Landscape Questions

As I am writing this article, it’s a beautiful  day in southeast Michigan.  Just the type of day you wish you could bottle for releasing in the months ahead. While no one can predict the weather with great accuracy, we know that if winter sets in quickly in November, late season plantings suffer higher loss rates. As you read this article, take stock of the weather, if a prolonged, mild fall doesn’t seem to be in the works, you may be time and money ahead by delaying planting until next spring. Certainly, perennial and evergreen plantings should be re- scheduled for next spring unless the client is willing to underwrite the risk. If rainfall has been sparse, advise clients to irrigate evergreen plantings before the soil freezes. Dry soil conditions can aggravate winter dessication damage; however, moist soil is not a guarantee against injury. All to often, I see broadleaf evergreens placed in sunny, open, and wind swept environments where damage can only be prevented with extensive physical barriers.

Q: We have a client with a wetland area that has a high water table.  Usually, planting holes deeper than about 24 inches will fill with water to the 24 inch depth. Flooding and ponding of watering is not a problem. To reforest the area with a naturalized appearance, we have been planting arborvitae. Unfortunately, the 6 to 8 ft. B & B plants have been dying.  Since these plants are native (white cedar) to Michigan swamps, why won’t they survive in this area?

A: Here’s my interpretation of the problem. Yes, it is true that arborvitae or white cedar are native trees that are adapted to swampy conditions.  However, there is a major difference between planting 6 ft. tall trees in these conditions and letting “Mother Nature” do the work. Here’s the difference. In the wild, the trees establish themselves from germinating seed. Many seeds land in areas that are too wet. These seeds may germinate but the plants can’t grow where there is not sufficient oxygen for root growth. Plants in these conditions may stay stunted or die after some period of time. Plants lucky enough to find a slight ridge or knoll where there is more aeration in the soil will grow more vigorously. As the plants grow, the roots that find suitable conditions will prosper and multiply. In turn, the plant will continue to grow as the root system increases. Over time, large specimens can develop in wetland areas. But, the roots have found suitable conditions for growth.  Your procedure is exactly the opposite. You’re taking a nursery grown tree with a root system that developed in a well aerated, nursery soil. The plant is dug with a portion of the root system included in the rootball. Next, you’re taking this plant and placing the rootball into a very moist and poorly aerated soil condition. Most of the roots can’t withstand these conditions and they die. Between the root loss during digging and the root loss from excessive moisture, the plant simply can’t absorb sufficient water and nutrients to stay plant alive. After all, the plant developed with a matching root system, and it can’t thrive or even live if much of it is lost. If you’re still determined to grow white cedar in this area and if you have patience, try this approach. Find some much smaller plants, such as seedlings or small transplants. Plant these plants on any areas of high ground or create small knolls with topsoil. As the plants grow, they will largely root in the surface soil where the aeration is suitable for root growth.

Q: Many of our lawn mowing customers are asking us to lower the mowing height in the fall. We have been using the “mow high and let the clips lay” approach. What do you think?

A: Dropping the mowing height is not required in the fall. However, you should continue to mow your lawns until all growth has ceased. You don’t want your lawns to become excessively long before winter sets in because the grass may matt down and become more susceptible to snow mold and rodent damage. If reducing the mowing height will help with fall cleanup, you can reduce the mowing height to about 1 ½ inches for the last couple of mowings.  Be careful not to “scalp” the grass by mowing too short. Even the 1 ½ inch height can be too short if you have irregular areas within your customers’ yards. If you “scalp” the grass, you can kill the grass plants. This damage can be far more serious and lasting than allowing the grass to be just a little too long before winter moves in. Too many gardening books suggest moving the mowing height up and down during the season. Except for renovations and clean ups, these changes are not needed.  Q: The M.S.U. Plant Diagnostic Lab has indicated that some of our clients’ plants are dying from verticillium wilt. Since no treatment is completely successful, we need to replant with plants that won’t be infected. Any suggestions?

A: Since you failed to mention the types of plants that are causing the problem, I’ll provide a brief overview of some possible replacements. Here goes... apple, beech, birch, conifers, mountain ash, dogwood, hawthorn, locust, oak, pear, sycamore, plane tree, hornbeam, and Katsuratree. Note, Ohio State University pathologists report that red maple cultivars “Armstrong”, “Autumn Flame”, “Bowhall”, “October Glory”, “Red Sunset”, “Scarlet”, and “Schlessinger” seem to be resistant. However, always proceed carefully when using limited data.

Q: We seem to be having a tough time transplanting spruce successfully.

Until recently, we never seemed to have a problem with 6 foot, B & B stock.  To compound the problem, most of the plants don’t die. They develop scattered and clustered dead branches, and then the clients want replacements for plants that aren’t dead but look lousy.  

A: Assuming the planting sites are well drained but provide reasonable soil moisture, spruce should be easy to transplant. If the roots are damaged or if the rootballs are too small, you can expect dieback or death of individual branches. However, another possible culprit is a “little known” spruce disease called phomopsis blight. Most landscapers are familiar with a close relative that causes serious damage to many juniper cultivars, but they are not familiar with this disease on spruce. Plants that are stressed due to transplant shock and site conditions are prime candidates for this disease. The symptoms are identical to your description. Yes, a spraying program can protect plants and be used to save plants with a modest infection level. However, before you jump to conclusions, you should obtain a copy of M.S.U. Extension publication E-2417, “Phomopsis Blight of Spruce.” This publications provides color photos of the disease and considerable diagnostic information plus suggestions for fungicide applications. I would also strongly advise that samples be sent to the M.S.U. Plant Diagnostic Lab for confirmation of the disease. Contact your local M.S.U. Extension office to obtain the publication and guidelines for submitting samples to the M.S.U. Lab.