Integrated Pest Management for Greenhouse Crops

Integrated pest management for greenhouse crops is complex, and each problem situation or production objective is accompanied by a wide range of potentially acceptable solutions. There are also a great many legal implications regarding the recommendations and use of any management tactic or pesticide product in accordance to instructions specified on the product’s label. The user of any pesticide is always responsible for his or her own actions.

The following are some general considerations for the development of an integrated pest management program for commercial production or maintenance systems:

Determine Your Objective

Pest management programs should be designed to meet a specific production objective. In greenhouse production, this objective is usually to produce pest and damage-free plants. However, in some situations, the objective may be to maintain healthy plants. This would allow for some tolerance of minor insect or mite pest damage. Additionally, a preference for the use of no or low-toxic pesticides may be desirable. This is particullarly important in regard to the potential contamination of surface and groundwater. Financial constraints also play a role in determining the overall objectives of an IPM program. All of these factors significantly effect the suppression tactics to be implemented.

Sanitation Practices

The first steps to take in a program to manage plant pests are preventative, and starting with a clean production area is essential. Greenhouses can be fumigated or otherwise treated prior to establishing a new crop to help eliminate pest problems from previous crops. However, where plants at different stages of growth or species are grown in the same area, treatment of pests is recommended prior to establishing the next crop. Elimination of weeds and other alternate hosts of plant pests will also help prevent problems on the new crop.

Start With Pest-Free Plants

Selection of uninfested plants, plugs, cuttings or transplants is critically important. Carefully inspect all plants brought into the production area and discard or treat those found to be infested. When possible, pest resistant or tolerant plant species or cultivars should be utilized in order to reduce the potential need for pesticide applications . Becoming knowledgeable about the susceptibility of a plant species and/or cultivar to pests will greatly aid your ability to anticipate problems throughout the production cycle. Use of preventative treatments, such as systemic insecticides applied to the growing media at or shortly after planting, may protect young, rapidly-growing plants if pest pressure at planting time is high.

Maintain Optimum Cultural Practices

Plants under stress are more attractive to and can withstand less injury from pests. Utilize optimum fertilization and irrigation practices to help reduce conditions which predispose plants to infestation. Temperature, humidity and light may also be important factors for both the pests and the use of certain pesticides.

Early Detection is the Key to Good Management

Once plants are established, there are several methods for monitoring the onset of pest problems. Yellow sticky traps placed around the production area can be used to detect early movement of adult whiteflies, thrips, adult leaf-miner flies, fungus gnats and aphids. Plants should also be regularly inspected , paying particular attention to the undersides of leaves, or by beating portions of the plants on off-collored paper to dislodge pests. This method is useful for detecting small, hard-to-see pests such as spider mites and thrips. Regularly inspecting plants that are highly attractive to certain insect pests can be useful for detecting low populations of pests. Control tactics or programs should be implemented when significant numbers of pests, or related damage, are first detected.

Recognize Damage and Define the Problem

Insect damage is largely caused by the manner in which they feed. Learn to recognize damage produced by major arthropod pests and always attempt to detect and estimate the population density of the pest prior to selecting a control method. Many of the insect and mite species seen in greenhouse operations are not harmful. Avoid using pesticides for “ghost” pests or unsolved problems. Become familiar with beneficial insect species (parasites and predators), and consider the fate of this free help when making management decisions.

Consider All Management Tactics

Many producers conduct a preventative program in an attempt to insure the elimination of any and all potential pest problems. The economic and environmental impact of this approach can be harmful. Monitoring for pests is mandatory for evaluating a programs success, as well as for detecting “escape” species. This early detection is essential. Upon detection, define the problem and consider all potential management tactics, evaluating economic, toxicological (worker safety and pesticide residue) and environmental implications of each approach. Non-chemical methods should be high on the list of priorities. However, if pesticides are necessary, compare the mode of activity, cost and application methods for each registered product. When using a product for the first time on a new plant or in a new mixture, apply it to a small number of plants first and observe possible phytotoxic reactions.

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