Vegetable Garden Troubleshooting: Holes in Leaves

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Slug and earwig damage on leaves

It was only a few weeks ago that your newly planted garden seemed to be doing great, perhaps even picture perfect. But now the season of mysteries has begun, with leaves showing spots, holes, and missing parts, usually with no insect in sight. Good thing we live in age of easy digital photography, which makes it possible to get a closeup view of holes in leaves, making the clues easier to see. Here are some seasonal problems you are likely to discover when you snap closeups of distressed leaves, or make use of a simple magnifying glass.

Slugs and Earwigs

Slugs are the most common cause of holes in leaves, but they often remain unseen because they feed at night. Sometimes larger slugs eat leaves from the edge inward, but small slugs make irregular holes inside leaves, as shown in the chard leaf on the right in the above photo. Slug holes always have smooth green edges.

The pepper leaf on the left has been sampled by slugs, but most of the damage was done by earwigs, which make ragged, irregular chomping patterns. The bane of container gardeners and those with framed raised beds, earwigs hide under pots or in bed frame crevices during the day and feed on tender plant leaves at night. They love basil and the new growth of peppers and artichokes.

What to Do: Use homemade traps to manage slugs and earwigs, and be ready to move containers to interrupt infestations. Delay mulching when slugs and earwigs are present in the garden, because mulches provide daytime cover for these nighttime feeders.

Trim off low leaves to slow the spread of early blight, the main cause of spots on tomato leaves

Tomato Tribe Troubles

Flea beetles make tiny round pinprick holes in tomato, aubergine, pepper and potato leaves, but while aubergine needs the protection of a fabric barrier in areas where this is a problem, tomatoes, peppers and potatoes usually outgrow flea beetle damage. Leaf spots caused by fungi are a much bigger threat to tomatoes. Tomatoes have juicy leaf hairs that retain moisture in wet weather, making them easy targets for fungal diseases like early blight, which causes spots to develop on lower leaves in early summer. Spots on leaves caused by early blight have a bulls-eye pattern, with rings of dead tissue surrounding a sporulating center. Leaf tissues between the spots turn yellow, and then the whole leaf withers to brown.

What to Do: Grow plants at proper spacing to promote good air circulation. When lower leaves show spots, use sharp pruning shears to remove all leaves up to at least 12 inches (30cm) from the ground. This basal pruning removes inoculum and helps the plants dry faster after rain or heavy dew.

Cercospora lesions on chard and beet leaves are sometimes called frog-eye spots. Aggressive harvesting sets back the disease and invigorates plants

Frog-Eye Spots on Chard

Warm summer rains often give rise to cercospora fungi, which cause spots and holes in leaves of chard, beetroot, carrots, celery and a few other crops. Different cercospora strains infect the two plant families, but in both cases blister-like spots form that often crack open in the center. With cercospora-related carrot leaf blight, infected foliage becomes weak and brown, though the carrots may continue to produce new growth.

What to Do: You can’t stop the rain that contributes to cercospora outbreaks, but you can keep plants thinned and weeded to help them dry out between showers. Problems often begin on the oldest leaves, which can be cut out and composted to slow the spread of this widespread disease. Harvest aggressively to remove inoculum and encourage new growth.

We like to think of a garden as a natural ecosystem created by a human for the benefit of plants, but it’s actually a very wild place where the fate of a crop is up to very tiny life forms. The more you understand about them, the more fascinating your garden’s secret world becomes.

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Show Comments


"I have a bell pepper plant gowning under a grow light. It is in a 5-gallon pail. There are no bugs on plant. Leaves are malformed and have holes. They also look like they are being eaten. I've cut down on watering, no luck, added water no luck, added calcium, no luck. Plant produces a number of blossoms and fruit. The soil is a mixture of clean dirt and compost. I started the plant from seed. It was successful in a 5-gallon pot outside. The grow light is about 12" from plant. What's missing?"
Bob on Wednesday 16 November 2022
"Bob, so sorry I missed your question. Mature bell peppers will barely survive under a grow light. It is sufficient for overwintering plants that have been pruned back, but not strong enough for active growth. Most peppers are actually short-lived, semi-tropical perennials."
Barbara Pleasant on Monday 17 April 2023
"I have done everything under the sun to keep the aphids off of my tomato plants and nothing has helped. My plants are dying and it just breaks my heart because I’ve invested so much time and money into these plants only to have them die. Don’t know what to do anymore. I’ve seven I’ve used Nemo. I’ve used water with dish soap. I’ve used everything I could think of and nothing is helping. Help"
Karen Douglass on Tuesday 4 June 2024

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