Bacillus Subtilis as a Biofungicide and Biostimulant for Plants

In the realm of sustainable agriculture, Bacillus subtilis for plants has gained recognition as a highly effective plant growth-promoting rhizobacterium (PGPR). This makes it a bacterial biocontrol agent that has the ability to combine the roles of a biofungicide and a biostimulant, which is very effective in promoting plant growth, suppressing various pathogens and increasing crop production. It is used widely for stimulating suitable root development and nutrient network, enhancing plant resistance to hostile environmental conditions and therefore is fundamental in today’s advanced, efficient agriculture practices.

Benefits of Bacillus Subtilis for Plants

Bacillus Subtilis plant Disease Control

Bacillus subtilis fungicide is renowned for its antagonistic activity against a variety of plant pathogens, making it an effective biofungicide. Here are some of the key fungal diseases it combats:

• Tomato Botrytis: Causes gray mold on tomatoes.
• Cotton Verticillium Wilt: Leads to wilting and yellowing in cotton.
• Cotton Fusarium Wilt: Results in wilting and death of cotton plants.
• Pinellia Ternate Root Rot: Affects the root systems of Pinellia ternata.
• Kiwi Root Rot: Damages the root systems of kiwi plants.
• Cotton Blight: Leads to defoliation and boll rot in cotton.
• Rice Blight: Causes lesions on rice plants, reducing yields.
• Citrus Canker: Creates lesions on citrus fruits, stems, and leaves.
• Apple Ringspot: Produces ringspot symptoms on apple leaves and fruits.

Bacillus Subtilis Plant Growth Promotion

Bacillus subtilis for plants significantly enhances plant growth through several key mechanisms:

1. Nutrient Uptake:
   • Solubilization of Essential Elements: Bacillus subtilis fungicide solubilizes crucial nutrients like phosphorus, calcium, potassium, and magnesium. This process converts these nutrients into forms that are easily absorbed by plant roots, thereby improving overall plant nutrition and growth.
2. Hormone Production:
   • Growth Hormones: The bacterium produces growth hormones such as indole-3-acetic acid (IAA). IAA is a type of auxin, a plant hormone that promotes root elongation and development. Enhanced root systems allow plants to absorb more water and nutrients, leading to increased plant vigor and robustness.
3. Stress Resilience:
   • Abiotic Stress Tolerance: Bacillus subtilis as biocontrol agent enhances plants’ tolerance to abiotic stresses like drought, high salinity, and extreme temperatures. It does this through the synthesis of stress-related hormones that enable plants to contend with and regain equanimity in demonstrably inhospitable environments. This resilience ensures that plants are able to grow and produce even when the situation for the plant is not so favorable.

Usage of Bacillus Subtilis for Plants

Application Methods

Soil Drench

• Mixing and Application: Dissolve 3 kg of Bacillus subtilis per acre in water. Apply this solution by soil drench, irrigation, or spray during sowing.
• Reapplication: Repeat every 28 days throughout the growing season to maintain effectiveness and soil health.

Foliar Spray

• Mixing and Application: Mix 2.5 grams of Bacillus subtilis per liter of water. Apply this mixture to plants at 20-30% bloom or when conditions are favorable for disease development.
• Reapplication: Spray at 7-day intervals to ensure continuous protection against pathogens.

Timing

• For bacillus subtilis plant Disease Control: Apply Bacillus subtilis before or at the beginning of the growing season to establish early protection against pathogens.
• For Soil Health: Apply in the fall to enhance soil structure and prepare the soil for the next planting season. This application improves soil health over the winter months, ensuring a fertile start in spring.

Practical Recommendations for Bacillus Subtilis for Plants

• Ensure thorough mixing of Bacillus subtilis with water to achieve even distribution.
• For soil drench applications, focus on the root zone for maximum absorption and effectiveness.
• For foliar sprays, cover both sides of the leaves for optimal protection against foliar pathogens.
• Reapplications should be done repeatedly in order to have a constant impact during the growing season.

It is therefore interesting to note that by adopting the application methods herein and sticking to the recommended timing for the use of the Bacillus subtilis, farmers can massively benefit from the potential of increasing the overall health of the plants and in turn the yields of the crops grown.

Formulations and Storage

Bacillus subtilis fungicide is available in two primary forms to suit different agricultural needs: powder and liquid suspension.

Powder Form

• Bacteria Count: The powder formulation contains a high concentration of bacteria, ranging from 1 x 10^11 to 5 x 10^11 colony-forming units (cfu) per gram. This high density ensures a potent application for disease control and growth promotion.
• Application: The powder can be mixed with water and applied via soil drench, irrigation, or foliar spray, depending on the specific needs of the crops.

Liquid Suspension Form

• Bacteria Count: The liquid suspension contains 1 x 10^9 cfu per milliliter, providing a ready-to-use solution that is convenient for various agricultural applications.
• Application: The liquid form is particularly useful for foliar sprays and can be easily integrated into existing irrigation systems for uniform distribution.

Shelf Life and Storage

• Shelf Life: Both powder and liquid formulations have a shelf life of 24 months when stored in a cool, dry place. Proper storage conditions are crucial to maintaining the viability and effectiveness of the bacteria.
• Post-Opening Use: Once opened, the product should be used within 30 days to ensure maximum efficacy. Exposure to air and moisture after opening can reduce the bacteria’s effectiveness over time.

Conclusion

Incorporating Bacillus subtilis products into agricultural practices offers a robust, eco-friendly approach to managing plant health and boosting crop yields. The ability of this microbial inoculant to qualify as both biofungicide and biostimulant that is environmentally friendly and effective is perfect for farmers who want efficient farming and at the same time repellent to chemical use.

References:

1. Foughalia, Abdelhamid, et al. “A cinetobacter calcoaceticus SJ19 and Bacillus safensis SJ4, two Algerian rhizobacteria protecting tomato plants against Botrytis cinerea and promoting their growth.” Egyptian Journal of Biological Pest Control 32.1 (2022): 12.
2. Roberti, Roberta, et al. “Biocontrol of Rhizoctonia solani disease and biostimulant effect by microbial products on bean plants.” Italian Journal of Mycology 44 (2015): 49-61.