What are Mycorrhizal Fungi?

Mark HowiesonProduct Development Specialist

Becker Underwood, Inc.

Discussion Points

• Introduction to mycorrhizae

• Reasons to inoculate

• Benefits of mycorrhizal fungi inoculation

• Mycorrhizae products available from Becker Underwood

What are Mycorrhizae?

• A mutually beneficial association between a fungus and a plant– Fungus colonizes root of host plant

• Plant provides fungus with food in return for increased nutrient absorption from soil– Greek origin meaning “fungus root”

Common Occurrence

• Most common association between microorganisms and higher plants– Early fossilized plants were mycorrhizal– 95% of all plant families are mycorrhizal

Christine Engelbrecht

Enhance Nutrient and Water Uptake

• Increases soil volume accessible to plants– Improved absorption of immobile soil nutrients– Greater efficiency of water uptake

• Facilitates uptake from nutrient pools not normally available to plants– Phosphorus often is in forms not readily

absorbed by plant roots

Types of Mycorrhizae

• Endomycorrhizae– Most common with herbaceous plants but also

associated with some woody plants

• Ectomycorrhizae– Occur mainly on roots of woody plants

Endomycorrhizae

• Also known as vesicular-arbuscular mycorrhiza • Develop arbuscules and vesicles within root

cortical cells– Arbuscules are where carbohydrates and nutrients are

exchanged– Vesicles are used as storage organs

• Common in herbaceous plants• Form associations with maple, sycamore, ash,

gum, walnut, cypress, and poplar among others

Mark Brundrett

Ectomycorrhizae

• Fungi grow between root cortical cells

• Form a mantle that covers the root surface– Roots develop a swollen appearance

– Mantle acts as a barrier to pathogens

• May develop above-ground fruiting bodies– Mushrooms and puffballs

• Common in pine, spruce, fir, beech, eucalyptus, alder, oak, and hickory

Mark Brundrett

Mark Brundrett

Reasons to Inoculate

• Mycorrhizal fungi are present in almost all soils

• Intensive management practices limit viability and infectivity of native mycorrhizal fungi– Excessive applications of chemical fertilizers

and pesticides

Fungicides and Mycorrhizal Fungi

• Label usage rates and application methods (spray/injection) normally has no effect on mycorrhizal fungi– Metabolized by soil microbes

• Drenches/Soil Injection may have detrimental effects

• General rule: avoid use of fungicides 2 - 3 weeks before and after inoculation

Reasons to Inoculate

• Severe soil disturbances like erosion, tillage, compaction

• Often absent in sterilized or soil-less potting media

• Non-native transplants grown in soil and climactic conditions different from the areas where they are planted

• Plants established in areas prone to environmental stresses

Benefits of Mycorrhizae Inoculation

• Improves establishment rates– Enhances

phosphorus acquisition

– Increases solubility of normally unavailable forms of phosphorus

Benefits of Mycorrhizae Inoculation

• Enhances drought tolerance– Mycorrhizae improves

water uptake efficiency– Increases below ground

surface area for water absorption

Benefits of Mycorrhizae Inoculation

• Decreases transplant shock and increases survival and growth in the field– Transplant success depends on how quickly a

plant can reestablish its root system– Mycorrhizal fungi rapidly develop below

ground surface area for nutrient and water uptake

Rhizanova® Tree Injectable

• Ideal for newly planted or young non-coniferous trees

• Contains a blend of endo- and ectomycorrhizal fungi combined with humic substances

• Applied with professional soil injection equipment

Rhizanova® Pt Tree Injectable

• Beneficial for newly planted or young coniferous trees

• Blend of multiple strains of ectomycorrhizal fungi combined with humic substances

• Applied with professional soil injection equipment

Rhizanova® Tree Transplant

• A dry mix ideal for most transplanting applications

• Formulated with a blend of endo- and ectomycorrhizae– Water absorbing polymer– Organic fertilizer and humic acid

• Mixed into backfill or incorporated into potting media at planting

Advantages of Rhizanova®

• Emphasis on quality of inoculum– Becker-Underwood is an ISO 9001 registered

company– Species selected for effectiveness with the

broadest range of plants

• No unnecessary amendments– High rates of phosphorus fertilizers

Quality-Tested Inoculum

• INVAM at West Virginia University– Independent laboratory

analysis

– Verifies viability and infectivity of inoculum

• The only certified inoculum in the industry

Mycorrhizal colonization of Ponderosa pine roots by Becker-Underwood Tree Transplant and Tree Root Dip inoculants in tests conducted by Mycorrhizal Applications, Grant’s Pass, OR in 1998.

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Inoculum

Tree TransplantTree Root DipUntreated check

Take Home Messages

• Mycorrhizae improve plant growth– Increase supply of nutrients to plant

– Enhance water uptake efficiency

• Benefits of inoculating with mycorrhizal fungi– Improved plant establishment rates

– Increased drought resistance

– Decreased transplant shock and improved survival

Questions?

Host Plants

• Endomycorrhizae– Acacia, Ash, Bay, Boxelder, Buckeye, Cedar, Chokeberry, Cherry,

Cottonwood, Crabapple, Cypress, Dogwood, Elm, Ginkgo, Gum, Hackberry, Hawthorn, Holly, Horsechestnut, Juniper,Locust, Magnolia, Maple, Mesquite, Mimosa, Mulberry, Palm, Persimmon, Redbud, Redwood, Russian Olive, Serviceberry, Sumac, Sycamore, Tupelo, Walnut, Yew

• Ectomycorrhizae– Alder, Arborvitae, Aspen, Basswood, Beech, Birch, Chestnut, Fir,

Hemlock, Hickory, Larch, Linden, Oak, Pecan, Pine, Spruce• Both

– Eucalyptus, Willow, Poplar

Phosphorus Response Curve

Adapted from Jasper et al. 1994

Cassia pruinosa

Pesticide Interactions

– Toxic: Carbamates (Maneb, Zineb), PCNB, Chlorothalonil (Daconil, Bravo), Triazoles (Bayleton), Benomyl (Benlate)

– Non-toxic: Aliette, Captan, Carbendazim, Metalaxyl (Ridomil, Subdue)