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Showing posts from April, 2010

Japanese Beetles in Minnesota: Education, detection, and management

Dan Miller, Plant Health Specialist, University of Minnesota Landscape Arboretum

The Japanese beetle (Popillia japonica) was first detected in the United States in New Jersey in 1916 and has spread throughout most states east of the Mississippi and to parts of Arkansas, Missouri, Kansas, Oklahoma, Iowa, and Minnesota west of the Mississippi. In Minnesota, the beetles were first detected in 1968. Trapping programs conducted by the Minnesota Department of Agriculture (MDA) showed low but consistent numbers from 1991 to 1998. Trapping data in 1999 and 2000 showed a dramatic increase in Japanese beetles with the highest counts occurring in Washington, Ramsey, Hennepin, Dakota, and Carver counties. After trapping in 2002, the MDA concluded that the beetle was too widespread to be eradicated. The beetle was then deregulated and budget cuts shifted the direction of the program so the statewide trapping program was discontinued.

Arboretum exhibit demonstrates integrated control of Japa…

May 2010 Garden Calendar

Contributors: Karen Jeannette, Yard and Garden News Editor
Including Excerpts from the 2010 Minnesota Gardening Calendar


This month Bob Mugaas tells us the crabgrass has emerged early (Home Lawn Care - Recapping the very early spring of 2010 and what's next for timely information about Lawns) and Jeff Hahn says Spring Insects are Early this year, too. Gardeners across the state have been inquiring if they can plant and perform other garden and yard tasks earlier than in past years. Below we provide advice for this gardening season come early.

Advice for the Gardening Season Come Early
When to Plant Flowers
Despite the warmer and earlier growing season, the answer to, "Is it safe to plant perennials and annuals?" is still "Wait until mid-to late May to plant perennials and until after your area is frost free before planting flowering most annuals."

Why Wait?In most Minnesota locations, perennials can be planted after mid-month, but wait until you're certain …

Home Lawn Care: Recapping the very early spring of 2010 and what's next

Bob Mugaas, University of Minnesota Extension Educator
Snow mold recovery
This spring began with the very early snowmelt in mid-March that left in its wake one of the highest incidences of snow mold on many residential and commercial lawns in recent memory. Much of that could be attributed to the very wet snow that fell around Christmas time on unfrozen or barely frozen lawn surfaces. The high moisture content of the snow combined with the mostly unfrozen lawn conditions provided nearly ideal conditions for the snow mold fungi to grow and thrive. In addition, that snow cover was maintained throughout the winter months providing a very long period of total snow cover and good conditions for snow mold growth. However, as is often the case, even with as much snow mold as was evident this spring, most lawns will have recovered on their own and returned to healthy growth and good green color by early May. The severity of snow mold on some lawns did result in the need for some reseeding to …

Keeping Plants Healthy and Green While Going Green

Michelle Grabowski, University of Minnesota Extension Educator


Regardless of the time and effort put into a garden, inevitably at some point a plant disease will show up. These spots, rots and wilts can be quite distressing to a gardener working to beautify their yard or hoping for a fresh crop of fruits or vegetables. Often the first response to disease problems is to spray a fungicide. Many gardeners however are looking for alternatives to this management strategy. Whether you are going organic, trying to reduce the number of pesticides used in your yard or looking for a simple inexpensive means to reduce plant diseases, cultural control practices can be a great strategy for keeping plants healthy. The US Department of Agriculture Organic rule states that preventive and cultural control practices must be a grower's first choice for pest control. In yards and gardens, preventative and cultural control practices are often effective at reducing disease problems to a level where th…

Little Worms Under Elm

Jeffrey Hahn, University of Minnesota Asst. Extension Entomologist



Photo 1: Elm gall midge larvae on sidewalk. Unknown. Large numbers of very small, about 1/16th inch long, pinkish worms were found during mid April under elm trees. Looking like grains of rice, these 'worms' are actually a type of fly known as a gall midge. It is not clear what species is present but they appear to attack the developing samaras (winged seeds) in early spring. Later in the spring (sometime in April to early May), the mature larvae drop to the ground where they remain until the next spring. The galls are harmless to the tree and no control is necessary. The larvae can be a nuisance when they fall on driveways or sidewalks. The only necessary step is sweep them off. This is a short lived problem that will go away on their own.

Be on the Watch for Ticks

Jeffrey Hahn, University of Minnesota Asst. Extension Entomologist

With the early spring we have been experiencing this year, ticks have also been active sooner than normal. The two most common ticks we encounter are the American dog tick (also known as wood tick) and the blacklegged tick (formerly called deer tick). Both of these ticks are found in the underbrush of hardwood forests and adjacent open grassy fields

Both are annoyances because they bite people and our pets as they seek blood meals. However, blacklegged ticks are particularly a pest because of their ability to vector diseases. The most common disease they can transmit in Minnesota is Lyme disease (1,050 cases in 2008). Lyme disease is most common in central and eastern Minnesota. Blacklegged ticks are also known to vector human anaplasmosis (278 cases in 2008), babesiosis (24 cases in 2007), and Powassan virus (2 cases ever reported, both in Cass county).

Photo 1: Blacklegged tick close-up. Jeff Hahn.There are certa…

Spring Insects Are Early

Jeffrey Hahn, University of Minnesota Asst. Extension Entomologist

Photo 1: Recently hatched forest tent caterpillar.Jeff Hahn.We are experiencing a noticeably early spring. Consequently this has caused insects to become active earlier than normal. During April, insects such as forest tent caterpillar, European pine sawfly, and pine spittlebug were already active, about 3 - 4 weeks ahead of schedule. Undoubtedly, many garden insects are also active as well. That is not to say all of individuals of a species have become active, but at certain sites they have.



If you are anticipating a particular insect problem for mid May, look now, it probably is already present. If you are looking for an insect that normally comes out in early May, it probably is already is active. Inspect your garden and landscape now for potential insect pests.



What Should I Do With My Ash This Year?

Jeffrey Hahn, University of Minnesota Asst. Extension Entomologist


With the discovery of emerald ash borer (EAB) in Minnesota last year, people with ash on their property are concerned about possible attacks from EAB and what they should do, if anything, to protect their trees. Insecticides are an effective method to protect your ash from EAB but does this mean this is what you should do? There are a number of factors that people should consider when weighing their options.
The first factor you should consider is how far are you from a known EAB infestation. The general guideline is that the highest risk from EAB occurs when you are within 10 -15 miles from a known infestation. Right now, EAB is only confirmed in St. Paul and Minneapolis. This means that essentially all of the Twin Cites metropolitan area is at a high risk. However, if you are in Minnesota outside of this 10 - 15 mile radius, the risk from this exotic borer, while not zero, is much smaller and treating your ash …

Planting Bare-Root Woody Plants

Kathy Zuzek, University of Minnesota Extension Educator

Spring is here bringing planting season. Early spring between the time that the ground thaws but before bud break is one of two optimal times during the year for planting bare-root trees and shrubs.

What is a bare-root plant?

The name says it all. Bare-root nursery stock are trees and shrubs that are field grown for one to three years, undercut and dug in fall and spring, handled with no soil left around roots (Photo 1), and stored with moist roots and dormant tops at a temperature a few degrees above freezing until they are planted. If you have never seen undercutting in action check out this You Tube video: http://www.youtube.com/watch?v=LLYI6MVJqsg




Advantages and Disadvantages of Bare-Root Plants
Bare-root stock offer several advantages:
Bare-root plants are usually ½ to 2/3 of the cost of containerized or balled & burlapped plants because bare-root plants are easier to handle, store, and ship.Longer root lengths are possib…

Lawn Grass Varieties, Seed Labels, and What to Plant Where

Bob Mugaas, University of Minnesota Extension Educator
This is the third and final article in a series of articles related to choosing and selecting the best MN adapted lawn grasses for this area. This last topic will address the topics of what to do when you can't locate the particular grass varieties you've identified, how to read a grass seed label to know what you're really buying and some suggestions for the kind of grass seed mixes to use in various locations around our home landscapes. The previous posts are listed here:

Series: Choosing and selecting the best MN adapted lawn grasses

Part 1: Know Your Minnesota Lawn Grasses
Part 2: So what are the best grass varieties?
Part 3: This blog post, Lawn grass varieties, seed labels and what to plant where...
Tips for selecting the best available grass seed varieties

Selecting and then finding specific varieties of grass seed is not always as easy as you might think. Unlike the relative ease of finding your favorite tomato or…

Hackberry Witches' Broom

Michelle Grabowski, University of Minnesota Extension Educator and Jeff Hahn, University of Minnesota Asst. Extension Entomologist

As you look up at the trees this spring, watching for emerging buds or perhaps a returning song bird, you might notice many small clumps of short twigs scattered through the branches of some hackberry trees (Celtis occidentalis). These clumps of twigs are called witches' brooms.
Although witches' brooms are present within the trees canopy throughout the year, they are most easily observed in the winter or early spring, before leaves emerge. Hackberry trees growing in open areas, like a yard or along a street, are more likely to have witches' brooms than hackberry trees in a forest. Often one hackberry tree will have many witches' brooms while its near neighbors have none.

Witches' brooms occur when the bud of the tree is injured or infected. Normally, a healthy bud opens to produce one shoot. However, when a bud is damaged or killed, …

Repairing Spring Flooded Lawns

Bob Mugaas, University of Minnesota Extension Educator

Early spring, before lawns are actively growing (i.e., foliage is still mostly brown) lawn grasses can withstand several days of being submerged without suffering serious damage. If floodwaters are cold (<60 degrees F.), as they usually are in early spring, lawn grasses can withstand being submerged for even longer periods of time.

Moving water is usually less harmful to lawn grasses than is ponded, stagnant water. Ponding occurs in areas of poor drainage or results from water being left behind in valleys and depressions when floodwaters recede. Spring flooded lawn areas where the water has risen and then receded rapidly often escape serious permanent injury and death.

Post flooding lawn care

Once the soil has dried sufficiently such that it is no longer soggy and slushy underfoot, pick-up and remove debris such as wood, glass, stones, sheet metal, paper products along with other forms of junk deposited by flood waters. It i…

Rove Beetles

Jeffrey Hahn, University of Minnesota Asst. Extension Entomologist

An interesting sample was received from northwest Minnesota in March during a week when the weather was unseasonably warm. More than 20 insects were found on the carpeting in a couple of rooms in a Senior citizens' home. They were worried that they would be damaging and spread to other areas of the building.

The insects in question are a species of rove beetle. Rove beetles are very common insects, although the are often overlooked by people. Most are small, 1/16th - 1/8th long and are conspicuous because of the short wing covers they possess which leaves much of the abdomen exposed. Rove beetles are often associated with dead animals and dung as well as on the ground under stones and other debris. They are predaceous on other insects.

Fortunately, rove beetles are not harmful to people or our property. They do not reproduce indoors and are just a temporary nuisance. It is likely that these particular beetl…

Arboretum Challenge: Veggies by the Yard

Leslie Cooney, Membership Services Manager, Minnesota Landscape Arboretum
Are you thinking about your gardens? Starting seeds? Planning a vegetable bed? Need a garden plan?

The Arboretum is issuing a challenge to all gardeners out there to plant and compare with something we're calling "Veggies by the Yard." Part of our summer exhibition on Powerhouse Plants, we're going to find out just how much food can be grown on a 4x12 ft. plot. Our website offers several vegetable garden plans to choose from:
First-time gardeners
Salad lovers2 in 1 gardensRoots and tubersVeggie selections for the adventurous cook
We'll keep a harvest tally of our yields and ask you to do the same - entering the data online every Saturday June through September. It's a chance to go head to head with Ted Pew, our valiant veteran veggie guy and landscape gardener extraordinaire!
Photo: Will you be planting one of the Veggies by the Yard garden plans this year? Karen Jeannette. Find out more a…

April 2010 Garden Calendar

Contributors: Karen Jeannette, Research Fellow and Yard and Garden News Editor; excerpts from the 2010 Minnesota Gardening Calendar.


Plant tips
Prepare Your SoilSoil Testing: Take a soil test before you get ready to prepare your garden.   See "How to Take a Soil Test."Find tips for fertilizing, composting, maintaining soil health, and plants for tough sites here.
Vegetables Need ideas for the vegetable or edible garden?
Review last season's ideas and discoveries from the University of Minnesota Display and Trial Garden's Edible Landscape.Use the pre-designed veggie garden plans and participate in the MN Landscape Arboretum challenge: Veggies by the Yard.
LawnsFertilize your lawn to keep it growing vigorously enough to help keep weeds out. Wait until you've had to mow it once or twice though, so you know the roots are growing actively and can make good use of the added nutrients. Seep up and reuse any granules that land on hard surfaces such as sidewalk or driveway…