Radishes (Raphanus sativus) are annual crops gardeners enjoy for their edible roots and leaves and easy-to-grow nature. Often one of the earliest vegetables harvested from the garden each year, radishes are potentially bothered by a handful of pests including slugs, which can quickly devastate a planting. Slug damage to radishes and other plants appears as irregular holes chewed in the foliage, or seedlings that are entirely consumed. Slug activity is accompanied by telltale silvery trails of dried mucus.
Remove debris such as piled wood, rocks or other material, and thick leaf litter, wood chips or other mulch from near the radish plants. Thin out any dense ground cover and remove all weeds growing near the radishes. Slugs feed at night and need a damp, shaded and protected spot to hide in during the day.
Sprinkle diatomaceous earth in a protective circle around the radish plants or larger garden area. Diatomaceous earth is an organic, nontoxic material composed of the fossilized shells of tiny diatoms. These are porous and have sharp edges, so they scratch pest bodies and absorb protective oils, killing slugs and myriad other pests. Reapply the diatomaceous earth regularly when it is humid and after it rains, because moisture renders this material ineffective. Dry ashes can be used in the same way as diatomaceous earth.
Scout for the slugs at night when they are active, using a flashlight or headlamp. Handpick any slugs you find and crush them or drop them into a bucket of soapy water.
Create traps by placing 12-inch-by-15-inch or similarly sized boards so they are propped 1 inch off of the ground, or set flower pots, inverted melon rinds or similar materials around the radish planting or garden. Check under the traps daily; scrape off or hand-pick the slugs and crush them or drown them in soapy water.