Natural Fungicide for Organic Farmers

Kodiak, Serenade, and Sonata Treat Powdery Mildew and Root Rot

Aug 31, 2009

Organic farmers can use natural fungicides derived from unmodified bacteria to control powdery mildew, root rot, rust, and other fungal diseases of vegetable crops.

Although many of the products and tools organic farmers use have been around for decades, if not centuries, researchers are always finding new ways to exploit natural pest and disease pathogens that work invisibly in the soil, water, and air. Two such examples are the bacteria Bacillus subtilis and Bacillus pumilus, which naturally kill plant diseases by killing them or slowing down their growth.

Farmers have used one strain of B. subtilis to treat seeds and soil for plant pathogens since the 1930s, but researchers are still discovering new beneficial strains of bacteria that have horticultural applications. Learn which OMRI-approved products are used for seed, soil, and foliar applications in the organic vegetable field and orchard.

Kodiak Fungicide

The strain of B. subtilis present in the Kodiak fungicide multiplies naturally in the soil, forming harmless colonies on the roots of the crops. This leaves less room for harmful disease fungi to grow. This biological fungicide also consumes juices and substances the roots release into the soil, which normally feed the harmful fungi. Therefore, the fungi are deprived of the food they need to grow.

Farmers have relied on Kodiak for several decades to treat the seeds of cotton, soybeans, and vegetables at planting time. When organic farmers use Kodiak according to label instructions, they can protect their crops against pathogenic Aspergillus, Rhizoctonia, Fusarium, and Pythium fungi.

Serenade Fungicide

Researchers found a new naturally occurring strain of B. subtilis in 1995 which gave rise to the new natural fungicide marketed as Serenade. As opposed to the original strain of the bacterium, the bacteria present in Serenade don’t have much of a fungicidal effect of plant disease pathogens. Instead, the bacteria produce a natural antibiotic that helps crops out-compete the pathogens.

Organic farmers can buy Serenade as a foliar spray to control powdery mildew on crops. Specifically, Serenade has demonstrated efficacy against onion botrytis, onion purple blotch, and mildew diseases in grapes and greenhouse tomatoes.

Sonata Fungicide

Farmers can use Sonata on fruit and vegetable crops up to the day of harvest to control downy mildew, powdery mildew, and rust. The bacterium Bacillus pumilus manufactures a sugar compound that interferes with the metabolism of plant pathogens, leading to the death of the fungi. The bacteria also inhibit plant pathogens from becoming established on crops, while exhibiting little or no disease resistance problems.

Organic farmers can apply Sonata as a foliar spray, and its low toxicity makes it an idea partner in a rotational spray program with other fungicides when conditions are favorable to disease development. Farmers can use Sonata on a wide variety of crops, including berries, brassica crops like cabbage and broccoli, fruiting vegetables, cucurbits, leafy vegetables, root vegetables, and fruit trees.

The copyright of the article Natural Fungicide for Organic Farmers in Organic Farming is owned by Jamie McIntosh. Permission to republish Natural Fungicide for Organic Farmers in print or online must be granted by the author in writing.