Fungal diseases in plants are always a problem, likely even more so this spring since we’ve been living through monsoon season. Likely, many of you are starting to experience powdery mildew or some other form of moisture induced disease on some of your plants. However, as we learn more about soil chemistry, we are becoming aware of the relationship between plant roots and fungus, especially one called mycorrhizae.

Mycorrhiza means “fungal root” and this fungus exists in a relationship to plant roots that is beneficial to both the plant and the fungus. Because of this dependent relationship, the mycorrhiza fungus is not able to survive without a plant to call home for very long.

At the risk of getting too technical about this, there are two types of mycorrhizae: ectomycorrhizae and endomychorrhizae (spell check on this article is going crazy about now.) Ectomycorrhizae are found at the ends of young, tender roots, where they penetrate the outer walls of the root cells. Endomycorrhizae penetrate the plant’s roots to live and grow within the plant. Here’s out their mutually beneficial relationship works.

Mycorrhizae are not able to produce their own carbohydrates. So, the fungus extracts the carbohydrates it needs from the host plant. In exchange, the mycorrhizae absorb nutrients from the soil and pass those on to the plant.

Mycorrhizae have tiny little parts that reach out into the soil called hyphae. Think of these hyphae as similar to roots only much smaller than plant roots. For the most part they are about 1/60^th the diameter of small plant roots. Because of this small size, they are able to absorb nutrients in ways that the plant roots can’t. This additional is great for the plants, helping them increase their ability to absorb nitrogen, phosphorus, zinc, manganese, and copper.

As an added benefit, the mycorrhizae help increase the ability of plants to not only better tolerate drought, but can also help increase crop production, enhance flowering, and last but not least, improved soil structure.

Mycorrhizae are considered beneficial for about 90% of all plant species. Rather than list that 90%, here’s some of the plants that don’t seem to benefit from mycorrhizae: azalea, blueberry, beets, broccoli, cabbage/kale, Brussels sprouts, cauliflower, carnation, cranberry, cauliflower, mustard, huckleberry rhododendron, spinach, and sedge.

Mycorrhizae additives are available to purchase for your garden, but this is not typically necessary since the mycorrhizae fungi can be found in most soils. However, if you have had your soil tested and found that your nutrient levels in the soil are correct but you are still having issues getting your plants to grow, a little dose of store-bought mycorrhizae wouldn’t be a bad idea. These supplements are available in powdered form, as well as granular, or in a liquid solution. To supplement or not to supplement, that is the question. But now you know. Good luck!

You can get answers to all your gardening questions by calling the Tulsa Master Gardeners Help Line at 918-746-3701, dropping by our Diagnostic Center at 4116 E. 15th Street, or by emailing us at mg@tulsamastergardeners.org. Photo: Robert L. Anderson, USDA Forest Service, Bugwood.org