Integrated Pest Management
Definitions of IPM are nearly as numerous as invasive species management programs on planet earth. (That means there is a lot!) The California Department of Pesticide Regulation (DPR) has a brief synopsis on IPM. They lean heavily on the science provided by The University of California Statewide IPM program, which defines IPM as: ”an ecosystem-based strategy that focuses on long-term prevention of pests or their damage through a combination of techniques such as biological control, habitat manipulation, modification of cultural practices, and use of resistant varieties. Pesticides are used only after monitoring indicates they are needed according to established guidelines, and treatments are made with the goal of removing only the target organism. Pest control materials are selected and applied in a manner that minimizes risks to human health, beneficial and non-target organisms, and the environment.” http://www2.ipm.ucanr.edu/WhatIsIPM/
“Broadly speaking, IPM emphasizes selecting, integrating, and implementing complimentary pest management tactics to maintain pests at economically acceptable levels while minimizing negative ecological and social impacts of pest management activities. Although the details of IPM programs vary to meet the needs of individual cropping situations, all are based on several related principles” (J. D. Barbour, 2009).
Pest Management Methods
Knowing what management methods are available will help you understand the advantages and shortcomings of each type of program. Once a pest problem is anticipated or identified, you can begin planning your pest management program. Select methods that are the most effective and the least harmful to people and the environment. Whenever possible, combine the use of several compatible methods into an IPM program, and target the pest at the most susceptible stage for control.
Natural controls are the measures that check or destroy pests without depending on humans for their continuance or success. Natural controls include climatic factors such as wind, temperature, sunshine, and rain. Topographic features such as rivers, lakes, and mountains can influence pest movement. Naturally occurring predators, parasites, and pathogens can regulate pest populations. When natural controls have not held pests in check, humans must intervene and apply pest management controls. Applied controls include biological, mechanical, cultural, physical, and chemical methods.
Biological control is the use of natural enemies, predators, parasites, pathogens, and competitors to control pests and their damage. Invertebrates, plant pathogens, nematodes, weeds, and vertebrates have many natural enemies. Adding predatory agents to the ecosystem is referred to as augmentative biocontrol;
- Predator insects: Adult lady beetles and their larvae are voracious aphid-eaters. Green lacewing larvae feed on all kinds of pests, including mealybugs, whiteflies, mites and thrips. These and other beneficial bugs are probably already in your garden. Another example would be the release of predatory mites, Galendromus occidentalis and/or Neoseiulus fallacis, which can be purchased and released for management of twospotted spider mites.
- Parasitic insects: Parasitic wasps lay their eggs on and in their living targets. Eggs hatch, and then feed inside the pest. A mummified aphid with a round hole in its back is evidence that parasitic wasps have been at work.
- Microbial pesticides and fungicides: Bacillus thuringiensis, also known as Bt, is a soil-borne bacterium that fights mosquitoes and insects in the larval, caterpillar stage. Bacillus pumilus is good for powdery mildew management. These and other bacterial and fungal based controls can be effective at controlling pests and pathogens in the garden.
Cultural pest controls start with the decisions you make when choosing and caring for plants. Prevention is your first line of defense; healthy, nurtured plants resist pests and diseases better than unhealthy plants. Cultural controls in good IPM programs include these simple recommendations:
- Select disease and pest-resistant plant varieties. Plants proven to withstand your region’s most common pests hold up better under attack.
- Choose proper sites. Cannabis plants are sun-loving and are more vulnerable to problems when planted in shady areas.
- Avoid watering directly on the stalk. Some diseases, such as fusarium can take hold with a water logged stalk. Water the soil at least several inches away from the base of plants. Water in early morning. If leaves do get wet, they’ll dry thoroughly before evening. Avoid overwatering in general.
Mechanical and Physical Controls
Mechanical and physical controls kill a pest directly, block pests out, or make the environment unsuitable for it. Traps for rodents are examples of mechanical control. Physical controls include steam sterilization of the soil for disease management, or barriers such as screens to keep birds or insects out.
- Sticky traps are great for fungus gnats, thrips and leafminers.
- Use mulch in garden areas. Mulch prevents weeds and weed seeds from getting light and sprouting
- Use cover crops to act as a mulch barrier. Certain types of cover crops prevent weeds from growing and also facilitate the healthy development of soil biology.
- Hand-pick pests off plants. This physical control puts an immediate end to pests’ plant-damaging days.
Chemical controls include synthetic and natural pesticides used to reduce pest populations. Many newer synthetic pesticides are much less disruptive to non-target organisms than older, broad-spectrum chemistries. Selective pesticides should always be chosen over non-selective pesticides to preserve natural enemies and allow biological control to play a greater role in suppressing pest outbreaks. Insecticides derived from naturally occurring plants such as pyrethrin and azadiracthin are important tools in many organic farming operations, and are playing larger roles in cannabis crop production.
“In IPM, pesticides are used only when needed and in combination with other approaches for more effective, long-term control. Pesticides are selected and applied in a way that minimizes their possible harm to people, nontarget organisms, and the environment. With IPM you’ll use the most selective pesticide that will do the job and be the safest for other organisms and for air, soil, and water quality” (http://www2.ipm.ucanr.edu/WhatIsIPM/).
Our research defines appropriate pesticides for IPM to include the following types:
- Traditional, synthetic pesticides: IPM pesticides includes products such as: Safer® Brand insect killing soap, which utilizes the power of potassium salts of fatty acids (insecticidal soap). The potassium salts weaken the insect’s waxy protective outer shell.
- Natural, non-synthetic pesticides: Botanical-based pesticides fall into this IPM group and include products such as Pyganic, based on pyrethrins extracted from special chrysanthemum blossoms. Another example is azadirachtin, an extract from the neem tree.
- Preventive pesticide application is limited because the risk of pesticide exposure may outweigh the benefits of control, especially when non-chemical methods provide the same results.
Pest and Natural Enemy Identification
The ability to accurately identify pests or pest damage is central to IPM, as is the ability to recognize and accurately identify a pest’s important natural enemies. Accurate identification is needed to determine if pests are present and to obtain information on pest biology and life history that may be critical to effective monitoring and control efforts (Field Guide, 2009). For example, damage to cannabis from root feeding insects and pathogenic fungi/bacteria can be similar. In fact, damage caused by root aphids or fungus gnat larvae can in turn lead to pathogenic diseases. Therefore treating the disease and not the root cause would simply reduce the symptoms of the disease but not stop it. Management options may involve a combination of treatments, but positive identification is first required for effective treatment options to be selected. The misidentification about a pest could cause you to choose the wrong control method or apply the control at the wrong time. These are the most frequent causes of pest control failure.
Once you have identified the pest and confirmed that it is causing damage, become familiar with its life cycle, growth, and reproductive habits. Then, use this information to form your pest control plans.
Ways to Identify Pests
If you cannot identify the pest in the field and online resources have failed to confirm any corroborating information, the final option is to hire a laboratory or pest management specialist. Properly collecting specimens is an important aspect of identification. It is very important that you first contact the laboratory or specialist and ask them what their suggested methodologies are for submitting samples. We have a documented case where plant tissue was improperly submitted for a suspected pathogen. The plant was submitted in a sealed plastic bag and wasn't analyzed for 3 days. The humidity values rose causing the spread of mucor, a type of saprophytic fungi present all around in small levels. The laboratory analysis identified the abundant pathogen as mucor, thus creating a false positive which lead to improper treatment recommendations.
A general guideline for collecting specimens are as follows:
- Always collect several specimens.
- Have plastic bags, vials, or other suitable containers available when collecting samples in the field.
- For plant diseases, submit undamaged specimens, such as healthy foliage, along with the damaged foliage.
- For insects and their relatives, kill them first and send them to the specialist in a manner that will not damage body parts that aid in their identification.
- For certain types of pathogens, it is best to submit whole plants, including roots, vegetative structures, and flowers, if possible.
- Be sure to include the location and date of the collection.
Field identification can be difficult due to the microscopic size of pests like russet mites or plant pathogens. Accurate identification requires the use of a hand lens or microscope, special tests, or careful analysis of damage. The CHA Forum can also be a resource guide for members seeking answers.
Monitoring for Pests, Damage, and Treatment Success
The concepts of acceptable pest levels, economic injury levels, and economic thresholds imply a need to monitor for levels of pests or pest damage in relation to these levels. Monitoring is fundamental to IPM because it is used to objectively determine the need for control and also to assess the effectiveness of control after action has been taken. Sampling and monitoring requires the ability to identify pests, pest damage, and key natural enemies of pests, as well as knowledge of pest and natural enemy biology and life history. In monitoring, the grower or a scout takes representative samples to assess the growth status and general health of the crop, the presence and intensity of current pest infestations or infections, and the potential for development of future pest problems. Monitoring may take many forms such as presence/absence or counts of pests from visual inspection of plants or plant parts or traps placed in or aroundfields (e.g., sticky traps, pheromone traps, spore traps). Sampling should be conducted to provide a representative assessment of the pest population in all areas to be similarly treated, such as part of a field, a single field, or adjacent fields. Various sampling schemes have been developed to assist in monitoring efforts.
Monitoring an area for environmental conditions (especially temperature and relative humidity) that are favorable or unfavorable for pest development is also important. This includes the use of models (e.g., the powdery mildew risk index, degree-day for downy mildew spike emergence and spider mites) to forecast conditions conducive to disease or pest development, and surveying the area for the presence of alternate hosts of cannabis pests and natural enemies.
Monitoring, when conducted routinely— at least weekly during the growing season—and in combination with good record keeping and awareness of model forecasts, can help determine trends in pest and natural enemy population growth over time. This assists in planning for pest management decisions and assessing the effectiveness of control actions. Indoor environments will be more appropriately tied to monitoring specific environmental conditions and less focused on factors that affect outdoor plants.
Pest and Natural Enemy Biology and Life History
An understanding of the biology and life histories of pests and their natural enemies, as well as an understanding of the environmental conditions affecting growth and reproduction, provide valuable information for pest management. Knowing which development stage of a particular pest causes damage; knowing when and where the pest is located within or near the crop when this development stage occurs; knowing which pest stage is susceptible to particular management tactics; and knowing what host plant(s) and climatic conditions are favorable (or unfavorable) to pest development—all of these help determine when, where, and how to control the pests of interest. The continuing trend toward more biologically based pest management systems requires detailed information on the life cycles of pests, their natural enemies, unintended consequences of applying certain control measures, and the complex interaction of these factors with the environment.
Economic Injury Levels (EIL'S) and Economic Action Thresholds
In most situations it is not necessary, desirable, or even possible to eradicate a pest from an area. The presence of an acceptable level of pests in a field can help to slow or prevent development of pesticide resistance and maintain populations of natural enemies that slow or prevent pest population build-up. In IPM, acceptable pest levels are defined in terms of economic injury levels (EIL): the pest density (per leaf, cone, or plant, for example) that causes yield loss equal to the cost of tactics used to manage the pest. The economic injury level provides an objective basis for making pest management decisions. At densities below this level, management costs exceed the cost of damage caused by the pest and additional efforts to manage the pest do not make economic sense and are not recommended. At densities above the economic injury level, losses in yield exceed the cost of management and avoidable economic losses have already occurred: management efforts should have been used earlier.
Ideally, an EIL is a scientifically determined ratio based on results of replicated research trials over a range of environments. In practice, economic injury levels tend to be less rigorously defined, but instead are nominal or empirical thresholds based on grower experience or generalized pest-crop response data from research trials. Although not truly comprehensive, such informal EILs in combination with regular monitoring efforts and knowledge of pest biology and life history provide valuable tools for planning and implementing an effective IPM program. Economic injury levels are dynamic, changing with crop value (decreasing as crop value increases) and management costs (increasing as management costs increase). In theory, economic injury levels can vary from year to year or even from field to field within a year depending on crop variety, market conditions, and available management options.
The economic threshold (sometimes called an action threshold) is the pest density at which control efforts are triggered so as to prevent pest populations from reaching the economic injury level. Economic thresholds are probably more familiar to growers and field personnel than eco- nomic injury levels. The economic threshold may be close to or the same as the economic injury level for quick-acting management tactics, such as some pesticides, or much lower than the economic injury level for slower-acting tactics such as some biological control tactics. Planning for any lag period between application of a management tactic and its impact on pest numbers is an important part of utilizing economic injury levels and economic action thresholds for an IPM program.
Step-by-Step Procedures for Developing an IPM Program
Identify all potential pests (including all life stages) in the system. Verify damage symptoms associated with pests and identify natural enemies. For plant pests, this will require identifying plant species in the management area and developing pest lists for each host. Train all pest management personnel to accurately identify beneficials as well as major pests and their damage, and to seek help when they can’t make a conclusive identification. Have materials (e.g., a field manual or identification texts) and tools (e.g., a dissecting microscope and hand lens) available to assist in pest identification. Make provision for identifying new pests as they are observed (see step 9).
For each pest, establish monitoring guidelines. These may be crude at first but can be improved with experience. Monitoring methods vary from pest to pest, but all involve regular (e.g., weekly) checking, visually or with traps, for pests or damage symptoms, or other evidence of pest presence (e.g., feces); methods also involve some way of quantifying observations. Also provide for monitoring of beneficials and natural enemies. Overall, the objectives of a monitoring program are to pinpoint precisely when and where pest problems may become intolerable and to determine the effectiveness of treatment actions. To determine the need for treatment, the objectives must be used with action thresholds, as discussed in step 3.
Establish injury levels and action thresholds for each individual pest species before making any treatment. An injury level is the pest population size (e.g., 10 aphids per leaf or 2 cockroaches per trap) that is associated with intolerable damage. Action thresholds are the set of conditions required to trigger a control action, usually a pesticide application. ANR Publication 8093 Determine the infestation levels that will be intolerable to people or to structures or that will cause unacceptable damage at various times of the year, plant growth stages, situations, and so on. At the same time, devise a monitoring plan for detecting these pest levels and determining when to treat. Over time you will refine the injury levels and action thresholds; however, treatment is usually required when
- a regular monitoring program indicates that the pest population will reach the injury level if left untreated; and
- biological or environmental factors cannot be expected to reduce the pest prob- lem within a reasonable time; and
- treatment cost and health and environmental hazards are considered less than the potential pest damage.
Establish a recordkeeping system. Good records are essential for evaluating and improving your IPM program and for reference when the public wants to know how you handle certain types of pests. Any recordkeeping system should include observations such as
- identity of the pest (to species if possible) and how the identification was made the size (density) of the pest infestation
- the geographic distribution of the pest problem in the managed area (a map of your facility can be useful for this)
- complete information on how you treated the problem, including what, how much, where, when, who, cost, application difficulties, and the effectiveness of treatment in solving the pest problem (short-term and long-term)
- the side effects of the treatment on nontarget species
- public complaints or other problems that arise, and positive feedback
- Develop a list of acceptable management strategies for each pest. The preferred methods in an IPM program prevent pest problems and therefore eliminate the need for pesticide applications. These methods might include modifying structures or landscaping to be less conducive to pest survival, using pest-tolerant or pest-resistant cultivars, using cultural practices (such as mulches or mowing and the use of pruning and planting times that discourage pests), and educating the public to be more tolerant of pests. Encouragement of naturally occurring biological controls can be very important; in some cases, barriers, traps, or mechanical removal can be effective. Develop a list of pesticides that are effective against each pest but are least disruptive to the environment for instance, soap sprays, microbials, botanicals, oils, and synthetic pesticides with low LD-50 and short persistence. Investigate and document the potential for using low rates, spot treatments, and other selective ways to integrate pesticides into an IPM program that is least disruptive to biological control agents and nontarget organisms. For instance, using bait stations or other formulations that reduce exposure to humans or nontarget organisms is an important way to reduce potential risks.
Develop specific criteria for selection of pest management methods. Make the criteria known to employees and the public. Although all criteria may not be met in every case, choices should meet the majority of the following requirements:
- least disruptive of natural controls
- least hazardous to human health
- least toxic to nontarget organisms and least damaging to the general environ- ment
- most likely to produce permanent reduction of the pest
- easiest to carry out effectively
most cost-effective in the short and long-term
For instance, avoid the common practice of regularly scheduled perimeter sprays to keep invading species such as ants, beetles, spiders, or earwigs out of buildings. This strategy does not provide a long-term solution to a problem and may kill beneficials and promote pesticide resistance. Structural changes, habitat reduction around buildings, and the use of baits can provide long-term control in many cases.
- Develop guidelines to be followed each time a pesticide is used. Prepare a checklist to be used each time an application is made. Important items on the checklist should include:
- choosing the safest material that is effective
- considering label signal words, persistence, impact on nontargets, and potential chronic human health effects
- considering the potential for treating only the most seriously infested areas (i.e., spot treatments) to allow for survival of natural enemies (this works for some insects and mites only)
- making sure the pesticide is registered in your state for the situation and that you are aware of all laws regarding its use
- if required, making sure you have in hand a written recommendation for using the pesticide made by a licensed pest control adviser
- checking the pesticide label to make sure all precautions and legal requirements are being carefully adhered to
- making sure all safety equipment and clothing are used
- verifying that the person doing the application is certified and qualified to handle the equipment and material chosen and that the person has been adequately trained
- after the application, monitoring the pest population to see if the treatment was effective
- keeping written records
- obtaining the Material Safety Data Sheet (MSDS) for the pesticide from the manufacturer
- making sure your application equipment is appropriate for the job and calibrated
- being prepared for all emergencies and knowing whom to call for help and interim measures to take before help arrives
- Designate a person to be responsible for each step along the way. These are the people (e.g., job titles) who will be responsible for making decisions, carrying out the various pest management and emergency operations described in your policy, and regularly evaluating the effectiveness of the program.
- Develop a list of resources. Know where you can go when information or outside help is needed. Include resources for pest identification, pesticide recommendations, and information about pesticides, pest management, and handling emergencies. Build a library and have employees participate in training and continuing education pro- grams on a regular basis.
- Consider your IPM policy to be a “living document” that changes as you acquire experience and new information. Establish an oversight committee that includes persons with toxicological and pest management expertise to assist with initial review of procedures and future changes in the policy. Review the program regularly (e.g., annually). Involve environmental organizations, worker health advocates, and other interested members of the public or employee representatives from your facility in the development and revision of the IPM policy. http://anrcatalog.ucanr.edu/pdf/8093.pdf
Follow up topics:
Proper Application of Pesticides and Fungicides
Systemic Vs. Translaminar vs. Contact
Field Guide for Integrated Pest Management in Hops. A Cooperative Publication Produced by Oregon State University, University of Idaho, U.S. Department of Agriculture - Agricultural Research Service, and Washington State University. First Edition, 2009.