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Showing posts from April, 2016

Wise watering practices for newly planted trees and shrubs

Kathy Zuzek, Extension Educator

It is prime time for planting trees and shrubs in Minnesota. If planting is on your list of spring chores,
remember that proper watering is the most important practice to ensure survival and establishment of
your woody plants. No matter what planting stock you choose - bare root, containerized, balled and burlapped, or tree spaded – your new tree or shrub has a smaller root system than an in-ground, established plant. Frequent watering allows an under-sized root system to supply all the water needed by the plant while the root system expands and grows to a normal size. Under-watering and over-watering are both detrimental to plant health so it is important to know when to water, where to water, and how much water to apply. Wise watering practices for newly planted trees and shrubs can be found here.

Boxwood leafminer: A rare insect in Minnesota

Jeff Hahn, Extension Entomologist

Boxwood is a shrub or small tree that usually grows well up to hardiness zone 5. They are marginally hardy in Minnesota (hardiness zones 4 and 3). Despite that, boxwood can be found occasionally here in the landscape. Where boxwood is commonly grown in landscapes in states further south, the most serious insect pest is boxwood leafminer. In the upper Midwest this insect is rare. A resident in a Minneapolis suburb recently reported the presence of this insect in her boxwood.

As an adult, boxwood leafminer is a small delicate orangish mosquito-like fly belonging to the gall
midge family (Cecidomyiidae). This insect spends the winter as a larva inside boxwood leaves. It becomes active when the weather warms in the spring and eventually pupates and emerges as an adult. Adults lay eggs inside the boxwood leaves which hatch later in the summer where they remain through the winter. There is just one generation a year.

The feeding of the larvae c…

Water wisely: grapes in the home garden

By Matthew Clark, Assistant Professor
Grape Breeding and Enology
Department of Horticultural Science.
Grapes are a welcomed addition to home gardens. Successful grape breeding by universities and grape growers has resulted in a very good selection of varieties that perform well in our northern landscapes. These fruits can be grown for wine, jams and jellies, and as table grapes for fresh eating. University of Minnesota Grape Varieties
Some growers may make claims that a stressed grape plant will produce better wine. In reality, grapes need to have adequate water to enable systems like photosynthesis, evaporative cooling, and nutrient transport to work properly. Common symptoms of drought stress in grapes wilting leaves, change in leaf angle (away from the sun), and shriveling fruit. Drought stressed plants are less likely to survive Minnesota winters.Winter injury itself can cause symptoms of drought stress and allow vines to become infected with crown…

Garden offenders: get a jump on four common problem plants

Julie Weisenhorn, Extension educator

Typically people contact Extension with the question "How can I get get rid of  __________?" (fill in with a troublesome plant). Unfortunately, these offenders are well-established by the time we usually get this call. So here are four of the most common problem plants and what they look like now in their emerging stage, so you can get a jump on getting them out of your yard and garden!

Buckthorn (Rhamnus cathartica)
Public enemy #1, buckthorn was introduced as a hedge plant. Buckthorn was a favorite of urban homeowners for its interesting cherry-like bark, tolerance to many growing conditions and its receptiveness to pruning. Today, common or European buckthorn as well as glossy buckthorn (Frangula alnus Mill.)  are listed on the Minnesota Department of Agriculture Restricted Noxious Weed List. Buckthorn is leafing out right now and can be easily spotted by its silvery-gray park with white lenticels, bright green, rounded young leaves a…

Soil temperatures needed for germination

By Beth Berlin, Extension Educator-Horticulture
University of Minnesota Extension - Stearns & Benton Counties

ST. CLOUD, Minn. - Many gardeners were ready to get a jump start on their gardens when it was so warm back in early March. Although the frost is out early this year, soils need to reach a specific temperature in order for seeds to germinate. Click here for a list of common vegetables and the minimum and optimal soil temperatures for seed germination ...

Do your trees and shrubs need fertilizing this spring?

Kathy Zuzek

The most beneficial time to fertilize trees and shrubs is from early spring when soil becomes workable until the time in April or early May when woody plants move into active growth. Fertilizing at this time provides woody plants with nutrients just as they put on their main flush of growth during spring.

Water wisely: annual and perennial flowers

Japanese barberry infestations and their impact on human health

Kathy Zuzek, UMN Extension Educator  Japanese barberry is a popular landscape shrub known for its bright foliage color, attractive flowers and fruit, a wide variety of plant habit, and its deer resistance. More than 80 cultivars have been developed since it was first planted in the U.S. in the late 1870s. But Japanese barberry is also an invasive plant that has naturalized in more than 30 states across the U.S. 

In January of 2015, Japanese barberry was listed as a noxious weed in Minnesota. There is a wide variety of seed production among barberries and the 26 seediest cultivars, identified by research at the University of Connecticut, are being phased out of nursery production over a three-year period. On January 1, 2018, these cultivars will become restricted noxious weeds in Minnesota and their propagation and sale will be illegal. 

Minnesota noxious weeds are plants designated by the Commissioner of Agriculture to be injurious to public health, th…

Spring preemergent applications for crabgrass

Sam Bauer, Assistant Extension Professor, Turfgrass Science
Every year around this time I start receiving questions regarding when to apply preemergent herbicides for preventing crabgrass establishment in lawns. Crabgrass germination is driven by soil temperatures and because of this we cannot rely on a calendar date to tell us when to apply our preemergent products. The reality is, if we wait too long and miss the window of opportunity to apply crabgrass preventers, these products will not do much for control of crabgrass. For this reason I like to rely on a couple of website resources that help to determine when to make these applications.  The first website that I like to use can be found here: This is a site operated by Michigan State University and the model uses air temperature predictors to determine when to apply crabgrass preventers. Simply select the tab "Crabgrass PRE", enter your zip code, and the map will be created.  Below is the curre…