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Mushrooms growing amongst pines in a forest can be indicative of much more than merely the rotting of organic matter. Many fungi have symbiotic relationships with vascular plants. These relationships involve trees such as pines, oaks, and eucalyptus, and include your garden vegetable plants and flowers. Knowing about mycorrhizae, what they do for plants, and how you can grow them with your plants can enable you to obtain their benefits for yourself in your own garden plot or yard.
They're rooting for us!
Mushrooms are not just for eating, and that white webby stuff you see under your organic mulch is not necessarily just the mulch slowly rotting away. Within your soil is a whole hidden world of activity that affects how well your plants grow. Teeming microorganisms in healthy soil, including fungi and bacteria, work alongside each other to break down organic matter and free up vital elements for use by your plants. But what about our gardens? Oftentimes, we are trying to grow our plants in severely disturbed soil, plots that were once farmland, or land bulldozed for housing developments. Such situations are poor in the kinds of soil biota that your plants need. To make things worse, the application of chemical fertilizer can throw things even further off balance. The out-of-balance situation fosters the growth of what we call pathogenic organisms. Our response to those is often the application of toxic pesticides. Is it no wonder why we sometimes find it difficult to grow a nice garden?
Does my plant need an innie or an outie?
Amidst the bustling action in healthy soil are fungi that have special relationships with plant roots. These fungi actually grow together with, or even within, roots and by so doing vastly expand the ability of the roots to access soil nutrients. Roots with such assistance are called "mycorrhizae", meaning "fungus roots". Pine (Pinus) and Barberry (Berberis) are two well-known genera of trees that have ectomycorrhizae, or mycorrhizae that grow externally to the root cells. An example of Rhizopogon ectomycorrhizae found on Barberry roots can be seen in the picture below, left. Another example, below right, is Amanita ectomycorrhizae on Pine roots. You can think of these fungi as the "outies". These are also the types that most often produce mushrooms in the soil near their hosts. For example, note that Amanita, shown on the pine roots, is the fly agaric mushroom, and Rhizopogon is the genus of the North American truffle.
Another kind of mycorrhizal fungus is known as vesicular-arbuscular (VA), or endomycorrhizae. The thumbnail picture above shows an endomycorrhizal corn root, with spores also visible. These are the type found in association with your vegetable and flower plants. Hyphae of these fungi actually penetrate the root cells and tissue of the plants they are in association with. Endomycorrhizal fungi are the "innies". The innies are in the group of fungi known as "water molds". This group also includes such notorious pathogens as Pythium, the cause of damping-off, and Phytophthora, responsible for crown and root rot. The presence of the endomycorrhizae can help your garden plants fend off the nasties without the use of toxic chemicals.
Knowing whether your plant needs an innie or an outie is crucial to getting the kind of response you want from these special fungi. Inoculating an outie plant with an innie mycorrhizal fungus will give you little or no results. Since there are a large number of both types of fungi in nature, commercially available formulations of mycorrhizae are usually a blend of many species of the two types. Look for blends that include mycorrhizal spores, as some formulations may contain chopped-up fungal hyphae instead of spores.
Sometimes information on the mycorrhizal fungus specific to your plants is available. If it is, you can select the particular type that is best for your situation. Innies are generally non-specific as to their host, while outies are more particular to hosts.
The difference is clear
I've grown Rainbow Eucalyptus tree seedlings with and without the mycorrhizae and the difference is dramatic. Eucalyptus happens to require the outie, or ectomycorrhizal, type of fungus. With the mycorrhizae, the plant is much greener and healthier even when fertilized less often. The fertilizer that is applied is utilized much more efficiently. Without the mycorrhizae, more fertilizer is required and the trees lack in overall health. One caution: too much fertilizer can defeat the purpose of mycorrhizal inoculation. These fungi are most helpful in making phosphorus more available to plants, so an abundance of available phosphorus in the soil will nullify their usefulness. Besides helping with nutrient uptake, mycorrhizae can aid your trees and plants in withstanding stresses such as drought and heat. They are also vitally important in restoring areas stripped of vegetation, such as some kinds of surface mining sites or waste areas.
Where can I get mycorrhizae?
Mycorrhizal blends are available from a number of online vendors. Several of these sources are Fungi Perfecti, Bio-Organics, and Mycorrhizal Products. If you are growing a variety of plants, including woody shrubs, trees, and vegetables or flowers, an endo-ectomycorrhizal blend is your best choice. For those whose primary interest is vegetable crops, an endomycorrhizal blend will be optimal. Some blends even include micronutrients with the mycorrhizae. Study the information presented on these and other websites and you will become knowledgeable about the types of mycorrhizae that will be most beneficial for your use.
Endomycorrhizal photo by Sara Wright, USDA-ARS and ectomycorrhizal pictures by Randy Molina, Forest Mycology Team, Pacific Northwest Research Station, Forestry Sciences Laboratory.
About LariAnn Garner
LariAnn has been gardening and working with plants since her teenage years growing up in Maryland. Her intense interest in plants led her to college at the University of Florida, where she obtained her Bachelor's degree in Botany and Master of Agriculture in Plant Physiology. In the late 1970s she began hybridizing Alocasias, and that work has expanded to Philodendrons, Anthuriums, and Caladiums as well. She lives in south Florida with her partner and son and is research director at Aroidia Research, her privately funded organization devoted to the study and breeding of new, hardier, and more interesting aroid plants.
Posted by esteve59 (from Annapolis, MD) on February 22, 2008 at 8:09 AM:
Hi,
Can anyone tell me if " Espoma Bio-tone Starter plus" has suffifient Mycorrhizae.Currently I have many house plants,bonsai and outside plants.
Heres a link:
[HYPERLINK@www.espoma.com]
Thanks,
Steve
...
Posted by LariAnn (from Miami, FL) on February 22, 2008 at 11:14 AM:
The mix of ecto-and endo-mycorrhizae looks good, as well as the other beneficial microbes listed. I've written Espoma to determine if the mycorrhizae are spores or chopped up hyphae. Once I receive a reply, I'll post the information.
LariAnn
Aroidia Research
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Subject: T-22 fungus
Posted by Indy (from Alexandria, IN) on February 13, 2008 at 8:04 PM:
Cornell developed a strain of [bio]fungus called T-22. I understand that nurseries use this product which is designed to colonize on the roots and keep the bad fungals crowded out.
Johnny's Seed sells one type.
...
Posted by LariAnn (from Miami, FL) on February 13, 2008 at 8:14 PM:
T-22 is a selection of Trichoderma harzanium, a naturally-occurring beneficial fungus that functions differently from the mycorrhizal fungi I discussed in my article. I plan to cover Trichoderma as well as other beneficial fungi and bacteria in an upcoming article about biocontrol microorganisms.
...
Subject: possible purchase
Posted by dbsmith2 (from Amsterdam, NY) on February 13, 2008 at 1:56 PM:
I was inspired by your article, so I have written 2 of the companies about a possible co-op for Daves Garden members. I also called the manufacturer of pro mix with biofungicide to ask if I could use Mycorrhizal products with that particular blend. They said yes for the endo, but weren't sure about the echto.
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Posted by LariAnn (from Miami, FL) on February 13, 2008 at 2:13 PM:
I use the ProMix BX which, I believe, already has endomycorrhizae in the mix. Adding ecto should not hurt anything, since many mycorrhizal blends contain species of both fungi. Keep me informed about the possible co-op.
...
Posted by dbsmith2 (from Amsterdam, NY) on February 13, 2008 at 2:42 PM:
Apparently, you get the biofungicide or the mycorrhizae in their blends. Troy recommended that I use the biofungicide when I have issues with rot - cuttings, seedlings, small transplants, then change over to the BX when potting up. They found some synergistic action between the biofungicide and the endo in their research.
I'll inform you first when I start the thread for interest.
...
Subject: Orchids
Posted by rosa18 (from Bartlett, IL) on February 13, 2008 at 11:37 AM:
Hi LariAnn,
Would this be beneficial to put in Orchid plants that grow in a bark medium?
I've just started using it on other plants last summer, but have acquired some orchids and am curious as to using it in the potting medium.
Thanks much, Jill
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Posted by rosa18 (from Bartlett, IL) on February 13, 2008 at 11:41 AM:
I went ahead to one of the websites listed and saw that Orchids do not respond.
Thank you for a good article, and will continue to use it on my other plants.
Jill
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Posted by LariAnn (from Miami, FL) on February 13, 2008 at 12:14 PM:
Jill,
Actually, Orchids have their own kind of specialized mycorrhizae. Theirs is different from the other two kinds, and usually is systemic; i.e., it is there with the tiny Orchid seedling when it first starts out. I remember looking at Orchid root cross-sections in Plant Anatomy class; the Orchid roots were completely surrounded by fungal hyphae. The gray color of the Orchid roots is all fungal hyphae. The very tip of the root, the green part, is the "real" Orchid tissue. I didn't cover Orchid mycorrhizae in my article because you don't really need to inoculate them with it. They are "born" with it, as it were!
LariAnn
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Subject: Good article
Posted by doccat5 (from Fredericksburg, VA) on February 13, 2008 at 8:14 AM:
This is excellent information. Thanks for sharing :)
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Posted by cathy4 (from St. Louis County, MO) on February 13, 2008 at 10:58 AM:
Great information, thank you!
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Posted by darius (from Marion, VA) on February 13, 2008 at 11:17 AM:
Very Good! It sounds as if the mycorrhizae are among the critters that feed off the rock dust I wrote about.
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Posted by carrielamont (from Milton, MA) on February 13, 2008 at 3:18 PM:
Wow! I can see I have a lot to learn, but it ;looks like it' s important stuff to learn, so i may read this article about 300K times over the next 6 mos. to make sure I really understand it. Thank you, LariAnn!
x, Carrie
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Posted by margaran (from Jacksonville, FL) on February 22, 2008 at 12:18 AM:
Another kind of mycorrhizal fungus is known as vesicular-arbuscular (VA), or endomycorrhizae. The thumbnail picture above shows an endomycorrhizal corn root, with spores also visible. These are the type found in association with your vegetable and flower plants. Hyphae of these fungi actually penetrate the root cells and tissue of the plants they are in association with. Endomycorrhizal fungi are the "innies". The innies are in the group of fungi known as "water molds". This group also includes such notorious pathogens as Pythium, the cause of damping-off, and Phytophthora, responsible for crown and root rot. The presence of the endomycorrhizae can help your garden plants fend off the nasties without the use of toxic chemicals.
