operation’s cost-benefit structure and articulation of the managing entity’s strategic management goals.
Author’s Note
This manual is in draft form. It includes no foot notes or references and it contains significant omissions. Anyone interested in republishing using the content in this manual should first contact me, the author, Richard Freeman, to gain permission. The information I present is for educational purposes and I am not liable or responsible for anyone’s use or misuse of this information. For those interested in obtaining a final version with footnotes, please contact me. I am also interested in co-authoring a final version of this paper. https://www.designedecosystems.com/contact/ I will periodically post updates to this blog.
