Common Plant Diseases & 12 Methods for Treating Them

Getting a handle on understanding plant diseases can save you from devastating losses in your garden. They are responsible for the death of many plants and can spread quickly if not controlled.

Disease occurs when susceptible plants are introduced to a pathogen and the environmental conditions are just right. Some garden diseases target certain plant families, while others are less discriminating and will wipe out most of your garden.

Plant diseases typically fall into five categories: bacteria, viruses, fungi, water molds, and nematodes. 

Bacterial diseases tend to develop on older leaves first, whereas viral diseases will develop on younger leaves. 

Fungal diseases develop in moderate temperatures when plants stay wet for many hours a day. These diseases include blight, fusarium and verticillium wilts, powdery mildew, various rusts, anthracnose, and leaf spots.

If your plant isn’t flourishing, look for symptoms in order to diagnose the problem. Plants can fail to thrive due to a lack of nurture, pests, or even soil deficiency. If you think you might have a plant disease on your hand, inspect your plants carefully. Consulting pictures of various diseases may also be helpful.

• Wilted or stunted leaves
• Rapid death of leaves
• Discoloration on leaves or fruit
• Decay on fruit or stems

“An ounce of prevention is worth a pound of cure.” This saying especially applies to plant disease control. Many common diseases can be prevented by being proactive about how you manage your garden.

1. Follow planting guidelines - Plant when the soil is at the right temperature. If you’re not sure, consult your seed packets. The right environment for seed germination will allow the plants to grow and establish quickly and prevent seed decay and damping off.
2. Crop rotation - To prevent pathogen buildup, rotate the types of plants you grow from year to year. An ideal crop rotation is every 3-5 years, so consider planning a progression for the various areas in your garden.
3. Plant mindfully - Inspect seeds and transplants before they go into the garden. Only save seeds of healthy plants for growing in future seasons, and choose disease-resistant varieties when possible.
4. Encourage vigorous growth - Strong, healthy plants are less susceptible to disease.
5. Organic Amendments - Adding organic matter such as compost to the soil as needed will help the soil to retain water and nutrients as well as encourage a healthy soil with beneficial microorganisms to help you keep your plants in great shape.
6. Spacing and trellising - proper spacing of your crops and trellising will keep fruit and leaves off of the ground and allow for good air circulation.
7. Watering and drainage - Choose well-draining soil for your crops, or consider raised beds if you don’t have any suitable land. Do not overwater, and try to make sure that any leaves will dry quickly. Overwatering and soggy soil can lead to damping off in seedlings and various forms of root, crown, and stem rot in established plants.
8. Weeding - Other plants can bear pathogens that infect your plants, so it’s a good idea to keep weeds under control.
9. Insect control - Keeping your garden free of insects is important in disease prevention. Various pests that can eat up your plants can also harbor pathogens.
10. Mulching - Mulching can help with watering and weeding, but it also keeps the soil protected and your plants from coming into direct contact with the soil.
11. Sanitation - Remove plants and residue after your last harvest rather than leaving them in the soil. Trim and remove any diseased plants or leaves immediately.
12. Preventative chemical control - Bicarbonates, bacillus subtilis, oils, and copper and sulfur-based products can be applied in advance. These are supplementary and preventative, but they won’t cure an established disease.

In short, keep an eye on your garden! Check your plants often to monitor the general health of your plants so that you can act quickly if you do see signs of disease. 

Garden diseases can be frustrating to deal with, and after a plant is sick, it may never fully recover. If your garden does get infected with disease, you may need to take some steps to remediate the soil. It’s important to keep ahead of the game and do everything you can to set yourself up for success ahead of time. 

You can have a healthy, thriving garden by paying attention and practicing good gardening habits.

Disease Management in the Home Vegetable Garden - University of Massachusetts Amherst

Common Diseases in the Home Garden - University of Missouri Extension

Disease Control - University of Illinois Extension

Disease Management in the Home Vegetable Garden - University of Georgia Extension

Managing Garden Diseases - West Virginia University Extension

Disease Control - Texas A&M AgriLife Extension Service

Written by Teresa Chandler