Horsehair fungus–a mystery in the woods

Horsehair fungus–a mystery in the woods

Twigs dangle from a branch, held in place by horsehair fungus rhizospheres. Photo credit: Carrie Stevenson, UF IFAS Extension

Imagine walking through the woods, enjoying the fresh air and birdsong, when you notice a twig just dangling midair. On first glance, you might presume it is stuck in a vine or a large spider web. However, this material is thinner than a vine and there are no spiders or webs to be found. On closer inspection, you see the twig is entangled in a dark knot of string, slightly thicker than a human hair. Following the source of the black string leads to a lacy network of the same material, flat against and around the branch from which the twig hangs. Fifteen feet down the trail, you come across the same thing—more twigs hanging from “string” in the trees, dangling from a knot of thin black material. What is going on here?

After some research, my conclusion is that we have come across horsehair fungus (Mirasmius spp). Mushrooms and other fungi have long, thin, rootlike structures called rhizomorphs. Rhizomorphs are composed of large numbers of microscopic hyphae, which are tubular and exchange nutrients and water among other parts of the fungus. The hyphae are typically located underground, but in this instance, they are visible in the open.

The ropy network of rhizospheres is visible on the branch, then turns into thin fibers that can trap plant debris. Sample provided by Suzy Marshall.

Aerial rhizomorphs are an excellent example of an evolutionary strategy known as resource partitioning. By forming a netted trap to intercept falling leaf material on a tree, the fungus gets a jumpstart on the decomposition process, taking nutrients from dying plant material before it falls to the ground. The tree-dwelling fungus is thus not competing directly with fungi on the ground, and both types of fungi can thrive. In human terms, this is loosely analogous to co-workers labeling their own food in a shared refrigerator. Everyone eats, but no one has to compete with another for nutrition.

A bird’s nest in Argentina is composed primarily of strong horsehair fungus fibers. Photo credit: Danny Newman

The common name, “horsehair fungi” applies to many species around the world. They are most common in nutrient-poor subtropical and tropical forests, where any available nutrients in the soil are used up quickly by the lush tree growth. They can be found here along the Gulf Coast, up to the Appalachian Mountains, and as far away as equatorial rainforests. In a Malaysian study, researchers found that the aerial fungi trapped up to 225 pounds of fallen plant material per acre! This network of material also supported a significant population of arthropods, which were crucial parts of the overall ecosystem by providing pollination, herbivory, and serving as detritivores. One study of spruce-fir forests in the northeastern United States showed that birds are known to use the material as a nest lining, as it is lightweight but very sturdy. In this particular research, 85% of the nests (particularly of warblers and thrushes) examined utilized the material.

Video: Evergreen Shrubs in the Fall

Video: Evergreen Shrubs in the Fall

Fall is the season for leaf color changes on many plants, but we are often concerned when we see evergreen plants with brown leaves. Learn what is normal browning for evergreens and when to seek more help from UF IFAS Extension Escambia County.

Plant Growth Abnormalities

Plant Growth Abnormalities

Every so often while I am enjoying a walk through the garden, I notice a growth pattern on a plant that is just not normal.  One of the more interesting patterns I see is called fasciation.  This is a distortion of plant tissue that often causes flattened, curved, or the thinning of plant tissues.  I recently noticed this on the stem of a Coral Porterweed in the Escambia County Demonstration Garden.  The leaves were a normal shape but several inches of the stem were flattened and curved.

The distorted stem tissue of a Coral porterweed. Photo by Beth Bolles, UF IFAS Extension Escambia County.

So what is causing this type of growth pattern?

The most common cause of fasciation is usually some type of genetic mutation in the growing points of the plant.  The other possible causes could be a physical injury to new tissues, a bacterial infection, chemical injury, or even an insect injury.  Fasciation will be random in its occurrence and many gardeners may never have it occur on a plant in their yard. I have seen it on both woody and herbaceous plants in my own yard and in the demonstration gardens.

If you see a plant exhibiting this distortion of growth, you don’t need to take any action.  If the growth is unsightly to you, prune out the affected plant tissue.  It is probably best that you not propagate material from an affected plant just to prevent any transfer of the distortion to a new plant if the cause is genetic or from a living organism.

Fruit Tree Grafting Tips and Scion Selection

Fruit Tree Grafting Tips and Scion Selection

It’s mid-February, cloudy, and cold. It’s time to get outside and take cuttings for fruit and nut tree grafting. The cuttings that are grafted onto other trees are called scions. The trees or saplings that the scions are grafted to are called rootstocks. Grafting should be done when plants start to show signs of new growth, but for best results, scion wood should be cut in February and early March.

Scion Selection

Straight and smooth wood with the diameter of a pencil should be selected for scions. Water sprouts that grow upright in the center of trees work well for scion wood.  Scions should be cut to 12-18″ for storage. They should only need two to three buds each.

Scions

Scions ready for grafting. Photo Credit: Matt Lollar, University of Florida/IFAS Extension – Santa Rosa County

Scion Storage

Scions should be cut during the dormant season and refrigerated at 35-40°F until the time of grafting. If cuttings are taken in the field or far from home, then simply place them in a cooler with an ice pack until they can be refrigerated. Cuttings should be placed in a produce or zip top bag along with some damp paper towels or sphagnum moss.

Grafting

It is better to be late than early when it comes to grafting. Some years it’s still cold on Easter Sunday. Generally, mid-March to early April is a good time to graft in North Florida. Whip and tongue or bench grafting are most commonly used for fruit and nut trees. This type of graft is accomplished by cutting a diagonal cut across both the scion and the rootstock, followed by a vertical cut parallel to the grain of the wood. For more information on this type of graft please visit the Grafting Fruit Trees in the Home Orchard from the University of New Hampshire Extension.

Bench Graft

A bench graft union. Photo Credit: Matt Lollar, University of Florida/IFAS Extension – Santa Rosa County

Achieving good bench graft unions takes skill and some practice. Some people have better success using a four-flap or banana graft technique. This type of graft is accomplished by stripping most of the bark and cambium layer from a 1.5″ section of the base of the scion and by folding the back and removing a 1.5″ section of wood from the top of the rootstock.  A guide to this type of graft can be found on the Texas A&M factsheet “The Four-Flap Graft”.

Grafting is a gardening skill that can add a lot of diversity to a garden. With a little practice, patience, and knowledge any gardener can have success with grafting.

Why Don’t We Get Great Fall Color in Florida?

Why Don’t We Get Great Fall Color in Florida?

red fall color on a tree

Intense red fall color of Japanese Maple in Georgia is hard to replicate in our climate. J_McConnell, UF/IFAS

Fall is a favorite time of year for many people. Cool nights, short days, football games and the fast approaching holidays are all signs of summer coming to an end. Floridians who have relocated from other parts of the country may be disappointed to realize we get very little showy fall color even though we can grow some of the same trees in North Florida as other parts of the country. Why is that? Well, although plant breeders may promise “showy fall color” in certain selections, they really can’t promise that year after year because it’s more than just genetics influencing leaf color. Let’s take a deeper dive into the science behind fall color!

Why do the leaves change color?
Lower temperatures and shorter day length indicate to plants that winter is approaching and some physiological changes start to occur. Chlorophyll is a pigment found in leaves that, in addition to capturing sunlight and producing energy, also causes plants to display green during the growing season. As fall approaches, environmental changes tell plants to stop producing chlorophyll and existing pigment begins to break down. The reduction of chlorophyll allows the other pigments present (carotenoids and anthocyanin) to reveal their colors in an array of yellows, browns, oranges, reds, and purples. Different plants have different levels of these pigments and some may not exist at all in certain species. This explains why some plants typically turn only yellow and others may show yellow, orange, and/or red!

Why is there so much difference from year to year?

Variation occurs because environmental conditions and cultural practices play a part in determining how much color will be on display. Rainfall or irrigation amounts in the preceding summer and fall, drought cycles, nutrient levels, sunlight, and day and night temperatures all influence color from year to year.

How do I increase the potential for showy fall color in my landscape?

Choose plants with the reputation of producing desired fall colors in our area. However, keep in mind that because of the influence of outside conditions, you may be in for a surprise from year to year. To increase your chance of having a somewhat predictable fall display, use cultivars instead of seedlings of a plant species. A cultivar is a selection of a plant species that has been chosen for desirable traits, like growth habit, flowering, or fall color.  These attributes are usually easily identified by the way their names are assigned. For example, Acer rubrum ‘October Glory’ is a red maple cultivar known for a full rounded canopy and exceptional red fall color. The reason that cultivars appear more consistent is because they are genetic copies of the parent plant that they are named for. A species or seedling plant is not a clone but comes from seed, which means you will get as much genetic variation as you see in human siblings. Just like children in our own families, each will each shine in their own way and no two will be exactly alike. 

Florida Swamps Offer Fall Color

Florida Swamps Offer Fall Color

The blackgum/tupelo tree begins changing leaf color in early fall. Photo credit: Carrie Stevenson, UF IFAS Extension

Florida isn’t necessarily known for its vibrant fall foliage, but if you know where to look this time of year, you can find some amazing scenery. In late fall, the river swamps can yield beautiful fall leaf color. The shades are unique to species, too, so if you like learning to identify trees this is one of the best times of the year for it. Many of our riparian (river floodplain) areas are dominated by a handful of tree species that thrive in the moist soil of wetlands. Along freshwater creeks and rivers, these tend to be bald cypress, blackgum/tupelo, and red maple. Sweet bay magnolia (Magnolia virginiana) is also common, but its leaves stay green, with a silver-gray underside visible in the wind.

The classic “swamp tree” shape of a cypress tree is due to its buttressed trunk, an adaptation to living in wet soils. Photo credit: Carrie Stevenson, UF IFAS Extension

Bald cypress (Taxodium distichum) is one of the rare conifers that loses its leaves. In the fall, cypress tress will turn a bright rust color, dropping all their needles and leaving a skeletal, upright trunk. Blackgum/tupelo (Nyssa sylvatica) trees have nondescript, almost oval shaped leaves that will turn yellow, orange, red, and even deep purple, then slowly drop to the swamp floor. Blackgums and cypress trees share a characteristic adaptation to living in and near the water—wide, buttressed trunks. This classic “swamp” shape is a way for the trees to stabilize in the mucky, wet soil and moving water. Cypresses have the additional root support of “knees,” structures that grow from the roots and above the water to pull in oxygen and provide even more support.

A red maple leaf displaying its incredible fall colors. Photo credit: Carrie Stevenson, UF IFAS Extension

The queen of native Florida fall foliage, however, is the red maple (Acer rubrum) . Recognizable by its palm-shaped leaves and bright red stem in the growing season, its fall color is remarkable. A blazing bright red, sometimes fading to pink, orange, or streaked yellow, these trees can jump out of the landscape from miles away. A common tree throughout the Appalachian mount range, it thrives in the wetter soils of Florida swamps.

To see these colors, there are numerous beautiful hiking, paddling, and camping locations nearby, particularly throughout Blackwater State Forest and the recreation areas of Eglin Air Force Base. But even if you’re not a hiker, the next time you drive across a bridge spanning a local creek or river, look downstream. I guarantee you’ll be able to see these three tree species in all their fall glory.