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Most Common Garden Diseases

When your vibrant garden starts to look discolored and unhealthy, it’s important to find the source of the problem. While your plants may be in need of more water or light, you could be dealing with something more harmful. Plants are susceptible to various diseases and knowing what you’re dealing with will help you protect your plants. We’ve made a list of the most common garden diseases so you can identify and treat them.

Leaf Spot

Spots on leaves

Leaf spot makes it easy for you to identify it. This disease causes brown or dark spots on plant leaves. It can affect flowers, herbs, shrubs, and vegetable plants.

What Causes Leaf Spot?

Bacteria or fungus in the soil can attack your plants. Outbreaks typically occur when rain and warm air are present. When soil is disturbed and makes contact with the plant, it can spread. Though the disease starts as spots, the leaves will eventually die. When they fall off, they can infect other leaves and plants.

How to Deal with Leaf Spot

If you notice these symptoms, make sure to remove the fallen leaves to prevent further contamination. You can also add mulch to your garden to prevent bacteria or fungus-infested soil from touching your plants.


Several types of mold could develop on your plants. The most common type is botrytis or gray mold. This will appear as gray or white fuzz on the petals of flowers.

What Causes Mold?

Rainy and cool weather are the ideal conditions for gray mold. It also thrives in areas with high humidity. Often times, the mold spores remain dormant in the soil until the right conditions are present. Wind and water spread the spores. Gray mold can affect a variety of plants and flowers.

How to Deal with Mold

If gray mold begins growing on your plants, you’ll want to remove any dead or dying leaves. This can help to prevent the mold from spreading. Making sure you don’t overwater your plants can help you avoid gray mold.

Powdery Mildew

Powdery mildew on leaf

Powdery mildew is another fungal disease that attacks plants. White spots are an early sign of the disease. As the disease progresses, the spots begin to connect to one another forming large, white patches. This leads to the leaves turning brown and crumbling.

What Causes Powdery Mildew?

Powdery mildew thrives in dry soil and areas with high humidity. Powdery mildew usually develops late in the summer. Rose, tomato, and squash plants are a few plants often affected by powdery mildew.

How to Deal with Powdery Mildew

It’s important to remove infested parts of the plant. Adding mulch to your garden can help to prevent this disease. It preserves the moisture in the soil and keeps the fungus from touching the plants.

Downy Mildew

The most common symptom of downy mildew is fuzzy growth on the underside of plants. This fuzz can be white, brown, gray, or purple. Dark or yellow spots can also develop on leaves. It can lead to falling leaves, and it can also hinder the plant’s growth.

What Causes Downy Mildew?

While powdery mildew thrives in dry soil, downy mildew needs moisture to develop. Parasitic organisms cause downy mildew and many plants can be affected.

How to Deal with Downy Mildew

One of the best ways to avoid downy mildew is to prevent moisture build-up on leaves. Don’t pour water directly on top of the leaves. Instead, water under the leaves closer to the soil. The plants will still receive sufficient water, but water won’t be left sitting on the leaves.  


Apple with blight

There are two forms of blight disease—early and late. Signs of early blight include dark spots on leaves. A yellow ring surrounds these spots. When the spots dry, they fall off, which creates holes in the leaves. Late blight results in spots on the leaves and stems of the plant. This can lead to the wilting of leaves. For both diseases, symptoms often begin on leaves closer to the soil.

What Causes Blight?

Two different, but related, fungi cause blight. Blight is most likely to be present when temperatures and humidity are high and there has been rain. Rain helps the disease spread from the soil to the plants. Tomato and potato plants are most susceptible to blight.

How to Deal with Blight

Removing infested leaves and using mulch can help protect plants. You can also use a fungicide, like our 3-in-1 Garden Spray, to treat blight.

Crown Rot

Crown rot affects a variety of plants and trees. The rotting of plant stems is the main indicator of crown rot. Leaves usually turn dark brown, but sometimes foliage will become yellow. Wilting can also occur when crown rot is present.

What Causes Crown Rot?

A soil-borne fungus is responsible for the development of this disease. Crown rot can happen throughout the gardening season, but high temperatures and humidity allow it to thrive. When the fungus enters the plant, it damages plant tissue, which can lead to the death of plants. Unfortunately, crown rot often goes unseen until the disease has greatly progressed.

How to Deal with Crown Rot

When crown rot is noticed, you’ll want to remove any infected plants. Using a fungicide can help to prevent crown rot from developing and spreading.

Mosaic Virus

Mosaic virus on plant

Though mosaics are often pleasing to the eye, mosaic virus is not. This virus attacks a wide range of vegetable plants. Mosaic virus is often disguised as less serious plant problems. Symptoms include discoloration or spots that can be white, green, or yellow. Sometimes leaves wrinkle, and the plant’s ability to grow is hindered.

What Causes Mosaic Virus?

Garden pests, like whiteflies, aphids, and leafhoppers, spread mosaic virus. They can contaminate soil, seeds, and even pots and containers.

How to Deal with Mosaic Virus

If a plant becomes infected, it must be removed. While mosaic virus can’t be treated, you can still help prevent the disease. Eliminating disease-carrying pests can help to protect your plants. Using an insecticide, like our 3-in-1 Garden Spray, will help eliminate pests and prevent other fungal diseases.

If you begin noticing changes in the appearance of your plants, it’s important to find the source of the problem. This can help save your plant from further damage and prevent spreading of the disease. Whether you’re dealing with diseases or pests, we have your back! Check out our Maggie’s Farm Simply Effective™ Pest Control products.

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