Are exposed tree roots a problem?
"Fielding Questions" columnist Don Kinzler also answers reader questions about a white coating on a local lawn and if there are crack-proof tomato varieties.
Q: I’m attaching photos of the exposed roots of a maple tree in my yard. Since the roots are now so exposed, I can’t mow over them and I’m wondering if I can cover them with dirt and reseed grass? — Scott B.
A: Thanks for the chance to discuss roots that appear partially above ground. Roots are supposed to stay below ground, right? Well, not necessarily. A hike through the woods teaches us to watch where we’re walking, because it’s easy to stumble over the surface roots of older trees. A few surface roots, partially exposed, are natural, especially with some tree species like maples.
A tree’s root system is much shallower than we often consider, spreading horizontally much wider than deep. Most of a tree’s root system is contained in the upper 1 to 2 feet of soil, radiating out from the tree.
Although roots protruding slightly above soil surface are natural, admittedly they can cause trouble when mowing or walking near the tree. Although some sources suggest cutting and removing the offending roots, such as one per year, this is definitely NOT recommended by research universities like Cornell. Cutting large roots can weaken a tree’s support system.
There are several options. It’s generally safe to fill around the roots with 1 to 2 inches of non-heavy topsoil. Compost or loam is a better choice than heavy clay. Adding a too-deep layer of soil can smother roots and lead to tree decline.
Alternatively, instead of grass, mulch around the tree and between roots with shredded wood and forego mowing, if the roots are contained within a circular area that would make this feasible.
Q: After my last lawn application of fertilizer and the cooler weather, I now have white mold in my backyard. The lawn is shaded so it doesn’t get much sun. What should I do to make sure it will not cause more problems for my other plants or kill grass? — LeRoy J.
A: The white coating on grass is most likely the fungus called powdering mildew, which gives the turf a white or light gray appearance. Grass blades are covered with masses of white fungal spores.
As Purdue University mentions, “The disease is rarely responsible for any lasting damage to turf, so its effects are primarily aesthetic.” Powdery mildew occurs most often in shaded areas, and is favored by cool, cloudy conditions common in spring and fall, along with periods of high humidity. Nitrogen lawn fertilizer has also been associated with increased mildew in shaded areas.
Although the fungus doesn't harm the grass, if it's a recurring problem there are fungicides that can be applied to the lawn as preventatives before the mildew appears. Check garden centers for products labeled for powdery mildew control on Kentucky bluegrass turf.
The fungus that causes powdery mildew on lawns cannot infect other plants, so you don’t have to worry about causing problems for other plant types. Peonies, lilacs and other plants are also commonly affected by powdery mildews, but those mildews are caused by totally different fungi than the species that infects turf.
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Q: In your recent "Fielding Questions" column, you discussed cracking of tomatoes, and mentioned some varieties less prone to cracking . Remarkably, the sport we discovered on a Crimson Sprinter tomato plant, which we call Dakota Sport, does not crack at all. It has a very thin skin but perhaps it is elastic at the same time. — David Podoll, Prairie Road Organic Seed.
A: Thanks, David, for mentioning Dakota Sport tomato. Prairie Road Organic Seed Co., in Fullerton N.D., is a producer of a wide selection of garden seed varieties specially developed and grown for Northern gardens , including Sweet Dakota Rose Watermelon, Uncle David’s Dakota Dessert Squash, Dakota Tears Onion, Sweet Dakota Bliss Beets and many more, plus the tomato mentioned.
Dakota Sport tomato is a main season variety, maturing at 65 to 75 days. The fruits are bright red and very glossy. Besides its striking shiny appearance, it was developed for superior flavor, crack resistance, vigorous production and disease resistance. Fruits are medium-sized slicers and the plants tolerate cool conditions. Seed can be obtained from the Prairie Road Organic online catalog.
If you have a gardening or lawn care question, email Don Kinzler, NDSU Extension-Cass County, at firstname.lastname@example.org. Questions with broad appeal may be published, so please include your name, city and state for appropriate advice.