Research Report

Companion® Biological Fungicide Goes Above and Beyond Chemical Fungicides

What is Companion?

A broad-spectrum biological fungicide for soil-borne and foliar diseases

Companion's GB03 strain of Bacillus subtilis has multiple modes of action to prevent and control plant diseases. It produces a broad-spectrum Iturin antibiotic that disrupts the cell-wall formation of pathogens, and it triggers an advantageous Induced Systemic Resistance (ISR) in plants, whereby a plant's natural immune system is activated to fight plant diseases. Companion's fast-colonizing beneficial rhizobacteria stimulate root growth and promote turf vigor while also crowding out plant pathogens. Easy to use and handle, Companion is an environmentally-friendly fungicide with an unsurpassed safety profile and a low 0-4 hours REI. Because its modes of action circumvent the development of pathogen resistance and since it can be used alone or in combination with traditional chemical fungicides, Companion is the ideal foundation for an effective integrated pest management and disease management program.

Tomato plant grown with a conventional N-P-K fertilizer program.
"Sister plant" grown under same field & fertilizer conditions but with the addition of Companion shows improved branching and vigor.


Nine days after application, Sweet Peppers treated with Companion (the two on the right) show increased top growth and better rooting than the untreated peppers on the left.
A close-up of two tomato plants. The plant on the right had one application of Companion applied and shows denser, longer root growth promoted after only 9 days.

Break-Through Technology

Growth Products' pioneering research in environmentally safe solutions for Sustainable Agriculture led to Companion's technology.
Years of research went into developing Companion and gaining its EPA registration in every green industry market including Agriculture, Turf, Landscape, Greenhouse, Nursery, Ornamentals, Hydroponics, and Home & Garden Use. Companion has been tested at leading universities, by government agencies, and by the most prestigious agricultural facilities around the world.

Fusarium wilt on cucumbers usually attacks when plants are 60 to 80 days old and in the production stage. Its negative results on crop yield can be devastating.
By applying Companion every 21 days from seedling to transplant, and through the life of the plant, this grower was able to avoid Fusarium on his plants and get another 1 to 2 months of cucumbers for market.
The grower was so pleased with Companion that he washed the roots of one of his treated plants to show its dense, white, healthy root system.

Multiple Modes of Action

To prevent & control diseases and to improve crop vigor

  • Directly competes against soil-borne pathogens by quickly colonizing a plant's root hairs with beneficial bacteria, thereby crowding out disease-producing microbes and creating a "shield" to protect plants.
  • Produces strong Iturin antibiotics that kill pathogens by disrupting cell wall formation.
  • Creates a highly beneficial Induced Systemic Resistance (ISR) by stimulating the plant's phytohormones and natural immune system to better resist diseases.
  • Acts as a Plant Growth Promoting Rhizobacterium (PGPR) that stimulates better rooting and better overall growth.
  • Is an important tool in a turf manager's Disease Resistance Management Program, helping to prevent pathogens from building a resistance to chemical fungicides.
  • Is non-selective to plant materials, and thus is beneficial to all types of agricultural crops including vegetables, herbs, fruits, citrus and nuts. Works at all growth stages, from seeds to plug to harvest.
  • Contains gram-positive bacteria which survive in even extreme environmental conditions including heat and drought, making it a durable and reliable fungicide that growers can trust.
Bacillus subtilis spores populating the root hairs
Notice hyphae formation around root hair providing a protective glove

Resistance Management

A 100% natural and organic biological fungicide, Companion can play an important role in a grower's Integrated Pest Management (IPM) program. Chemical fungicides enable pathogens to build up resistance over time, but Companion's multiple modes of action prevent the development of disease resistance.

Other benefits include:

  • Low 0 - 4 hour REI for workers.
  • No special storage requirements; remains shelf stable for more than two years.
  • 100% miscible in water and may be applied through all types of irrigation systems.
Six weeks after transplanting, Iceberg lettuce that was treated with Companion showed excellent control of Sclerotinia, as shown in the photo above, taken at Serve-Ag Research in Australia.
In identical field conditions, this untreated Iceberg lettuce shows crop loss and lack of turgidity due to Sclerotinia. The untreated lettuce had a loss of nearly 60 percent.


During transplanting, tree roots are typically damaged when removed from their liners. Here, a Valencia orange on Swingle root stock was treated with Companion in order to prevent pythium root rot, which often damages stressed trees.
Fifteen months later the citrus tree has
grown nicely. Follow-up applications
of Companion biological fungicide have helped protect the tree from diseases such as Canker, Greening, and Alternaria.


Chemical fungicides are known to decrease plant growth and stunt qualities such as crop yield. In this study Companion produced the highest lettuce yield. The use of Companion mixed with reduced amounts of the chemical fungicide Procymidone increased the lettuce yield above the stand-alone use of the chemical used at regular strength.

The best disease control does not always produce the best yields. The phytotoxicity from chemical fungicides can stunt crop growth and decrease yield. In this study, Companion combined with the chemical fungicide Procure (triflumizole) increased the Procure's disease control but and most importantly yielded the most fruit per plot as measured by weight, and also increased the total number of marketable fruit.

Companion worked better than the chemical Procymidone in the control of Sclerotinia minor on lettuce crops. The best disease control was achieved with Companion and 25% of the regular amount of Procymidone. By using Companion with reduced amounts of chemical fungicides, a grower can save money and reduce chemical use and exposure by up to 75%.

Companion was highly effective at providing Powdery Mildew control on tomato plants. Companion preformed significantly better than the organic fungicides Taegro and Actinovate, and virtually as well as Kocide 3000 (Copper Hydroxide) and conventional chemical fungicides including Actiguard, Dithane, Bravo and Flint.


Growers in over 25 countries world-wide, with operations both large and small, have relied for years on Growth Products' Companion to keep their crops green, growing, and healthy. Why do these growers make Growth Product's biological fungicide their "valued companion"?

  • Companion has proven efficacy in preventing and controlling a wide spectrum of plant diseases.
  • Companion is cost effective when used alone or in combination with lower concentrations of chemical fungicides.
  • Companion's beneficial Bacillus subtilis not only prevents and controls fungal diseases, but stimulates root growth.
  • Companion is 100% organic and natural, is safe for workers, and is good for the environment.
  • Companion is compatible and can be tank-mixed with fertilizers, micronutrients, and most chemical fungicides, saving you time and money on spray applications.

Make Fungicides More Powerful With Companion®

Companion excels as a stand-alone biological fungicide and as a beneficial "companion" fungicide. Companion increases efficacy when tank-mixed with chemical fungicides, or used in rotation with other fungicides, thereby reducing your total chemical costs, and helps prevent the development of disease resistance.