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I have tiny black spots all over the outside of my home and it was suggested that they could be mulch mold spores. Do you have any information that may help me to stop or control this problem?
Artillery fungus spots, shown here, can appear on home siding and cars and are extremely difficult to remove. The fungus grows in organic mulches and can shoot spore masses into the air.
Have you ever noticed tiny fly-speck-like spots appearing on cars parked near mulched areas? The spots may be the spore-filled projectiles fired by an organism, Sphaerobolus stellatus, sometimes called the "shotgun fungus" or "artillery fungus".
While the spotting is worst near the mulch, some spots can be found up to 15 feet away from it. The organism grows primarily on small pieces of wood near the soil surface that stay wet. Eventually fugal mycelia knit the woody material together into a mat that can be pulled up in chunks. Small sockets can be observed where the spore masses have been ejected.
The fungus grows primarily on wood, rather than bark mulch and tends to eject its spore masses during cool, wet weather. The organism also seems to be somewhat phototropic, often firing its projectiles toward shiny or light colored surfaces. If your car is being targeted by Sphaerobolus artillery, simply covering woody mulch with bark mulch will reduce the problem.
Chris Starbuck
State Extension Specialist
Woody Ornamentals
I have a Colorado Blue Spruce tree that has been turning yellowish, but retaining its needles. Should I be concerned?
There are several possibilities that could cause this condition.
I would suggest taking a sample from the tree that has some green needles and some yellow and bringing it to the Plant Diagnostic Lab, 1-43 Agriculture Building on campus. A photo of the trees would also help (digital, polaroid or print).
Chris Starbuck
State Extension Specialist
Woody Ornamentals
In order to be effective, chemical treatment to prevent sweetgum trees from producing "gum balls," must be applied when the female flower, left, has opened below the male flowers.
I have two beautiful sweetgums planted beside the walkway and the balls fall off on the sidewalk and are dangerous. Is there chemical substance you can spread around the bottom of sweetgums to keep the tree from producing balls and if so is it safe for the tree?
Florel Fruit Eliminator, manufactured by Monterey Chemical Company, prevents fruit formation on sweetgums. It is used at a rate of 1 quart per 10 gallons of spray and must be sprayed to run off on the flowers when the flower clusters begin to separate and the leaves are about half expanded. There is a narrow time window, two weeks at most, when it will be effective and it should only be applied when the temperature is between 65 and 95 degrees Fahrenheit. Do not spray trees under stress from disease, drought, or other causes.
If you are interested in trying it, I have seen it in garden centers in central Missouri. Or it can be purchased from Hummert International in St. Louis, 314-506-4500. Perhaps a local garden center may be interested in purchasing some for you and a few other customers.
It may be challenging to spray to the top of a large tree. For large trees or when multiple trees must be treated, it is best to retain the services of a firm with the proper equipment to do the job. If one gets good coverage at the proper time, the product is usually effective in preventing fruit development.
A newer product called Snipper can be injected into the trunk using the Tree Tech microinjection. This product contains the growth regulator indolebutyric acid as the active ingredient. I have not heard about the effectiveness of this product. You might check with some of the local arborists and tree services in your area.
There is a cultivar of sweetgum, Liquidambar styraciflua ‘Rotundiloba’, that is fruitless. It was discovered in 1930 near Pinehurst, North Carolina. While several of these have been planted at Missouri Botanical Garden it should be noted that this planted is generally considered hardy only to Zone 6.
Chris Starbuck
State Extension Specialist
Woody Ornamentals
I want to purchase two to four awesome fall colored trees with good shape. I've been looking at the Autumn Blaze Maple, Red Sunset Maple and the Sugar Maple. I want bright orange, yellow and orangy-red, not marroon or plum. They will be planted in a new construction residential area with lots of clay in the soil and near an open field where there is a lot of wind from all directions. There will be plenty of room around the new trees. Can you recommend any other vibrant fall colored trees that are fast growers, easy to maintain and extremely hardy as far as soil and wind problems? Also, I like the birch trees with the white trunks that peel and again, they have to have beautiful fall colors. Can you recommend any birch trees that fall under the same conditions as my maple tree needs?
In general, you are on the right track with plants like Autumn Blaze maple. Red Sunset and October Glory are the most commonly planted trees for fall color because they tolerante a wide range of conditions. I have been impressed with Autumn Blaze because of its rapid growth rate and excellent fall color. As you note, however, red maples are red, not orange.
October Glory has more orange coloration than any of the other red maples.
Northwood is also somewhat orange. The only maple I know of with a true orange color is sugar maple. Unfortunately, this is a plant that does not perform well in your type of environment.
If you can live with reddish purple, some of the white ash cultivars like Autumn Applause are adaptable, fast growing and stiking in fall color.
My personal favorite for fall color (scarlet, yellow, orange, purple all on the same branch) in Missouri is black gum (Nyssa sylvatica). It also has a nice form but is somewhat difficult to get established and fairly slow growing.
Regarding the birch, most people plant Heritage river birch. This is fast growing and more tolerant of the suburban desert than any of the other birches I know of. The fall color is a clear yellow. I don't think any birches have a red or orange fall color.
Chris Starbuck
State Extension Specialist
Woody Ornamentals
I bought two potted red maple trees (October Glory and Red Sunset) about eight feet tall, at a local store. Both have been trimmed to have dual leaders at the top. Some side branches are also trimmed this way. I have always read that it is best to have a single leader. Do I leave them this way?
The branching pattern you describe is a function of the opposite bud arrangement of maples. I doubt that the plants were trimmed to make them like this. You are right that narrow branch angles with the main trunk are weak points that may increase storm damage in the future. I think you could easily correct the problem while the plants are still fairly small by simply removing the least vigorous of the two competing stems on each tree. Cut cleanly back to the main stem and do not leave any stubs. Eventually, the natural branching pattern will prevail, but maintaining a single leader to 10 or 15 feet will greatly reduce the chance of storm damage to the trees when they reach their mature size.
Chris Starbuck
State Extension Specialist
Woody Ornamentals
Updated 5/19/08