Yard & Garden Line News Volume 8 Number 14                                                               September 1, 2006

Features this issue: It's Prime Time For Lawn Repair Brace Yourself For Boxelder Bugs Garden Calendar Editorial Notes

It's Prime Time For Lawn Repair
Bob Mugaas, Regional Extension Educator, Horticulture

Mid-summer crispy

Same lawn, some rain, by Sept. 1 Photos: Bob Mugaas

Because of cooler temperatures, increased chances for rainfall and lack of competition from summer annual weeds, late summer is the best time of year for seeding new lawns or overseeding to repair weak and damaged lawns. For purposes of seeding lawns, late summer is considered to be from about August 15 to September 15 in the Twin Cities.

The high temperatures and dry conditions of this past summer put significant stress on our lawn grasses, even to the point of causing permanent injury. Thus, the first step in doing any lawn repair will be to assess the degree of actual lawn injury that occurred. Even though some areas may be quite brown, when examining the base of the grass plants, there may be some new growth just beginning to get started. If that is the case, these areas should recover on there own. A light dose of fertilizer along with a ample moisture will help them continue to grow and reestablish the area. For those areas where no there are no signs of life, additional seeding or sodding will be needed to restore the lawn.

If the grass has thinned out but is not completely dead, a process known as overseeding can be done to thicken up the existing turfgrass cover. Overseeding literally means to spread seed over an existing turfgrass cover. However, for the purposes of this article overseeding will also include the process of repairing areas that are completely dead. It is important to remember that the success of any overseeding project depends on achieving good seed to soil contact. For that reason, simply throwing seed over a lawn area in hopes that some will "take" usually has very limited success. Overseeding can be done either by machine or by hand. Most rental agencies will carry a couple different types of overseeders. Mechanical overseeders do a good job of placing the seed in contact with the soil and hence usually yield very good results when used correctly. They are also the more efficient way to reseed larger areas.

For lawns that are primarily bluegrass, choose similar seed mixtures such that the newly seeded areas will match the color and texture of the existing lawn. Where the lawn appears to be a mixture of very fine textured grasses and medium textured grasses, it is likely that there are both fine fescues and Kentucky bluegrasses present in the lawn. In this case choose a seed mixture that has both fine fescue and Kentucky bluegrass in it. Again, this will help ensure the best match to the existing lawn.

Where there are only limited areas of severely damaged or killed turfgrass, hand seeding can work just fine. First, aggressively rake out all of the dead grass and thatch from the area. If there are a few live plants that resist being raked out leave them to regrow and become part of the new lawn in that area. While doing this raking, try to leave about a ¼ to ½ inch of loose soil on the surface. This loose soil layer will become the seed bed for the new seeds that will help ensure good seed to soil contact.

Older grasses in front and far back. Brown portion was newer, less drought-tolerant. Photo: Beth Jarvis

Once the area has been prepared, lightly sprinkle seed over the surface. Enough seed should be sown such that the area is uniformly covered with seed but not so thick that it you can barely see the soil surface. Too high of seeding rate produces many small seedlings that will severely compete with each other for light, water and nutrients. This plant-to-plant competition can significantly slow down the establishment process and can open the door for certain diseases and weeds to invade. After seeding the area, lightly rake the seed into the existing soil and lightly tamp the area to firm up the soil surface. As a rule of thumb, after the seed has been raked into the soil, there should only be about 10% of the seed visible on the soil surface. Water thoroughly right after seeding and then keep the area just damp to the touch. Never keep the soil in a wet, muddy condition.

In many instances it may be more convenient or easier to match existing lawn varieties by resodding the area. Sod generally contains a blend of several different bluegrasses. Therefore, if repairing primarily a bluegrass lawn, sod will usually blend well with the existing grass. On the other hand, if the lawn is dominated by the fine fescues or it is an older lawn with fine fescues and common types of Kentucky bluegrass growing together, then seeding may be a better choice as sod may look distinctly different from all the rest of the area. Sod is also an excellent choice where there needs to be repair done on sloping areas. Sod will cover the soil to prevent or at least reduce erosion potential. Note that it is important to prepare the soil just as if you were planning to seed the area. This will help ensure rapid establishment of the sod. Sodding can be done well into October whereas seeding should be completed by the middle of September. Nonetheless, the sooner one can sod an area, the more time it will have to get established before the onset winter-like conditions.

New sod contain some drought-tolerant grasses. Photo: Bob Mugaas

Overseeding the entire lawn with fine fescues will help improve the overall drought tolerance of the lawn. This is best accomplished with a mechanical overseeder. Larger garden centers or retail garden product outlets will carry bulk seed of the fine fescues. Overseed at the rate of about 4 to 5 pounds per 1000 square feet. If the lawn is thin but not completely dead, begin the overseeding process by mowing the existing grass very short and rake up or collect the clippings from this process. The overseeding process can now be done with better assurance that the seed will be lightly incorporated into the soil giving better germination and seedling growth. Even when using a machine, overseeding is best done by going two directions across the lawn area. This checkerboard pattern of seeding helps avoid skips and misses thereby ensuring uniform distribution of the seed over the entire area. Remember to set the machine to apply half of your seed quantity in one direction and then repeat going perpendicular to your first direction putting down the other half of the seed.

It will be important to keep the existing grass cut short during the establishment process such that the existing grass does not overly shade the newly emerging seedlings. As the seedlings continue to grow, mowing heights can gradually be returned to normal heights (e.g., 2 to 3 inches). In order to avoid encouraging the existing grass to grow too rapidly, it will not be necessary to use a starter fertilizer at the time of seeding as would be done if it were a new lawn or larger area consisting of bare soil. A late season application of nitrogen at one pound per 1000 square feet can be applied around Halloween in the Twin Cities area. This will help the grass green up and resume growth more quickly in the spring. Water the areas to keep them damp during the early stages of seedling growth. However, avoid keeping the areas too wet as that can give rise to some disease problems and generally slow establishment.

While we have little control over existing weather conditions and their impact on our lawns, we can take some proactive measures to quickly repair and reestablish any damaged areas. Late summer is an ideal time for this repair and taking action now will go a long way in minimizing available ground space for weeds to invade either this fall or next spring. For additional information see the following on line Extension resources:

Lawn Renovation (http://www.extension.umn.edu/distribution/horticulture/DG3914.html)

Seeding and Sodding Home Lawns
(http://www.extension.umn.edu/distribution/horticulture/DG5775.html)

SULIS (Sustainable Urban Landscape Information Series; http:// www.sustland.umn.edu)

(Note that there are many other lawn care resources available from the general Extension Website (http://www.extension.umn.edu). From the Extension Home page, go to the left side of the page and click on garden. From the garden page click on lawns - culture.)

Brace Yourself For Boxelder Bugs
Jeffrey Hahn, Assist. Extension Entomologist

Adult boxelder bug Photo: Jeff Hahn

The warm spring and the dry summer we experienced this year has resulted in a larger than normal population of boxelder bugs. This has been obvious in a lot of places as immature boxelder bugs have been commonly seen in gardens and yards since June. The bad news is that these young bugs will grow up to be adult insects which will try to find places to overwinter in our homes. However, you can minimize your problems with them by taking steps to protect your home now.

Boxelder bugs feed primarily on the seeds of boxelder trees. They will also feed on maple and ash seeds. When these insects first hatch, they are bright red. As they start to grow wings, the wing pads are black which gives them a red and black appearance. In normal years, boxelder bug nymphs are usually not very conspicuous. However these brightly colored insects have been found on all types of garden plants and even occasionally on trees and shrubs in yards. They often cluster together to make them even easier to see. Despite any circumstantial evidence, boxelder bugs do not damage garden or landscape plants.

Fortunately, the nymphs are not interested in seeking shelter in buildings at the end of the summer and fall. Those that are still around when temperatures freeze will die. Only the adults will try to get into your home. They are the only stage that survives the winter.

If you have had a garden and yard with large numbers of nymphs that have been present during the summer or your home has a history of attracting boxelder bugs in most years, you should anticipate having problems with them this year. The key to reducing boxelder bugs is to prevent them from entering your home from the start. It is best to use a two pronged strategy to maximize your results.

Boxelder bug nymphs feeding on maple seeds. Photo: Jeff Hahn

First seal as many opening as possible that may allow insects into your home. Concentrate along doors, windows, fascia boards, where utility lines enter buildings and similar places. Seal any openings 1/8 inch or larger. This should be done as soon as possible before boxelder bugs start to enter buildings.

You won't be able to make your home so tight that you can keep all insects out. You should supplement your exclusion efforts with a residual insecticide treatment. Make any applications just as these insects first to cluster on the outside of your home, usually early to mid September. Spray insecticide around doors, windows, and roof lines, paying particular attention to the south and west sides where the insects are most common. You can treat your home yourself or contact a licensed pest control service to do it for you. The following are common examples of effective insecticides available to the public:

* bifenthrin, e.g. Ortho®Home Defense MAX® Perimeter & Indoor Insect Killer
* B-cyfluthrin, e.g. Bayer Advanced^TM Home Pest Control Indoor/Outdoor Insect Killer
* deltamethrin, e.g. Buggspray®Buggslayer^TMInsecticide
* lambda cyhalothrin, e.g. Spectracide® Ant Shield® Home Barrier Insect Killer
* permethrin, e.g. Bonide Eight Garden & Home
* tralomethrin, e.g. Schultz Home Insect Control

These steps should reduce the number of boxelder bugs but it may not completely eliminate the number that get inside. This will be particularly true if high numbers of boxelder bugs are present where you live. For the insects that do get inside, your only real option is to physically remove them, e.g. with a vacuum.

Some boxelder bugs will get into wall voids and attics and will periodically emerge during mild winter days and again in the spring. They did not lay eggs that just hatched. Rather, they are all the result of insects that entered your home during the fall. Just physically remove any that you see.

Get the low down on this month's insect pests at Insects
http://www.extension.umn.edu/yardandgarden/EntWeb/Ent.htm

Contributors: Nancy Rose Patrick Weicherding Bob Mugaas

Lawns

Now is the time to focus on repairing drought-damaged lawns. See Bob's article at the top of this document. In the Sept. 15th, issue we'll talk about fall weed control.

Trees and shrubs:
Even though we've had some rain, be sure to keep trees and shrubs well watered to ensure they will be able to harden off for winter. If your trees and shrubs looked tough this summer, they most likely were inadequately watered last year. You need to water more now.

Don't fertilize any woody plants including roses. Don't prune any woody plants, either. Pruning prompts growth that will not harden off in time for winter.

Fruit and flowers:

Coleus and petunias hang together. Photo credit: Beth Jarvis

Keep watering perennials, vegetables and fruit plants. They need an inch of water per week

Fall-bearing raspberries should be producing now. Canes that bore fruit in summer can be snipped off, down to the ground.

Early apples should be ripe. Bite into apples and feel for starch sticking to your teeth. Dark brown seeds also signal ripeness.

Keep harvesting anything that's producing. Pick up windfall apples and any spoiled fruits or vegetables. Insect-infested or diseased produce should be destroyed rather than composted. The same applies for diseased foliage when clearing out the garden.

Parsley, pansies and ornamental kale can go into planters for fall interest.

Plant spring-flowering bulbs now. Narcissus (daffodils) need to be planted in September. Tulips can be delayed.

Peonies can be divided and moved in September. The foliage will start to fade from green to brown when the peonies are done for the year. Remember to plant them so "eyes" are just barely covered by soil. There should be at least 3 eyes per division, if you're dividing them.

If overnight temperatures are hovering close to 40 at night, bring indoors any houseplants that have been summering outdoors. These plants don't do well in temperatures of 40 or below. Before you bring them indoors, wash the leaves, top and bottom and check for insects. Keep the plants isolated from other plants until you determine they're not harboring pests.

Editorial Notes

Narrow-leaf angelonia Angelonia angustifolia, Serena Pink Lavender Photo: Beth Jarvis

Dave Stevenson, the Arbopretum plant curator, has agreed to be interviewed about his job. We'll do that some time this fall. Also upcoming is an article by Nancy Rose on the trees of the family Fabaceae. I'm hoping to catch up with some more of the plant breeders at the Horticulture Research Center and report back to you. I'm still hoping to have an article on the physiological drawbacks of growing evergreens in shade vis a vis incidence of winter injury, among other things, one of these days.

Please feel free to cut and paste any of the articles for use in your own newsletters. All we ask is that you give our authors credit.

Back issues Yard & Garden Line News are on the Yard & Garden Line home page at www.extension.umn.edu/yardandgarden/.

Deb Brown answers gardening questions on Minnesota Public Radio's (MPR) "Midmorning" program on the first Friday of every month at 10 a.m. The program is broadcast on KNOW 91.1 FM, and available state-wide on the MPR news radio stations. (Scroll down for map.)

For plant and insect questions, visit http://www.extension.umn.edu/askmg. Thousands of questions have been answered, so try the search option in the black bar at the top left of the board for the fastest answer.

If you would like to receive an e-mail reminder when the next issue of the Yard & Garden Line News is posted to the web, just send an e-mail to: listserv@lists.umn.edu (note: the second E in listserve is omitted), leave the subject line blank, then in the body of the message, type: sub yglnewslist or to unsubscribe, enter: unsub yglnewslist

Happy gardening!

Beth Jarvis
Yard & Garden Line Project Coordinator


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