Saturday, January 14, 2023

Mycorrhiza: Scientific proof

Treating roses with Mycorhizza fungi decreases growing and flowering stress in times of drought and low nutrition conditions.

Some people keep repeating that treating roses with Mycorhizza is useless and that it's claims are not scientifically proven.
THIS IS NOT TRUE.
I'm gonna give two examples of  experiments regarding the symbiosis of roses and Mycorhizza. The outcome of these studies are published in scientific literature and / or in rose literature. They can be found online.
Both studies only used roses so no other plants, perennials, shrubs or trees. 

1) Royal Horticulture Society (RHS)

The British RHS is the most renowned plant society in the world. They are the authority when it comes to growing plants, trees etc so also roses.
The gardeners of the RHS began to use Mycorhizza (rootgrow, a mix of 5 mycorrhiza fungi especially for roses) in 2000. The results were so convincing and undeniable that the RHS gave the product "rootgrow" their RHS label in 2008. This meant that the RHS recognized rootgrow as a very effective and proven product in the care of roses. Well known rose nurseries such as David Austin, Peter Beales and Harkness lauded this decision because they had the same experiences with the product Rootgrow.
They stated that Rootgrow:

Decreases planting stress. Rose roots treated with mycorrhiza show a remarkable better and faster start with increased health and vigor. 
Effectively counters replant disease. Switching soil is no longer needed
Better resistance against drought

In Holland the same testimonials were heard.
The city of Amersfoort wanted to redesign its Rosarium. They planted 4000 roses treated with mycorrhiza in soil which previously contained roses for 30 years. All roses made a remarkable healthy start and no replanting disease was detected.

In 2008 the rose festival in Lottum decided to treat all their ADR roses with Mycorhizza fungi when planted. They were astonished by the speed and vigor of the roses. Some ADR roses were planted in the wrong spot together with other roses. The ADR roses grew much faster, more vigorously and could be recognized immediately by their Hight and better foliage.

The Whittington Estate in Buckinghamshire wanted to replace 400 roses in their rosarium. Each attempt failed so they tried rootgrow. They treated the roots and didn't change the soil. They added leaf compost and a mulch of manure compost. The next year not one rose had fallen out and their roots had 30% more Mycorhizza than the older roses. The second year the roots had 70% more mycorrhiza. They stopped using artificial fertilizer, chemical fungicides etc. They definitely switched to organic.

Mottisfont Abbey is probably the best know rose garden in the world together with Sissinghurst gardens. During an 8 year renovation they tried the methode used in Whittington Estate so without changing the soil. All newly roses thrived, even in soil which contained roses for more than 80 years.
Since 2012 all National Trust gardens in the UK switched to rootgrow and organic gardening.

I can add similar experiences in Belgium and Germany but you get the picture by now.

Sources:

Linderman R.G. 1988 Mycorrhizal interactions with the rhizosphere microflora: The mycorrhizosphere effect. Phytopathology 78, 366-371. 
Scagel C.F. 2001 Cultivar specific effects of mycorrhiza fungi on the rooting of miniature rose cuttings. J. Environ. Hort. 19, 15-20.
Whipps J.M. 2001 Microbial interactions and biocontrole in the rhizosphere. J. Exp. Bot. 52, 487-511.
Horticulture Week 20 May 2004; 30 June 2005
Brian Schoffield, Mycorrhizal Fungus and its Use, The White Rose News, 2005
GardenWeb forums: www.gardenweb.com

Mycorrhiza foto’s Ingrid Weissenhorn © Servaplant

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