Using Soil Microbes to Control Turfgrass Disease

Implementing soil microbe-based strategies for disease control involves the application of microbial treatments via aerated compost tea or using specific strains of beneficial microorganisms selected for their ability to target fungal pathogens. Several types of soil microbes with different modes of action can be used to control fungal diseases of turfgrass surfaces and are often selected based on their effectiveness against specific pathogens.

How do soil microbes control fungal disease?

There are a few ways soil microbes can help control fungal diseases in turfgrass surfaces:

1. Antagonism

Some soil microorganisms naturally compete with pathogenic fungi for resources, effectively reducing the population of the harmful fungi. For example, certain beneficial fungi, like Trichoderma spp., are known for their antagonistic properties against various plant pathogenic fungi. They can produce enzymes that degrade the cell walls of pathogens, compete for resources, and induce systemic resistance in plants. Like Trichoderma, certain species of Gliocladium fungi are used for their antagonistic effects on plant pathogenic fungi. They can colonize plant roots and protect against soil-borne pathogens.

2. Predation

Certain soil microbes, such as nematodes and protozoa, are known to feed on fungal pathogens, thereby reducing their populations. Beauveria bassiana and Metarhizium spp are entomopathogenic fungi and are used for insect pest control, but they can also have indirect effects on plant diseases by reducing insect vectors that can spread fungal pathogens.

3. Induced Resistance

Some beneficial soil microbes can induce a defence response in plants, making them more resistant to fungal diseases. This is often achieved through the activation of plant defense mechanisms. Some strains of Pseudomonas bacteria have been found to produce secondary metabolites with antifungal properties, and also induce systemic resistance in plants.

4. Production of Antifungal Compounds

Some beneficial microbes can produce compounds that are toxic to pathogenic fungi. These compounds can inhibit the growth and development of fungal pathogens. Certain species of bacteria from the Bacillus genus produce antifungal compounds that inhibit the growth of fungal pathogens. Bacillus subtilis and Bacillus amyloliquefaciens are examples of bacteria used for biocontrol. Streptomyces are filamentous species of bacteria and are known for producing a wide range of bioactive compounds, including antifungal compounds. have been studied for their potential to suppress fungal pathogens.

5. Competition for Nutrients

Beneficial soil microbes can outcompete pathogenic fungi for nutrients in the soil, limiting their growth and spread.

6. Improved Soil Health

When beneficial microbes are introduced into the soil, they can improve soil structure, nutrient availability, and overall soil health. This indirectly supports turfgrass growth and health, making the grass more resilient to diseases. Arbuscular Mycorrhizal Fungi (AMF) can enhance the overall health and stress resistance of plants, making them less susceptible to diseases.

Which fungal diseases can be controlled using microbes?

Several fungal diseases of turfgrass plants can be controlled or suppressed using soil microbes. Here are some examples of fungal diseases and the corresponding soil microbes that can help manage them:

Fusarium Patch (Microdochium nivale)

Microbe species: Trichoderma spp., Bacillus spp.

Mode of Action: Trichoderma and Bacillus spp. can limit the growth of Microdochium nivale through competition and production of antifungal metabolites.

Dollar Spot (Sclerotinia homoeocarpa)

Microbe species: Trichoderma spp., Bacillus spp., Pseudomonas spp.

Mode of Action: These microbes compete with the dollar spot pathogen for resources, produce antifungal compounds, and induce systemic resistance in turfgrass.

Brown Patch (Rhizoctonia solani)

Microbe species: Trichoderma spp., Bacillus spp., Gliocladium spp.

Mode of Action: These microbes can inhibit the growth of Rhizoctonia solani through competition and production of antifungal metabolites.

Anthracnose (Colletotrichum spp.)

Microbe species: Trichoderma spp., Bacillus spp., Streptomyces spp.

Mode of Action: These microbes can suppress Colletotrichum spp. by antagonism and production of antifungal compounds.

Take-All Patch (Gaeumannomyces graminis)

Microbe species: Trichoderma spp., Bacillus spp.

Mode of Action: Trichoderma and Bacillus spp. can inhibit Gaeumannomyces graminis through competition and production of antifungal metabolites.

Red Thread (Laetisaria fuciformis)

Microbe species: Bacillus spp., Trichoderma spp.

Mode of Action: These microbes can help manage red thread disease by suppressing the growth of the causative fungus.

Pythium Blight (Pythium spp.)

Microbe species: Trichoderma spp., Bacillus spp., Pseudomonas spp.

Mode of Action: These microbes can suppress Pythium spp. by antagonism, nutrient competition, and production of antifungal compounds.

Which microbial treatment can I use?

SigmaBio is a blend of microbes that suppress fungal diseases and increase soil health. It contains:

i. 17.0 Billion Total Beneficial Bacteria

Colony Forming Units (CFU's) per Gal.

Bacillus subtilis - 750,000 CFU/mL

Bacillus amyloliquefaciens - 750,000 CFU/mL

Bacillus licheniformis - 1,500,000 CFU/mL

Brevibacillus laterosporus - 1,500,000 CFU/mL

ii. 37.8 Thousand Total Mycorrhizae / Endomycorrhiza Propagules per Gal.

Glomus intraradices - 2.5 propagules/mL

Glomus etunicatum - 2.5 propagules/mL

Glomus aggregatum - 2.5 propagules/mL

Glomus mosseae - 2.5 propagules/mL

iii. Contains 2.8 Billion Total Trichoderma

Colony Forming Units (CFU's) per Gal.

Trichoderma viride - 375,000 CFU/mL

Trichoderma harzianum - 375,000 CFU/mL

It is important to note that the effectiveness of soil microbes to control turfgrass diseases can vary depending on the specific fungal pathogens present, the local environmental conditions, and the specific turfgrass species being grown. Proper application methods, including timing and dosage, are essential for achieving successful disease control using soil microbes. Additionally, ongoing research and field trials are important for validating the efficacy of these biocontrol agents in different turfgrass management scenarios.

South West Agronomy are expert advisors on implementing microbial control methods on turfgrass diseases. Call us today for a friendly chat on how we can help you.