Integrated Pest Management: Why?

February 24, 2022
Category: Growing Tips

Today we’ll begin a series on Integrated Pest Management by doing a thorough overview of what IPM is, looking at its key terms, and discussing why you should implement IPM in your commercial greenhouse. 

In this article, we’ll cover:

  • What is IPM?
  • What are the four types of pests?
  • The three main goals of IPM: prevention, suppression, and eradication
  • Chemical classes and types of pesticides
  • Key terms to know
  • Benefits of IPM for your commercial greenhouse
  • Basics of formulating and implementing an IPM program to reap those benefits

What is IPM?

IPM stands for Integrated Pest Management, which is a strategy for reducing pests and their damage to plants by employing appropriate coordinated pest control methods. From mulch to poison and repellent, IPM requires growers to consider all aspects of pest problems and to treat those problems as a whole with targeted and thoughtful tactics. This holistic approach to pest management aims to use the most effective strategies to control pests with as little impact on the growing environment as possible.

Four Types of Pests

Growers face four categories of pest:

  1. Weeds – anything unwanted that grows, removing nutrients from the soil and potentially attracting other types of pests
  2. Invertebrates – this includes insects, spiders, mites, ticks, snails, slugs, and worms
  3. Disease / Pathogens – from root rot and powdery mildew to blight and leaf spot, this category encompasses any plant-harming pathogen
  4. Vertebrates – depending on the location of your plants, this could include mice, rabbits, deer, etc

Three Main Goals of IPM

Integrated Pest Management has three primary goals: preventing pest issues, suppressing pest populations, and eliminating pests.


Prevention involves stopping pests before they arrive. This includes strategies like putting down plastic mulch to prevent weeds, focusing on sanitation in the greenhouse, maintaining healthy culture and crops, fertilizing and irrigating plants appropriately, isolating new plants, and monitoring for insects and disease. Basic preventative measures increase greenhouse health and can prevent epidemic insect and pathogen issues. 


Suppression involves reducing pests to prevent epidemic infestation. Many methods can work to this end, and integrated pest management employs a variety of effective methods rather than focusing on just one. Suppression may include:

  • spraying a chemical fungicide
  • using a biological control like beneficial insects or beneficial mites, bacteria, or fungi
  • applying horticultural oils or soaps
  • using insect growth regulator chemicals
  • using physical barriers between plants and the outside
  • isolating infected plants from healthy ones when regular monitoring reveals the beginnings of an infestation


Eradication involves eliminating pest populations, most often by spraying poison to kill pest populations. There are different options for pesticide sprays, varying from plant-originating botanicals to synthetic chemicals. They pose different degrees of toxicity and benefit. 

Chemical Classes and Types of Pesticides

It is important to research and choose pesticides based on the needs of your greenhouse, how effective the pesticide is known to be for your needs, and what kind of toxicity it may introduce to your crops. Let’s briefly discuss what a pesticide is, the different types of pesticides, and the chemical classes. 

A pesticide is a substance applied to plants or soil to injure or kill pests in order to reduce the damage done to crops. There are about 24 different types of pesticides with a wide variety of purposes, including the commonly known insecticides, herbicides, rodenticides, and fungicides and, less commonly known, disinfectants, attractants, plant defoliants, and plant growth regulators. You can find a thorough list of pesticide types here

Pesticides fit into several chemical classes, determined by their chemical structure and mode of action. Some of the major classes are organophosphates, organochlorines, carbamates, pyrethroids, botanicals (pyrethrum, nicotine, limonene, neem), insecticidal soaps, microbials, biochemicals, nicotinoids, spinosyns, benzoylureas, and antibiotics.

Carefully research the chemical structure, mode of action, typical uses, benefits, and side-effects of each pesticide you consider before choosing the ones that are best suited for the pest control strategies in your greenhouse. 

Integrated Pest Management Key Terms

Let’s go over six of the most common terms you’ll need to know as you learn about Integrated Pest Management.

Mode of Action

As mentioned before, the mode of action is one way that a pesticide’s chemical class is determined. Mode of action is simply the means by which a pesticide works. It may function as a repellant, a poison (through several different chemical means), a desiccant, an antimicrobial, a defoliant, etc. 

Mode of action is probably the most important aspect of IPM, as integrating many modes of action into your pest management strategy can prevent pesticide resistance. This doesn’t mean you must use a different chemical, pesticide, or mode of action every time you treat your greenhouse for pests. But it does mean it is vital to carefully track preventative measures and pesticide applications so you can wisely use many modes of action.


While broad spectrum pesticides will affect multiple pests or life, more selective pesticides hone in on an individual pest. Some pesticides are even more narrow, destroying only certain pests at certain stages of growth. For example, organosulfurs effectively kill mites in the egg stage with very little toxicity to other organisms. 

Systemic Pesticide

Systemic pesticides enter the plant or animal they’re intended to destroy through roots and tissues or ingestion. The pesticide is then transported throughout the organism.

Contact Pesticide

Contact pesticides kill pests on external contact. 

Residual Activity

Residual activity refers to the amount of time a pesticide stays in a plant or animal after first contact. While contact pesticides don’t remain in plant tissue, systematic chemicals can live on in dead plant tissue for days, weeks, or longer. 

Pesticide Resistance

Pesticide resistance typically occurs when one pesticide is used repeatedly rather than exposing pests to different modes of action. While one mode of action may be effective on individual pests, a lack of variety can end in pest populations developing resistance to the pesticide, lessening or ending its efficacy. Avoid pesticide resistance by using many modes of action against pests. 


Benefits of IPM for your Commercial Greenhouse

Beginning an IPM program for your commercial greenhouse is a lot more work than simply spraying pesticides on all your crops. So, why do it? IPM offers many benefits to your crops, you as a grower, and your budget.

  • You’ll maintain a healthier, more balanced ecosystem in your greenhouse by using many methods of pest control. While pesticides alone can cause a small-scale ecosystem to shift by killing or reducing one population and encouraging another to dominate, employing many control strategies benefits the environment by not singling out one species.
  • Employing non-chemical strategies allows you to control pest populations while meeting the public demand for responsible pesticide use.
  • Save money by doing fewer treatments. Each IPM program is individual and based on the need for pest control rather than a predetermined spraying program, or a baseline need to use pesticides. You may rely heavily on prevention with few other expensive strategies to implement.
  • Manage pesticide resistance and prolong the usefulness of chemical treatments by not overusing them.

It’s worth the time and effort to create a pest management strategy that serves your crops and business!

Basics of Formulating and Implementing an IPM Strategy

As you develop an IPM strategy for your greenhouse’s needs, you will need to follow these steps:

  • take preventative measures against pests
  • identify and understand pests
  • monitor pests
  • determine threshold levels of populations
  • consider management choices
  • implement tactics that will control pests with the lowest amount of impact on everything else
  • carefully track practices and results
  • make adjustments

Diligently Practice Preventative Strategies

One of the basic building blocks of integrated pest management strategies is greenhouse sanitation. 

  • Keep walkways clear of soil, weeds, and any organic matter. 
  • Disinfect pots, flats, and trays and maintain sanitary practices anytime you interact with plants. This includes washing your hands.
  • Be sure water sources aren’t carrying pathogens and keep hoses off the floor. You should also fix any problem with your irrigation and drain systems. 
  • Use pasteurized growing media and keep it clean and covered prior to use and separate from plants until it is mixed and ready. 
  • Employ a system to sanitize or dispose of contaminated media and containers and remove sick plants from the greenhouse. Keep the area around the greenhouse tidy, neat, and free of weeds and debris.

Identify the pest and understand its biology

After preventative measures, identifying and understanding each pest you encounter is the most important step of IPM. You can’t control pests effectively if you don’t know what they are. While a broad spectrum spray might kill any pest, targeted measures are the most greenhouse-friendly and are only possible with careful, correct pest identification. Most pest control failure happens because of incorrect identification. 

Many pests have different physical forms during each stage of their life cycle, and often weed seedlings look different from mature weeds. Keep this in mind and familiarize yourself with pest life cycles, so you recognize pests in the early stages and later stages. 

As you scout for insects, pathogens, or weeds, have a hand lens or microscope available to help you identify pests you can’t see easily. Identifying the problem is the first step to resolving it. 

Monitor the pest to be managed

Devise and implement a plan for systematic weekly scouting of crops to be aware of pests and monitor populations. Be sure to include the major greenhouse entryway with particular attention to plants near any opening in the greenhouse. Be systematic in the method of observing plants and inspect as many as possible. Check at least 20 plants for every 1,000 square feet of greenhouse production space, aiming to check at least three plants on each bench.

Be thorough, carefully observing pots and trays, soil, and all leaves for insects or disease. Check hanging plants too. Repeat your checks twice a week in the same manner and maintain careful records of your findings.

Monitor pest populations with traps. Yellow sticky cards attract bugs and can indicate pest activity. Use at least one trap per 1,000 square feet, and replace traps in a systematic fashion to monitor the same areas each time for accurate comparison over time. 

You might also employ an indicator plant (a highly susceptible plant grown among the crops) to be checked daily as the first indicator of trouble. 

Determine if threshold levels of pest populations have been reached

The threshold level of pest population is the level at which you must take action to prevent crop damage. A low pest population that isn’t growing may not be worth controlling with expensive pesticides. Consider the pest population in economic terms. The economic injury level compares the potential loss of crop yields due to pests to the potential cost of pest control and finds that they are equal. The point at which control measures must be implemented to prevent economic injury is known as the economic threshold or action threshold. To determine if you have reached an economic threshold, consider:

  • stage of crop development
  • anticipated yields and value of the harvested crop
  • expected loss or damage due to the estimated pest population
  • overall cost and efficacy of proposed control measures

Just as you carefully research and weigh the risks and benefits of each mode of action, thoughtfully consider the economic implications of your pest management strategy. The greenhouse environment is one element to protect when you choose how to manage pests; the commercial greenhouse business and budget are another significant consideration. 

Consider various management choices

Once you’ve determined whether the threshold population has been reached, consider all the control strategies available to you. There are many solutions for dealing with pests.

  • Natural control involves weather, temperature, wind, predators, and any other natural measures or elements that prevent or eliminate pest populations.
  • Biological controls use natural enemies to suppress pests, including predator insects, parasites, or pathogens.
  • Mechanical controls prevent pest activity with screens, machines, fences, traps, and careful sealing of greenhouse cracks and crevices.
  • Cultural controls suppress infestation by changing the conditions to be less suitable for pests, including mulching to prevent weeds and sanitizing equipment to control disease.
  • Physical / Environmental modification alters conditions in an enclosed space to reduce pests — for example, lowering humidity in a grain storage area reduces mold, fungus, and disease risk.
  • Host resistance or genetic control can employ plant varieties that naturally repel some pests or are resistant to pathogens or those plants which are specifically bred or selected to resist pest problems.
  • Regulatory pest control addresses issues that endanger public health or cause widespread damage to crops, animals, forests, or ornamental plants beyond an individual greenhouse. This large-scale control employs quarantine to keep pests out of pest-free zones and eradication programs that usually involve government agencies carrying out widespread spray programs or introducing sterile insects into a population to eliminate pests that pose serious ongoing health risks. 
  • Chemical controls play a large role in IPM and include insecticides, miticides, ovicides, fungicides, algaecides, herbicides, and more. These can be derived from plants or other natural sources, or they can be developed synthetically. They are effective, fast-acting, and often cheaper than other methods. Long-term use, however, can minimize effectiveness as pest populations develop resistance to chemical controls after repeated exposure. These controls can also be harmful to non-target organisms and can cause environmental problems by moving with drift or runoff.

Implement the tactic or tactics that control the pest with the least harm to everything else

Select the modes of action and methods of prevention, suppression, and eradication most suited to your environment, accounting for factors like indoor or outdoor crops, crop size, economic impact, and pest population. Start early and plan ahead. Employ several methods to tackle pests, rather than spraying chemical controls constantly. A variety of control strategies from cultural controls and physical alteration to biological and chemical controls will prevent pests from developing resistance and will more effectively and efficiently address pest problems.

Record and evaluate results

Tracking all control strategies and their results is extremely important so you can continuously evaluate which methods are most successful and where your IPM program has failed. This allows you to adjust incrementally, gaining wisdom as you go. Keep careful records of your data.