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Extension > Yard and Garden News > Archives > June 2009 Archives

June 2009 Archives

A Summer Minnesota 'Snowstorm'!!!

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David C. Zlesak, University of Minnesota Extension Educator

‘Snowstorm’ is the first wand flower (Gaura lindheimeri) release from the Flower Breeding and Genetics program led by Dr. Neil Anderson! Wand flower is a prized garden subject because it: blooms continually throughout the summer, is a great filler plant that mixes well with other plants in garden beds and containers, and it moves in the wind adding extra ornamental appeal. Gaura lindheimeri has grown in popularity over the past decade and is among the top 25 selling perennials in the US market today. Although this Gulf Coast native (Texas and Louisiana) is reliably hardy only to zone 6, it serves as a great annual in Minnesota.

Mid-June Lawncare Tips

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Bob Mugaas, University of Minnesota Extension Educator

While this past May went down as one of the driest Mays ever, many areas around the Twin Cities have received some rain during the first part of June. That has both been very helpful for our lawn grasses and has also provided the needed moisture for many of our weed seeds, especially crabgrass to begin actively germinating. In most areas of southern Minnesota we are past the time when preemergent herbicides for crabgrass control will be effective. However, that doesn’t mean control is not possible. Those small crabgrass seedlings can effectively be controlled with postemergent herbicides. One of the newer active ingredients for crabgrass control is quinclorac. This is a very good herbicide for controlling crabgrass once it’s germinated and the seedlings are visible. However, it is usually mixed with other broadleaf control products and marketed for home use as general weed and crabgrass killers. However, it is important to note that with these combination products, you will be applying other herbicides that are not needed or even effective at controlling crabgrass. Hence, this unnecessarily introduces these other materials into the environment; something we try to minimize doing whenever possible.

Rose Rust Takes Off this Spring

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Michelle Grabowski, University of Minnesota Extension Educator

Cool temperatures this spring seem to be encouraging rust fungi on roses. Several different species of Phragmidium (the rust fungus) can infect both wild and cultivated roses. Gardeners should keep an eye out for two different forms of this fungus.

Bright powdery orange spores, known as uredinia, are likely to catch a gardener’s eye. These spores form in raised pustules on the underside of infected leaves, stems, or petioles (central portion of the leaf that the individual leaflets are connected to). Yellow to brown leaf spots may be noticeable from the top surface of the leaf but may not form on all rose cultivars. Infected petioles and young green stems may actually become twisted and distorted around the site of the infection. Rust fungi can infect all plant parts except the roots and gardeners may notice bright orange pustules in unusual places!

Water-Wise Hardscapes

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Waterosity, the 2009 summer exhibition at the Minnesota Landscape Arboretum, opened on June 6 and explores and celebrates the beauty and the complex interdependence of people, plants, and water. Providing homeowners with environmentally responsible ways to manage water on their property is a key theme of Waterosity. Water-wise hardscaping includes green roofs and permeable paving and both technologies help to reduce the amount of stormwater that washes over roofs and paved areas (driveways, sidewalks, and streets), carrying sediment and pollution into lakes, rivers, streams, and wetlands. Green roofs and permeable paving displays are part of the new permanent arboretum exhibit called Harvest Your Rain.

For more information on Waterosity displays and programming, please visit the Waterosity website and Waterosity Comes to the Arboretum in the May 1, 2009 Yard and Garden News.

Permeable Paving

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Peter Moe, Director of Operations, University of Minnesota Landscape Arboretum

Permeable, or porous, paving is a type of paving that allows water to drain through to the ground below. Water can then directly infiltrate on-site rather than being diverted to a drain for off site treatment. These systems protect surface water, recharge aquifers, reduce flooding and reduce the need for traditional storm sewer systems.

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Jonathon Hensley, University of Minnesota Graduate Student

The dense, accelerated pace of modern urban development has affected many of the earth’s natural processes. Asphalt and concrete rooftops, roads, and parking lots cover up to seventy percent of land area in dense cities like New York, while open space in sprawling cities like Phoenix, Arizona is lost to development at a rate of 1.2 acres per hour.1

Approximately 1.5% of the continental United States, an area roughly equivalent to the state of Ohio, was covered by impervious surfaces in 2004.2 This percentage continues to grow and can be as high as 75% in urban areas. Of those impervious surfaces (not allowing the permeation of water), roofs can constitute a significant percentage. Such growth in impervious surfaces can result in a variety of environmental impacts including reduced aquifer recharging, overwhelmed storm water systems, urban heating, decreased surface water quality, and increased air ozone and particulate concentrations. These negative environmental effects impact residents and municipalities by affecting: clean water availability, storm water and sewage infrastructure costs, decreased runoff water quality, decreased employee productivity, decreased wildlife habitat, and increased operating costs of buildings through increased heating and/or cooling costs. Alternative solutions to traditional impervious building methods are being sought in order to mediate these negative environmental impacts and reestablish the green spaces desperately needed in our metropolitan spaces.

Oriental Poppies Take Center Stage!

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David C. Zlesak, University of Minnesota Extension Educator

Glowing, vibrant blooms bring oriental poppies (Papaver orientale) to center stage this time of year. The large (4-6”) flowers have crêpe paper-like petals and are held high above the foliage on strong, yet wiry stems. In a gentle breeze they almost appear to dance. The finely cut foliage makes a great backdrop to the flowers and the abundant, almost downy hairs that cover the foliage and stems set Oriental poppies apart from most other commonly grown poppies.

Native to central Asia where summers are warm and dry, these magnificent poppies have developed a unique adaptation method. When moisture is relatively abundant in spring, leaves emerge and plants quickly come into flower. As temperatures rise and moisture becomes less abundant, the foliage begins to die back and plants go dormant. As temperatures begin to cool in the fall and rains return, new foliage again emerges.

Caterpillars on Blueberries

Jeff Hahn, Asst. Extension Entomologist

There are several caterpillars that have been detected feeding on the leaves of blueberries recently. One species is the copper underwing, Amphipyra pyramidoides. This insect, also known as the pyramidal fruitworm, is bluish green with a thin yellow stripe running the length of its body along its sides and small whitish patches. It also possesses a conspicuous hump on the end of the abdomen and grows to about 1 ½ inches when fully grown. This caterpillar feeds on a wide variety of plants in addition to blueberry, such as trees (e.g. apple, basswood, maple, oak), shrubs (e.g. lilac, viburnum, and rose), and fruit including grape, raspberry, and currant.

You can also find forest tent caterpillars, Malacosoma disstria, in your blueberries. Also referred to as armyworms, these caterpillars are easily identified by their blue and black bodies, the distinctive white footprint shaped spots on their back as well as hairs that stick out along the sides of their body. These caterpillars are about two inches long when fully grown. Despite their name, they do not make conspicuous webs in trees. They commonly feed on many deciduous trees, including aspen, birch, maple, crab apple, apple, ash, oak, and elm.

Click Beatles

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Jeff Hahn, Asst. Extension Entomologist

People have been finding click beetles lately in their yards and around their homes. They are generally between 3/8 - ½ inch long, are dark brown or black with an elongate oval and flattened body. The prothorax, the area behind head, appears ‘loose’ with the rest of the body. The back corners of the prothorax are prolonged back into sharp points.

Click beetles are found commonly on foliage and flowers as well as under bark. They are also attracted to lights. A click beetle is unique because it can right itself when it is on its back. It does this by arching the area between the prothorax and mesothorax (where it looks loose) and then snaps it back, usually producing an audible ‘click’. This action will cause it to jump up, often allowing the insect to regain its feet. If it remains on its back, it will keep trying until it succeeds.

What's Up With That?!

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Michelle Grabowski

Powdery orange golf balls (or larger spheres) have been spotted on pine trees across Minnesota. What are these strange growths? They are galls, a woody tumor like growth that is part plant, part fungus. In this case the pine trees have been infected with one of two different gall forming rust fungi: pine-pine rust (Endocronartium harknessii) or pine-oak rust (Cronartium quercuum). The diseases get their names from the trees they infect. Pine-pine rust only infects 2-3 needled pine trees like Jack pine, Scots pine and Ponderosa pine. Pine-Oak rust lives half of its life in galls on pine trees and the other half on the leaves of oaks like northern pin oak or bur oak. The galls are present year round. In the spring, both fungi release powdery yellowish orange spores, drawing attention to otherwise discrete brown woody galls.

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Terrance T. Nennich, University of Minnesota Extension Educator

The gardening season in Northern Minnesota is brutal and harsh to say the least. Lack of heat units, freezing temperatures in early June and late August, very cool nights and high winds are very challenging to even the most experienced and patient gardeners. The long period of times that plants are wet from dew or prolonged rain can make disease control nearly impossible some years. Gardeners in Northern Minnesota are usually very optimistic people, continually telling themselves that next year things will be much better and the weather will be much more cooperative to help produce that lush, bountiful harvest that we all hope for. Then about every five years, somewhat ideal conditions come together and that super abundant crop is produced. And so the cycle goes.

High tunnels can help gardeners produce that great crop every year with little risk. High tunnels can lengthen the growing season as much as 5-6 weeks in the spring and also in the fall. What are high tunnels?

Tips for creating successful window box planters

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David C. Zlesak, University of Minnesota Extension Educator

The popularity of creatively combining different plant materials in window boxes has soared in recent years. Combining plants of various color, texture, and plant habit to design what in essence become miniature landscapes provides gardening enjoyment from both outdoor and indoor vantage points.  Designing and having window boxes can become a very fun, creative, and rewarding endeavor. The diversity of plant materials to choose from and effects that can be generated seem almost limitless.  Many people choose to try different combinations and overall themes each year.  This makes it exciting for neighbors and passersby as they anticipate what will be next.

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If you are looking to get fresh ideas for your garden, to see the latest in University flower, fruit, and vegetable varieties and accompanying research for yourself, or just to experience a beautiful, accessible garden, you will want to visit the 6-acre Master Gardener Education & Research Display Garden! There are over 25 different display and trial gardens to see.  They are well-labeled and a fantastic resource for Minnesota gardeners.

The garden is free to the public and open daily (sunrise to sunset) with plenty of free parking available. It is located on the South side of Highway 46 in Rosemount, Minnesota, just two miles East of Highway 3. It is within and part of the 5,000 acre UMore Park (University of Minnesota Outreach, Research, and Education Park). The garden started in 2001 with the purpose of being a display garden serving the public through education and research.  It is located in the Southeast metro and has a much different flavor and a unique purpose compared to the Minnesota Landscape Arboretum located in the West metro. 

Early June Lawncare Tips

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Bob Mugaas, University of Minnesota Extension Educator

In some areas of the state, lawns have received ample moisture this spring to maintain good growth and color while others have been quite dry; Twin Cities included.  In fact, supplemental lawn watering has already begun in many areas around the Twin Cities.  In most cases, it will take about 1.0 inch of water per week to keep Kentucky bluegrass lawns green and actively growing through the summer months.  One question frequently asked by homeowners is “How do I know how much water my sprinkler or irrigation system is putting out?” 

Seeing Spots

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Michelle Grabowski, University of Minnesota Extension Educator

As the season warms up and new leaves reach their full size a few gardeners are noticing unsightly spots in a wide variety of plants.

What are these spots?

Many of the spots that gardeners are seeing are caused by fungal or bacterial pathogens infecting the leaf tissue. There are a few look a likes, however, so gardeners should pay attention to the details. Fungal and bacterial leaf spots are typically randomly scattered across the leaf. There are often several sizes of leaf spots because the spots get bigger as the pathogen grows. In addition leaf spots caused by a pathogen start out on one leaf and eventually spread throughout the plant or to other plants. A gardener may notice fluffy white cobweb like fungal growth, powdery spores or other signs of the pathogen in the spots themselves.

Insecticide Options For Treating Emerald Ash Borer

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Jeffrey Hahn, Asst. Extension Entomologist

By now, I am sure that everyone has heard about the confirmed emerald ash borer (eab) find in St. Paul on May 14 near Hampden Park (northeast of the intersection of I-94 and Highway 280).  There are lot of questions being asked by homeowners about what to do, especially about insecticides.

First, if you are further than 10 to 15 miles from St. Paul, we do not suggest you treat your ash.  Without being closer to known eab infestations, you are very likely just wasting money and insecticides.

But if you are within this 10 to 15 mile radius, treating your ash is a consideration.  However, this issue is more complicated than just what product to use.  There many factors to consider.  There is a new fact sheet written by entomologists from Michigan, Ohio, Indiana, Wisconsin, and Illinois that discusses this topic in detail.  You can find this publication on the Extension Emerald Ash Borer web page. Look under Resources and then under Management.  This page also contains a lot of other important information concerning eab.

Photo 1: EAB galleries in infested tree in St. Paul. Jeff Hahn

Azalea Sawflies

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Jeffrey Hahn, Asst. Extension Entomologist

There have been reports of sawflies defoliating azaleas recently.  The larvae hatch during May and are active into June.  They are smooth, slender and grow to about 3/4 inch long.  They are light green which allows them to blend in really well with the azalea leaves, making them difficult to see. 

It isn’t unusual for gardeners to overlook azalea sawflies when they first start feeding.  Often the first symptom of their presence is chewed leaves or droppings on the foliage.  Azalea sawflies start feeding on the edge of leaves and work their way down to the midrib.  On heavily defoliated branches, all that remains is just a series of veins sticking out, resembling a skeleton.

Fourlined Plant Bugs Are Now Active

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Jeffrey Hahn, Asst. Extension Entomologist

If you are out in your garden and notice small, uniformly sized spots on your favorite perennials, be suspicious of fourlined plants bugs.  Fourlined plants bugs hatch in late May or early June and feed until early to mid July.  Newly emerged nymphs are about 1/16th inch long and bright red.  As they grow larger, they develop black wing pads which eventually develop yellow stripes.  Eventually they mature into 1/4 - 1/3 inch long insects with a reddish orange head and greenish yellow wing covers with four black stripes.

Masked Hunters in Homes

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Jeffrey Hahn, Asst. Extension Entomologist

Some residents have discovered masked hunters in their homes recently.  A masked hunter is a ½ - 5/8 inch long, dark colored insect.  It has a moderate sized body with slender legs and medium length antennae.  A masked hunter, a type of assassin bug, gets it name from the fact that the immature nymphs cover themselves with dust and debris to help conceal themselves, thus becoming camouflaged.  Both adults and nymphs are predators, feeding on other insects.

Garden Calendar for June

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Contributors: Kathy Zuzek and David C. Zlesak, University of Minnesota Extension Educators

June is an amazing month in Minnesota- perhaps the most enjoyable one of all with generally nice weather and the fast rate of growth of plants in our gardens.  It is definitely a month when there is a lot to enjoy in our gardens.  Early season vegetables are ready for harvest and our ornamental plants are growing strong.  In the midst of everything going on, please don’t forget to take time to relax and “smell the roses”.

Danger of frost and very cool night time temperatures are finally over for most parts of Minnesota.  This means we can put out our warm season vegetables and flowers that are sensitive to chilling injury.  This includes: tomatoes, peppers, cucumbers, squash, melons, cannas, coleus, and impatiens.  Perhaps we have put some of these crops out earlier and protected them from frost.  It is amazing how just cool night time temperatures in the high 30’s and low 40’s F can stunt growth of warm season crops. Warm season plants put out in our gardens now can outgrow those that may be suffering from chilling injury from our excitement to get them in early even if we protected them from frost. 

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