Mycorrhizae: Do They Belong in the Pot?

Chad P. Giblin and Jeffrey H. Gillman

University of Minnesota

Department of Horticultural Science

Mycorrhizae Facts

• Colonize roots and surrounding soil
• Ectomycorrhizae surround roots
• VA (vesicular-arbuscular) myorrhizae “infect” roots
• Can improve nutrient and water uptake
• Assist in disease and pest resistance
• Fungal pathogens
• Soil nematodes

Current Knowledge – Forestry

• Improved adaptation to poor soils
• Better transplant success
• Most effective under low fertility
• Mycorrhizae colonization inhibited by high phosphorus levels

Current Knowledge – Mycorrhizae in Containers Stock

• Most research done on forest trees
• Different responses found when compared to field grown trials
• Slow-release fertilizers have shown both positive and negative responses

Experiment Setup

• Rooted Cuttings
• Hypericum kalmianum
• Potentilla fruticosa ‘Fargo’
• Spiraea X bumalda ‘Anthony Waterer’
• Four Mycorrhizae Inoculants
• Rhizanova
• Local Nursery Mix
• MycorTree Saver
• Bio/Organics

Results

Spiraea X bumalda ‘Anthony Waterer’ Dry Shoot and Root Mass

Potentilla fruticosa ‘Fargo’ Dry Shoot And Root Mass

Hypericum kalmianum Dry Shoot and Root Mass

Why Didn’t the Mycorrhizae Really Help?

Mycorrhizal Parasitism

• Container media provides a rich growing substrate
• Container media is usually high in fertility
• The cost-benefit relationship is upset causing the fungi to parasitize the host