Yard and Garden News

What's Up With That?!

Thu, 01 Oct 2009 12:00:07 -0600

Birch Abnormal Growth Syndrome (BAGS) aka. Mouse Ear Disorder

Carl Rosen, Extension Soil Scientist and Karl Foord, Extension Educator

The strange leaf symptoms on this river birch tree, taken on August 7 (Photo 1, left) were diagnosed as birch abnormal growth syndrome or BAGS. New leaves are severely stunted and take on a mouse ear appearance. For many years the cause of this disorder was a mystery, but it is now known to be due to a deficiency of nickel.

Photo 1 (left): River Birch 'Summer Cascade' at planting time showing symptoms of nickel deficiency (BAGS). Photo taken August 7, Karl Foord.

Nickel is an element only recently shown to be essential for plant growth and is required in very small amounts. Almost all soils have enough nickel to support plant growth, but under some conditions, nickel deficiency can still occur. The mouse ear symptoms on this river birch were first seen when growing in a peat-based container mix, and were initially misdiagnosed as bud damage from a late frost. However, after the tree was transplanted into the soil in mid-May, the symptoms, after continuing for the next few months, have now begun to appear normal.

Based on research conducted at the University of Minnesota and in other areas of the country, BAGS almost exclusively occurs on river birch when grown in peat-based media and can be corrected by soil or foliar applications of nickel.

Photo 2 (right): Close up of 'Summer Cascade' river birch leaves with BAGS. Photo taken August 7, Karl Foord

Research has also shown that when soil is added to the peat media (20-30% by volume), the nickel deficiency symptoms will not occur, suggesting that there is enough nickel in the added soil to meet the nickel requirements of the plant.

In cases where the symptoms are most severe, an analysis of the peat has shown excessively high levels of zinc. These high levels of zinc in the peat likely accentuate the nickel deficiency. Therefore, adding soil to the peat mix may help by 1)alleviating BAGS symptoms by adding the needed nickel, and 2) by tying up or diluting some of the excessive zinc in the peat.

Photo 3 (left): Up close. Mouse ear symptoms of nickel deficiency on peat-based media. Carl Rosen.

As shown by the picture taken on September 14 (Photo 4, below), the tree has nearly recovered from its mouse ear symptoms and is expected to make a complete recovery once the roots have fully established into the native soil.

In general, BAGS has been a problem most apparent to the nursery industry, as trees showing the symptoms are usually not sold. However, if the problem does occur in containers, it can be corrected with nickel applications or by transplanting to a medium containing at least 20% soil. Soils in Minnesota have enough nickel to support plant growth, therefore nickel application to river birch growing in the landscape is not necessary.

Photo 4 (left): Recovery of river birch 'Summer Cascade' from BAGS. Photo taken September 14, Karl Foord.

Field Guides Can Be Fun

Thu, 01 Oct 2009 12:00:06 -0600

Jeff Gillman, Nursery Management Specialist

Different people collect different things. Some like baseball cards, some like shoes, and some like coins. I like books about insects. No, really, I do. Just glancing up from my desk I can count something like 5 field guides, 10 general entomology texts, and a slew of others that fit into categories like insect control, insect taxonomy and insect physiology (I have a lot more at home). If you were to spend some time with these books you would discover rather quickly that, all in all, entomologists are boring writers. No zip, little spark. And that, in a nutshell, is why I like Jeff Hahn's new book Insects of the North Woods so much.

Photo and Cover: Insects of the Northwoods, by Jeffrey Hahn. © Kollath-Stensaas Publishing.

Just looking at the cover of Insects of the North Woods you might be convinced that this is just a typical insect field guide. It's got some pretty pictures and, on the back, the obligatory author photo. But when you open the pages of this book, you quickly discover that it is not only as informative as you would expect from a University of Minnesota Entomologist, it's also entertaining. This book literally drips with Hahn's personality and sense of humor. Between talking about receiving a gift of a dead insect being every woman's dream when referring to scorpion fly mating rituals, and the mini scuba tanks that predaceous diving beetles use, you soon come to realize that this isn't just an entomologist reciting dry facts. Instead, this is an author who loves his subjects and who wants the reader to love them too. Like most people, I don't read field guides cover to cover, but with this book I have often found myself going through the book page by page because I don't want to miss one of Hahn's insightful comments (or one of his amusing analogies).

Besides the writing, this field guide has everything else that you'd expect a field guide to have, including great pictures (mostly by the author), a nice index system for finding the insect you're looking for, and a good, but not overly-done introduction. Though this guide concentrates on insects of the North Woods and so is, at least in theory, intended for use in northern Wisconsin, Michigan, and Minnesota, it is also the best book available for identifying insects in forests around the Twin Cities area and is a great first field guide for any budding entomologist. If you enjoy insects, or if you're just interested in knowing what some of the insects that flit about your trees are, then you shouldn't miss this book.

Airborne Aphids

Thu, 01 Oct 2009 12:00:05 -0600

Jeffrey Hahn, Asst. Extension Entomologist

Many people in Minnesota, including the Twin Cities, that spent time outdoors during mid-September encountered large numbers of small dark-colored 'gnats'. Upon closer examination, these insects turn out to be winged aphids (examples include soybean aphids, basswood aphids,and oat bird cherry aphids). This has been a favorable summer for aphids and large numbers were produced.

Photo (left): 'Winged and wingless soybean aphids on buckthorn in spring'. Christina DiFonzo, Michigan State University, Bugwood.org.

While the relatively cool summer had only a minor impact on the development and reproduction of aphids, these conditions had a more significant effect on aphids' natural enemies, such as lady beetles. The cooler weather slowed down their rate of reproduction which ultimately allowed aphid numbers to thrive.

Aphids have a very unusual and complicated life cycle. Many typically live on two different host plants. They spend the summer on their primary host (e.g. soybeans for soybean aphids) feeding on sap and producing many generations. Aphids reproduce parthenogenetically, i.e.eggs are not fertilized and only females are produced. Females give
birth to live young.

The end of summer brings shorter day length. When combined with a few days of below average temperatures, these events trigger the production of a generation of winged females aphids (winged males are produced about a week later). This year, that cold weather occurred at the end of August. These winged aphids take flight and look for their alternative host plant (e.g. buckthorn for soybean aphids). It is this migration that people have been seeing recently.

Once aphids land on their second host, they produce several generations of wingless aphids. When the males arrive, they mate and then the females lay fertilized eggs. Most aphids overwinter in the egg stage. When spring arrives, the eggs hatch into wingless females which produces two or three generations. Eventually a winged generation is produced, and these aphids fly back to their original host plants to start the cycle all over.

A common question people have asked is whether these insects will bite. Even though they are gnat-like, the answer is no. They are harmless to us and do not bite like a mosquito or black fly. However, it is possible that they may taste test people by trying to insert their
mouthparts into us which can result in a mild prick. Fortunately,aphids then realize that we are not food.

People have also wondered whether using a mosquito repellent will help keep these aphids off of us. Repellents are designed to hide our chemical scent from blood-feeding insects, especially mosquitoes. Since aphids are not seeking us out to feed on us, but just encounter us randomly, repellents will have no effect against them. However, they are attracted to the color yellow so one step you can take to reduce the aphids that land on you is to avoid wearing any clothes of yellow color.

There have been a few reports of people applying insecticides into the air to try to kill the aphids around their homes. This, of course, is an entirely futile gesture and just puts the individual at more potential risk from an accident with pesticides. People should not
attempt to spray the aphids in their homes.

Fortunately, this migration of aphids is a short-lived problem and goes away on its own. The greatest numbers of aphids were out for about a week during mid-September and have noticeably declined since then. By October, there should be very few still actively flying.

Lawn Care Tips for October

Thu, 01 Oct 2009 12:00:04 -0600

1.Cease lawn mowing when temperatures are cool to cold and the grass shoot growth has essentially stopped. Reducing mowing heights to 2.0 - 2.5 inches for the last two or three lawn mowings of the season will reduce the amount of leaf tissue present over winter and can reduce the amount of snow mold that may occur. It is not necessary to collect clippings as long as they can filter down into the turfgrass canopy at the soil surface. Excessive amounts of grass clippings should not be left on the lawn surface in the fall or at any other time of the year. Photo 1 (left). Lawn mowing should continue through the fall. Bob Mugaas.

2. A thin layer of leaves can be left on the lawn as long as they are ultimately chopped up as the lawn is mowed through the fall.

3. When confronted with several inches of leaves over the lawn, it is best to rake off the majority of those leaves before mowing and either compost them or use them as mulch material in other parts of the landscape. A thick layer of leaves left on the lawn blocks out sunlight to the grass and may even smother the existing grass beneath that layer resulting in large areas of thin or even dead grass come next spring. Photo 2 (left): Acceptable leaf cover that can be ground up adequately with a lawn mower. Bob Mugaas.

4. Early October can still be an excellent time for controlling those pesky perennial broadleaf weeds such as dandelion and creeping Charlie. Best control with most available herbicide products is achieved when daytime temperatures are above 50o F. but less than about 80o F. That's usually not a problem at this time of year. Be sure that neither the grass nor the weeds you are intending to treat are under any drought stress. Drought stress will usually result in less than satisfactory control and may even injure the desirable lawn grasses because they can become susceptible to broadleaf herbicide injury under such circumstances. Always follow product label directions for proper use whether in the fall or any other time of the year. Photo 3 (below and right). Young and mature dandelion plants are best controlled in the fall. Bob Mugaas.

5. In the Twin Cities, a late season application of nitrogen fertilizer should be put down around Halloween. At this time of year, the nitrogen is taken up into the plant and stored in the crowns, rhizomes, tillers and/or stolons where it can be quickly accessed next spring by the growing grass plant. Follow this application with about ¼ to ½ inch of water to move the nutrients into the soil where they can be taken up by the roots. Never apply fertilizer to frozen ground. You would like about two to three weeks of unfrozen ground following this fertilizer application to allow for root uptake of the nutrients.

6. As a general rule-of-thumb, it is best to avoid stimulating excessive shoot growth during late September to mid-October. Succulent growth associated with higher nitrogen levels, can contribute to increased incidence of snow mold over winter. A fertilizer application about the time of the State Fair provides the additional nutrients for the fall growth period, while the late season application is primarily stored for growth next spring. It is often easy to tell which lawn has had a late season application of nitrogen as they will usually be noticed as the first lawns with healthy growth and a dark green color in early spring. Photo 5 (above and left): Photo taken in early May. Dark green strip received a late season N application the fall before; surrounding turfgrass area did not. Bob Mugaas

7. With the current dry period we are experiencing, regular watering should be continued throughout the fall period or until more frequent rainfall returns. While you may not need the one inch of water per week as during the summer months, applying that same amount during the fall may be sufficient for two or perhaps even three weeks depending on weather. Late summer and the fall period are a naturally active growth period for our lawn grasses. Making sure they have ample water and nutrients during that time will aid their recovery from summer stresses and encourage healthy growth for the next growing season. Photo 6 (left). Lawn watering. Bob Mugaas.

Any reseeding of the lawn should have been completed by mid-September in the Twin Cities area. It is best to avoid seeding during the early to mid-October period, as the very young seedlings that do emerge often have poor survival over the winter. If you would still like to do some seeding, you can do what's known as dormant seeding. Before the ground is frozen, but while the soil is cold (so as to not encourage seed germination in the fall), incorporate the seed into the soil surface. Incorporating the seed into the soil surface will help protect it through winter. Seed remaining in that 'dormant' condition until next spring, can get a head start on germination and growth for the next growing season. In the Twin Cities area, dormant seeding is usually done in early to mid-November depending on weather conditions

With a little effort and planning this fall, successfully preparing the lawn will help it survive the upcoming winter months, while also encouraging a healthy start for next spring. It may seem a little backwards, but preparation of a healthy spring lawn begins the previous fall. For additional information on any of the topics mentioned in this newsletter, please see the lawn care section in our Sustainable Urban Landscape Information Series website at www.sustland.umn.edu.

Put your garden to bed without plant pathogens

Thu, 01 Oct 2009 12:00:03 -0600

Michelle Grabowski, University of Minnesota Extension Educator

As the Minnesota growing season is winding down and first frost is just around the corner, many gardeners are starting to prepare their landscapes for the long winter ahead. Plants are making physiological changes that will allow them to survive Minnesota's cold winter and so are the plant pathogens that have plagued the garden this year. Many plant pathogens overwinter in infected leaves and herbaceous stems that will soon fall to the ground and become part of the leaf litter. Other pathogens survive in live plant tissue like perennial crowns and tree branches. Reducing the number of pathogens that survive from one season to the next is a great way to reduce potential disease problems in the next growing season. Sanitation, the removal of infected plant parts, is an important part of disease prevention. Although sanitation will not prevent all future disease (pathogens can often move in from long distances away), it can reduce the severity of disease or delay its appearance.

In the Flower Garden

Photo 1 (left): Peony with a fungal infection on leaves and stems. M. Grabowski.

A wide variety of fungal and bacterial plant pathogens cause leaf spot and blight diseases in annual and perennial flowers. After the first frost hits, these infected leaves, stems, and flowers fall to the ground. The pathogens spend their winter nicely insulated within this old plant tissue, covered by snow. In the spring, warming temperatures and moisture from spring rains and melting snow stimulate the pathogens to start reproducing. Fungal spores and bacterial pathogens are then soon being splashed or blown onto the newly emerging plant shoots, starting the disease cycle all over again.

What can a gardener do?

Scout your gardens now and take note of any plants with leaf spot or blight diseases. Even mild cases are worth addressing now.

Do not bother spraying fungicides at this time. It is too late. Fungicides are protective and preventative in nature. They may be useful early in the season to protect young growing tissue but are unnecessary as the plants go dormant.

After the first hard frost, go back to each infected plant and collect all of the fallen leaves. Cut herbaceous stems back to the ground. Remove all of this infected plant material from the garden.

Infected plant debris can be composted if the compost pile heats up to 160 degrees F. Don't forget to check with municipal compost facilities. These are often more intensely managed than a backyard compost pile and are often an acceptable place to take infected plant material. If composting is not an option, infected plant material can be buried to speed up decomposition or thrown away with the trash.

If any perennials are found to be infected with a virus or with aster yellows, remove the plant. These pathogens survive in the live crown of the plant. Once infected, the plant will always carry the disease. Virus and aster yellows infected plant material can be composted since these pathogens do not survive without a live host plant.

Trees and Shrubs

As in the flower garden, fungal and bacterial pathogens that infect tree leaves, survive the winter on these same leaves once they have fallen to the ground. New fungal spores and bacterial pathogens will be produced in the following spring to infect the newly emerging leaf buds. Other pathogens survive within live branches, the trunk or roots of the tree. Depending on where the pathogen is living, the control strategy is different

Photo 2 (right): Black knot on Prunus. M.Grabowski
.

Scout trees and shrubs for any signs of infection before the first hard frost. Make notes as to where the pathogen is found. In leaf spot diseases, the pathogen infects the leaves. With cankers or galls, the pathogen survives in the infected branches.

After leaf drop, rake up and remove all leaves from trees suffering from any leaf spot diseases. If there are too many leaves to collect, use a mulching lawn mower to chop of the leaves and speed up their breakdown.

Infected leaves can be composted, burned (if allowed in your city) or buried.

If cankers and galls are found, mark them for later removal. The best time to prune out cankers and galls in Minnesota is in February and March. At this time pathogens and insect pests that might infect the pruning wound are not active. For more information about dormant season pruning, see: http://www.extension.umn.edu/projects/yardandgarden/YGLNews/YGLNewsMar12007.html

It is also important to help trees prepare themselves for winter by providing adequate water until the ground freezes. The trees root system will continue to take up water even after leaf drop. Research has shown that trees stressed by dry soil conditions are more likely to suffer from frost cracks. For more information about frost cracks visit http://www.extension.umn.edu/yardandgarden/YGLNews/YGLNews-Oct0106.html#frost

If the base of the tree is mulched, make sure that the mulch is not piled up against the tree trunk. Volcano mulch cones provide excellent hiding places for rodents in the winter and can result in damage from rodent feeding along the trunk of the tree. Rake any mulch away from the trunk so that an air space occurs between the trunk and the mulch.

Lawns

Snow mold is a common disease of Minnesota lawns. Although this disease most commonly causes problems in early spring, there are many cultural control practices that can be implemented now to reduce problems next year. The fungi that cause snow mold love moist cool conditions.

Photo 3 (left): Lawn with pink and gray snow mold B.Mugaas

Reduce mowing height to 2.0 - 2.5 inches. This will allow the turf to remain upright underneath the snow cover. Longer grass flops over creating moist pockets that favor snow mold growth.

Remove all leaves from nearby trees and shrubs from the lawn. This can be done by using a mulching lawn mower to break up the leaves or by raking and removing the leaves. Clumps of leaves left on the grass, do not allow the grass leaves to dry properly and create conditions favorable to snow mold.

If making a second application of fertilizer, wait until the grass blades have stopped actively growing. This typically occurs about mid to late October in the Twin Cities. The roots and crowns of the grass plant will still be active and will use the fertilizer nutrients to build up the plant's food reserves. If fertilizer is applied very late in the season, while the turf is still growing above ground, new leaves may not have time to harden off before winter. This soft succulent tissue is especially susceptible to snow mold.

Components of and Factors Influencing Fall Color

Thu, 01 Oct 2009 12:00:02 -0600

The tree's response to the decreasing day lengths in the fall is to form an abscission layer at the base of each leaf. As this layer forms, it slowly cuts off water and mineral supplies to the leaf and reduces the manufacture of chlorophyll. As chlorophyll supplies decrease, previously masked carotenoid pigments in the leaf become visible. Carotenoid pigments are split into two classes based on oxygen content: xanthophylls and carotenes. Xanthophylls, which contain oxygen, are yellow. Carotenes, which do not contain oxygen, are orange. Carotenoid pigments absorb light energy like chlorophyll and serve to protect chlorophyll molecules from photo damage. A carotene you may have heard of is β-carotene which is a precursor to vitamin A. In humans, vitamin A is a pigment essential for good vision.

Anthocyanin pigments are another important component of fall color, contributing reds and purples to the fall palate. These pigments are not present in the leaf during the active growing season, and form in the leaf in the fall. Anthocyanin pigment formation is a function of sunlight, which is why you may see leaves at the tops and southern facing parts of trees turning colors before the rest of the tree. When the first leaves of the season fall, the remaining leaves receive more light and develop more color. This phenomenon can also be observed in wooded areas where trees on the edge of woods or those that are taller develop color first. The smaller trees that have been shaded by taller trees will not develop color until sunlight reaches them.

Photo 1 (left): Maple turning fall colors. Note the outer most leaves exposed to the most sunlight are turning first. Karen Jeannette

Anthocyanin pigments are also present in many fruits. For example, if you see an apple that is highly pigmented on one side and not on the other, it may be because the colored side was exposed to light and the other side was shaded by leaves. Many of our favorite fruit species, such as blueberries, cranberries, raspberries, blackberries, cherries, grapes, and eggplant contain anthocyanin pigments.

Functions of superior fall color

One environmental component that does not add to fall color is frost. A severe frost that is premature will kill the leaf cells and not permit the colors to develop. The leaves will instead turn brown, and drop

Superior fall color displays are a function of weather and the condition of the trees. When healthy, pest free plants with sufficient nutrients and water experience bright, sunny, and cool autumn days, and cool but not freezing autumn nights, we are treated to a magnificent display of fall color. Varying weather conditions can influence the timing of fall color. To get an up-to-date fall color report go to the following website. http://www.dnr.state.mn.us/fall_colors/index.html.

The following figure shows the average time "peak" color is obtained in different parts of Minnesota.

Image courtesy Explore Minnesota @ http://www.exploreminnesota.com/

Wealth of Education Found in the Display and Trial Garden

Thu, 01 Oct 2009 12:00:01 -0600

Emily Tepe, Research Fellow, Department of Horticultural Science

If you walk through the St. Paul campus Display and Trial Gardens these days you're bound to see a lot of activity. No, I'm not talking about bees on the flowers (although there were a lot of those with the unusual warm weather in September), I'm talking about students. With the start of the fall semester comes a plethora of courses on plant identification, propagation, diseases and insects. The Display and Trial gardens offer a convenient and valuable living laboratory for these courses. In fact, throughout the year (save for a couple of months in the depths of winter) these gardens offer education to many people in the University community and beyond.

Photo 1 (left): Edible landscape portion of the University of Minnesota Display and Trial gardens. Emily Tepe

An Inspiring Outdoor Classroom

The Display and Trial gardens are comprised of various areas between Alderman Hall (home of the Department of Horticultural Science) and the Plant Growth Facilities on Gortner Avenue. Trees, shrubs, and hardscaping create the foundation for the gardens, and break it up into beds, each with their own theme. These themes change from year to year as new varieties are introduced, student projects are realized, and interesting gardening styles bring an opportunity to explore and experiment. The 2009 season brought some inspiring plantings and great educational opportunities.

These educational opportunities often get started while there is still snow on the ground, as students propose projects for the garden and begin designing beds and planting seeds in the greenhouse. Classes ,such as Professor, Neil Anderson's Floriculture Crop Production, research and schedule their assigned crops, working backwards from the planned finish date (mid-May), to assure their annual flowers are at the perfect stage for judging before being planted out in the gardens. Many of the varieties they grow are trials for major seed companies.

When spring arrives, students who have proposed projects for the gardens, begin breaking ground, laying out beds, sowing seeds, and eventually setting out transplants. They are responsible for maintaining their plantings throughout the season, keeping the beds watered, weeded and looking good. It's a great experience for students to take what they've learned in the classroom and put it all into practice. These projects bring the fresh ideas of students to the forefront, allowing them to experiment with new concepts and interesting designs, and even showcase some of their research.

By the time the gardens are in full swing, the St. Paul campus is pretty quiet. Most of the student body is gone for the summer, and the gardens become an inspirational outdoor venue for summer camps, youth enrichment programs, Master Gardener events, and horticulture industry field days.

Photo 2 (right): Master Gardeners tour the Edible Landscape at the University of Minnesota State Master Gardener Conference. Emily Tepe

On any given summer day you are bound to find a group of high school students cutting flowers for a design and marketing program, or a flurry of youth in matching t-shirts tending a plot of vegetables; kept on task by their nurturing and enthusiastic mentors. Members of the local community often visit the gardens to view the new varieties released by the University, the vast array of annual flowers, and the creative ideas such as this year's Edible Landscape.

A Living Laboratory

Once classes start in September, University students begin spending a lot of time in the gardens. Many of the students in the introductory horticulture courses have never seen some of these plants before, and the gardens offer a close-up look at the topics they're studying. Tom Michaels, professor in the Department of Horticultural Science (teaching Plant Propagation this semester) said of the Edible Landscape portion of the gardens, "Students pass right by those beds every time they come to lab. They can't help but see examples of the food they buy in the produce department actually growing in front of them. It gives me the opportunity to talk about those foods and encourage them to stop by the beds and find examples of how chard differs from lettuce or dinosaur kale, or similarities and differences between beans and peas". The gardens are indispensable for the plant identification courses as well. Students find examples of hundreds of species, and with hand lenses and forceps, can scrutinize tiny flower parts to determine the plant family to which they belong.

Photo 3 (above): Plant pathology students observing symptoms of apple scab in the Display and Trial garden. Emily Tepe.

Horticulture students aren't the only ones spending time in the gardens. The Display and Trial Gardens provide a wonderful laboratory for plant pathology and entomology students as well. Todd Burnes, scientist in the Department of Plant Pathology, said numerous courses spend time in the gardens identifying and studying various plant diseases. While in the home garden, powdery mildew, leaf spot and white mold would likely prompt immediate action, here we aren't so hasty. The opportunity for students to observe the symptoms of diseases, collect samples and study them in the lab is worth a few ugly plants here and there at the end of the season. Entomology students roam the gardens, sweeping their longs white nets along the edge of the prairie strip, or carefully trapping unsuspecting insects on the zucchini flowers. Once back in the lab, they'll identify and study their specimens.

Photo 4 (below and right) : Powdery mildew on zinnias in the Display and Trial Gardens. Emily Tepe.

It is truly amazing the wealth of education that can be found in a garden. Here on the St. Paul campus, the Display and Trial gardens offer many people a chance to get up close and personal with flowers, grasses, trees, fruits and vegetables. And whether in class or just wandering through, there are countless opportunities to discover. Every garden offers such opportunities for young and old alike.

September gardening endings and beginnings

Tue, 01 Sep 2009 12:25:00 -0600

Dear Yard and Garden News readers,

September represents both an ending and a beginning to me (see the 2009 September gardening list and tips related to these beginning and ending activities). It represents a time that much of the garden is hitting (or has hit) its peak and must become prepared for winter rest. Yet September brings with it another growing season's knowledge and discovery in which a gardener can formulate his or her new future gardening plans for the next year. As your new University of Minnesota Extension Yard and Garden News editor, it is with great enthusiasm, that I look forward to continuing the tradition of helping gardeners and yard caretakers in Minnesota become connected with the horticultural science and research that manifests itself into useful gardening information, tips, and discoveries.

Before I move forward with this and other issues, I would like to thank David Zlezak and past editors for producing and developing what I have always experienced as interesting, intriguing, and informative Yard and Garden News. The Yard and Garden News has always been a central place for me to stay connected to University of Minnesota horticulture research and information.

Before David crossed the Minnesota-Wisconsin border to take his new position as assistant professor at University of Wisconsin - River Falls, we had an opportunity to discuss and brainstorm infinite and exciting possibilities for Yard and Garden News readers. Similar to David, exploring gardening and horticulture is what led me to pursue both undergraduate and graduate degrees in horticulture. Even after two horticulture degrees, I'm still just as curious and interested in knowing the what, how, and why for just about everything plant-related (In fact, more education just makes me aware of how much more there is to know that I don't know!). Whether you read the Yard and Garden News with the same spirit of curiosity and interest in the science-based "when", "why", or "how", or whether you just want to find out what gardening methods or yard care tips the University of Minnesota Extension recommends so you care for your garden and yard in a way that meets your personal goals, I hope you will all join me in this and future editions of the Yard and Gardens News.

As the gardening season is winding down, the Yard and Garden News will be issued once per month. We will continue to be here for you with the standard monthly issues and a wealth of information available to you in the ten years of archived issues. Thank you for your faithful readership of the Yard & Garden News. Please look forward to the next issue of the Yard and Garden News October 1, 2009.

Happy Gardening!

Karen Jeannette
Yard and Garden News Editor
University of Minnesota

The Yard and Garden News: Features in blog format

Tue, 01 Sep 2009 12:24:00 -0600

Karen Jeannette, Horticulture Research Fellow & Yard and Garden Editor

Last month, former editor David Zlezak explained the Yard and Garden News has moved to a blog format. Here we explain a little bit about how this new type of format has enhanced options, but still the same quality information you've come to depend on. These are some new features:

Readers can comment on articles - we want to hear from you!
RSS feeds - read Yard and Garden News in your favorite feed reader
View articles chronologically (under Archives) or by topic (under Recent Posts) - choose what works for you
More options to use media (video, voice, slidshows, etc...) to support articles

We encourage you to explore these new features, or you can sit back, relax and read the Yard and Gardens News as always. You will continue to receive email notifications linking to new Yard and Garden News articles. And don't forget: The old Yard and Garden News archive is still accessible from the new site by searching for information under the "Search 1999-2008 archive" (see left column).

Printing and photo captions

With the switch to the new format, we are still working on improving printing and photo caption options for our readers.

Printing instructions: To print the newsletter in blog format, click on the desired month in the archive (right column), then select print from your computer's file menu. Note: When printing pages, you currently may be experiencing the text clipped a bit short around the margins. We hope to resolve this problem in the next few issues. We appreciate your patience while we are working to get this problem corrected.

Photo captions: The blog format does not currently have the ability to produce captions around the images. Until this is corrected, we will be providing descriptions and photo credits in the body of each article.

We want to reassure our readership that your Yard and Garden News team is working to correct these printing and photo caption issues. We hope you'll enjoying using the new blog format. We're excited about the additional possibilities for sharing the latest Yard and Garden News with you.

A honeydew list

Tue, 01 Sep 2009 12:22:00 -0600

Jeffrey Hahn, Asst. Extension Entomologist

There have been various reports lately of trees weeping or dripping some kind of sticky substance. There have been different speculations about what causes this problem. Is it some kind of disease? Is it just sap? The answer: insects.

Photo: Typical aphids. Jeff Hahn.

Aphids and certain scale insects feed in the phloem layer of plants using their needle-like mouthparts. They are not able to digest all of the sugars in the sap, and consequently, excrete a sugary liquid called honeydew. Honeydew is clear (can appear white) and is sticky. This material is not harmful to the health of trees but can be annoying when it coats deck furniture, cars, or other objects that are below infested trees. If this is a problem, try to remove it as soon as possible as honeydew can be very challenging to remove the longer it stays on.

Many ant species enjoy sweets and are attracted to honeydew. Some ants actually tend aphids to maintain their supply. Yellowjackets change their dietary habits during late summer and fall and are quite interested in the sugary content of honeydew. There can be so many yellowjackets attracted to a tree infested with aphids or scales that people may think that there is a nest in the tree.

Predators, especially lady beetles,may also be indirectly attracted to the honeydew. Of course they are interested in the aphids or scales that are producing the sugary liquid. One resident wanted to have a lady beetle larva identified. They were concerned because their tree was 'weeping' and these larvae were present. The owner was convinced that the larvae was causing the weeping and as a consequence started spraying them with an insecticide. Of course the lady beetle larvae were there to eat the aphids which were producing the honeydew.

Another consequence of honeydew is that it supports a fungus called sooty mold. Like the name suggests, it is black and sooty in appearance and is found on branches and leaves where honeydew is found. Although it is unsightly, sooty mold does not harm plants and should be ignored.

If you have a situation where you would like to reduce aphids, whether from the nuisance of the honeydew or from the insects themselves, there are several environmentally friendly options you can take. First, you can take a hose and direct a hard spray of water at infested leaves and branches. This knocks them off, effectively killing them. You can also apply a low impact insecticide, especially insecticidal soap or horticultural oil. These kill aphids while preserving natural enemies like lady beetles, lacewings, and syrphid fly larvae. Or just ignore them. As we approach fall, their activity slows down and they eventually stop producing honeydew.

Is late blight a threat to Minnesota tomatoes?

Tue, 01 Sep 2009 12:20:00 -0600

Michelle Grabowski, University of Minnesota Extension Educator

Many articles about the late blight epidemic of potatoes and tomatoes in the northeastern United States have been appearing in the news this summer. These reports are making some Minnesotans worried about late blight here in Minnesota. Although the extreme level of disease that is occurring in the northeast is not currently present here in Minnesota, late blight is present in the state and disease is possible. Gardeners should be aware of what late blight infected plants look like, what environmental conditions favor late blight, and what to do if late blight occurs. At this point, however, there is no need to panic.

Photo 1: Late blight on leaves. H.Schwartz, Colorado State University, Bugwood.org.

About late blight

Late Blight is a disease caused by a fungus-like organism called Phytophthora infestans. Phytophthora literally means 'plant destroyer' in Latin. This pathogen has earned its name by causing several famous epidemics including the Irish potato famine of the 1840's that resulted in the death or emigration of millions of Irish people. Late blight is most severe on potatoes and tomatoes but can also infect related plants like petunias and nightshade. Olive brown spots on leaves or stems are often the first obvious symptoms of disease. These spots grow until the entire leaf is affected, progressing into petioles and stems. Eventually the entire plant is brown and wilted. Under very moist conditions, fine white cobweb like fungal growth may be visible on infected plant parts. Infected tomato fruit have a large greasy brown spot. Infected potato tubers have sunken brown lesions on the surface and reddish granular rot extending into the flesh of the potato. Rot can start in the field and continue in storage.

Phytophthora infestans thrives in cool wet weather. Temperatures ranging from 60-80 degrees F are ideal. In addition, moisture on leaves and other plant parts is necessary for the pathogen to infect and spread. This moisture can come from rain, irrigation or dew. The late blight pathogen is so devastating because once an infection starts the pathogen reproduces and spreads very rapidly. One lesion can produce 100,000 to 300,000 spores in the right weather conditions. These spores are carried on wind or splashing rain to other plants, devastating an entire field in as little as a week's time.

Photo 2: Late blight causes olive brown lesions on stems. Photo credit: H.Schwartz, Colorado State University, Bugwood.org

2009 late blight epidemic in northeastern states

In the northeastern states this summer, several factors combined to create the perfect conditions for a late blight epidemic. First, Phytophthora infestans was brought into several states on infected tomato transplants. These infected plants were then sold at big box stores and distributed throughout the area in home gardens. This early season arrival of the pathogen, combined with unusually cool wet weather, allowed the disease to take hold and spread rapidly from gardens to farm fields.

2009 Minnesota late blight outlook

Until August, most of Minnesota was extremely dry with a few areas in moderate to severe drought conditions (US drought monitor - link to http://climate.umn.edu/doc/journal/drought_2009.htm ). These conditions are not favorable to late blight and it is not surprising that the disease was not found in Minnesota until August.

With recent rains, the possibility of late blight on tomatoes and potatoes in Minnesota has increased. Although very few cases have been reported in Minnesota, late blight has been found in North Dakota, South Dakota and Wisconsin. Because the disease spreads so rapidly, there is still time for damage to be done. In large part, the spread and development of late blight in Minnesota will depend on the weather conditions, but spread and disease development also depends on growers and gardeners properly caring for plants that may become infected. Commercial potato growers are already vigilantly looking for new late blight infections and have been spraying fungicides to protect their crop

Photo 3: Late blight on tomato fruit. R.Wick, University of Massachusetts, Bugwood.org

Monitoring and controlling late blight

What can you do?

Monitor: First monitor tomatoes and potatoes in your garden at least once a week, and more frequently if rainy weather persists. Examine the lower and inner leaves where humidity is highest and disease is most likely to appear first. Use the UMN extension online diagnostic tool to identify the problem you are seeing on your tomato plant (www.extension.umn.edu/gardeninfo/diagnostics/ ) or send a sample to the UMN plant diagnostic clinic (http://pdc.umn.edu).
Remove diseased plants: If late blight appears, immediately remove the infected plant, place it in a tightly sealed plastic bag, and throw it in the trash. This will prevent the pathogen from spreading to nearby gardens and farms.
Apply fungicides: Some gardeners may choose to protect their tomatoes and potatoes with a fungicide spray. Chlorothalonil is the only product available to home gardeners that will provide adequate control of late blight. The vegetable being sprayed MUST be listed on the fungicide label, and all label instructions MUST be read and followed. Organic gardeners can use a copper based fungicide, but should be aware that it will only provide partial protection. Fungicides must be applied before the disease starts in order to control the disease.

Photo 4: Late blight on potato. S.Bauer, USDA ARS, Bugwood.org

With luck, the season will pass without further disease development. The active management strategies already in place by Minnesota farmers will reduce the amount of fungal spores available to spread the disease. Gardeners can do their part by keeping a watchful eye over their plants and responding quickly if disease occurs.

Lawn care checklist: late summer - early fall

Tue, 01 Sep 2009 12:19:00 -0600

Bob Mugaas, University of Minnesota Extension Educator

Fall lawn care cultural practices employed during the active fall growth period of our grasses can be some of the most important and beneficial activities for your lawn. These practices will aid in good winter survival, early spring green up and growth, as well as provide many other helpful benefits.

Photo 1: Bluegrass lawn recovered from early season drought stress. Bob Mugaas.

With the return of rainfall and moderate temperatures, many of our lawns have come back to life after drier than normal conditions during May, June and early July. With that regrowth beginning, now is a good time to start getting your lawn in tip top shape for the active fall growing period. Below are some good cultural practices to consider.

Seven fall lawn care practices to consider

1. Overseeding and sodding: If the lawn did suffer some permanent injury during the dry conditions of late spring and early summer, now is a good time to do some overseeding or resodding to repair those areas. The very best time of the year to sow grass seed is from about the middle of August to the middle of September in the Twin Cities area. To help ensure a successful overseeding, lightly work the seed into the soil and then keep the area uniformly damp, NOT SOGGY, until seeds start to germinate and emerge from the soil. As the new grass plants get taller and more established, watering can be done a little less frequently but with more water applied per application.

2. Fertilizing: The period right around Labor Day is an excellent time to put down an application of fertilizer. Putting down about one pound of actual nitrogen at this time of year helps provide the plant with the necessary available nitrogen needed to support and sustain active grass plant growth through the fall period. Taking a soil test will help determine whether or not you need either of the other primary nutrients, phosphorus or potassium. Find University of Minnesota Soil Testing Lab at: http://soiltest.cfans.umn.edu/. Remember, it is a violation of Minnesota state law to apply phosphorus containing fertilizers to your lawn unless a soil test indicates there is a need for the nutrient or you are (re)establishing a new lawn. Additional information about this law can be found at: https://www.revisor.leg.state.mn.us/statutes/?id=18C.60.

3. Watering: As days get shorter, temperatures become cooler, and rainfall occurs on a somewhat regular basis, the need for additional or supplemental watering usually diminishes during the fall period. While an inch of water per week is usually necessary to keep lawns actively growing during the summer months, that same one inch of water may now be sufficient for two or even three weeks depending on weather conditions. Nonetheless, it is important to not severely drought stress a lawn if rainfall is not forthcoming. Periodic watering during the fall will help sustain active growth, allowing the grass plants to make and store food that will help it survive winter and resume healthy growth next spring.

4. Manage mowing height: Maintain mowing heights between 2.5 and 3.0 inches throughout most of the fall period. That will allow for plenty of leaf tissue to be actively involved in making food for the grass plant and a more robust root system that can take advantage of available water and nutrients in the soil. For the last two or three cuttings of the year, gradually reduce mowing heights to about 2.0 - 2.5 inches. This can help in the reduction of snow mold and allow for easier clean up of the lawn surface just prior to colder conditions arriving later in the fall.

5.Lawn aerification: If your lawn has significant compaction problems, the period right around Labor Day and through the early fall is an excellent time to do some core aerification. Lawn aerification machines are usually available through most rental businesses.

Photo 2: Lawn aerifier. Note the hollow tines for removing soil cores. Bob Mugaas.

Be sure to rent a core aerifier, one that actually pulls cores out of the soil and redeposits them on the lawn or soil surface. The extra aeration in the soil will encourage more active root growth as well as benefit the soil microbial community. Healthy plant roots and a healthy soil microbial population make for a healthy, vigorous grass plant better able to withstand stress along with normal wear and tear of lawn activity. The cores can be left on the soil or lawn surface to naturally decompose. This will also help control the buildup of thatch in the lawn. It is best to make two or three passes over the lawn to increase the number of holes needed to maximize the benefit.

6. Thatch control: Occasionally, a thick layer of brown fibrous material will build-up between the soil surface and where the grass plant shoots begin to turn green. This brown fibrous mat is known as thatch. It is actually composed of both living and non-living material. Thatch develops from the regular sloughing off of plant roots and other dead and decaying parts of the grass plant. It is however, NOT composed of any grass clippings. While there may be some grass clippings left on the surface, they are not part of the true thatch layer. So, whether you pick up your clippings or not, it will make no difference on the build-up of thatch. The living component of thatch consists of some roots, rhizomes and, of course, the many microorganisms and other living creatures.

If thatch develops at a faster rate than can be broken down by microorganisms, it can accumulate to undesirable levels. Generally, thatch greater than half-inch is undesirable. Cultural practices that contribute to thatch buildup are excessive nitrogen fertilizer, overwatering, infrequent mowing, compacted soils and simply the genetics of the particular grasses. Some grasses are more prone to thatch build-up than others.

Photo 3: Vertical mower or dethatcher; sometimes referred to as a power rake. Bob Mugaas.

Late summer (i.e., early September) is a good time to work at removing excess thatch build-up. Machines know as vertical mowers or de-thatchers can be rented and used to mechanically remove some of the thatch build-up. Leaving the soil cores on the surface will also help begin to break down thatch. In fact, where very thick thatch layers exist, using both a vertical mower and core aerifier may be helpful. If this is the case, thoroughly aerify the lawn, than perform vertical mowing. This operation can be done back to back on the same day if desired. It's a good idea to follow-up with a quarter to half-inch inch of water to reduce lawn stress incurred from the dethatching and aerification processes.

7. Broadleaf weed control: The month of September into early October is an excellent time for controlling those pesky broadleaf perennial weeds such as dandelion and creeping Charlie. There are many different broadleaf weed control products available that can be used around the home. Always follow the product's label directions exactly as printed on the container. Remember, it is a violation of federal law to handle or use any weed killer inconsistent with its label directions.

Photo 4: Creeping Charlie growing in a partially shaded lawn area. Bob Mugaas.

Most broadleaf weed killers work best between the temperatures of 50 degrees F and 80 degrees F. Late summer and early fall is an especially good time as these perennial broadleaf weeds are actively growing and the material is moved throughout the plant and root system, resulting in better control. While you may not see the weeds completely dying this year, chances are that few, if any, will be around come next spring. For more information about many other common lawn and landscape weeds and how best to control them, check out the section: 'Is this Plant a Weed?', on the Gardening Information web page (http://www.extension.umn.edu/gardeninfo/) .

Fall is for tasting and rating University of Minnesota apple varieties

Tue, 01 Sep 2009 12:17:00 -0600

Excerpts from Arboretum News, Judy Hohmann, Arboretum Marketing & Public Relations Manager

The University of Minnesota's Horticultural Research Center (HRC) breeds northern-hardy apples. Twenty-six robust varieties of apples have been introduced in the marketplace thus far. Some of these apples will be available for tasting at the Arboretum's Oswald Visitor Center (see weekend apple tasting details below). Apples for purchase will be available at the Arboretum's AppleHouse in early fall. After 20 years of research, testing, and cultivation, SweeTango® -- the offspring of Honeycrisp and Zestar parentage will burst on the scene this year with predictions over time to jostle Honeycrisp from its superstar perch. Look for a limited supply of SweeTango® apples for sale at the Arboretum AppleHouse in early Fall.

Photo: Zestar apples in bowl. David Hansen.

Weekend apple tastings

Sample and rate test apple varieties - each weekend features different apples. Drop in and complete a short survey, and talk with Master Gardeners. Your feedback is compiled for research scientists in the apple breeding program.

1 - 3 pm on September 19 and 20, October 3 and 4; 10 and 11
Oswald Visitor Center, Great Hall

Arboretum AppleHouse opens

Tuesday, Sept. 1
The AppleHouse apple and garden market opens September 1. This is a great source for a variety of freshly picked apples from the trees of the Horticultural Research Center. Continues through October. Located at the intersection of Rolling Acres Road and State Highway 5, just over a mile west of the Arboretum.

® Minneiska apple

Animal part, plant ,or rare mushroom found in Anoka County?

Tue, 01 Sep 2009 12:16:00 -0600

Lynne Hagen, Master Gardener Program Coordinator, Anoka County

One never knows what curiosities can arrive in a county Master Gardener office. A phone call from a client came in with the request of identifying an object that was found in her yard. The client wasn't sure if it was an animal part, a plant or fungus. Since the person calling raised chickens and ducks, she thought perhaps it was a deformed body part but wasn't convinced. This piqued my curiosity. Upon receiving the photos, the image was forwarded a couple of Master Gardener and Extension colleagues, as well as the Bell Museum. After a little sleuthing, David McLaughlin, from the Department of Plant Biology confirmed that it was a rare stinkhorn mushroom and most likely, a Lizard's Claw Stinkhorn Mushroom, Lysurus cruciatus. He stated, "What is shown in the pictures are the stem and apical, spore-forming area. These arise from a sack-like structure in the substrate. The spores usually have a strong odor and attract beetles and flies which carry the spores away. This genus is believed to be introduced here."

Photo: Lizard's Claw Stinkhorn Mushroom, Lysurus cruciatus. Jill Libby.

Some of the information found stated that the origin is New Zealand and Australia. McLaughlin said there are only two records of this genus in Minnesota. The client that found the object saved the specimen and donated it to the Bell Museum for their collection. Anoka County continues to be full of surprises.

2009 September gardening list and tips

Tue, 01 Sep 2009 12:15:00 -0600

September 2009 gardening tips are compiled from past conversations with University of Minnesota Extension Educators through 2004, 2006, 2007 Yard and Garden News calendars, and through email conversations with Ask a Master Gardener volunteers:Barb Harlan, Theresa Rooney, Claire Kari, and Darla Medic-Johnson.

Photo: (from left to right) Sneezeweed and Joe Pye Weed in the September garden. Karen Jeannette

While some might consider September the end of another gardening season, it might also be considered a beginning for enjoying the harvest of the garden or planning next year's activities. This time of year you may notice some central themes helpful in remembering seasonal garden and yard care tips, such as: watering, cleaning up, moving, harvesting, and preparing for next season, just to name a few. As always, this September gardening list is far from all-encompassing, yet a good reminder of where to start.

Watering

Providing adequate water in fall is especially critical for increasing plant survival in winter and providing year-round health:

Help your plants prepare for the long winter by adequately watering plants. This is especially true for trees and shrubs planted in the last 5 years. Provide these plants 1.0 - 1-.5 inches of water per week.. See Fall Watering advice for more information.

Follow this month's Lawn care checklist: late summer - early fall, (#3 out of the seven fall lawn care practice to consider)

Cleaning Up

A little clean up now can prevent a lot of weed and disease problems in the future.

Remove weeds and diseased plant materials from your gardens. Do not compost diseased plant materials in your home compost. For more information on other fall clean up recommendations, see Fall is Clean Up Time.
Remove overripe fruits from plants or the garden so as not to encourage insects or other stray critters.

Moving plants

Plant newly purchased perennials, trees, and shrubs. Make sure to provide adequate water through the fall. After the ground starts to freeze, add a 6 - 8 inch layer of mulch around your new plants.
Plant spring flowering bulbs.
In the vegetable garden, plant quick-growing greens (arugula, spinach, mizuna, cilantro, leaf lettuce) and garlic.
Plant grass seed. For overseeding information, see: Lawn care checklist: late summer - early fall, ((#1 out of the seven fall lawn care practice to consider) and/or Seeding and Sodding Home Lawns.
Now is the time to divide and move peonies.
Bring in tropical houseplants and tender bulbs such as begonias, montbretias and caladiums as temperatures near or dip below 50 degrees F. For more information, see: Over-Wintering Tender Bulbs and Plants
Bring in canna and calla lilies, gladiolus, dahlias and tuberoses after frost damages foliage on these tender bulbs, see: Storing Tender Bulbs and Bulblike Structures
For advice regarding moving established trees and shrubs, see:Transplanting,Transplanting Trees and Shrubs? Part I: Preparing for the Move and Transplanting Trees and Shrubs-Part 2: Making the Move

Harvesting & Storing

For information on storing home produce, see: Storing Home Grown Produce.

Apples are ripe when the starches have converted to sugars. You can feel the starch on your teeth when you bite into an unripe apple. Just because it's red doesn't mean it's ripe. If you want to become more proficient in your apple tasting abilities, see Apple Tasting Training with host University of Minnesota apple breeder David Bedford,

Preparing for next season

Read Bob Mugaases Lawn care checklist: late summer - early fall
Save tomatoes, peppers, peas, and beans seeds for next year's crop, see Saving Vegetables Seeds: Tomatoes, Peppers, Peas and Beans
Take notes and or pictures about what worked and what didn't this year. You will thank yourself next year when your notes help provide you clues about what to plant or not to plant. when to apply certain gardening methods, or pest control methods.