Hesperian Health Guides

Plant Diseases

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HealthWiki > A Community Guide to Environmental Health > Chapter 15: Sustainable Farming > Plant Diseases

A man looks at a diseased tree.

Plant diseases can be recognized by their effects on plants, such as making leaves change in color, causing leaves to wilt, or making parts of the plant grow in unusual ways. Plant diseases may be caused by a fungus, a bacteria, or a virus. All of them can be controlled with natural methods.

Plant diseases are best prevented by maintaining healthy soils and following the other principles for sustainable farming. When you are certain a disease is affecting your crop, you can prevent the disease from spreading to other plants.

  • Destroy diseased plants. Infected plants can pass diseases or pests to future crops. For diseases that kill the entire plant or severely reduce production, the entire plant should be removed and burned at the first sign of disease. Do not compost it, because some plant diseases survive composting.
A man rinses his gardening tools under a tap.
  • Clean tools used on diseased plants. Plant diseases can be spread when your body, tools, and clothing touches infected plants and then touches healthy plants. Wash everything with warm soapy water before touching healthy plants.
  • Control sap suckers. Many plant diseases are carried between plants by sap sucking insects. See “Natural pesticides for sap-sucker insects.”
  • Milk kills fungus diseases, caterpillar eggs, and spider mites. Mix 1 liter of milk with 15 liters of water and spray on your crops. For fungal diseases, repeat after 10 days. For caterpillar eggs, repeat after 3 weeks.
  • Ashes kill fungus diseases. Planting ashes together with seeds will prevent some fungus. For late blight of tomato and potato crops, spray crops with a strained mix of ashes and water.