Crop Protection Solutions Through IPM Principles

Integrated pest management, more commonly known by its acronym IPM, combines the most effective and safest methods to obtain adequate pest and disease management in crops and landscapes. The concept is decades old, but available tools are as current and cutting edge as the latest research. As research and your experience continue to unfold they can be incorporated into improving your overall IPM plan.

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The ingenuity and cleverness in an IPM program comes from combining tools and efforts in a way that most efficiently and effectively deals with pest issues. In other words, putting it all together in a plan.

The Five IPM Steps

Tools available for an IPM plan vary depending upon crop types, but the five basic concepts are consistent, no matter what the crop or setting. They are monitoring, often called scouting for the pests; accurately identifying the problem; deciding on control actions; utilizing pest prevention techniques when possible; and evaluating results and “recalibrating” your plan for greater effectiveness based upon your experience and results.

It is also important to understand the difference between eradication and suppression of pests. Eradication only occasionally works for new pests or diseases that are caught very early in their establishment period and within a limited geographic area. The most commonly thought of example is Mediterranean fruit flies in Florida. For most pests a more realistic strategy is suppression where populations are kept down to “acceptable” levels or thresholds. With aesthetic thresholds, this often means how much damage the customer will accept. And example in the landscape is whitefly suppression on Ficus benjamina before defoliation occurs. With vegetables or other food crops as examples, some insect damage may be acceptable prior to development of the harvested marketable portions of the plants. The level where treatment is necessary is called treatment threshold.

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1. Scouting frequency depends on the types of pests or diseases you encounter. For example, monitoring short life cycle problems like spider mites or rapidly developing diseases may require that you take a look once a week, or even more frequently. Nursery operations often train some of the laborers to generally know what to look for. All those extra pairs of eyes add to the probability that problems will be seen early. It also provides opportunities for an employee who may excel at spotting problems to be noticed, and possibly advance their careers into a valuable area. Early detection is key because it often allows the use of less extensive pesticide applications. It also may result in more effective use of biological methods that may help preventatively keep low pest populations low. Biological methods often are not as effective in controlling large pest populations or disease outbreaks. Regular scouting also helps you get to know your crops or landscape so that you can recognize when something “unusual” is occurring, and get to know pest or disease hot spots where problems tend to recur.

2. Accurately identifying pest or disease problems is very important because it allows precise targeting of control or management efforts. An obvious example is when an insecticide is needlessly used when the actual problem was a pathogen. Or, if a fungal disease is the issue, many of the available fungicides may not be effective in helping. Additionally, making the effort to accurately identify helps train you in identifying problems, and thus as a pest management professional.

The question arises, how can the cause of a problem be accurately identified? The answer is by submitting samples to the network of commercial or University of Florida extension diagnostic laboratories. For example, the University of Florida has labs that can identify plant diseases, mites, insects, nematodes, soil nutrients, soil salts and pH, and some limited tissue nutrient testing. Your local county extension agent, depending upon their area of expertise, may also be able to accurately identify problems and/or direct you to these labs. The labs can also be found through an online search. Local pesticide and biological suppliers often have a great deal of expertise and may be able to help identify problems. Also, do not forget about good quality local crop advisors. Developing your own library of pest and disease reference guides and online links for your landscapes or crops will be very beneficial. A couple of useful online University of Florida ones are the Featured Creatures http://entnemdept.ufl.edu/creatures and Solutions for Your Life http://edis.ifas.ufl.edu websites. Be aware, however that plant diseases and nematodes are often more difficult to identify than insects or mites without the use of diagnostic labs.

3. Select tools for control actions based upon research recommendations when available. More detail on tools will be provided a bit later in this article. Sources of information on available tools can also be found at the University of Florida Solutions for Your Life and websites in management guides and publications specific to the crop or plant group that you are concerned about. Other sources of this type of information are again your local county extension agent, pesticide and biological suppliers, other land grant university online and printed publications, and knowledgeable crop consultants. Remember, a good IPM program needs you to properly explore and select the tools that make the most sense for your situations. Over time, you will be able to decide what sources of information are most useful and credible for you.

4. Prevention can be among the most helpful and cost effective pest and disease management tools if enough thought is given prior to planting crops or installing landscape plants. For example, proficient organic producers have learned that fighting pests and diseases with organically approved pesticides is often a frustrating battle. Alternatively, selecting crop varieties resistant to the prevalent pests and diseases, soil preparation for optimal crop growth, planting and harvesting prior to major outbreak seasons, and spot treating with pesticides when necessary can all have amazing results. Clearly, experience and trial and error are part of the costs to gain much of this knowledge. However, plenty of exploration and planning prior to planting are equally, if not more important in many situations. In landscapes, one of the mantras is “right plant in the right place.” This simply means selecting landscape plants that are appropriate for conditions like the soil, climate, sunlight, moisture, nutrient levels, mature size desired and obstructions in the area. This helps produce crops and landscape plants that are less stressed, and thus less prone to pest or disease problems.

5. Evaluation is linked to accurately determining how effective control and prevention measures were, and keeping appropriate records that will help you make improvements the next time similar problems arise. It also helps you eliminate the costs and risks of using ineffective pesticides or tools for the same problem in the future. Another way to look at it is that accurate evaluation helps you refine and target your efforts.

The difficulty in doing all five of these IPM steps is often a lack of time, people or other resources to get them done. An important point to remember is, try and design your IPM program to match your ability and resources to get it done. A plan that it too grandiose is likely to be dropped before long, or be a never ending struggle for those who do not like to give up. Remember, even a simple and easily accomplished plan, if consistently followed is likely to yield better results than no plan. Systematic consistency is the key to a successful IPM plan, so keep it workable. You can always make it more complex or sophisticated if needs dictate and resources allow.

Control Options

Management options are clearly a major consideration when deciding how to deal with a pest or disease problem. Find out as much as you can about the biology and life cycle of the pest or disease. This allows you to exploit weaknesses helping you suppress the problem. Ongoing and ever-increasing research often presents new strategies to include in your IPM efforts.

Cultural controls are defined as plant growth practices that can be altered or adjusted to optimize the crops resistance to pests or diseases, or alter the pests behavior in a way that suppresses the problem. Examples include fertilization, removing or disking under crops before the pests have a chance to develop, rotating to non-susceptible crops, enhancing the growth though soil improvement, appropriate irrigation, and proper pruning. Something as simple as plant spacing in the landscape can also be effective by allowing more air circulation and drying of moisture on the foliage and thus potentially reducing incidences of plant diseases. Many commercial landscapes are densely planted and become even more crowded as they grow. Removing some plants as the landscapes mature can help improve air movement and reduce diseases.

Trap crops are also sometimes used for agronomic crops. These are rows of a crop, such as early maturing beans, that can be planted in between rows and a couple of weeks prior to the later maturing crop variety. Some insects are more strongly attracted to the early maturing crop which can then be heavily treated with insecticides to reduce overall insect populations. The trap crop becomes a sacrifice that will not be harvested, and allows reduced or no application insecticides to the desirable crop.

Biological control is the use of predators, parasitoids, pathogens (diseases), growth regulators, or pheromones in the case of insects, or competing organisms in the case of plant diseases, to suppress the problem. Strategies that may be used, depending upon the crop or landscape might be encouraging naturally occurring biologicals, or actually releasing organisms like predatory mites, parasitoid wasps or flies, Orius predators, or spraying insect pathogens like Isaria fumosorosea, Beauveria bassiana or Bacillus thuringiensis, or using insect growth regulators.

Generally, biological control measures are most useful when applied prior to pests or diseases becoming a huge problem and when population or instances are low. Control often requires the biologicals be released in large numbers, or can successfully increase to levels adequate to stop pests before unacceptable crop damage occurs. An effective strategy, for spider mites for example might be to carefully monitor, and then begin the release of predator mites when populations of the pest mites begin to be seen. In the case of pests where attraction pheromones can be used, the combination with traps can help identify early infestations when pesticide use probably will be most effective. Another strategy, known as banker plants, uses movable plants that have the beneficial insects already colonized on other insects or mites. These serve as a reservoir of the beneficials that can moved into crop areas when pests begin to develop.

Control Options ctd.

Pesticides should be used judiciously and in ways that minimize damage to beneficial insects. For example, many broad spectrum insecticides like the pyrethroid and organo-phosphate groups are very tough on beneficials. Also, pesticide formulations that physically mostly avoid beneficials can be helpful. An example is soil applied systemic insecticides which should have minimal impact on beneficial insects attacking leaf feeding insect pests.

Mechanical or physical control is the use of equipment or physical efforts to manage pests and diseases. Examples might include pruning affected branches, screens on greenhouse air intakes, mulch or weed barriers, mowing to remove affected turf leaf tissue and other methods.

Host resistance utilizes crop or plant varieties that are resistant to, or at least tolerant or recover from the pests or diseases of concern. At the least, the need for other control measure can be greatly reduced even if 100% resistance is not achieved. Breeding and selection efforts are commonly employed to find resistant varieties. Examples include citrus for resistance to citrus canker, and avocado variety resistance to laurel wilt and tomato resistance to nematodes and pathogens. The more genes that are involved in the plant resistance, the less likely pests or pathogens will overcome them.

Sanitation works by avoiding or suppressing pest or disease problems through cleanliness and exclusion. For example, nursery quarantining of new plant materials before introducing them the general crop areas allows the new introductions to be assessed for transmittable problems before these spread to other crops. Another example is the use of certified seed for turfgrass planting that keeps weed seed contamination to a minimum. Removing or destroying crop residues can also break pest and disease cycles in some situations. Cleaning or decontaminating equipment and trucks when traveling between lawns, citrus groves, and crop field sites is another example. In nursery plant propagation, maintaining sanitized conditions and insuring that soil, containers and plant material are pathogen free is critical.

Pesticides provide a broad range of control measures that should be integrated with other measures. Some growers or pest management professionals may rely almost exclusively on pesticides to manage pest and disease problems. If this is the case, they will fairly quickly discover that this strategy frequently does not produce desirable results. Over reliance on pesticides, especially if limited to just a few mode of action categories may easily result in resistant pests or pathogens. This is especially true with short life cycle, and rapidly reproducing pests. Pesticide companies are attempting to reduce this risk by limiting the number of times per year that some of the newer products can be used on a site.

Timing of pesticide applications may be important. In general, insecticides will be most effective with younger, more susceptible pests and when populations are low. Some, like ovicides (manage the egg life stage), only control limited portions of the lifecycle.

Some pesticides might be classified as both pesticides and some other control option category. For example, insect growth regulators or insect diseases might be classified as both pesticides and biological control measures.

Weather also is important. Systemic pesticides that move from roots and into the rest of the plant will not be as effective during slow growth times of the year. And, most pest managers understand that pesticides should not be applied prior to a heavy rainfall because they will wash off or be carried with drainage water into canals and waterways.

Many excellent reference materials are available on the web. The following publications available via the links below should be read before taking the exam associated with this article:

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