Holes in leaves on Plants

Symptoms

The sign to look for is irregular holes with smooth edges on leaves. The source describes the same kind of holes on flowers too. The holes vary in shape, and their edges are smooth. Leaves and flowers of plants such as basil, lettuce and hosta are among those the source says these pests seriously damage. Holes of this kind on leaves and flowers match what the source describes for damage from snails and slugs.

Causes

The cause named for this problem is snails and slugs feeding at night. These animals are most active at night and on cloudy or foggy days. Boards, pavers, excess mulch, and thick or shady ground cover are the daytime hiding places the source tells you to remove. It also advises watering at the base of the plant in the morning rather than overhead or in the evening. Foliage and the soil surface dry faster that way.

Diagnosis

Start with the holes themselves. Snail and slug damage appears as irregular holes with smooth edges on leaves and flowers. Look at both the leaves and the flowers, because the source describes holes on both. Snails and slugs are most active at night and on cloudy or foggy days. The source describes handpicking snails and slugs from plants at night, and that is when you can find them on the plants. It also describes a raised board or similar trap set on the ground, which collects snails and slugs underneath for removal. Boards, pavers, excess mulch and thick or shady ground cover are the daytime hiding places the source names, so look around them too. The source names basil, beans, cabbage, dahlia, delphinium, hosta, lettuce, marigolds and strawberries as plants these pests seriously damage. It says citrus are especially susceptible to damage. Smooth-edged holes together with night feeding by snails and slugs are what set this problem apart from a general care fault. If you find snails or slugs on the plant at night and the holes match, the description fits your plant.

Treatments

Cultural methods come first. Remove daytime hiding places such as boards, pavers, excess mulch, and thick or shady ground cover. Water at the base of the plant in the morning, or irrigate near sunrise, instead of watering overhead or in the evening. Foliage and the soil surface then dry faster. You can also grow plant species that snails and slugs tend to avoid instead of their preferred plants. Handpick snails and slugs from plants at night and drop them in soapy water. Another option is a raised board or similar trap set on the ground, which collects snails and slugs underneath for removal.

The organic option is a bait formulated with iron phosphate. The source describes it as safer for use around children, domestic animals, and birds.

Two chemical baits are listed. One uses ferric sodium EDTA. It works similarly to iron phosphate and can kill snails and slugs faster, but it is not labeled for organic use. The other is a metaldehyde bait, and the source cautions that metaldehyde baits are particularly poisonous to dogs and cats.

Whichever product you choose, the product label is the legal instruction and you must follow it for the crop and site being treated. This page gives no dose, rate or spray interval, so read the label for those. Keeping plants healthy with proper cultural care is also part of the treatment advice.

Prevention

Clear away boards, pavers, excess mulch, and thick or shady ground cover, the daytime hiding places the source names. Water at the base of the plant in the morning rather than overhead or in the evening. Watering near sunrise lets foliage and the soil surface dry faster. Choose plant species that snails and slugs tend to avoid in place of their preferred plants. Plants such as basil, lettuce and hosta are ones the source says these pests seriously damage, and citrus are especially susceptible. Provide proper cultural care so your plants stay healthy. A raised board on the ground collects snails and slugs underneath for removal. Handpicking at night removes the ones you find. Cloudy or foggy days are when these animals are most active, so those are the days to be watchful.

Plants most often affected

The source names several plants that these pests seriously damage: basil, beans, cabbage, dahlia, delphinium, hosta, lettuce, marigolds and strawberries. It adds that citrus are especially susceptible to damage. Many other vegetable plants are also listed as damaged. These plants are the hosts recorded for snail and slug damage on this page.

No plant page in this build records this problem yet.