Following on from the blog I wrote a year and a half ago:
''Mycorrhizal Fungi and Disease Suppression
Among the most beneficial root-inhabiting organisms, mycorrhizal fungi can cover plant roots, forming what is known as a fungal mat. The mycorrhizal fungi protect plant roots from diseases in several ways:
- By providing a physical barrier to the invading pathogen. A few examples of physical exclusion have been reported (4). Physical protection is more likely to exclude soil insects and nematodes than bacteria or fungi. However, some studies have shown that nematodes can penetrate the fungal mat (5).
- By providing antagonistic chemicals. Mycorrhizal fungi can produce a variety of antibiotics and other toxins that act against pathogenic organisms.
- By competing with the pathogen.
- By increasing the nutrient-uptake ability of plant roots. For example, improved phosphorus uptake in the host plant has commonly been associated with mychorrhizal fungi. When plants are not deprived of nutrients, they are better able to tolerate or resist disease-causing organisms.
- By changing the amount and type of plant root exudates. Pathogens dependent on certain exudates will be at a disadvantage as the exudates change.
In field studies with eggplant, fruit numbers went from an average of 3.5 per plant to an average of 5.8 per plant when inoculated withGigaspora margarita mycorrhizal fungi. Average fruit weight per plant went from 258 grams to 437 grams. A lower incidence of Verticillium wilt was also realized in the mycorrhizal plants (6).
Protection from the pathogen Fusarium oxysporum was shown in a field study using a cool-season annual grass and mycorrhizal fungi. In this study the disease was suppressed in mycorrhizae-colonized grass inoculated with the pathogen. In the absence of disease the benefit to the plant from the mycorrhizal fungi was negligible. Roots were twice as long where they had grown in the presence of both the pathogen and the mycorrhizal fungi as opposed to growing with the pathogen alone. Great care was taken in this study to assure that naturally-occurring mycorrhizal species were used that normally occur in the field with this grass, and that their density on the plant roots was typical (7).''
NCAT Agriculture Specialist
© NCAT 2004
ATTRA Publication #IP173
The above article is 6 years old and many more recent studies, particularly using Potatoes, Tomatoes and Chillies are proving that Mychorrizal is a positive addition to any land management in halting to suppress diseases. In place of any product which can eradicate the onslaught of diseases is it time to seriously consider mychorrizal products to be included as standard.
Swansea University has been one of many research centres working on and discovering uses of fungal treatments to pest and disease management.
I haven't changed my mind altogether with regards Mychorrizal products in general. They have a more specific purpose than many believe and the over use of the products could be dangerous in the long term. But following from experimentation in Paris and from previous experience in poor soils I can highly recommend using the products as standard if used properly in the following scenarios for a practitioner:
1) Tired Urban Soils, for gras, plantations, beds and urban tree planting. The risk of contaminants, lack of nutrients etc., allow the perfect location to use mychorrizal additives.
2) To allow a rapid change from a 'chemical' management regime into a natural or organic management regime.
3) In large containers for long term pot plants, for a client who is unlikely to feed at the recommended intervals.
4) Initial landscaping following the new build of a house.
We now use 'Novozyme' products habitually in Urban landscaping and the results certainly give us an edge and allow for safe guarantees. The assistance offered by agronomists working for the company give them an edge over competitors as site specific solutions are often given free.