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The Honolulu Advertiser
Posted on: Friday, July 25, 2008

'Invinci-bugs' can spell trouble for gardens

By Jari Sugano and Steve Fukuda

Have you treated a crop over and over only to discover the pests you are targeting are still alive?

Pesticide resistance has become a major issue in crop production. Each year, more agricultural pests (insects, diseases, weeds, etc.) are becoming resistant to crop protection chemicals such as insecticides, fungicides and herbicides.

What is pesticide resistance? Simply put, resistance occurs when a pest is exposed to a chemical for an extended period of time at the recommended label rate, but repetitive chemical treatments are ineffective in controlling the pest. Difficult-to-kill pests become "super bugs" or "invinci-bugs" and can cause extensive crop damage.

Managing insecticide resistance is important, particularly when it comes to the diamondback moth. In Hawai'i, the diamondback moth, Plutella xylostella, is a serious pest of brassica crops, including vegetables such as cabbage, broccoli, mustard greens, watercress, collards and other leafy greens.

The diamondback moth was first detected in 1892 and is now widespread throughout the Islands.

In November 2000, field populations of diamondback moth showed moderate to high insecticide resistance levels in commercial crucifer-producing areas. Since then, cooperative extension professionals from the University of Hawai'i College of Tropical Agriculture and Human Resources have worked with commercial crucifer crop growers on an insecticide resistance management program.

Through ongoing laboratory and field testing, UH extension professionals can detect an increase in insecticide resistance before it becomes a significant problem.

Understanding the genetics behind resistance has been important to managing the diamondback moth. Highly resistant pests can carry a gene that allows them to survive chemical applications. Incorrect application of chemicals can leave behind highly resistant pests that continue to reproduce and become difficult to manage, so growers have been encouraged to modify crop protection chemicals in accordance with the diamondback moth insecticide resistance management program.

Managing pesticide resistance is an important component in not only maintaining the sustainability of Hawai'i's diversified agricultural industry, but also preserving backyard operations.

Science-backed, research-based information about pesticide resistance has demonstrated that resistance can be minimized in backyards and commercial operations by following these basic recommendations: 1) rotate chemicals in different chemical classes, 2) utilize recommended rates and intervals, 3) achieve optimum spray coverage to reduce persistence of resistant populations, 4) establish host-free periods, and 5) remove crop residues after harvest to minimize opportunities for pests to harbor and reproduce.

If you suspect pesticide resistance in your garden, the best thing to do is to back away from pesticides and consult the University of Hawai'i Master Gardener Help Line at 453-6055.

Managing "super bugs" in Hawai'i's croplands is just one of the many concerns facing producers of our locally grown, "Island Fresh" commodities. You can show your support of Hawai'i's producers by attending this year's Hawai'i State Farm Fair this weekend at the Bishop Museum. By supporting Hawai'i producers, you are strengthening the local economy and communities, preserving agricultural space and supporting family farms, all while reaping the benefits of premium taste and freshness.

Think about it: Where would we be without local homegrown products?

Imagine ... no papaya for breakfast, no green onions in your saimin, no limu in your poke, no ginger for your sushi, no lei at graduation, no pork in your laulau, no egg on your loco moco. Buying local is as easy as going down to your community farmers market, eating at restaurants that support Hawai'i agriculture, or simply looking for the Island Fresh label on products at the supermarket. Buy Island Fresh. Buy local. Buy Hawai'i.