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Showing posts from May, 2012

Cutworms Gone Wild

Jeffrey Hahn, Asst. Extension Entomologist

Many parts of Minnesota experienced large numbers of adult cutworm moths recently. However, it was not so much the moths that were noticed as were the many eggs that were laid on homes on windows, siding, soffits and other places. Clusters of eggs were reported from the Twin Cities up to northern Minnesota, especially in the northeastern part of the state. Some towns found that essentially all buildings had at least some eggs on them. One resident said he found as many 15 clusters of eggs on his home. Wisconsin also experienced a similar phenomenon with cutworm eggs found in much of the northern half of their state.
Insect eggs are often challenging to identify, especially to species. While it was fairly easy to diagnose the eggs as belonging to a moth, it wasn't until someone was finally able to catch the culprit in the act of laying eggs that the species could be identified as a variegated cutworm. Variegated cutworms are native …

Watch Out for These Insects

Jeffrey Hahn, Asst. Extension Entomologist

Insects are out in full force in gardens and yards this spring. Are any of these pests at your home?

Aphids are small pear-shaped, soft-bodied insects. They have been reported on roses and red elderberry this spring so far, but will feed on a wide variety of herbaceous and woody plants.

They feed on plant sap with a long, needle-like mouthparts. Plants typically do not exhibit noticeable symptoms when infested by small to moderate numbers of aphids, although large numbers can cause wilting and loss of plant health. There are many natural enemies to help keep aphids under control, especially ladybird beetles. If you are dealing with larger numbers of aphids, try spraying them off with a hard stream of water. If you need a low impact insecticide, consider insecticidal soap or horticultural oil. Fourlined plant bugs have just started to hatch.

They feed on a wide variety of herbaceous plants as well as shrubs and fruit. Look for reddish nymp…

Look out for disease problems on new plants

Michelle Grabowski, University of Minnesota Extension

I always recommend that gardeners thoroughly inspect every plant for disease problems before they purchase it. Examine both the upper and lower surfaces of the leaves, especially those leaves closest to the soil. Look at the stems and even the roots. Any spots, streaks, dark discolored or soft, mushy tissue is a warning sign that your new plant may come with a disease problem. Once a new pathogen is introduced into a garden, it may cause problems for years to come. In addition, nursery plants may move across the country before they make it to a local garden center. As a result infected plants can bring new plant diseases to Minnesota.

Boxwood Blight


Virginia Tech, Plant Disease Clinic
Photo 1: Leaf spots and blighting due to boxwood blight

One disease of concern is boxwood blight, a fungal disease caused by Cylindrocladium buxicola (syn C. pseudonaviculatum). Boxwood blight was first identified in the eastern United States in 2011. …

Flowering Plant Video Library - Shade Plants

Karl Foord - Extension Educator, Horticulture

Click on the link to see the video with host Dr. Mary Meyer, Professor of Horticulture

Great White Trillium, Trillium grandiflorum



Karl Foord
Photo 1: Great White Trillium (Trillium grandiflorum)


False Solomon's Seal (Maianthemum racemosum, syn. Smilacina racemosa)



Karl Foord
Photo 2: False Solomon's Seal (Maianthemum racemosum)



Lungwort, (Pulmonaria officinalis)



Karl Foord
Photo 3: Lungwort (Pulmonaria officinalis



Heucherella 'Stoplight' (Hybrid of Heuchera and Tiarella)



Karl Foord
Photo 4: Heucherella 'Stoplight'



Foam Flower, Tiarella 'Sugar and Spice' and Lungwort, Pulmonaria 'Trevi Fountain'



Karl Foord
Photo 5: Foam Flower (Tiarella 'Sugar and Spice')


Jacob's Ladder, Polemonium reptans 'Stairway to Heaven'



Karl Foord
Photo 6: Jacob's Ladder (Polemonium reptans 'Stairway to Heaven')


Lenten Rose, Helleborus orientalis





May 1, 2012 Issue

Native Grasses for Wildlife

Mary Meyer, Extension Horticulturist and Professor

Grasses, especially native grasses, can attract a wide range of wildlife and insects. While you might first think of the cover grasses provide in summer and winter, they also supply food for many grassland birds and are critical for butterfly larva food. Planting a prairie gives you the best environment for wildlife habitat; however, you can still make an impact with grouping 2-4 kinds of grass and using 3-5 plants of each kind. You could even try a stylized prairie by grouping the grasses in drifts similar to a traditional border. Diversity in a garden not only looks good, but can attract a wider variety of insects and birds. Leaving the grasses standing in winter can provide cover and winter shelter to wildlife. We rarely think of grasses being attractive, let alone critical for butterflies, but many species of skippers, satyrs, pearly eyes, wood nymphs, and browns, REQUIRE grasses and sedges as larval food, so these plants attract …

Orange Gooey Fungi on Junipers: Local Natives or Alien Visitors?

Michelle Grabowski, UMN Extension



N. Gregory, UDEL, Bugwood.org
Photo 1: Sporulating gall of Japanese apple rust on juniper


Cool wet spring weather stimulates galls of several rust fungi (Gymnosporangium spp.) to produce bright orange gelatinous spore producing structures that readily catch a gardeners eye. Several species of Gymnosporangium rust fungi are native to Minnesota and infect eastern red cedar trees, Juniperus virginiana during part of their lifecycle and trees and shrubs from the Rosaceae family during a different part of their lifecycle. Native Gymnosporangium rusts include cedar apple rust, quince rust, hawthorn rust and juniper broom rust. Photos and descriptions of these plant diseases can be seen at the UMN Extension online plant diagnostic tool What's wrong with my plant?


A new Gymnosporangium rust has recently been found in the United States but not yet in Minnesota. Japanese apple rust is caused by Gymnosporangium yamadae. This fungus does not infect Minnesota&…

Forest Tent Caterpillars Are Out Now

Jeffrey Hahn, Asst. Extension Entomologist

Did you have a problem with forest tent caterpillars (FTC) last year? If you did, expect to see them again soon as they have started to hatch during late April. You can recognize these caterpillars from their blue and black body and white footprint or keyhole shaped spots on their back. Despite their name, FTC do not construct conspicuous webs. If you find a large tent in a tree this spring, that is from eastern tent caterpillars.



Jeffrey Hahn
Photo 1: Forest tent caterpillar and damage

FTC are primarily a problem because they feed on the leaves of trees and shrubs, especially aspen, birch, oak, and linden/basswood. If they are abundant and their normal food is in short supply they will crawl down trees and also feed on fruits, vegetables, and flowers. They can also become nuisances when they wander around looking for sites to pupate (which has earned them the nickname 'armyworms'). This can lead them to crawl onto nearby buil…

An Imprelis Update

Kathy Zuzek, UMN Extension Educator, Horticulture

The History of Imprelis
In October of 2010, a new broadleaf weed killer by the name of Imprelis became available to turf professionals. Key to DuPont's release of this herbicide was its effectiveness at very low concentrations, its low toxicity to humans and other mammals, and its effectiveness on difficult-to-control turf weeds such as creeping Charlie, wild violets, clover and Canada thistle.

During the spring of 2011, damage to ornamental plants in landscapes where Imprelis had been applied began to appear in the eastern half of the United States including Minnesota. Damage to new growth of plants became visible within a matter of weeks after an Imprelis application and included twisting and/or browning of shoot tips, leaves, and needles (Photo 1).


K. Zuzek
Photo 1: Brown, twisted, & drooping shoot tips from Imprelis applications


As the summer progressed, impacted shoots and their associated leaves, needles, and buds oft…

Flowering Plant Video Library - Spring Ephemerals

Karl Foord - Extension Educator, Horticulture

Click on the link to see the video with host Dr. Mary Meyer, Professor of Horticulture

Trout Lily (Erythronium americanum)



Karl Foord
Photo 1: Trout Lily (Erythronium americanum)


Virginia Bluebells (Mertensia virginica)



Karl Foord
Photo 2: Virginia Bluebells (Mertensia virginica) flower


False Rue Anemone (Enemion biternatum)



Karl Foord
Photo 3: False Rue Anemone (Enemion biternatum)


Minnesota Dwarf Trout Lily (Erythronium propullans)

Clover Mites in Homes

Jeffrey Hahn, Asst. Extension Entomologist

Some people have been experiencing clover mites around their homes recently. Identification is important as they could be misidentified as other types of mites or even very small ticks. Clover mites are about the size of a pinhead (about 1/30th inch long) and are reddish or brownish in color. They have a round body and eight legs with the first pair of legs particularly long. People find them on the outside of their homes as well as around windows.



Rayanne Lehman, PA Dept of Agriculture, Bugwood.org
Photo 1: Clover mite

Clover mites feed on grass and clover during summer (they are not pests on these plants). They take shelter in and around buildings during the fall. You might see them then but they are much more commonly noticed during spring. They can potentially occur in very large numbers around buildings and have no problem getting inside, especially around windows, because of their small size. They love being in the sun and are …

Downy Mildew on Impatiens

Michelle Grabowski, UMN Extension



M. Grabowski, UMN Extension
Photo 1: Symptoms of Impatiens Downy Mildew
If you grew impatiens last summer, you may have noticed that some plants were stunted, turned yellow, and soon became barren stalks with perhaps one or two small yellow leaves clinging to them. These symptoms are caused by downy mildew, a disease caused by the water mold Plasmopara obducens. Had you turned a leaf over, you would have seen a fluffy white fungal 'down' covering the lower surface of the leaf.


Downy mildew of impatiens has been observed in the United States since 2004, but became widespread and highly destructive in 2011. Cool wet weather likely contributed to the disease epidemic of 2011 since the downy mildew pathogen thrives under these conditions.

Plasmopara obducens produces tough survival spores called oospores that can overwinter in soil and plant debris. As a result if downy mildew was present in your garden last year, it is likely to show up again in 2012.…

Plant Video Library - Early Spring Bloomers I

Karl Foord - Extension Educator, Horticulture

Click on the link to see the video with host Dr. Mary Meyer, Professor of Horticulture

American Pasqueflower (Anemone patens) and Prairie Smoke (Geum triflorum)




Karl Foord
Photo 1: American Pasqueflower (Anemone patens)




Karl Foord
Photo 2: Prairie Smoke (Geum triflorum)


Bloodroot (Sanguinaria canadensis)



Karl Foord
Photo 3: Bloodroot (Sanguinaria canadensis


Double Bloodroot (Sanguinaria canadensis 'Multiplex')



Karl Foord
Photo 4: Double Bloodroot (Sanguinaria canadensis 'Multiplex'


Marsh Marigold (Caltha palustris)



Karl Foord
Photo 5: Marsh Marigold (Caltha palustris)


Wild Ginger (Asarum canadense)



Karl Foord
Photo 6: Wild Ginger (Asarum canadense)


Plant Video Library - Early Spring Bloomers II

Karl Foord - Extension Educator, Horticulture

Click on the link to see the video with host Dr. Mary Meyer, Professor of Horticulture

Pigsqueak (Bergenia cordifolia)


Karl Foord
Photo 1: Pigsqueak (Bergenia cordifolia)

Lenten Rose (Helleborus orientalis 'Ivory Prince')


Karl Foord
Photo 2: Lenten Rose (Helleborus orientalis 'Ivory Prince')


Bleeding Heart (Dicentra spectabilis 'Gold Heart')



Karl Foord
Photo 3: Bleeding Heart (Dicentra spectabilis 'Gold Heart')




Plant Video Library - Bulbs I

Karl Foord - Extension Educator, Horticulture

Click on the link to see the video with host Dr. Mary Meyer, Professor of Horticulture

Glory of the Snow (Chionodoxa luciliae)



Karl Foord
Photo 1: Glory of the Snow ( Chionodoxa luciliae) flower close-up


Checkered Lily (Fritillaria meleagris)



Karl Foord
Photo 2: Checkered Lily (Fritillaria meleagris) flower


Species Tulips (Tulipa tarda)



Karl Foord
Photo 3: Species Tulips (Tulipa tarda)


Garden Hyacinth (Hyacinthus orientalis)




Karl Foord
Photo 4: Garden Hyacinth (Hyacinthus orientalis)


Autumn Lily (Lycoris squamigera)



Flowering Plant Video Library - Bulbs II

Karl Foord - Extension Educator, Horticulture

Click on the link to see the video with host Dr. Mary Meyer, Professor of Horticulture


Triumph Tulip (Tulipa 'Gavota)



Karl Foord
Photo 1: Triumph Tulip (Tulipa 'Gavota')



Grape Hyacinth (Muscari armeniacum)


Karl Foord
Photo 2: Grape Hyacinth (Muscari armeniacum)


Daffodils (Narcissus)


Karl Foord
Photo 3: Daffodils (Narcissus" Saint Keverne')



Dwarf Bearded Iris (Iris 'Joyce McBride)