Garden Diseases 101 – Identification, Elimination and Prevention

Every gardener fears garden diseases. The plants that you’ve so painstakingly nurtured from seeds are constantly threatened by disease. Fortunately, it’s rare for a disease to kill a plant outright, so with early identification, you can normally save them.

What to Look Out For

To list every possible plant disease would be a task of Herculean proportions. Below are the signs of the more common diseases that may attack your plants.

  • Powdery Mildew – A white, dusty fungus that can attack most plants. Visible on leaves and stems. Common in hot, humid climates.
  • Rust Disease – Found on leaves, this rusty looking fungus is caused by poor air circulation.
  • Potassium Deficiency – Stunted growth, yellow/red curled edged leaves and poor flowering are all symptoms.
  • Blossom End Rot – Affecting tomato plants, this disease leaves fruits with a dark, water soaked spot on them. Caused by a wet start to growing season.
  • Tomato and Potato Blight – Caused by wet weather, leaves, fruits and tubers are all affected. Rotting and dark stains become visible.
  • Halo Blight – A bacterial fungus that affects beans. Look for dark spots on leaves with a yellow halo.
  • Apple Scabs – Another fungal disease, caused by excessive wet, humid weather. Fruit looks scabbed.
  • Downy Mildew – Characterized by yellow patches and white mold affecting the leaves of lettuce plants.

How to Treat a Disease

Generally, the infected areas can be cut off and discarded. They should be buried or burnt rather than composted. If the entire plant is infected, it’s best to remove and destroy it. It’s worth checking the leaves, stems and fruits of your plants for any defects regularly. Prompt removal is key to your plants’ survival.


Fully preventing diseases is extremely difficult. You can look for disease resistant varieties when choosing your plants, but more often than not, at some point something is going to get attacked. Anti-fungus sprays help prevent spores from growing on your plants and pesticides can be used to halt the spread of diseases caused by insects. Ensure the growing conditions are right for your plants, with good air circulation, rich soil and a suitable climate.