Hawaii’s year-round growing conditions mean home gardeners must also deal with year-round pests and diseases.
Ongoing home-garden pest and disease control can be achieved through an ecological and economic approach known as Integrated Pest Management — using a variety of methods to manage pests and optimize plant health.
It takes advantage of all appropriate pest-management options, including judicious use of pesticides. However, by incorporating a variety of control tactics, it is possible to reduce or eliminate pesticide applications while still addressing garden problems.
This comprehensive approach gives gardeners the tools and options to implement strategies that protect human health and make environmentally friendly pest-management choices.
The method does require a certain investment in time and energy, but is less complex than it may appear, and it will eventually make achieving your garden goals easier. Simple tips to get started:
>> Identify insects and animals that live in or visit the garden. Identifying harmful insects and learning about their life cycles will provide more options for management. Only a few insects are actually pests; many are beneficial or do no harm.
>> Inspect for pests and disease. Check your garden regularly for insects and signs of disease to detect problems early. Jotting down this information in a garden journal will be useful if seeking outside help with your garden problem.
>> Select healthy plants. They are better at resisting diseases and tolerating insects. Choose well-branched, stocky transplants with healthy leaves, sturdy stems and well-established root systems. Roots should be well-formed, white and hold the soil mass together. If possible, select plant varieties with disease and insect resistance.
>> Provide proper plant care. Avoid injury to plant stems and roots and give plants enough space to grow. Crowded and injured plants tend to be weaker and more stressed, making them more vulnerable to pests and diseases.
>> Right plant, right place. Match a plant to its desired environment and soil conditions. Most vegetables grow best in well-drained soils and full sun, whereas some landscape plants may need partial shade.
>> Get a soil test. Learn your soil type, pH and nutrient concentrations, and follow recommendations to improve the soil.
>> Water wisely. Water plants at ground level to minimize wet leaf surfaces, which are more susceptible to disease. If possible, use drip irrigation or soaker hoses instead of watering overhead. Water will be directed where the plant roots can use it and not sprayed into the air, where it is lost to evaporation.
>> Use good sanitation practices. Keep tools and equipment clean and disinfect tools after using them on diseased plants. Remove debris and destroy diseased plants or those severely infested with insects.
>> Control weeds all year long. Weeds compete with crops for water and nutrients and often provide a place for pests to hide and disease to take hold. Remove weeds before they go to seed. To control, hand-pull, cultivate soil or hoe. Limit herbicides to spot treatments or prior to planting. Mulches can keep weeds down and retain soil moisture.
>> Prevent or limit pest damage. Establish tolerances for pests and pest damage. Some insect damage can be tolerated and will still allow a good-quality harvest. Consider installing pest barriers or repellents and promoting beneficial insects to help manage pest populations.
>> Crop rotation. If space is available, rotate the location of the garden every few years to avoid the buildup of pests and plant diseases. At minimum, consider rotating plant families within the garden area. For example, plants in the Solanaceous or night-shade family (e.g. tomatoes, peppers and eggplants) share several insect pests and diseases. Rotating plants in the same family to different locations for each growing season can lessen or prevent problems.
>> Manage harmful pests. Consider using physical controls, such as pruning, hand-picking and washing off with water before using a pesticide. If using a pesticide, start with a selective pesticide first to target specific pest and minimize harm to beneficial insects. Always follow label directions for application and use only pesticides that are registered for the crop.
For assistance with plant and insect identification, soil testing and management recommendations, contact your local University of Hawaii Cooperative Extension office.
Cynthia Nazario-Leary is an urban horticulture extension agent with the University of Hawaii’s College of Tropical Agriculture and Human Resources and is the statewide master gardener coordinator.
