Organic Cures for Plant Fungus

Sulfur

• Three-thousand years ago, the ancient Greek poet Homer described using sulfur as a pesticide. Sulfur controls fungal diseases that include powdery mildew, leaf blights, fruit rots and some rust diseases. It is especially used on food plants. Sulfur is relatively safe, although a related organic fungicide, lime sulfur, is highly toxic. Avoid applying sulfur during hot weather or in combination with other organic pesticides.

Baking Soda

• Baking soda and the related potassium bicarbonate disrupt the salts found inside of fungal cells and cause the cells to collapse. Both compounds control powdery mildew on peach, melon, lettuce, grape and apple, as well as other diseases of food crops. These treatments are safe for people and the environment and require only a day between treatment and harvest.

Copper

• Fungi absorb copper, which interferes with the protein function inside of their cells. Copper is a key ingredient in several organic fungicides, including Bordeaux mixture, another fungicide with a lengthy history. It does a fair-to-good job controlling powdery and downy mildews, certain blights and fireblight. Copper is toxic to both plants and animals in high doses, so use copper-containing products with care. European vineyards that have regularly used Bordeaux mixture for the past hundred years have demonstrated toxic buildup of copper in the soil. Copper also threatens certain wildlife, including fish and honeybees, and domesticated animals.

  Copper is toxic to both plants and animals in high doses, so you should use copper-containing products with care. European vineyards that have regularly used Bordeaux mixture for the past hundred years have demonstrated toxic buildup of copper in the soil. Copper also threatens certain wildlife, including fish and honeybees, and domesticated animals. (See References 2 and 4)

Oils

• Oils from plant and petroleum sources are used in organic gardening controlling fungal diseases like powdery mildew. Some products include oils combined with other fungicides with the oils enhancing the product's performance. Oils damage some plants or reduce yields from food crops. Do not apply oils on humid days, as humidity slows evaporation and increases the chance of damage. Oils are relatively safe for people, animals and the environment.

Soaps

• Insecticidal soaps are a common choice for organic insect control, but some formulations also suppress powdery mildew. Soaps are relatively safe for people and the planet, although some formulations cause eye damage if misused. Some pesticidal soaps kill fish if the product washes off into a water source.