Mycorrhizas

FUNGUS
Fungi are neither plant nor animals but a very different type of organism. They do not contain chlorophyll or the molecule used in   photosynthesis to produce sugars with the help of sunlight. They do not have a root system like that found in trees, shrubs, flowers, and grasses. As a result, they cannot manufacture their own food, but, do feed themselves by digesting organic matter.

Mushroom hunters are familiar with many of the mycorrhizal fungi characteristics of the north temperate forests; especially basidiomycetes such as gilled mushrooms, chanterelles, boletes, corals, puffballs, and jelly fungi. Mycorrhizas in these forests have a small percentage of ascomycetes such as morels, truffles, cup fungi, and elfin saddles. Lesser known of the more common mycorrhizal fungi are the zygomycetes, relatives of black bread mold.

Fungi can be divided into three basic categories based on their relationship to their environment:

  • Parasitic fungi that live off of living plants and animal tissue.
  • Saprophytic fungi that live on dead wood, dead tissue of living trees, or dung.
  • Mycorrhizal fungi that have a symbiotic or mutually beneficial relationship with the rootlets of other plants and are not limited to trees.

MYCORRHIZAL FUNGI
In 1885, A. B. Frank coined the word mycorrhiza by combining the classic Greek word for fungus (=mykes) root (=rhiza). Mycorrhizas are  ancient. Fossil records show that roots evolved alongside fungal partners about 350 to 500 million years ago. It is believed that this “mutualistic  association” was crucial in assisting plants evolve and colonize the land millions of years ago.

While many species of fungus do not form a symbiotic relationship, the vast majority of land plants, between 80% and 90%, have mycorrhizas.

In this symbiotic relationship, plants photosynthesize providing carbon and other vital substances to the fungi. In return, the fungi provide the plant with mineral nutrients, such as phosphorus, nitrogen, and extra water that they take up from the soil.

Plants, being capable of producing their own food can potential survive without the fungus. Fungi, however, are often completely dependent on the live plant for sustenance and, thus, it could be considered a parasite of the plant.

For example, orchids are very dependent on mycorrhizas for all or part of their life cycle. They cannot germinate fully without being infected by a fungus. These plants have thousands of tiny seeds that contain no food reserves for growth (unlike nuts). They therefore depend on help from  fungi in order to obtain enough food to survive. The fungi perish in the course of the orchid’s development and are absorbed by the orchids. If this host specific action does not take place, the fungus spreads and becomes parasitic. This is why only a small percentage of seedlings develop in many orchid species.

Dwarf Rattlesnake Plantain Orchid (Goodyera repens) is dependent on mycorrhizas (Rhizoctonia lanuginose) that live within the plant’s roots and are given protection by the plant. Before the orchid has begun to photosynthesize, the fungus provides it with carbon. When the plant is mature, the mycorrhiza will mainly provide the nutrients.

There are over 400 species of plants that lack chlorophyll. These achlorophyllous plants are found in many families and the majority relies on
fungal associates for the carbohydrates that these plants would produce through photosynthesis. In some cases an entire plant family is  achlorophyllous like the Indian Pipe (Monotropaceae spp.) while in others (Orchidaceae spp.) only certain genera lack chlorophyll.

MUTUAL BENEFITS OF MYCORRHIZAL FUNGI AND PLANTS
If you have ever admired the beauty of an orchid, eaten some freshly picked blueberries, or sat in the shade of a magnificent oak tree, you have benefited from the underground world of mycorrhizal fungi.

Many botanists and ecologists are coming to the realization that lowly fungi play a major role in the ecosystem. Fungi are the cornerstones of a woodland ecosystem and yet their impact is often overlooked.

The sketch reveals something of the world beneath the surface of the forest floor.

There are parasitic fungi that have their hyphae penetrating the roots of the plant resulting in some mushrooms at the base of the trunk of a small tree.

The mushrooms from the mycorrhizal fungus are shown linking several plants. The buried fruiting bodies of a mycorrhizal, truffle-like fungus also can connect several plants. The mycelium of yet another mycorrhizal fungus can form fruiting bodies on dead wood (saprophytic mushrooms).

Mycorrhizal associations can be fairly complex, with more than one fungal species and more than one type of mycorrhiza, simultaneously  attached to the roots of one plant. Conversely, a given mycelium may be attached to more than one plant, perhaps even to plants of different species.

This latter plant-mycelium-plant connection allows the carbohydrates produced by one plant to move through the attached mycelium to another plant. As shown in the sketch, a seedling growing in heavy shade benefits from the photosynthesizing activities of another plant growing under more favorable conditions.

The formation of the mycelium-root connection is not just a simple matter of fungus meets plant and fungus hooks onto plant. There are soil bacteria, known as mycorrhizal helper bacteria, which promote the formation of mycorrhizas.

Plants allow and most require mycorrhizal fungi to colonize their roots. In this mutually beneficial relationship, the hyphae of the fungus greatly increases the surface area that is open to nutrient and water absorption, maximizing the plants access to these essential compounds and elements. In return the plant supplies the fungus with carbohydrates for use as energy. The fungi also can help the plants contend with summer droughts and protect them from pathogens, like nematodes, that attack their roots.

Phosphorus is a relatively immobile element in the soil. Mycorrhizas are able to absorb large amounts of phosphorus by decomposing its organic sources. The mycorrhiza hyphae also maximize the surface area available to access phosphorus. Research indicates that mycorrhizas increase the phosphorus concentration in host plants by up to 40% compared to non-mycorrhizal plants.

DIFFERENT TYPES OF MYCORRHIZAS
There are a number of different kinds of mycorrhizas but those that most mushroom hunters are interested in are the Ectomycorrhizas (mushrooms and truffles).

Ectomycorrhizas: Ectomycorrhizas (“ecto” = outside) is the fungus growing on the surface of the feeder roots of plants and can usually be distinguished with the naked eye. Their name comes from a well-developed furry growth called the fungal hyphae (= mantle or sheath) that that covers the outside of the fine root tips (periradical phase). Many hyphae emanate from the mantle into the soil to form the extraradical (radical = root) phase. Sporocarps develop from the extraradical mycelium. Sporocarps are the fruiting body of a fungus that produces and releases the
reproductive spores. Large sporocarps found above the ground are called mushrooms and those below the ground are called truffles.

The fruiting bodies of truffles, being completely submerged beneath the soil, do not forcibly discharge their spores and rely upon underground vectors and mammals, such as squirrels, chipmunks, and voles, for spore dispersal. These genera are often found living with the roots of oak,  hazel, sweet chestnut, pecan, and a few other trees.

Ectomycorrhizas are composed of at least 65 fungal genera; most are in the phylum Basidiomycota, although some are Ascomycota. Well known genera in the Basidiomycota include Amanita and in the Ascomycota, Tuber (truffle) and Morchella (morels).

Ectomycorrhizas colonize about 3% of all seed plants (Angiosperms and Gymnosperms) or about 140 genera including but not limited to Pinus (pine), Picea (spruce), Eucalyptus, Fagus (beech), Betula (birch), and Quercus (oak).

The ectomycorrhizas display varying degrees of host specificity. Some fungal species colonize many plant species and some fungal species colonize the same individual plant. There is some evidence that non-native ectomycorrhizal fungi are “invasive” and are becoming associated with plants with which they have never had an association with in the past.

Ectendomycorrhizas: This is a subgroup of the Ectomycorrhizas. These exist with or without a mantle, with a Hartig net, and cellular penetration by hyphal coils. They are restricted mostly to the plant families Pinus (pine). Most place these fungi in the phylum Ascomycota.
Endomycorrhizas: Endomycorrhizas (“endo” = inside) do not form a mantle around the fine tips and thus do not have a periradical phase. They often have a well-developed extraradical phase as a mycelial network throughout the soil. These do not form complex sporocarps (mushrooms and truffles) and instead reproduce by means of large spores (10 to 50 times greater than mushroom spores) that remain in and move with the soil.

The Endomycorrhizal group has been essentially dismantled and specific types are now recognized. These are:

  • Vesicular-arbuscular mycorrhizas (VAM)
  • Arbuscular mycorrhizas (AM) since they lack vesicles
  • Orchid mycorrhizas
  • Ericales: Ericoid, Arbutoid, Monotropoid.

The mycorrhizas associated with order Ericales are:
Ericoid Mycorrhizas:
Ericoid mycorrhizas are somewhat similar VAM, in that the fungus invades the host cells, but affect only plants in the family Ericaceae (heather, rhododendron, and blueberry family).

Arbutoid mycorrhizas: These have a mantle, Hartig net, and cellular penetrations by hyphal coils are mostly found in the Theaceae family (Camellia spp). The fungi of Arbutoid mycorrhizas are in the Basidiomycota phylum.

Monotropoid mycorrhizas: These may have a mantle, Hartig net and cellular penetration. They are found in Montropa species (Indian pipe).

MYCORRHIZAL FUNGI AND HOST PLANTS
Of the roughly 70,000 fungi species and 300,000 plant species, only a very small percentage plants can or must enter into mycorrhizal relationships. There are about 5,000 types of ectomycorrhizal species but only about 150 endomycorrhizal species.

It appears that mycorrhizal fungi have evolved different strategies to out compete other mycorrhizas in the ecological environment. Ectomycorrhizal fungi species tend to form associations with specific host plant species or a restricted number of them. Endomycorrhizal fungal species are “generalists” and can associate with hundreds of different host plant species.

For example, research indicates that Ectomycorrhizas and Ericoid mycorrhizas can process organic nitrogen most efficiently for their host plants whereas Endomycorrhizas can process inorganic nitrogen most efficiently for their host plant. Ectomycorrhizal plants can exist, therefore, in soils that are poor in inorganic nitrogen but very high in organic nitrogen.

A summary of the various plants and their predominant mycorrhizas are given at the end of the newsletter.

Azaleas For The Southern Garden

There are over 900 species of azaleas (Rhododendron spp.) and over 8000 recognized hybrids. Azaleas belong to the Ericaceae family (the heath family which includes blueberries and mountain laurels) and are used extensively by gardeners. These plants freely hybridize and there are new cultivars introduced every year. Gardeners should seek out the new cultivars to add excitement to the spring garden.

The azalea is found all over the world but most notable horticultural species are indigenous to Japan, China, and the United States. In the US, native azaleas are found in the Pacific Northwest and the Southeastern US. Most azaleas grown by home gardeners are the Asian evergreen varieties, although the native deciduous Piedmont Azalea is still prized by many. The plant’s beautiful blooms and stout character has earned it a place in most American gardens. The azalea is a favorite of gardeners and is grown by the millions in southeastern nurseries.

The azalea is a tough plant when properly planted in an adequate site. Azaleas prefer cool, partially shaded sites. Although some varieties tolerate sun better than others, they all prefer an area that is not exposed to long periods of hot full sun and drying winds. Flowers last longer when plants  are partially shaded. Azaleas exposed to full sun are more susceptible to lace bugs.

Proper cultural practices are the first line of defense against insects and diseases. Cultural factors to consider when choosing a site for an azalea include the soil type and drainage (azaleas require good drainage), the amount of sun (azaleas are primarily a shade species), pH of soil (azaleas require low/acid pH), and temperature (azaleas are killed by frost in zones lower than 5). Iron is essential for healthy azaleas. Iron is available for uptake by azaleas when the soil pH is low (acidic). When soil pH is too high (alkaline), iron becomes unavailable and chlorosis, or yellowing of the youngest leaves, may occur. A sign of iron chlorosis is the area between the veins turning yellow or light green, and the veins are darker green.  Application of iron as a foliage spray will usually give quick, temporary results when applied during the growing season.

Poor drainage is the main cultural factor that predisposes azaleas to attacks by pests. Azaleas are shallow rooted, have very fine roots, and will  wilt rapidly. They must be kept adequately irrigated at all times to prevent stress. Plant azaleas in shallow holes with several inches of the root ball above the soil surface and mulch deeply with decomposed mulch. Prune in the spring after flowering. Pruning after July will remove the blooms that have been set for the following year. Fertilize with an “acid loving” plant fertilizer and water as needed. When planted and maintained correctly, the azalea will resist pests and bring beauty to the garden like few other plants can.

Creating Curb Appeal – Do it Right The First Time!

Is your week hectic like mine? Running from one task to another? Juggling family, career, household, volunteer activities, and more…leaving no time for the landscape? After the day is done and you drive into your neighborhood and approach your driveway, are you squinting your eyes filtering out what uglies lurk in your landscape? As you enter your home, throw your keys and mail on the counter, do you shut the blinds to hide what you don’t want to see outside? If you answered, “yes” to any of these questions, you have LAS, Landscape Avoidance Syndrome…………..O.K., I just made that up but many of us suffer from it!

How about making a spring and summer resolution? Thou shalt make thy dwelling beautiful! Perhaps, like many, you’re inexperienced at this, have no idea where to start, and you’re overwhelmed. Hopefully, the following tips will take the fear out of gardening and get you on the right track to creating the beautiful curb appeal you so desire.

QUICK TIPS
Keep a clean edge
Trench around existing pine islands 3” deep and wide. This will help to keep the grass/groundcovers out as well as have a neat appearance. This works much better around pine islands in the lawn than using borders such as pavers or rock. It is much easier to maintain and mow along the edge.

In areas where shade has increased over the years and your lawn is declining, it will be best to expand the bed line and eliminate the declining lawn. When laying out new bed lines, use a hose to create gentle curves. Try to stick to an ‘S’ curve and keep it to two waves. Once you’re satisfied with the shape spray it out with spray paint. Landscape spray paint is available at most hardware stores. If this new bed encompasses lawn, either dig the existing lawn out (I prefer this) or spray with glyphosate (Roundup) prior to planting.

Spruce up the mulch
Keep a good layer of 3” deep mulch on your beds all year. This will help to discourage seed germination, keep roots moist, will break down and amend the soil, and keep soil born diseases from plants. Add your mulch in the winter after leaves have fallen and in mid summer when it starts looking faded. Avoid using gravel as a ground cover in beds. Gravel will act as a heat sink and does not amend the soil. It’s also very difficult to re-work the soil or add additional plants to soil that have a layer of gravel on it. If you have a slope, use shredded pine park mulch; it will adhere to the slope better than pine straw.

Maintenance
Pruning can be very time consuming so avoid plants that need lots of pruning; this also falls into the category of choosing the right size shrub/tree for the space. Prune leggy or sparse looking shrubs and remove any dead or diseased branches. More mature shrubs often look better “limbed up” and turned into a topiary tree-like shape. Winter is usually the best time to prune trees and shrubs. If pruning in the summer, don’t  remove more than 25% of the foliage. If the plant is a spring bloomer (blooms before May), then prune just after it blooms to avoid cutting off bloom buds.

Avoid plants that require lots of watering. Using drought tolerant plants will save you time and money. Remember to water you’re newly planted shrubs, trees, etc. until established. Even during the winter, watering is needed. The best means to water is by soaker hose, especially during a drought. This will save at least 50% more water than a traditional sprinkler.

Use native plants. Plants that are native to our area can tolerate are heat and drought conditions better than most non-natives. They are also more disease resistant than most non-natives. So there’s usually no need to use harsh chemicals.

Stay ahead of “weeds”
The definition of a weed is a plant out of place…so Bermuda grass can definitely be considered a weed at times. Avoid plants that re-seed all over your garden or have underground runners that invade and smother other plants. Use a pre-emergence in mid September to prevent germination of cool season weeds in winter. Use again in late February or early March to prevent germination of warm season weeds in summer. If you’re organically minded, use corn gluten and top with 3” of mulch in garden beds. For existing weeds, use a post-emergence for broadleaf and grassy weeds. Remember to always read the label carefully. If you need help in identifying weeds and diseases, contact your county extension office. Staying ahead of the weed game will definitely lighten the maintenance burden.

DESIGN TIPS
Plant in swaths and groupings
Try to group smaller plants together in odd numbers. For shrubs that are 3’ x 3’ and smaller, I tend to put in a group of at least 3-5. Place larger  shrubs, those at least 4’ x 4’ and larger, in groups of 3 or treat the shrub as an accent or focal point (if it is very unusual) and plant it by itself. Don’t have more than one focal point in the same garden “room”. Stay away from planting in rows or perfect circles but plant in “drifts” or triangular shapes.

Repeat plant groupings and balance
Repeat certain groupings for unity and harmony throughout the landscape. Balance your plantings. It can be asymmetrical and still be balanced. Especially balance your evergreens so the landscape looks attractive in the winter.

Selecting the plants
For starters, challenge yourself to stick with seven different species (NOT seven plants total). Mix sizes, shapes, colors, and textures for interest…but remember that simple is sometimes best. You don’t have to have a plant in every space.  Sometimes a piece of sculpture works well to break up, add interest, or just give your eyes a rest.

Remember finer small foliage gives the appearance of being further away; larger foliage (especially glossy leaves) looks closer. So in an area you want to give the appearance of being larger, use finer foliage. In an area you want to look smaller (cozier), use larger, glossy foliage.

Dark colors and shades of blue look further away and cooler. Bright and light colors jump forward. Red, yellows, oranges add warmth. Stick with 1 to 2 main colors and have 1 or 2 accent colors. Try to stick with a total of 3…sometimes 4 will work if you stay in the same or similar hues.

Remember the size relationship between plants. Know the size and shape before planting. Watch for power lines, water pipes, rooflines, walkways, etc. Also know the plants desired growing condition. Does it prefer sun, shade, moisture, dry, etc? Keep in mind that plants that prefer part to full shade can handle early morning sun (eastern exposure) but need protection from afternoon sun.

Plant your largest trees first. These might be a combination of deciduous and evergreen. Then place your large and medium evergreen shrubs so that they are balanced throughout the landscape. If you’re not sure what’s evergreen, plant in the winter to be sure. Then place your deciduous shrubs. Then fill in with perennials and groundcovers.

Do not plant aggressive ground covers (like ivy or vinca) in beds with perennials or low growing shrubs; it will smother them. It’s actually easier to care for a bed in a wooded area with no ground cover than with. In the winter, blow or rake your leaves into the beds (with no ground cover) and top with a thin layer of pine straw for a neater appearance.

A good place to grow a low growing groundcover (such as lamium, creeping jenny, mondo grass, which are less than a few inches tall) is in a walkway or perhaps around stepping-stones. But keep in mind; eliminating weeds is easier to tackle when there is no ground cover to pick  through.

If you are one of those impulse buyers (must have that cool new plant, like me), designate ‘nursing beds’. These are planting beds that can  temporarily house some of those new buys. Last but not least, it’s important to have a landscape design plan so you know what the big picture is.
This way it won’t look like a hodgepodge of plants. You might want to contact a landscape designer to draw up a design (to scale) for your landscape. Once you have a plan in place, then you can concentrate on a particular area and do it at a pace that is comfortable for you.

Important numbers to remember
Call before you dig to get utilities marked! Call 1-800-282-7411 (usually within 2 weeks of installation). Get a soil test to determine nutrient deficiencies. This information and much more is available through your county extension office. To find the contact information for your County Extension office, call 1- 800-ASK-UGA1.

Great Websites
Publication Soil Preparation and Planting Procedures for Ornamental Plants in the Landscape:
http://pubs.caes.uga.edu/caespubs/pubcd/B932-w.htm
Publication Lawns of Georgia: http://pubs.caes.uga.edu/caespubs/pubcd/b773-w.html
Walter Reeve’s website: www.walterreeves.com
Georgia Native Plant Society: www.gnps.org

Looking Forward to Spring Ephermerals

Once again the spring ephemerals are carpeting the forest and woodland floor only to be quickly admired and sleep again until next year. Spring ephemerals (i fem’ ur als) are plants whose glory lasts but a few days but the memory of their haunting beauty will remain with you for months come. You will find yourself looking expectantly for their return the following spring. These native wonders emerge before the trees leaf out as they must acquire enough sunlight to produce seed and store energy before the forest canopy fills in. Then they fade away until next year. Let’s walk gingerly along an imaginary path and enjoy the fleeting beauty of spring’s earliest wonders.

Hepatica americana, Liverleaf, is one of the earliest harbingers of spring. It bears dainty 1/2” white flowers blushed with pink or deep blue. The flowers are born on stalks which leap into view directly from the plant’s center. You will find fine hairs growing along the stalks. The leaf cycle is interesting as before the new leaves unfurl, the blossoms are often bursting into bloom. The leathery leaves will then open to bask in the sunlight. Once established, the Liverleaf will blanket a woodland floor. You will need to look carefully to admire its beauty; however, as this miniature plant never reaches more than 6 inches tall.

Further along our woodland path we find our next attractive ephemeral, the Trout Lily or Dogtooth Violet, Erythronium americanum. Trout Lilies are said to acquire their name from the speckled leaves which are reminiscent of the speckled skin of a trout. It generally grows in colonies of dozens to hundreds of plants and will spread prolifically on underground runners. Small yellow to brownish flowers may be hidden beneath the leaf litter on the woods floor or may be too pale to be easily noticed. Once you recognize the leaf pattern, there will be little doubt as to the plant’s identity. They are found frequently near streams, rich woods, or on wooded slopes, Erythronium americanum will bloom from March to May on 4 to 10 inch plants that sport the often pale-colored one inch flowers.

The exceptionally flashy Jack-in-the-Pulpit, rising heads above the Trout Lily and the Liverleaf, is terrific and found in moist woodlands. Its coloration varies with deep purple, red, brown or white stripes on its slender green spathe. Also known as Arisaema triphyllum, Jack-in-the-Pulpit displays its unusual hooded “pulpit” on tall stems. Standing 1 to 3 feet, it exhibits only two or three leaves with each leaf consisting of three glossy green leaflets, hence the triphyllum portion of it name; tri meaning three and phyllum meaning leaf. This is one woodland native that boldly announces its presence. Clusters of red berries appear under the wilted spathe and provide food for passing wildlife.

While enjoying your stroll down our woodland path, you will most likely be tempted to “bring a little piece of this or that plant home” with you. This is not a good idea. Many our ephemerals are protected by the Endangered Species Act. Others are sheltered in Georgia by the Georgia  Department of Natural Resources. Also, most wild plants do not transplant well. They are growing in conditions that are often difficult to duplicate in the home garden. Native mycorrhizal fungi exist in natural habitats. These fungi are critical to successful growth of many ephemerals and wildflowers. Commercial propagation makes many of these plants available for you to purchase at garden centers or nurseries without damage to them in their native habitat. Be responsible! Purchase your plants from nursery-propagated stock from reputable, licensed mail order  catalogues or at specialized nurseries.

Stay alert on your next outdoor excursion and you will surely find one of these beauties to mystify you. Once you recognize them for what they are, ephemerals will captivate you. Have fun and choose from any number of outstanding native ephemerals that are available commercially.