Frequently Asked Questions

“Who questions much, shall learn much, and retain much.”
— Francis Bacon

Mycorrhiza is defined as the mutually beneficial relationship between plant roots and fungi. Specialized fungi that are classified as mycorrhizal fungi can colonize and grow into roots, inoculating them and forming a biological link between the root and the soil. The mycorrhizal inoculated roots effectively extend the root system in the soil and enable better access to water and nutrients. In addition, these mycorrhizal fungi also transform unavailable forms of these nutrients into more accessible forms that the plant can effectively use. Mycorrhizal fungi have also been shown to improve soil structural characteristics such as soil porosity. Mycorrhizal fungi are known to produce specific compounds and “glues” (glomalin) that promote the binding of soil aggregates and improve soil porosity.
Glomus intraradices (also known as Rhizophagus irregularis), the active ingredient in all Rootella® mycorrhizal inoculants, is a naturally-occurring arbuscular mycorrhizal fungus (AMF) that has been identified and well-researched as a powerful and effective plant symbiont that enhances nutrient uptake and water absorption and protects plants against various types of stress. Rootella® products all include an especially vigorous strain of Glomus intraradices that was originally isolated from the harsh conditions of the Israeli Negev desert, along with Glomus intraradices strains from other territories to ensure quick acclimation to other soil types and climates.

Not all mycorrhizal inoculants were created equally! Groundwork BioAg employs a unique production process to produce Rootella® inoculants, which truly stand out among the competition:

  • Rootella® mycorrhizal inoculants are highly-concentrated and cost-effective. When it comes to mycorrhizae, the cost/benefit of an inoculant is mostly dependent upon product concentration. Groundwork BioAg’s unique production technology results in extremely high concentrations of endomycorrhiza – up to 20,800 viable propagules per gram! Only in high concentration can a mycorrhizal inoculant achieve the following:
    • Cost effectiveness – High inoculant concentrations are essential to achieve high-efficacy at low application rates.
    • Relevance to seed treatment – Seed treatments are typically limited in load factor, as seeds can only carry a limited amount of material without becoming too bulky to use. Thin film-coating is typically preferred over thick seed encrusting. Effective seed treatment requires high application rate in terms of propagules per seed; this can only be achieved in a film coating with high product concentration.
  • Groundwork BioAg has developed its products from vigorous strains of endomycorrhiza, sourced from the harsh Israeli desert. These fungal strains have evolved to be true survivors, able to adapt and to thrive in the most difficult conditions.
  • All Rootella® products contain only naturally-occurring fungi (non-GMO).
  • All Rootella® products are OMRI-listed and suitable for organic farming according to EC 834/2007 and NOP Regulation.

Yes, Rootella® products are OMRI-listed and suitable for organic farming according to European regulation EC 834/2007 and American NOP (National Organic Program) regulation.

No, Rootella® products contain only naturally-occurring (non-GMO) fungi. Based on over 400 million years of evolution, natural mycorrhizal fungi are already well-adapted to help 90% of all plant species, without the need for any genetic modification.

A propagule is a unit of fungal inoculum that is determined by the amount of infectious tissue it contains. Such tissue can consist of viable spores, hyphae, or even pre-inoculated plant root tissue (which contain hyphae). Spore counts are typically determined visually, by examining stained inocula under a microscope. Propagule counts are obtained by means of efficacy tests, such as the Most Probably Number (MPN) test, which is performed on live plants which are each tested for inoculation. Groundwork BioAg regularly conducts three types of efficacy and visual quality tests on its products to assure calibration, accuracy and product quality. Rootella® inoculant concentrations are reported in propagule measurements, as our products contain live fungal tissue, and not merely spores.

It is estimated that 90% of the world’s plant species form mycorrhizal relationships to achieve maximum performance in their natural environments. Generally speaking, plants can be categorized as (1) non-mycotrophs, which repel mycorrhizae and cannot be inoculated, (2) facultative mycotrophs, which benefit from mycorrhizae, and (3) obligate mycotrophs, which require mycorrhizae in order to grow optimally.

Endomycorrhizal fungi, otherwise known as arbuscular mycorrhizal fungi (AMF), physically penetrate the cortical cells of plant roots, thus directly availing the plant with nutrients. Ectomycorrhizal fungi typically do not penetrate the plant root, rather wrap around the root tips. Endomycorrhizae occur in 90% of all vascular plant species and are especially relevant in the initial stages of plant growth. Ectomycorrhizae are only relevant for 10% of vascular plants, mostly trees and woody plants such as birch, eucalyptus, oak, pine, and rose, and contribute to later plant growth stages in those plants.

Rootella® products vary in formulation and in application method, as different crops and growing conditions call for different solutions. In any case, application of Rootella® mycorrhizal inoculants changes almost nothing else in your cultivation process. In general, each Rootella® product is intended for the following crops and application methods:
Product Recommended Application Method Crop Recommended Application Rate Particle Size
Rootella® G Nursery, growing media in containers Nursery vegetables, floriculture, horticulture 0.2-0.4 gr. (0.007-0.014 oz.) of Rootella® G per seedling for most small seedling plugs < 1000 µm
Rootella® P · Root dip · Root ball dip · Dusting · In-furrow dry application Row crops, tubers, bulbs, nursery vegetables, floriculture, horticulture Varies per application method < 500 µm
Rootella® S Dry applicator seed treatment Seed treatment, such as cereals and legumes, or seed pelleting for smaller seeds 120 gr/hectare or 1.76 oz./ac. for most row crops   < 250 µm
Rootella® F Planter box mix Row crops 150 gr/ha (2.14 oz./ac.) for most row crops < 250 µm
Rootella® WP · Liquid seed treatment · In-furrow liquid · Sprayer / hydro-seed · Sub-surface drip irrigation Any mycotrophic crop Varies per application method < 150 µm

No, however we wouldn’t want good product to go to waste, either! Please be advised of Groundwork BioAg’s recommended application rates (see answer to question above: “When is it good to apply Rootella® and how much?”), but don’t worry about over-application, as the plant autoregulates its mycorrhization and limits the fungi to the ideal rate.

Rootella® should normally be reapplied every season, because mycorrhizae generally survive only as long as do their host plants. In addition, when a field is tilled, or heavy pesticides are applied to the soil, etc., the mycorrhizae in the soil tend to die. Under some specific scenarios of no-tillage, cover crop cultivation or certain types of harvesting, mycorrhizae can survive from season to season, but reapplication tends to reinforce and help the existing population, and is recommended nevertheless, albeit at lower rates after the first couple of seasons.

Depending on the crop, soil type and weather conditions, effective Rootella® inoculation may likely become apparent within 1-3 months. Visual differences may include faster plant growth, heavier fruit weight, richer plant color, and fewer signs of stress in comparison to non-inoculated plants.

First, one must ascertain that the plant is in fact a mycotroph, i.e. susceptible to mycorrhizal inoculation.

Second, please make sure to follow Groundwork BioAg’s storage recommendations (as written on the product label), to make sure that the product was not exposed to sunlight or extreme temperatures or humidity, any of which can harm mycorrhizal fungi.

Finally, take note that some pesticides can kill mycorrhizal fungi. To ensure compatibility with other treatments, please check Groundwork BioAg’s Rootella® Compatibility Tool.

We recommend asking us before using fungicides together with Rootella® inoculants. As a rule of thumb, foliar fungicides (which are not systemic), herbicides and insecticides are generally compatible with Rootella® inoculants, while most systemic fungicides are incompatible. When drenching soil with fungicide, we recommend doing so at least two weeks prior to inoculation or at least four weeks after planting. To ensure compatibility with other treatments, please check Groundwork BioAg’s Rootella® Compatibility Tool. When in doubt, our technical staff are always available to help.

It is difficult to know specifics regarding natural mycorrhizal fungi already in the soil without specialized testing which describe the species, amounts and ratios, as well as how far away the most beneficial mycorrhizal fungi are from the roots of your plants. These uncertainties may delay the formation of mycorrhizae with the plant roots and therefore your plants may miss critical benefits during this time. The sooner mycorrhizae form, the sooner they start to benefit plant, and as any agronomist knows, the first days of the plant’s life cycle can be critical to success.

Also, when a field is tilled, or heavy pesticides are applied to the soil, etc., the mycorrhizae in the soil mostly die. Importantly, sterile potting soil used for containers do not contain mycorrhizal fungi, therefore it is especially beneficial to add them in these cases.

The endomycorrhizal species Glomus intraradices, which is the active ingredient in Rootella® products, is considered the “universal soldier of mycorrhiza”, as it exhibits relatively little host specificity and thus will benefit most crops. However, certain soil conditions may enhance plant responsiveness to Rootella® products. Certain unfavorable soil conditions may promote the effectiveness of Rootella® products such as low water and organic matter content, deficient soil phosphorus and nitrogen levels, heavy metal toxicity, and acidic or alkaline soil conditions. Acidic conditions limit crop production in 40% of the world’s soils, mostly because many plants do not absorb nutrients (especially phosphorus) well in acidic (pH < 5.0) or in alkaline (pH > 7.5) soils. Glomus intraradices adjusts soil pH levels in order for plants to better absorb nutrients.

High rates of fertilizers, especially inorganic and soluble phosphorus fertilizers, can hinder the formation of mycorrhizae. Mycorrhizae are sensitive to soil phosphorus levels because if there is already a surplus of phosphorous available to the plant mycorrhizae have less reason to perform. High phosphorus contents will therefore also mean that the mycorrhizae will be delayed or not perform other important duties such as increasing water and other nutrient uptake into the plant.

Available phosphorus levels should be kept in the low to moderate range per soil type, especially at the time of mycorrhizal inoculation (when the mycorrhizae attach to the plant roots). However, organic forms of fertilizers have been shown to have less inhibitory effects on mycorrhizae than inorganic, soluble fertilizers. The use of organic fertilizers, kelp, humic acids and other carbon sources have been shown to be suitable when combined with mycorrhizae. Composts are mostly compatible with mycorrhizal fungi, but caution should be taken as some compost sources may have high salt or other nutrient content that can inhibit Rootella®’s mycorrhizal fungi.

Mycorrhizal fungi increase the surface-absorbing area of roots by a magnitude of 100 to 1,000 times, thereby greatly improving the ability of the plants to access and utilize soil water, nutrients, and other resources. The fungi break down “bound” unavailable forms of these nutrients into smaller molecules that are available to the plant. In addition, these fungi then mobilize these nutrients directly to the plant roots.

Rootella® products are labelled with “best if used by” dates and will remain above the specified active ingredient concentration up to those dates (two years after manufacturing) if stored according to recommendations. After that period, the products can still be used effectively, however Groundwork BioAg cannot guarantee their potency, and would recommend increasing application rates.

Rootella® mycorrhizal inoculant must be put in direct contact with inoculable roots, which is easier (and more cost-effective) to do during the seeding or planting stage. However, if mature plants show signs of stress, then a soil injection of Rootella® WP into the root system may be advantageous.

Fallow syndrome is caused by low nutrient uptake as a result of lack of mycorrhizae. Obligate mycotrophic crops may suffer from fallow syndrome if natural mycorrhizae levels are low. Common causes of fallow syndrome are extensive tillage, soil fumigation or sterilization, or flooding. Plants grown in soilless media may also lack mycorrhizae. In addition, naturally acidic or alkaline, highly saline, heavy metal contaminated, drought-stressed or nutrient-deficient soils will likely need the aid of Rootella® for plants to better withstand these harsher soil environments. Plants grown in highly disturbed sites like road cuts, mine sites, highly eroded soils will also benefit greatly from Rootella® inoculation.

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