Greenhouse Operations Management GOM5 Pests and Diseases in the Greenhouse Greenhouse Operations Management: Pest and Diseases Notes Date _______________Topic___________________________________ ----------------------------------------------------Summary of Main Ideas------------------------------------------------------- -----------------------------------------Notes-------------------------------------- -------------------------------------------Main Ideas, Key Points, Formulas------------------------------------------------ Healthy Plants: IPM:
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Greenhouse Operations Management GOM5 Pests and Diseases in the Greenhouse
Greenhouse Operations Management: Pest and Diseases Notes
Date _______________Topic___________________________________
----------------------------------------------------Summary of Main Ideas-------------------------------------------------------
Greenhouse Operations Management GOM5 Pests and Diseases in the Greenhouse
Greenhouse Operations Management: Pests and Diseases GOM5.4
Integrated Pest Management
IPM focuses on long-term prevention of pests or their damage by managing the ecosystem. With IPM, you take actions to keep pests from becoming a problem, such as by growing a healthy crop that can withstand pest attacks, using disease-resistant plants, or caulking cracks to keep insects or rodents from entering a building. Rather than simply eliminating the pests you see right now, using IPM means you'll look at environmental factors that affect the pest and its ability to thrive. Armed with this information, you can create conditions that are unfavorable for the pest.
The basic goal in insect pest management is to prevent insect populations from reaching a level that can cause substantial damage to a crop. This is referred to as the economic injury level (EIL). The economic injury level is the amount of damage insects do to a crop that equals the cost it requires to use measures that suppress the insects. It is not always necessary to start insect control measures when insects are seen on a crop. The economic threshold is used to determine when insect control measures should be considered. The economic threshold indicates the level of damage done by an insect that is used to warn the agriculturalist of potential problems. To determine when the economic threshold is reached, careful sampling must be done. This may involve counting the actual number of individual insects per unit. Other methods used involve some form of removal, trapping, visual estimates, or assessing the amount of plant damage. When the economic threshold is reached, it is necessary to use methods to keep the insect populations from reaching the economic injury level.
These IPM principles and practices are combined to create IPM programs. While each situation is different, six major components are common to all IPM programs:
1. Identify the problem 2. Assess the damage 3. Prepare cost/benefit analysis 4. Select a management strategy 5. Implement the management strategy 6. After action is taken, assessing the effect of pest management
1 | Identify the problem: Never try to control a problem until you are sure what it is. Identifying the cause of a plant problem or symptom correctly can be very difficult. There may be many reasons why a plant is not growing properly. For example, plant leaves may turn yellow because of insect attacks, plant diseases, nutrient deficiencies, or herbicide injury. Insects may be the indirect cause of poor plant health. A plant that is already nutrient deficient tends to attract insects. The insects are not the direct cause of the problem, the nutrient deficiency is. Even if the insects are eliminated, the plant would not recover until the nutrient deficiency is corrected.
Identifying the problem incorrectly may cause the wrong method of control to be selected. This not only wastes money but probably will not fix the problem as well. In fact, the real problem will usually get worse.
Greenhouse Operations Management GOM5 Pests and Diseases in the Greenhouse
Greenhouse Operations Management: Pests and Diseases GOM5.4
2 | Assess the damage: In addition to finding the root cause of the problem, it is very important to determine exactly how extensive the damage may be. Plants have a remarkable ability to recover from insect attack. Some injuries are only on the surface. Even though it may look bad, the crop is not damaged to the point of economic losses.
The stage of development of the plant and insect is another point to consider. When assessing plant damage, there is no substitute for a knowledgeable person. It can be very expensive and unnecessary to start measures to suppress or contain insects that may not be causing real damage.
3 | Prepare cost/benefit analysis: A cost/benefit analysis can be difficult to do. A cost/benefit analysis means comparing the cost of an insect control plan with the benefits that the control plan will give. The value of the increased crop yield should be equal to, or higher than, the cost of the actions taken to control insects. The benefits include the short term value of increased crop yield as well as the long term value of keeping the insect population under control for the rest of the growing season and following years. Often, it is possible to control an insect population by suppressing the first generation. Later in the season, the number of insects may be greater and more difficult to control. You also need to consider what effects control measures may have on beneficial insects. Lowering the beneficial insect population can increase the harmful insect population and increase control costs overall.
Insect control is necessary only when the insect is causing more damage than is reasonable to accept. Even though an insect is present, it may not do much harm. It could cost more to control the insect than would have been lost by insect damage.
4 | Select a management strategy: There are many insect management strategies to choose from. You need to consider the various factors that influence the selection of a plan. If an insect problem has been identified, and you know how the insect grows, how it spreads, and what damage it does, you can begin to plan how to control it. Using an insecticide is one of many ways to control pests. The use of a combination of methods is basic to all pest control. Be sure to think about what other methods might work before you decide to apply an insecticide. IPM programs combine management approaches for greater effectiveness. The most effective, long-term way to manage pests is by using a combination of methods that work better together than separately. Approaches for managing pests are often grouped in the following categories.
Mechanical controls are the first practices to consider when pests have reached an unacceptable level (economic threshold). These controls kill a pest directly, block pests out, or make the environment unsuitable for it. They include erecting barriers, using traps, hand-picking and other activities that disrupt insect breeding and feeding. For instance, spraying plants with a water hose to knock off aphids and mites is a mechanical practice. Mechanical and physical controls Mechanical practices include: Sanitation Keep the landscape and greenhouse clean and free of scenarios that might attract insect pests. This includes removing unwanted debris in contact with the ground, dead limbs, piles of decomposing organic matter and eliminating standing water that are not landscape design elements.
Greenhouse Operations Management GOM5 Pests and Diseases in the Greenhouse
Greenhouse Operations Management: Pests and Diseases GOM5.4
Control Abiotic Elements Many nuisance pests are present due to physical characteristics of the local environment. Piles of rocks, deposits of leaf litter, and presence of ground debris are favorable habitats of creatures like snails and slugs, sowbugs and pillbugs, centipedes and millipedes, and scorpions. Presence of shade, moisture, and structure (cracks and crevices) profoundly affect arthropod populations favored in those habitats. Other Mechanical Methods Other mechanical methods for insect control include hand destruction, exclusion of pests from plants using fine mesh screens or other types of barriers. There are petroleum-based sticky material often used to make sticky barriers that are difficult for insects to cross. This material is available as both a gel and a spray. This material can be used to make yellow sticky cards as well. Newer products containing Teflon® either as a tape or as a spray may also be useful for similar purposes. Use of high pressure water sprays, using special equipment can remove small insects and mites from foliage. Rose growers report good results using such devices. However, care must be taken in certain situations. In some cases, spraying mites off one hose only serve to spread infestations to alternate hosts nearby. On the other hand, for host specific wingless pests such as the crape myrtle aphid, these devices can be an effective
method for temporary suppression of pest numbers. In addition, the high-pressure sprays can remove some of the honey dew that can lead to hard-to-remove sooty mold. Biological control 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. Cultural controls Cultural controls are practices that reduce pest establishment, reproduction, dispersal, and survival. For example, changing irrigation practices can reduce pest problems, since too much water can increase root disease and weeds. Chemical control Chemical control is the use of pesticides. 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; use pesticides in bait stations rather than sprays; or spot-spray a few weeds instead of an entire area.
5| Implement the management strategy: When selecting a management strategy, a major factor is the ability to actually put it into action and see it through to completion. There are many strategies and alternatives from which to choose. One who is devoted to biological control may be unable to implement it effectively or efficiently. On the other hand, some people are all too ready to employ chemical control exclusively because the materials are readily available. An experienced individual will consider a variety of measures for any particular situation or problem.
6 | After action is taken, assessing the effect of pest management: Following up on a regular basis is an important part of any insect management program. The effectiveness of the measures selected can be judged only by carefully watching the insect populations and crop growth. This can be done through regular sampling. We cannot assume that an insect problem has been thoroughly controlled just because the control measures have been put into action. Control measures may need to be alternated, modified, increased, or decreased. Keeping careful records will give a great deal of information on how well the selected plan is working and how efficient and effective the measures are.
Greenhouse Operations Management GOM5 Pests and Diseases in the Greenhouse
Greenhouse Operations Management: Pests and Diseases GOM5.5
Using IPM in the Greenhouse
Research more about your assigned pest or disease, considering how IPM can be used. Create a
single PowerPoint slide answering the following questions:
• What types of biological controls can be used to control the pest or disease? (If any)
• What types of physical or mechanical control can be implemented to control this pest or
disease (i.e. removing infected leaves)?
• If all else fails what sprays can be applied to control this pest or disease? There must be at
least one least toxic non-synthetic spray recommended.
Suggested Resources:
• University Extension Papers
• www.insectimages.org
• University of Missouri Extension Publications
http://extension.missouri.edu/publications/
• Nebraska Extension Publications “NebGuides”
http://extensionpubs.unl.edu
• University of California Agriculture and Natural Resources IPM