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Showing posts from July, 2009

Quick Update on Colorado Potato Beetles

Jeffrey Hahn, Asst. Extension Entomologist

Do you have a problem with Colorado potato beetles in your garden? If you grow potatoes, there is a good chance you see them at one time or another on your plants. Don’t forget that in addition to potatoes, they can also attack eggplants, tomatoes and peppers. This insect can be challenging to manage but here are a few tactics you can use to deal with this pest.

Monitor susceptible plants regularly so you know if Colorado potato beetles are present in your garden. If you have a history of these insects in your garden, the odds are good you will see them again. Because you can have overlapping generations, you can find all life stages in your garden at any given time. Once they are active in spring, you will generally have Colorado potato beetles in your garden all summer.

If you have a smaller garden, and the time, handpicking is a great nonchemical control method. To be sure they are killed, just toss adults and larvae into a bucket…

What are Those Leaf Spots on my Tomatoes? - Speck, Spot or Something Else

Michelle Grabowski, University of Minnesota Extension Educator

Several kinds of blight are common on tomatoes grown in Minnesota. Almost every gardener has struggled with the fungal diseases Septoria leaf spot or early blight on their tomato plants at one time or another. This year bacteria are the primary pathogens being isolated from tomato leaf spots.


There are two bacteria that result in leaf spots on tomato; bacterial speck caused by Psuedomonas syringae pv. tomato and bacterial spot caused by Xanthomonas campestris pv. vesicatoria. Bacterial speck and spot can cause spots to form on the leaves, stems and fruit of tomato plants. The leaf spots caused by bacterial speck and spot look identical but the two pathogens can be distinguished by differing types of fruit spots that form later in the season.


Leaf spots are dark brown to black, small (about the size of a pencil tip) and have a yellow halo around them. Often the center of these leaf spots dry up and drop out leav…

New Lily Classes Grow in Availability and Popularity

David C. Zlesak, University of Minnesota Extension Educator

Martagon, Asiatic, Oriental, trumpet, and tiger lilies (blooming approximately in this order from late spring through summer) are groups of amazing lilies that have beautifully graced our Minnesota gardens for decades. The martagon lilies have beautiful whorled foliage, flower early with wonderful clusters of typically downward facing flowers with recurved petals, and are even relatively shade tolerant. The Asiatic lilies are probably the easiest for us to grow here in Minnesota. In amenable sites they typically multiply well and provide a glorious show of blooms in probably the widest color range possible of all the different commercial lily classes. The Oriental and trumpet lilies have large, intoxicatingly fragrant flowers. The fragrance is especially powerful in the evening and throughout the night. I love coming home at night and being taken back by the rich, wafting fragrance of my Lilium regale lilies (a whi…

Clematis Growth Types and Pruning

Karl Foord, University of Minnesota Extension Educator
Clematis is a genus that is best known for its vining members that produce large, colorful, showy flowers. This is at best only half of the truth. In fact many of the cultivars do produce spectacular flowers with colors from almost all 360 degrees in the gardener’s color wheel. In addition there are varieties with smaller nodding flowers that add a certain delicacy to the garden as well as some herbaceous types that are more shrub-like and die back to the ground each year. Clematis require a certain effort to make them thrive but it is well worth the effort.

The dizzying array of cultivars can be intimidating, but this can be simplified by categorizing plant types by when they set their flower buds. This will then determine when they will flower and how they should be pruned. As such, the categories are often labeled as pruning groups.


Group A*

In this group flower buds are initiated on this year’s vine in July and then …

University of Minnesota Edible Landscape - A Demonstration Garden Incorporating Fruit and Vegetables into the Home Landscape

David C. Zlesak, University of Minnesota Extension Educator

Earlier this year in the May 15th Yard & Garden News, we featured Emily Tepe’s informative article on Woolch™ in the Mid-May Yard and Garden News as a new mulch for both commercial and home garden use. Emily planted a fantastic demonstration garden where Woolch™ would be featured. She invited us to come and see this garden on the St. Paul campus in front of the Plant Growth Facilities near the ‘Seed of Knowledge’ sculpture (across the street from the Display and Trial Garden). This garden is looking great and has much more to see in addition to strawberries and other plants growing with Woolch™. This garden integrates fruits, vegetables, and flowers into a very ornamental and functional landscape. Please come and visit the garden this summer. If you are not able to make it out or would like to just learn more about this great garden, Emily has created a blog about the garden at http://umediblelandscape.blogspot.…

What's Up With That?!

David C. Zlesak
Why do dandelions all look so similar? Other plants that reseed tend to result in individuals that have noticeable differences from each other. These differences among seedlings may be dramatic or subtle and can involve traits such as flower color, petal number, or plant habit. The answer is that dandelions primarily reproduce by apomixis. Apomixis is commonly defined as asexual reproduction through seeds. The embryos are genetically the same as the mother plant and are not the result of the union of two sex cells. Most plant and animal species rely on sexual reproduction to enhance genetic variability among individuals in populations. Variability can improve the chance that at least some individuals will have a competitive advantage when disease or other challenges come. Those individuals will hopefully survive and be able to reproduce in order to perpetuate the species. Dandelions, some turf grass species, and many citrus have a different strategy that uses apomixis. …

Rose Acacia - A Shrub with Showy Pink Flowers

David C. Zlesak, University of Minnesota Extension Educator
Rose acacia (Robinia hispida) is in full flower across Minnesota. It is a plant many people are unfamiliar with and are asking what it is. The abundant pendulous clusters of rosey pink, pea-shaped flowers makes it especially showy this time of year. Although it is native to the Southeastern United States and is often listed as hardy to zones 5 or 6, forms of it are perfectly adapted across Minnesota and do not suffer dieback. Although not readily for sale in the garden centers, once planted (typically shared among friends) it tends to persist. The amount of it therefore continues to increase across Minnesota landscapes.


Photo 1: Rose acacia flowers are showy and produced over an extended period. David Zlesak

It is an easy to grow plant because of its tolerance to poor soil and drought. Often it is seen growing on old farmsteads or along the roadside. The plant habit is somewhat open and airy because of coarse stems…

Hennepin County Master Gardener Garden Tour July 11th from 9am-4pm

You are invited! Come and join us for our 2nd Annual Hennepin County Master Gardeners Learning Garden Tour. We have 10 very unique gardens designed and maintained by Master Gardeners for you to enjoy. The Master Gardener homeowner and other Master Gardeners will be on site to respond to your questions. For a preview of some of some of the gardens and event please view this video.
Each garden has a different theme and demonstration. Themes include a fairytale garden, a low maintenance garden, urban and woodland retreat gardens, a farmhouse in the city, container gardening, a sanctuary garden, and a shade garden with a labyrinth. There will be practical, informative demonstrations at each site. Master Gardeners will conduct interactive demonstrations at 10, 12, and 2 p.m. on a wide range of topics. You can learn how to create small space, container, and vertical gardens, build low maintenance water gardens in a weekend, create garden rooms and rain gardens, using color to c…

Lawn Mushrooms

Bob Mugaas, University of Minnesota Extension Educator
With some areas of the state receiving moderate to heavy amounts of rainfall over the past couple of weeks, mushrooms are beginning to randomly appear in lawnsTheir appearance often causes people to be concerned about the health of their lawn and whether or not a serious disease might be getting started.
It’s important to remember that mushrooms are the ‘fruiting bodies’ of fungi living in the soil and thatch. They are responsible for the production of microscopic spores that in turn help propagate the fungus. The vast majority of those fungi are not associated with any lawn disease causing organisms. It’s quite common for them to appear during periods of moist conditions resulting from either natural rainfall or excessive irrigation. Again, they are not necessarily indicative of any particular lawn problem. The fungi are living on decaying organic matter in the soil and/or thatch layers. This breakdown of organic matt…

Choose Weed Control Products Carefully

Bob Mugaas, University of Minnesota Extension Educator
When trying to select the ‘right’ weed control product, consumers are often confronted with a bewildering array of possibilities at retail gardening outlets. This prompts the honest question of ‘Which one of these products should I choose?’ Likewise, this question can have a variety of responses depending on what weeds are being targeted. This could easily be the topic of several articles.
However, there is one word of caution that is worth noting. Nonselective weed killers, that is, those that will kill all green vegetation, should not be used to treat weeds in lawns and expect the lawn not to be damaged. The result will end up like pictured where all the plants that contacted the herbicide, including the lawn grasses are killed leaving small to large patches of brown dead grass. These will now need to be reseeded or resodded since none of the grasses in these areas will come back. The two most common ingredients in the…

Thousands Visit Morris Bedding Plant Trials

Steve Poppe, University of Minnesota Scientist, West Central Research and Outreach Center
In the past, no other segment of the floriculture production industry has enjoyed public interest and use of its product more than bedding plants (annual flowering plants). Bedding plants are an indispensable item for landscape use, presenting an array of flowers and foliage that add color and texture to the landscapes of homes, apartment complexes, shopping malls, public buildings, city streets and parks.
The University of Minnesota supports this growing industry through annual flower trials conducted at Morris, St. Paul and Grand Rapids. In 2008, we evaluated annual flowers from eighteen major plant companies. Our gardens are open to the public and industry for selfguided tours throughout the growing season, providing a unique opportunity to compare performance of bedding plant cultivars under regional conditions. The public's response to the 2008display gardens at all locations …

'Go Green with a Splash Party' Weekend at the University of Minnesota Landscape Arboretum Saturday and Sunday, July 11 & 12

This special weekend features an information fair and water-wise demonstrations, art activities, music and a Heart of the Beast Puppet Theatre performance! Part of the 2009 Waterosity theme, this special weekend brings together additional resources and events surrounding the theme of water usage and water-wise practices. Here are just some of the special highlights:
The renowned In the Heart of the Beast Puppet and Mask Theatre will present Are You Thirsty?" (11 a.m. & 1 p.m. July 11 & 12).
Performances will be free with Arboretum admission.
Volunteers will be on hand to help showcase the various exhibits
The information fair will include several area industry and non-profit groups that are involved in water use and management.
While at the Arboretum, don’t miss all the great art displays dispersed throughout the grounds. The over a dozen special art displays celebrating Waterosity will be in place through early October. Artists far and wide submitted ideas t…

Water-Wise Gardening

Julie Weisenhorn and Kathy Zuzek, Director, University of Minnesota Master Gardener Volunteer Program & University of Minnesota Extension Educator

Watering your garden and lawn… it seems so straight forward. When the soil is dry or a plant wilts, water. If it doesn’t rain for two weeks, water. If you happen to have the hose on, sprinkle on a little water.

Not so. There are many factors – the type of soil and the amount of sun and wind in your yard, the types of plants that you grow, weather patterns, and your cultural practices – that play into a landscape’s water needs. The water-wise gardener considers and plans for these factors to produce beautiful landscapes while minimizing water use.


Photo 1: Understanding factors in ones yard that impact water availability will help one choose amenable plants, cultural techniques, and water management strategies. David Zlesak

Study your Yard

Let’s address the soil first. Knowing your soil type – sandy, loam, clay – is the most i…

The Cutting Edge Lawn Care Exhibit

Bob Mugaas, University of Minnesota Extension Educator

The Cutting Edge is an educational display that is part of the 2009 Minnesota Landscape Arboretum’s Waterosity Educational Exhibit. The display focuses on how more water conservative lawn grasses combined with some small changes in lawn care practices can reduce water needs and other inputs going into the lawn.

The exhibit features small plots of several lower maintenance lawn grasses that are starting to see greater use in more water conservative lawns. For more information on low maintenance grasses, please visit Cool Season Grass Selection. Additionally, a plot of tall fescue, an up and coming turfgrass species with good drought tolerance and some adaptability to shady conditions, is featured. Prairie junegrass, a native of Minnesota prairies, is also be on display as it would appear in a lawn situation. As it already has very good drought tolerance, this shorter growing native species is currently involved in a …

Drought-Tolerant Plants

Kathy Zuzek, University of Minnesota Extension Educator


Do you live in a geographic area with little rainfall? Do your sandy soils allow water to percolate away quickly? Are you looking for a drought-resistant landscape? Are attractive landscapes and water conservation both goals of yours? Below is a partial list of trees, shrubs, and herbaceous perennials that once established, grow well with little supplemental watering. Within most of the species listed, there are cultivar choices that will provide you with a wide variety of ornamental traits.



Photo 1: Japanese tree lilac. Kathy Zuzek

Deciduous Trees
Common NameScientific NameExposure*Autumn Gold Ginkgo Ginkgo biloba ‘Autumn Gold’SBlack Walnut Juglans nigra SBlue BeechCarpinus carolinianaS/Psh/ShBur OakQuercus macrocarpa SCockspur hawthornCrataegus crus-galli SCrabappleMalus spp. SDakota Pinnacle® BirchBetula platyphylla ‘Fargo’SHackberryCeltis occidentalis SIronwoodOstrya virginiana S/PshJapanese Tree Lilac Syringa reticu…

Here Today Gone Tomorrow - spring leaf spot diseases make a short visit to Minnesota

Michelle Grabowski, University of Minnesota Extension Educator
For most areas of Minnesota, the spring of 2009 has been an unusually dry one.  This cool dry weather has kept many of the spring leaf spot diseases of trees at bay.  Diseases like anthracnose on oak, ash and maple have been absent up until the most recent wet weather.  Anthracnose is now being reported, especially in areas that received significant recent rain like southern Minnesota. The fungi that cause anthracnose, however, may not be causing problems for long. Anthracnose fungi thrive in cool wet weather and with the recent onset of hot temperatures, the growth and spread of this disease is likely to slow down.


Photo 1: Oak anthracnose. Michelle Grabowski
The biology of these fungal leaf diseases explains why in some years anthracnose is a big problem and in other years only minor damage occurs. Anthracnose fungi survive Minnesota’s winter in infections on twigs, buds, and last year’s infected leaves.  Spring…

Poplar and Willow Borer

Jeffrey Hahn, Asst. Extension Entomologist
All species of willow, most poplar (but rarely quaking aspen), and occasionally birch and alder are susceptible to attack by the poplar and willow borer, Cryptorhynchus lapathi.  This insect, a type of weevil, is 5/16 - 3/8 inch long with a slender snout as long as its head.  It has a roughly textured black body with mottled cream to tan colored patches on its body and its legs, including the back 1/4 of its wing covers.


Photo 1: Poplar and willow borer. Jeff Hahn
Poplar and willow borers overwinter as larvae in small cavities they excavate under the bark.  The larvae continue feeding in the spring, expelling frass (a mixture of sawdust and excrement) out of openings as they tunnel around stems or branches.  They eventually pupate in June and then emerge as adults in late July or August.  Adults feed on young stems, laying eggs in slits in the bark.  The larvae tunnel under the bark, creating galleries in all directions.  They chew …