Ever Green

By Lois Taylor

Friday, August 29, 1997

By Bryant Fukutomi, Star-Bulletin

Ugh, Slug!

SLUG is a dirty word. Its meanings -- a counterfeit coin, a large fast shot of alcohol, a bullet and a slimy plant-destroying mollusk-aren't particularly upbeat. It's the slimy stuff we're talking about today.

According to Trent Hata, research associate in entomology at the University of Hawaii, the early summer dry period followed by recent rains has been like a week at a spa to local slugs.

They're healthy, happy and hungry, and they're grinding their way through Oahu's gardens, particularly those in the heights and the valleys. Hata and his boss, Arnold H. Hara, are on the Manoa faculty, but work at the Beaumont Agricultural Research Center in Hilo where their field is slugs. With Christopher Jacobsen, they have written a treatise on slug control. You probably wouldn't want to read it.

The only good slug is a dead slug, and it takes some doing to rub 'em out. Slugs are usually defined as a snail without a shell, although Hata and his friends will explain that some slugs have a vestigial shell inside their bodies. The two slugs of the study are the brown slug and two-striped slug, which were first reported in Hawaii in 1978 and 1985, respectively.

"Since initial reports, populations of these slugs have sufficiently increased, resulting in severe damage to many ornamental, vegetable and landscape plants," they write.

"Of particular concern is the impact on Hawaii's $104 million vegetable and floriculture industries." Quarantine officials by law will delay or reject export shipments where slugs or snails are present.

LIKE all slugs, they are soft bodied and up to 4 inches in length. They range in color from beige to dark brown, and the two-striped slug has two longitudinal stripes, solid or broken, down its back.

A slug's eyes are at the tips of the smaller tentacles, the slightly longer ones are his nose. Slugs feed on seedlings, climbing plants, soft-stemmed plants, some lilies, some vegetables and fruit -- anything they can chomp through with their mouths, which are located under their bodies.

You can tell if slugs have been picnicking when holes appear in foliage and the stems may be stripped of leaves. The sure sign is a silvery slime trail on leaves, the soil surface or paved areas of your garden. Slugs feed mainly at night, and after rain. They hole up underground or in damp garden litter during the day.

"Juveniles and slugs past the reproductive stage are the most difficult to control," Hata said. This may be because their reproductive stage is so complicated that it must take all their time. Slugs are hermaphroditic, each having both male and female reproductive organs. Courtship involves circular slime trails and a kind of bungee jumping exercise where they climb trees then lunge downward on cords of slime. They both lay eggs in a damp spot among roots or under a rock, and the eggs hatch into sluglets in about a month. There's a horror movie in here someplace.

So assuming that you have slugs, how do you get rid of them? Hata says that unfortunately, your best bet is to go out at night with a flashlight. With a trowel, scoop them off the plant and into a zip-lock plastic bag. Keep the bag closed or they will ooze their way out. Place the bag, securely closed, in full sun the following day and the slugs will be dead within a matter of hours.

OR if this seems needlessly nasty, they can be dropped into a jar filled with soapy water, which is a faster way of dispatching them. They have, however, been known to crawl out. It's your call. The alternative is a chemical control.

Hata's team tested 15 slug killers for efficiency against the brown and two-striped slugs, and 13 of them "caused significant mortalities against both species." The most successful products, with peculiarly lethal names, are Deadline One Last Meal; Deadline 40; Deadline Bullets; and Slug and Snail AG Pelleted Bait.

Mold grew on the majority of molluscicides after application. Liquid paste and liquid formulations were more resistant to mold than pelleted, granule or coated granule formulations, they found. None of them was 100 percent effective, and the level of control does not meet the quarantine security required for export.

Once you've effected your slug massacre, the next job is to remain pest free. One way is through Integrated Pest Management, involving six simple steps:

Monitor your plants. Inspect them once a week for the first sign of pest problems.

Identify the pest. Catch it in the act so you are sure of what you're dealing with.

Assess the damage. Is it worth doing something about, or can you live with it?

Choose the least toxic control. If that one doesn't work, try something stronger. A strong spray of water from the hose may be all you need.

Reevaluate the pest damage. After a week, check to see if pests are still present.

Determine the cause of the plant stress. A healthy plant does not attract pests or disease. Is it getting too much or not enough water, too little or too much sun? Does the plant have sufficient air circulation? Is the soil too rich or not rich enough? Have you got the right plant in the wrong place?

THIS system was developed for commercial growers who found that crop pests were developing a resistance to the chemicals used to control them. Increasing the dosage was risky and often futile. Integrated Pest Management is an earth-friendly way to grow your garden, and it becomes a satisfying routine.

Gardening Calendar

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