Frequently Asked Questions

Q. What are mycorrhizal fungi?
A. Mycorrhizal fungi live in soil and colonize roots forming a biological link between the plants and the soil. The fungus grows on or into the root and extends hyphae into the soil. Mycorrhizae absorb water and nutrients from the soil and introduce them into the root. Mycorrhizae can solubilise nutrients like phosphate that are locked up in the soil.  They effectively enlarge the root system and its surface area from double to up  to 1000 times so mycorrhizal plants have access to much more nutrient and water than non mycorrhizal plants to grow faster and larger.

Q. Which plants associate with mycorrhizae?
A. About 95% of plants form a symbiotic association with mycorrhizal fungi , for the average garden the only plants that do not associate are brassicas e.g. cabbages, brussel sprouts and beets very few annual plants and grasses.

Q. Do all plants need the same mycorrhizal fungi?
A. No. Most perennial plants, shrubs trees, vegetables and grasses associate with endo mycorrhizae that live in the root system. Coniferous trees and oak beech birch chestnut and hickory associate with ecto mycorrhizae. These live in the soil on the outside of the root. Ericaceous plants and orchids associate with their own species as well.

Q. When is inoculation with mycorrhizal fungi needed?
A. Mycorrhizae live on the roots of plants so if your field, vegetable patch or flower bed has been left without plants for more than a few weeks there will not be any mycorrhizae present inoculation is needed. Nursery grown plants grown in sterile growing media and fed with fertiliser, water and pesticides will not have mycorrhizal associations and inoculation is needed. If you plant a conifer or beech tree into a lawn or grassland the mycorrhizae in the soil will be endo mycorrhizae the wrong type for conifers so inoculation with ecto mycorrhizae will be needed. If you are planting into heavily disturbed soil, salted or fertilised soil on a building site, ploughed field, roadside or landscaping project inoculation will be needed.

Q. How do I apply mycorrhizal inoculums?
A. Mycorrhizal fungi live on the roots so any method you employ to get the mycorrhizae onto the root of the plant will work.
For seeds you can mix with inoculum before planting or dust power into the seed drill.

For all other transplants either dust or drench the mycorrhizae onto the roots before planting or apply to the planting pit.
For stressed established trees either drill down to the roots with a fork or augur around the drip line approx 0.5 meters apart,  put the mycorrhizae  in a solution with enough water to reach the feeder roots and pour it down the holes; or use specialist ground aeration equipment e.g. Gwazae to aerate and inject the soil.

Q. Can I overdose?
A. Effectively no but do not put too much carrier around seeds.

Q. What is the minimum amount of inoculum needed to form mycorrhizae?
A. In theory Mycorrhizae can form from only one spore that germinates and infects a root,
In practice you get a better result by spreading spores evenly around the root system. Different products have different spore quantities so we suggest that the manufacturers recommendations are followed.

Q. Are some types of mycorrhizae better for some plants or soil conditions?
A. Yes that is why Symbio has eight different species of endo mycorrhizae and seven different species of ecto mycorrhizae in its products to account for most conditions and plants.

Q. Can I apply pesticides with mycorrhizal fungi?
A. Foliar pesticides usually do not have any adverse effects on mycorrhizae formation or function. Some fungicides applied to soil do inhibit mycorrhizae a link to fungicide compatibility; soil fumigants such as steaming or methyl bromide do kill mycorrhizal fungi.

Q. Do fertilizer applications affect mycorrhizae?
A. Mycorrhizae absorb nutrients into the plant and take carbon from the plant to grow. If the plant is sitting in a sea of inorganic soluble fertiliser especially phosphorous it does not need mycorrhizal fungi to access nutrients and mycorrhizal formation will be inhibited or cease. Use organic forms of fertilisers where possible or as a general rule reduce inorganic fertilisers by about 50% to get the same growth result.

Q. Do mycorrhizae control plant diseases?
A. Mycorrhizae improve the health of plants and their roots, so diseases may cause less damage. Mycorrhizae and symbiotic bacteria and fungi also form a barrier around the root system so it may be more difficult for pathogens to attack the plant allowing mycorrhizal plants to better resist infections by plant pathogens.

Q. Are mycorrhizal fungi present in compost?
A. No. Mycorrhizae need living plant roots to survive.

Q. How long do mycorrhizal fungi survive in soil without an active root system?
A. Endo mycorrhizae survive for a short term most no more than a few weeks without a host plant to live on. Ecto mycorrhizae may survive for longer periods.

Q. Are mycorrhizal fungi present in compost?
A. No. Mycorrhizae need living plant roots to survive.

Q. Can mycorrhizal inoculum be applied to established plants?
A. There is little point in adding mycorrhizae to a healthy well established plant as it will most likely be colonised. However if the tree, shrub or vine is stressed due to compaction, over fertilization with inorganic fertilisers (mineral salts), road salt or if the plant has not grown since being transplanted then inoculation will probably help.

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