By John Hibma – Pests and diseases are an unavoidable reality in agriculture. In this immensely diverse biosystem that we call Earth, humans must share with other species and compete with crop diseases and those creatures we call “pests.” If you’ve ever grown a garden or raised crops on a commercial scale, sooner or later you’ve had to deal with pests and diseases that either kill crops or cause so much damage that you wonder why you’re trying to grow anything at all. More often than not, most people resort to purchasing pesticides, herbicides or fungicides to correct or control problems with crops, but I advocate for a natural pest control in gardens and on farms through Integrated Pest Management (IPM).
Agricultural pests and diseases are costly, reducing the yield of crops, resulting in less food for the world’s masses while increasing the cost of those crops due to the added inputs necessary to grow them. With the world’s population increasing by thousands each day, farmers strive to attain the greatest yields of fruits and vegetables from a finite amount of acreage. At the same time, a growing population seeks to preserve natural resources with low environmental impact—all while farmers are expected to increase crop outputs. Both commercial agribusiness and the home gardener are faced with the challenge of how to deal with crop pests in a cost-effective and ecologically responsible manner.
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Commercially manufactured pesticides, herbicides, and fungicides have been around for decades, enabling food to be both plentiful and inexpensive. However, many of those chemicals have adversely affected human health as well as causing environmental damage. It has also been found that when many of these chemicals are used repeatedly on the same plants, they can lose their efficacy in controlling pests and diseases as plants develop resistance.
Rather than focusing on reactive methods in addressing these challenges, scientists and educators have, for many years, been advocating a more proactive approach to disease and pest control in plants. Known as Integrated Pest Management, or IPM, this approach integrates diverse control methods that pose minimal threat to human health and natural resources.
The heart of an IPM strategy seeks to manage pests and diseases through an understanding of their interactions with other organisms and the environment. The general focus of IPM programs is to prevent these problems from developing while, at the same time, reducing or eliminating the use of chemicals as a way of managing those problems.
IPM seeks to restore and enhance the natural balances in an ecosystem and not to necessarily eliminate species, making it an ideal approach to natural pest control in gardens and farms.
Regular monitoring makes it possible to evaluate the populations of both pests and beneficial organisms.
IPM allows a producer to take steps to enhance natural controls — or at least avoid or limit the disruption of natural controls.
IPM practitioners base decisions on information that is collected systematically as they integrate economic, environmental, and social goals. IPM can be used within the context of both agricultural and urban environments and is flexible enough to accommodate the changing demands of agriculture, commerce, and society.
IPM emphasizes the integration of a number of pest suppression technologies and the most effective use of IPM usually involves a combination of these different approaches:
• Biological control — use of beneficial organisms to manage pests.
• Cultural control — crop rotation, improved sanitation, and other practices that reduce pest pressure.
• Mechanical and physical control — for example, traps and cultivation.
• Chemical control — judicious use of selective pesticides.
• Host plant resistance — use of pest-resistant varieties.
• Regulatory control — state and federal regulations that prevent the spread of pests and diseases.
Biological controls involve the release of specific predators or parasites that can attack a particular pest while the predator itself is not being invasive to the environment and causing other problems. There are also many native predators and parasites out in the fields and orchards. For example, there are at least two dozen pests just for the apple crop alone. Growers need to be able to recognize these and learn how to manage them to implement natural pest control in gardens and farms. Every type of fruit has its own unique set of challenges during the growth process.
Cultural controls can include crop rotation. Nematodes are a common problem in vegetables such as onions, carrots, and lettuce. Rotating a field or plot out of those vegetables and growing sweetcorn or other grains (which are not affected by nematodes) for a season, will help break the life cycle and lower the persistence and damage of the nematodes the following season. In some areas, a cover crop such as sudan grass can be rotated in to reduce nematode load and the sudan grass can then be plowed under to help improve the soil quality.
Excessive tillage tends to reduce the soil’s biomass. Soils with high levels of humus (organic matter) will support more of the good organisms and exclude the pathogenic organisms.
The best soil for vegetable gardens helps your plants resist pests and diseases. On the flip side, poor quality soils and poorly drained soils provide an open door to damaging pests and diseases.
Cultural control can also involve the removal of certain plants that are the source of a disease for a particular fruit. Cedar Apple Rust is a problem for the apple crop. Cedar trees should be removed from around an apple orchard to help control that particular blight.
In the case of growing cucumbers, physical controls can be put in place by placing row covers on the cucumber plants so the cucumber beetle can’t get at the plant.
Diseases such as apple scab, a fungus, and fire blight, a bacterial disease, are dependent upon temperature and moisture, degree days and leaf wetness. Those problems don’t necessarily emerge the same time each year. Setting up weather stations to monitor temperature, humidity and rainfall is useful in predicting when the conditions are ideal for a known problem to occur in a particular region.
IPM programs continue to evolve based on field situations and innovations that develop. A technique called “Perimeter Trap Cropping” (PTC) involves planting an attractive plant species (to the pest) so that it completely encircles the main crop like a fortress wall. PTC functions by concentrating and/ or killing the pest in the bordering area while reducing pest numbers and disease spread on the unsprayed cash crop in the center by preserving natural enemies.
Researchers in the Northeast U.S. found that when blue Hubbard was planted around yellow summer squash, the pests that had been damaging the squash crop were more attracted to the Hubbard. Spraying only the perimeter crop significantly reduced the damage to the summer squash.
They were also successful in managing pepper maggots in bell peppers by learning how to grow bell peppers with hot cherry peppers as a companion plant. Growers reported that their pesticide use was reduced by 89 percent and the percentage of undamaged bell peppers increased significantly.
In many cases, when IPM techniques are incorporated into farming and gardening, the use of pesticides can be reduced. If the application of a pesticide is needed, growers must determine the best choice and timing of a pesticide once an “action threshold” has been reached for a pest.
Every region of the country has its own unique growing conditions and challenges to agriculture. Working closely with your ag extension agent or crop professional will help in establishing an IPM protocol for the crops you like to grow. IPM programs have been instrumental in increasing people’s awareness of how fragile our environment is and the responsibility farmers have in reducing the impact of chemicals on the environment.
Originally published in 2014 and regularly vetted for accuracy.