Mycorrhizal Fungi

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Mycorrhizal fungi form mutually beneficial relationships with over 95% of common plant species.

They surround and even enter the roots of these plants, and provide nutrients such as phosphorus (and to a lesser degree, nitrogen) and water to plants in exchange for carbohydrates.

In fact, some plants may trade more than 50% of their carbohydrates with these fungi and other microbes. Fungal mycelium represents carbon drawn from the atmosphere and stored in solid form underground.

The fungi also greatly improve soil characteristics by improving soil structure and porosity.

And, amazingly, they act as a line of defense, protecting the roots in the soil environment.

My clients and I have both seen huge benefits from using mycorrhizal fungi when planting.

Gardeners have also reported reduced plant losses when planting in less than ideal conditions.

The product seems to be especially helpful in improving the quality and health of a newly seeded lawn.

In soil that has recently been tilled/worked, compacted, waterlogged, drought-stressed, or treated with chemicals, mycorrhiza will be lacking. They are not present in imported topsoil or most potting soil mixes, either, and they cannot be multiplied in compost as they need a living plant host to survive.

In any of these scenarios, they need to be added back to the soil. They are essential to optimum plant health and should always be used whenever planting or seeding.

Mycorrhizae Categories

There are two main categories of mycorrhizae relationships:

• Endomycorrhizal fungi (arbuscular mycorrhizal fungi) form relationships with over 90% of plants, including turf grasses. Interestingly they do not form fruiting bodies (mushrooms), but instead release their spores directly within the soil.
• Ectomycorrhizal fungi form relationships with fewer plant species, but some of them are quite common, such as hedging cedars, other conifers, and many hardwood trees.

This short mycorrhizae list (pdf) shows many common plants forming relationships.

And here’s a much more detailed mycorrhizal list (pdf) if you are looking for something in particular.

Please note that there are a few plants that do not respond to either endo or ectomycorrhizal fungi, namely members of the brassica family (broccoli, Brussels sprouts, cabbage, cauliflower, collards, kale, and rutabaga); members of the Ericaceae family (rhododendron and azalea, blueberry, cranberry, heath and heather, huckleberry, lingonberry), as well as beets, mustard, spinach, and orchids.

Mycorrhizal Fungi Products

Endomycorrhizal Fungi

Myke Pro WP, also sold as Myke Pro Turf or Greenhouse, is a highly concentrated wettable powder containing Glomus intraradices.

Used for seeding, laying sod, taking cuttings, potting up, and generally planting/transplanting/dividing plants, or for applying to established lawns and gardens.

Suitable for most annuals, herbs, flowers, and vegetables; turf grasses and ornamental grasses; ferns; perennial flowers; most fruit trees; common deciduous and broadleaf evergreen ornamental trees and shrubs.

Endo/Ectomycorrhizal Fungi

Root Rescue is a concentrated wettable powder containing eighteen different species of Glomus, Gigaspora, Rhizopogon, Pisolithus, Laccaria, and Suillus fungi.

Used for propagating, planting, or transplanting. Besides plants that partner with endo-mycorrhizae, Root Rescue also covers those woody plants that benefit from ectomycorrhizal fungi (or take both endo and ecto), such as:

Most conifers including hedge cedars, Douglas Fir, true fir, hemlock, larch, pine, and spruce; as well as alder, arbutus, beech, birch, chestnut, eucalyptus, filbert/hazelnut, hickory, linden, oak, pecan, poplar, and willow.

Root Rescue offers larger units and case discounts — contact me if you’re a commercial grower.

Mycorrhizal Fungi Application

The best time to apply mycorrhizal inoculant is at the plant production stage, but since your plants probably didn’t have that done, the next best time is at planting/seeding/sodding. This will promote contact between the fungi and plant roots.

Rub the product directly on the root ball if possible, or sprinkle in the planting hole. You can also mix the powder with water and apply the liquid. Bare roots can be dipped into the liquid. For seed, mix the dry powder with the seed before spreading. For sod, sprinkle it dry or spray the liquid on the soil right before laying the sod, or even better, right on the bottom of the sod (I know that can be time-consuming). You could spray it on after as well.

The other choice would be to apply the mycorrhizal fungi products to existing landscapes. For trees and shrub beds, grab a garden fork and poke a lot of holes around the feeder root zone, away from the trunk. This will help both powder or liquid to enter the soil and get to where it’s needed.

For turf, it is best to do this right after aerating so that more of the spores get down to the roots. Otherwise, it can be watered in, but will not be as effective on heavy clay or very compacted soils.

Be sure to keep agitating/stirring the liquid as the powder tends to settle at the bottom. Mixing several smaller batches rather than using the entire amount at once helps ensure even distribution.

The powder can be mixed with other microbial products and organic fertilizers and applied at the same time, although there is no benefit to foliar feeding with mycorrhizal fungi products, as they need to touch the roots.

Application rates for powdered endo (Myke Pro WP)

Mix with tepid water to avoid temperature shock, or mix into compost for even distribution in the soil.

If mixing with water, use 200 liters for a full bag of 600g, or 100 liters for 300g, or 50 liters for the starter size of 150g; generally, a heaping tablespoon of powder (30g) in 10 liters of water will cover 1,000 square feet. Start by pre-mixing the powder with a small amount of water and dilute gradually.

Keep agitating the tank (or shake the watering can or spray bottle) so the product stays in suspension. Should the spray equipment become clogged, remove the filter or adjust the nozzle to make larger drops.

Applying the liquid:

• 50 ml per cutting
• 80 ml per 4″ pot
• 125 ml (1/2 cup) per 1gal container
• 250 ml (1 cup) per 2gal container
• 625 ml (2 1/2 cups) per 5gal container
• 1250 ml (5 cups) per 10gal container
• Or pour into trenches or holes around plant root zones at approximately these rates.

Applying to turf:

Use 30g (a heaping tablespoon) of powder mixed with 10 liters of water per 1,000 square feet. 150g covers 5,000 sq ft; 300g covers 10,000 sq ft; 600g covers 20,000 sq ft. Especially effective after aeration, before backfilling with compost.

When seeding turf, mix dry powder uniformly with seeds at 30g per 1,000 sq ft.

Applying dry powder to plants and soil:

Use approximately one teaspoon per tree, a pinch per shrub or flower, or a quick root dip for a vegetable start. It is easier to mix the product with finely screened compost or dry soil for even distribution.

Turf Product Info | Greenhouse Product Info

Application rates for powdered endo/ecto (Root Rescue)

This finely powdered, dark-coloured endo-ecto product is used much like the Myke powder, and best mixed with water, except the dosage is a bit different. If the amounts of water recommended by the manufacturer seem high, this is because you should saturate the rootball and also drench the soil used for backfilling the planting hole.

How much do you need? Generally, use 4.5g (1 teaspoon) of powder in 7.5L (2 gallons, the volume of a standard watering can) of water. The 22.5g package mixes with 37.5 liters (10 gallons) and can treat 20 one-gallon plants or one 60mm tree. The 45g package makes 75 liters (20 gallons) and can treat 40 one-gallon plants or two 60mm trees, and the 90g package yields 150 liters (40 gallons) of solution and can treat 80 one-gallon plants or four 60mm trees.

Applying the liquid:

• 0.7 liters per cutting
• 1.2 liters per 4″ pot
• 1.87 liters (1/2 gallon) per 1gal container
• 3.75 liters (1 gallon) per 2gal container
• 37.5 liters (10 gallons) per large shrub or tree

How long does it keep? Store tightly sealed, dry, cool and dark. After the best before date, Root Rescue is still 90% viable for another full year if stored correctly, so just use 10% more for normal effectiveness. Mix and use only what you want to apply the same day. Diluted mixed product does not keep long.

Good Application Instructions | MSDS