The likely culprit is not some mystery disease or fungus. Instead, your plants are probably being feasted upon by gastropods, more commonly known as snails and slugs.

Snails and slugs prefer damp conditions and tender-leaved vegetables, fruits, and ornamentals, which is why hostas are among their absolute favorites. Because snails and slugs feed at night or very early in the morning, they're not always visible–but the damage they do sure is!

To determine whether you're dealing with snails and slugs, set a trap by putting a couple of tablespoons of cornmeal in a clean, empty jar. Lay the jar on its side near your damaged plants and check it in the morning. If you find one (or more) of these slimy pests inside, it's time to take action.

Try One of These Do-It-Yourself Remedies to Control Snails and Slugs.

1. Remove their habitat. Get rid of anything that provides a cool, moist area for daytime hiding, such as fallen leaves, large pieces of bark, and old flower pots. Water plants only when needed, and do it early in the day so that the ground is dry by sunset.
2. Invite their enemies. Snails and slugs aren't attracted to scented, tough- leaved plants like geraniums, so plant more of what they aren't tempted to feed on. Also, consider peppering your garden and landscape with plants that attract natural snail- and slug-eating predators, such as toads, spiders, and birds.
3. Block them out. Protect especially vulnerable plants like hostas by placing a wide copper strip around the base of each plant so snails and slugs can't get to them.
4. Kill them. Sprinkle snail and slug bait pellets on the soil around your plants.