Each year the University of Hawai'i College of Tropical Agriculture and Human Resources sponsors a 'Plant Doctor' booth at the Made in Hawaii Festival. Technicians from CTAHR's Agricultural Diagnostic Service Center, researchers, extension agents and master gardeners volunteer to man the booth and answer gardening questions.

At this year's event, my favorite question from an enthusiastic backyard gardener was, "How do I make my black thumb green?" The most popular question seemed to be, "What's killing my plant?" After some investigative agricultural CSI, we found the majority of questions were pest-related.

The first step to managing pests in your garden is identification.

Typically, pests have two types of mouthparts, chewing and sucking. Chewing pests damage plants by feeding on the foliage, stems, fruit or roots. Pests within this group include beetles, caterpillars, earwigs, leaf miners, etc. Sucking pests pierce plant's vascular tissue and withdraw plant sap. Pests with sucking type of mouthparts such as aphids, grasshoppers, whiteflies, mealy bugs, scales and leaf hoppers cause plants to discolor, twist and distort.

Pests with sucking mouthparts like aphids, thrips and mealy bugs are commonly associated with transmitting viral diseases such as banana bunchy top disease, papaya ring spot disease and pineapple mealy bug wilt. In some instances, whiteflies can inject toxins into tissue causing the plant to react. Aphids, whiteflies, mealy bugs and scales commonly excrete attractive honeydew that turns black with the formation of a fungal sooty mold.

There are many different types of ants in the home garden. However, the most serious problem associated with ants is they are honeydew consumers and protect pests from natural enemies.

Mites are not insects but continue to be a major pest in home gardens. They have rasping and sucking mouthparts similar to thrips that result in a brown to russet discoloration of leaves, stems, fruit and flowers. A scarring effect is the result of their feeding damage and can be seen with a hand lens.

There are four types of fruit flies in Hawai'i. Adult females lay hundreds of eggs under the skin of fruits and vegetables resulting in blemishes.

Let's not forget snails and slugs. Snails and slugs are often a problem for low-growing vegetables. They are active in the evenings and are commonly associated with seedlings magically disappearing overnight.

Need help understanding your garden pest? Consult the UH CTAHR master gardener program by calling the Pearl City Urban Garden Center, 453-6055.