What’s eating my plants? What can I spray to kill those bugs?
These are frequent questions posed to the University of Hawaii Master Gardeners, volunteers who help the public answer their gardening questions. Instead of always reacting to the latest pest or disease outbreak by reaching for a pesticide, we recommend that farmers and gardeners practice integrated pest management.
This is a sustainable process to maintain or improve your garden production while minimizing impacts to the environment and human health. For example, you may not have time to go out every night hunting for Chinese rose beetles, but you can build a trap out of a solar-powered garden light and a few other inexpensive materials (visit 808ne.ws/rosebeetle for a DIY video).
Learn to identify the different insects you find in your garden. Some may not be pests at all, but are actually beneficial. Most of us already know about lady beetles, which eat aphids, scales and mealybugs. Other beneficial insects include hoverflies, lacewings, pirate bugs and parasitoid wasps. Many of these beneficial insects feed on pollen and nectar in their adult stages, so you can attract them by planting flowering plants such as cilantro, dill, buckwheat, marigold and basil.
A good crop rotation can also help to reduce the need for pesticides. Plants that are in the same taxonomic family often share the same pests. For example, members of Cucurbitaceae include squashes, melons and cucumbers. They can all host pickleworm, a voracious pest that can ruin an entire harvest of zucchini. Reduce pest and disease populations by rotating crops from different families in your garden.
Choosing plant varieties that are resistant to pests and diseases can make life much easier. For example, a common problem affecting our beloved plumeria trees is plumeria rust, indicated by orange spots on the underside of the leaves. This fungal disease can be controlled by sanitation (picking up dead leaves), cultural practices (planting in drier locations, pruning to allow more air and light into the canopy) and with fungicide sprays.
Inspect the plants you buy for weeds or signs of pests. Assure clean planting material by buying seeds from reputable sources.
Pesticides are the last option. Pesticides applied in the home garden can contribute to pollution in the watershed and can have undesirable effects on beneficial insects, native insects and honeybees, so please do your part to minimize risks to the environment.
To find more information about integrated pest management or to contact your local Master Gardeners, visit the University of Hawaii Master Gardener Program on the web, www.ctahr.hawaii.edu/uhmg.
Kalani Matsumura is a junior extension agent with the University of Hawaii’s College of Tropical Agriculture and Human Resources’ Master Gardener Program.
