Top 10 Plant Diseases to Look for in Gardens

By Amy Grant | January 21, 2017
by Amy Grant
January 21, 2017

Just as many of us workout, eat healthy, reduce stress and drink plenty of water, the key to healthy plants is in prevention. But the best laid plans can often be thwarted by Mother Nature. Despite our best efforts, sometimes diseases infiltrate our plants, wreaking havoc in the garden. Once disease has been spotted, we need to identify it in order to treat it.

Plant disease may be abiotic (such as temperature fluxes and moisture stress, wind damage or nutrient deficiencies) or biotic (those caused by living organisms such as fungi, bacteria, nematode or virus). While there are many diseases that can afflict plants, the following are the top 10 plant disease to keep an eye on.

1. Angular Leaf Spot – Fungal diseases are certainly one of the most common afflictions found amongst plants. Amongst these are angular leaf spot, which results in angular spots on foliage that yellow then become brown.

2. AnthracnoseAnthracnose is another fungal disease that starts out as lesions similar to angular leaf spot but with black leaf veins. The leaves brown and wither and in damp weather the fungus produces clusters of pink, sticky spores.

3. Powdery Mildew – yet another common fungal problem in gardens, powdery mildew is the bane of many a gardener. It can affect almost any type of plant, appearing on leaves, flowers, fruits and vegetables as a white or gray powder that coats the surface of the plant. If left untreated, it can turn more severe, causing leaves to turn yellow or brown.

4. Bacterial Spot – Both tomatoes and peppers are susceptible to bacterial spot, which presents as irregular water-soaked lesion on foliage. The infected leaves yellow and drop and fruit may have raised crusted scabs.

5. Early BlightEarly blight is yet another fungal disease that is common in tomatoes. It begins as dark brown rings on leaves with a yellow halo. The leaves then wither and dry.

6. Fusarium WiltFusarium wilt causes vines to yellow and wilt just prior to fruiting and is common amongst many of the melons but can afflict cucumbers and summer squash as well as tomatoes.

7. Downy MildewDowny mildew causes yellow spotting on the upper surface of leaves along with a white/purple downy growth on the underside of them. The leaves curl, brown and then die. An entire plant may become stunted and yellow. The cucurbit family is most affected along with the onion family, including garlic and leeks.

8. Bacterial Wilt – Disease may also be caused by insects, such as the cucumber beetle, which is responsible for spreading bacterial wilt to any members of the cucumber family.

9. Blossom End Rot (BER) – Disease may also be physiological, such as blossom end rot. This occurs when the fruit becomes water soaked at the blossom end, resulting in tissue collapse. The fruit then dries out leaving a white papery area, which is often then invaded by fungi and turns the fruit black. While found in many vegetable crops, it’s most commonly seen in tomatoes.

10. Mosaic – Viruses, such as tobacco mosaic and cucumber mosaic, are also common diseases. They result in yellow mottling or streaking on leaves combined with distortion and stunting.

Prevention is the key to thwarting disease in plants. Keep your plants healthy by watering and fertilizing regularly, keep the area surrounding them weed free, plant disease resistant cultivars when possible, and practice crop rotation to minimize the incidence of disease in your garden.

This article was last updated on
Read more about Top of the Crop
Did you find this helpful? Share it with your friends!

Browse Dozens of Our FREE Gardening Guides Today

Whether your dream garden is a houseplant sanctuary, a bountiful vegetable garden, a pollinator paradise, a bright and bold flower bed, or a backyard oasis – Gardening Know How has the perfect gardening guide just for you.

Click the button below to access more than 3 dozen of our completely free and completely comprehensive guides to growing your dream garden.

Join Us - Sign up to get all the latest gardening tips!