Yard & Garden Line News June 1, 2002

Yard & Garden Line News
Volume 4 Number 8 June 1, 2002

Features this issue:
Have Fun With Composting!
Careful Use of Herbicide Tips
Septoria Leaf Spot of Turf
Do Your Daisies Need a Doctor?
Pine Bark Adelgids
Editorial Notes

Have Fun With Composting!
Thomas Halbach, Extension Specialist, Waste Management

Add water when needed.
Photo credit:
Tom Halbach

June is a great time of the year to review your composting program. Much of the hectic fervor of gardening in April and May is over. The soil has been prepared, the soil fertility program is underway, and most of the plants are "in the ground." We hope that the threat of frost is past. So let's take a look at composting.

How are those compost piles from last fall doing? Haven't had a chance to look at them yet? Are they a little "dried out"? When were they last turned last? Do you have any new organic waste materials from this spring? If you don't have any compost piles now but were thinking that it might be a good time to start composting, this article is for you!

Composting is primarily a microbial process that converts plant materials such as grass clippings and leaves to a more usable organic soil amendment or mulch. Gardeners have used compost for centuries to increase soil organic matter, improve soil physical properties, and supply some of the essential nutrients for plant growth. Mulching refers to the practice of applying a substance such as compost, leaves, or grass clippings to the soil surface with the purpose of modifying soil temperature and moisture as well as controlling weeds and soil erosion.

With the ban on outdoor burning and with laws that prohibit dumping of leaves and grass clippings into landfills, composting and mulching have become attractive alternatives for managing yard waste and recycling natural materials. Many gardeners may find it more convenient and economical to compost these materials in their own backyards

Turning speeds decomposition.
Photo credit:
Tom Halbach

Composting is an efficient method of breaking down organic materials into an end product that is beneficial to the soil and growing plants. Adding organic materials directly to the soil without first composting may initially have some undesirable effects. For example, if large quantities of noncomposted leaves are incorporated into the soil, microbes will compete with plant roots for soil nitrogen during leaf decomposition. This competition for nitrogen can result in nitrogen deficiency and poor plant growth. Adding composted material reduces the competition for nitrogen. Another benefit of composted material is that it is much easier to handle and mix with soil than noncomposted material. Furthermore, improvement of soil physical properties, such as infiltration, drainage, and water holding capacity, will usually be faster if composted materials are added.

So what do we need to compost? We need to put organic materials into a pile and provide the composting microorganisms with the correct amount of air, water, food, and mass to heat up to 131 F to 150 F in temperature. These temperatures, maintained for over fifteen days or longer, reduce weed seed viability and most pathogens.

We would like to keep Oxygen levels above 16 % inside the pile. The microorganisms need Oxygen to live and give off carbon dioxide as they process the organic materials. A compost pile needs to breath, both in and out.

The moisture content in the compost pile should be kept between 46% and 61%. This is "moist" but never "wet." A "rung out sponge" feeling is just about the right amount of water. To maintain this level of moisture may require weekly or even daily watering of the compost pile, especially in hot windy weather. If your fall leaves are all dried out you may want to "turn" the old pile and add water while you are building the new pile to get things off to a quick start this June. We need the correct amount of moisture to compost quickly.

Compost microorganisms thrive with a Carbon to Nitrogen Ratio of 25:1 - 35:1. When ever possible, adjust the raw materials going into the compost pile to get into this range.

Adequate bin size is important.
Photo credit:
Tom Halbach

Generally we want compost piles that are more than 3 ft. and less than 6 feet tall. This gives the amount of mass needed to heat up the piles.

The colder 35% of the outside of the pile doesn't cook as well as the center of the compost pile does. This is the reason why we need to turn the pile 2 - 7 times, to mix the cooler out sides into the hotter inside of the pile so that we get faster composting and better pathogen reduction.

With experience, adjust and fine-tune your management, to your unique materials and conditions. Good housekeeping is a must. A neat and clean pile is a thing of beauty. Make composting a part of your daily routine. Using finished compost to grow new plants completes the cycle. June is a great time to compost!

For more in-depth information and ideas about different bins and end uses we have some excellent publications on composting available.

Composting and Mulching: A Guide to Managing Organic Yard Wastes, BU-3296-GO, Revised 2000 http://www.extension.umn.edu/distribution/horticulture/DG3296.html

Options for Disposing of Leaves, FS-5570-GO, Revised 1999 http://www.extension.umn.edu/distribution/horticulture/DG5570.html

Soil Test Interpretations and Fertilizer Management for Lawns, Turf, Gardens, and Landscape Plants BU-1731-GO, 1998 http://www.extension.umn.edu/distribution/horticulture/DG1731.html

The University of Minnesota, Department of Soil, Water, and Climate, Extension Unit is developing a comprehensive guide to backyard composting. The interactive CD-ROM includes photographs, movies, and animated diagrams to explain the key concepts of backyard composting. Two levels of text will meet the needs of homeowners as well as master gardeners, students and teachers. Narrated by Mark Seeley -- Extension's State Climatologist and weather commentator on Minnesota Public Radio's Morning Edition.

Available June 2002. $19.95 Please visit our web site http://www.compost.umn.edu/ for more information.

Careful Use of Herbicide Tips
Deborah Brown, Extension Horticulturist

Weedy lawn. Photo credit: Deb Brown

Everyone is becoming more aware of the need to use pesticides responsibly, in order to protect our environment. Here are some guidelines for using post-emergent weed-killers carefully and efficiently:

* Target weedy areas in your lawn rather than spraying the entire yard. Spot treat individual weeds when possible.

* Choose ready-to-use formulations if you don't need much herbicide. If you buy a concentrate, dilute it exactly as the label instructs, no stronger.

* Hold your sprayer or hose close to the ground to avoid accidental drift onto other plants. Weed-killers can't discriminate desirable from undesirable plants.

* Wet the surface of weed leaves with herbicide; don't soak herbicide into the soil.

* Spray only when wind is calm, temperatures range from the low 60's to low 80's, and no rain is expected for 48 hours.

Remember, improving the health and vigor of your lawn will go a long ways towards keeping weeds at a tolerable level and reducing herbicide use.

Septoria Leaf Spot of Turf
Janna Beckerman, Extension Plant Pathologist

Photo credit: Y & G Clinic

Our recent bout of cool, wet weather has led to the development of a relatively rare disease problem on area lawns: Septoria leaf spot. Not having seen this problem on turf before, I contacted Dr. Jon Powell, our commercial turf grass pathologist, for a second opinion. The rareness of this occurrence was confirmed when he said he had never seen this disease before, either!

Septoria leaf spot, also known as Septoria tip blight, is considered a minor disease affecting turf grass, including Kentucky bluegrass, bentgrass and fescues. The overall symptoms of Septoria resemble scorch, dull mower blade damage or dollar spot. Leaf blades yellow from the tip downwards. Lesions are tan or grayish. When the lesions enlarge, they girdle the leaf, causing tip blight. These leaves die, resulting in thinning patches of turf. As this disease spreads, entire areas of lawn may be affected and develop a patchy appearance . Although this disease is more severe in neglected lawns, even highly manicured lawns can become infected.

Eventually, little black pustules (called pycnidia, pycnidium, sing.) develop on the leaf tip and can be seen with a magnifying glass or hand lens. The pycnidia are a key diagnostic sign for this disease, and allow you to eliminate dull mower damage or winter injury as the cause of the thinning patch. To conclusively diagnose this disease requires the use of a microscope. Careful examination of a pycnidium will reveal that it contains tens of thousands of long, needle shaped spores.

Spores are released by wind, splashing water, shoes and mower blades. The spores can infect injured or uninjured leaves. After infection, new fruiting bodies will develop and the cycle is repeated every 7 to 14 days as long as the temperature remains between 60 and 75 degrees F. The fungus overwinters in infected grass as pycnidia and as fungal threads called mycelia.

Cultural practices should promote an environment that is not conducive for pathogen infection and disease development. As always, use grass (sod, plugs, seed) that has been selected to tolerate the harsh conditions of Minnesota. Keep grass healthy and stress free. To do so, when mowing, remember the 1/3 rule: Only remove 1/3 of the grass whenever you more. Removing more than 1/3 causes additional stress on your grass. Recommended grass height is 3". This means you should mow when the grass blades reach 4.5" (approximately 10 to 14 days). As always, keep your mower blade sharp and never mow when the grass is wet!

Conditions that contribute to Septoria include thick thatch layers and compaction. De-thatching and aeration can remedy these two situations. Remove excess thatch in early spring or fall, and core compacted areas once or twice per year. Try to minimize foot traffic in compacted areas until the lawn has recovered. Dead patches should be reseeded with Septoria resistant cultivars, like like 'Adelphi,' 'Majestic,' and 'Nugget'. Homeowners who follow low-maintenance practices should reseed with the cultivar 'Park,' which has intermediate resistance to Septoria. Phosphorus application is still permissible when establishing grass seed and will aid in grass establishment.

Although the use of resistant varieties will go a long way in minimizing infection by Septoria, remember to strive for a healthy lawn, not a perfect lawn. Set realistic goals for yourself, and your lawn. Healthy lawns harbor beneficial insects and microorganisms that help keep pests under control; this balance is lost through the use of inappropriate lawn care practices (excessive fertilizer use, scalping, overwatering) and favor weeds, insects and pathogens. Many homeowners focus only on the dead area and fail to think about the entire lawn ecosystem. Whenever we receive turf samples, we are usually asked what fungicide to spray on the problem. All too often, this is the only course of action considered by the homeowner. In the case of Septoria leaf spot, only the fungicides containing Myclobutanil (e.g., Eagle WSP) are labeled for home use. Fortunately, Septoria leaf spot, like most home lawn disease, can be adequately managed without the use of fungicides. All too often, homeowners see fungicides as a "silver bullet." In reality, fungicides are more like the plaster casts that we use for broken bones. Most fungicides, like casts, stabilize a bad situation, prevent it from getting worse and allow the site to heal. Just as casts don't cure a broken bone, fungicides don't cure plants: Most fungicides only act to prevent additional infections from occurring, just as a cast prevents further injury.

Before the next turf crisis strikes, think about lawn care as preventive health care. The idea is to prevent problems from occurring so you don't have to treat them. A healthy lawn can out-compete most weeds, survive insect attacks, and fend off most diseases--before these problems become unsightly. A preventive health care program for your lawn should have the following steps:

1.Develop healthy soil
2.Choose a Minnesota- appropriate grass type
3.Mow high, often, and with sharp blades
4.Water deeply but not too often
5.Dethatch and aerate as needed
6.Tolerance-for yourself and your lawn. Set realistic goals
For more information on Low Maintenance Lawns, check out the article at:
http://www.extension.umn.edu/projects/yardandgarden/ygbriefs/h325lawn-lowmaint.html

Do Your Daisies Need a Doctor?
By Janna Beckerman, Jennifer Love and Elizabeth Wiggins

Are you looking for a doctor to diagnose your daisies? Perhaps you are wondering if your cucumber needs a cure for the crud? The Plant Pathology staff at the Yard and Garden Clinic is excited to unveil two new additions to the Plant Disease Diagnostics web pages (http://www.extension.umn.edu/projects/yardandgarden/diagnostics/) designed to help you diagnose vegetable and bedding plant disease.

The Plant Disease Diagnostics web page guides users through the process of plant disease diagnosis. Categories are divided into: Bedding Plants, Fruit, Roses, Shrubs and Vines, Trees, Turf and Vegetables. After clicking on a category, you begin by identifying the host plant that is affected. By identifying the host, you can narrow down the possible problems affecting your plant. Can't identify your host plant? We've provided links to help you in that process, too! With the latest addition of two new categories, Bedding Plants and Vegetables, you can now access information to help you diagnose these disease problems. New host plants will continue to be added, so we encourage you to check back with us soon if you don't currently find what you're looking for. Of course, the Yard and Garden Line (612-624-4771) is available to assist you in this process.

A Primer for the Plant Disease Diagnostics Web Page
After clicking on the name of the host, the next step is to determine which part of the plant appears to be affected (leaves, flowers, stems or roots). This links you to a page that provides photographs of common disease problems, and descriptions about the symptoms. This page is designed to help you match the problems you are seeing with a specific disease.

Once a particular disease is diagnosed by matching it to the picture provided, clicking on that images links you to more information about that disease problem. Additional information and photos are provided regarding the causal agent, lifecycle of the pathogen, how the disease over-winters and causes new infections, and how the disease can be managed. Management suggestions include disease resistant cultivars, cultural practices designed to minimize disease and pesticides labeled for chemical management. There are also links for additional information from other websites. In addition to plant diseases, the web pages also offer information on other causes of plant problems including deer damage, herbicide injury, and other weather-related conditions.

Early diagnosis of plant disease problems is the most critical step in managing plant pathogens and minimizing their impact. These web pages were created to assist home gardeners and nursery professionals diagnose plant diseases and manage them effectively. However, don't rely on a single text or website. Consult the University of Minnesota Yard and Garden Clinic when in doubt. Remember, without an accurate diagnosis, you cannot proceed to the next step, and any management strategy that you develop will fail.

Crystal Floyd and Chad Behrendt originally developed the Plant Disease Diagnostics web site in 1999. Plant Pathologist Janna Beckerman has maintained and updated the site since 2001, with new pages being developed by her and plant pathology technicians Jennifer Love and Elizabeth Wiggins.

Please check out the new diagnostics web pages at
http://www.extension.umn.edu/projects/yardandgarden/diagnostics/

Pine Bark Adelgids
Jeff Hahn, Assistant Extension Entomologist

Pine bark adelgid. Photo credit: Entomology Dept.

Adelgids are very close relatives of aphids. Like aphids, they are small, soft-bodied insects with piercing-sucking mouthparts. The differ from true aphids by lacking cornicles (small tailpipe-like appendages on the abdomen) and having generally shorter antennae. Many adelgid species commonly produce tufts of whitish, waxy material. Heavy infestations can make trunks and branches look like they have been flocked. All adelgids feed on conifers.

A common species in Minnesota is the pine bark adelgid, Pineus strobi. They prefer white pine but are also known to occasionally feed as Scotch and Austrian pine. These small (1/32 inch long), dark-colored insects spend the winter as immature females. When temperatures warm to about 50 degrees F in the spring, they become active and produce large amounts of white, waxy material which covers their bodies. The immature adelgids finish developing and turn into adults. This generally occurs sometime during late April in Minnesota.

The females lay eggs which hatch into small crawlers. Most are wingless but a few possess wings. They disperse and eventually settle down and attach themselves on the tree. They are commonly found on the trunk and underside of branches as well as smaller twigs and new growth. They insert their stylet mouthparts into the bark and feed on sap from the phloem tissue. Crawlers develop into immature adelgids which are incapable of moving. Eventually they mature into adults and repeat the cycle. There can be as many as five generations a year.

Pine bark adelgids cause little injury to healthy, mature trees, especially when only light or moderate numbers are present. Natural control by several predators, especially lady beetles and syrphid fly larvae, help keep adelgid numbers down. Even when infestations are so heavy that trunks or branches to appear to be white, very little harm is being inflicted on the trees. However, it is possible that young or unhealthy trees can be damaged by large populations of pine bark adelgids. Their feeding could result in discolored or distorted foliage, reduced plant growth or even (under extreme conditions) death.

Infestations by these adelgids usually affect just the tree's appearance, especially if they are on a vigorously growing, well-established pine. In most cases, just ignore the pine bark adelgids that you find. If you have trees that need to be protected, e.g. recently transplanted or unhealthy trees, first try to knock the adelgids off with a hard spray of water. If this is not sufficient, try dormant oil, applied during early spring before new growth emerges.

It is possible to apply a residual insecticide, such as acephate, during the spring or summer, although this should only be done with great reservation. There should be obvious risk to the tree's health due to adelgid feeding to justify such action. Keep in mind that the same insecticides that help manage adelgids would also kill their natural control agents. This could ultimately make the adelgid problem worse. Insecticidal soap is an alternative to residual products. It is much easier on insect predators but it may not be as effective on the adelgids.

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

Editorial Notes

Matricaria/feverfew (top) California poppies (below) Photo credit: Beth Jarvis

What a month! A typical, untypical spring. At least some of us are a little behind in garden tasks. Some of my favorite annuals are those that reseed freely. If you planted California poppies last year, be sure to check the area now for seedling poppies. Planting them once can sow the seeds for future gardens. Cleome/spider flower is another that keeps on as does matricaria/feverfew, portulaca/moss roses to name a few. Pansies come back as Johnny jump-ups.

I'm always interested to hear what topics you would like to read about in these pages (so speak). Drop me an e-mail and tell me what you'd like to read more about.

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/. Our home page has clickable links to most of the components of the Yard & Garden Line, such as Bell Museum of Natural History, INFO U and the Soil Testing Lab.

Deb Brown answers gardening questions on Minnesota Public Radio's (MPR) "Midmorning" program on the first Thursday of every month at 10 a.m. Katherine Lanpher hosts the program that is broadcast on KNOW 91.1 FM, and available state-wide on the MPR news radio stations.

If you have gardening questions, please call the Yard & Garden Line at (612) 624-4771.

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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