Herby Gardens


5 Common Pests and Diseases in Gardens and How to Manage Them

Read time: 5 minutes


Gardening is a fulfilling  and enriching activity that allows you to grow your own fresh herbs, vegetables, and flowers. However, it comes with its challenges, one of which is pests and diseases that can damage or even destroy your plants. In this article, I will discuss five common pests and diseases in gardens and provide tips on how to manage them effectively without using harmful chemicals or pesticides.


Aphids are small, soft-bodied insects that suck the sap from the leaves and stems of plants. They come in a variety of colors and usually feed on stems and the underside of leaves They reproduce quickly and can cause significant damage to your vegetable garden if left unchecked. Commonly found on plants such as lettuce, cabbage, and beans, aphids can stunt plant growth and cause the leaves to curl and wilt.

ladybug eating aphids on a plant

To manage aphids, start by spraying them off the plants with a strong jet of water. You can also prune the infected area and squish the aphids (gross, I know). Another method is to introduce natural predators like ladybugs, lacewings, or parasitic wasps, which will feed on aphids and keep their population under control.

I encourage ladybugs to move into my garden by planting yarrow, dill, and angelica. One single ladybugs and their larva will eat around 50 aphids per day. Take note of what ladybug larva and eggs look like so you don’t accidentally remove them.
diagram of ladybug lifecycle
Ants and aphids have a unique symbiotic relationship. Aphids produce a sugary liquid waste called honeydew, which is highly sought after by ants. Ants will protect aphids from predators and even move them to new feeding grounds in exchange for the honeydew they produce.

Ants will often tend to aphids by stroking them with their antennae to stimulate the production of honeydew. They also move the aphids to different parts of the plant to ensure a steady supply of food. In some cases, ants will even keep aphids as “livestock” and move them to different plants to create their own aphid colonies.

One way to deter ants from plants is by planting garlic or placing crushed garlic cloves around them. The strong smell of garlic contains sulfur compounds that are known to repel ants, though it’s important to use garlic in moderation to avoid any harmful effects on plants and other beneficial insects in the garden.

Tomato Blight

Tomato blight is a fungal disease that affects tomato plants, causing the leaves to turn brown and wilt. The disease is caused by a fungus that thrives in warm, humid conditions and can be spread by water, wind, and contaminated soil. There are two main types of tomato blight:

Early Blight: Early blight is caused by the fungus Alternaria solani and affects tomato plants in warm, humid conditions. Symptoms of early blight include dark spots or lesions on the lower leaves of the plant, which can eventually spread to the upper leaves and cause them to yellow and die. Infected fruits may also develop sunken, leathery spots.

Tomato leaves with early blight

Late Blight: Late blight is caused by the fungus Phytophthora infestans and is a more serious and destructive disease than early blight. Late blight typically occurs in cool, wet conditions and can spread rapidly throughout a tomato plant, causing leaves to wilt and turn brown, with a white, fuzzy growth on the underside of the leaves. Infected fruits may have dark, sunken spots and can rot quickly.

Tomatoes with late blight

To manage tomato blight, remove the affected leaves and stems immediately to prevent the disease from spreading. Don’t compost the infected leaves – burn them or throw them away. Add a layer of mulch around the base of the tomato plants to prevent the fungal spores from splashing up onto the leaves and stems during waterings.

Cabbage Worms

Cabbage worms are the larvae of the cabbage white butterfly and can cause significant damage to cabbage, broccoli, and other members of the brassica family. They eat large holes in the leaves and can reduce yields significantly.

Cabbage white butterfly on leaf
Cabbage white buttefly

To manage cabbage worms, start by manually removing the worms and their eggs from the leaves. You can also use row covers to prevent the butterflies from laying their eggs on the plants. Finally, consider introducing beneficial insects like parasitic wasps, which will feed on the cabbage worms and help to control their population.

Cabbage worm
Cabbage worm
Cabbage white butterfly eggs on leaf
Cabbage white butterfly eggs


Slugs are common garden pests that feed on the leaves of plants and can cause significant damage to seedlings and young plants. They are particularly active during wet weather and can be challenging to control.

To manage slugs, start by removing any debris or mulch from around the plants, which can provide a hiding place for slugs. You can also use slug bait or traps to control their population. Another option is to introduce natural predators like birds, toads, or ground beetles, which will feed on slugs and keep their population under control.

Slug on a stem

Beer traps are an effective tool for reducing slugs and snails in the garden. Simply take a shallow dish, fill it with beer, and place it in the garden beds. The slugs and snails are attracted to the beer and will crawl in and drown.

Japanese Beetles

Japanese beetles are shiny, metallic green beetles that feed on the leaves, flowers, and fruits of plants. They can cause significant damage to a wide variety of vegetable crops, including tomatoes, peppers, and beans.

To manage Japanese beetles, start by handpicking them from the plants early in the evening when they are less active. Another option is to introduce natural predators like birds, which will feed on the beetles and keep their population under control. Place bird houses and bird baths close to your gardens to help attract birds.

Japanese beetles on a leaf
Japanese beetles

Researchers found that hand-picking Japanese beetles once a day can reduce feeding damage, and the most effective time is in the evening around 7pm. This reduces injury to the plants and they are less likely to be recolonized over night.

Fill a container with soapy water for drowning the beetles. Hold the container under the plant and gently shake the branches or leaves. This will cause the beetles to fall off the plant and into the container. Pick off any remaining beetles by hand and drop them into the container.

The Japanese beetle larvae, also known as white grubs, cause damage to lawns by feeding on grass roots, causing the grass to turn brown and die. Controlling Japanese beetle larvae can be done by adding beneficial nematodes to lawns.

grub in lawn

Pests and diseases can be a significant challenge for gardeners, but with a little knowledge and effort, they can be managed effectively. By following these tips and taking a proactive approach to pest and disease management, you can enjoy a bountiful harvest.

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Hello and welcome! My name is Kate and I am an herbalist and backyard farmer. If you are a beginner herbalist or just looking for information on plants, I write about gardening, natural remedies, and herbalism.




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