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Showing posts from May, 2017

Late spring flowers for pollinators

You can support pollinators by providing flowers throughout the growing season. Spring flowering plants like willows, maples, plums, and gooseberries provide bountiful nectar and pollen for bees that are active in spring. Many bee species in Minnesota are only out flying as adults during the first month of spring, taking advantage of these abundant floral resources to gather pollen to feed their young, which will be developing within the nest the rest of the year. After the early spring flowers have faded there is a gap before the next bounty of long-blooming flowers appears in early to middle summer. Flowers such as bee balm, purple prairie clover, and joe-pye weed, will continue sustaining bees throughout most of the summer.

In many landscapes, there is a lull between these two heavy blooming periods. Although the early spring bees have gathered all the food they need, there are other bees active throughout the growing season like bumble bees, sweat bees, small carpenter bees, and …

Check your garden for flea beetles

Jeffrey Hahn, Extension Entomologist

Flea beetles are very small, 1/16th – 1/8th inch long. They are usually dark colored although some can have red or yellow on them. An easy way to identify flea beetles is that they can jump. Now is a
good time to check your garden for their presence.

Flea beetles attack a variety of vegetables, including beans, broccoli, cabbage, potatoes, squash, and radish. Flea beetles chew shallow pits and small holes into leaves. This feeding can be particularly damaging to seedlings and cole crops.
 For more information on flea beetles, including management, see Flea beetles in home gardens.

Powdery mildew covered shoots

M.Grabowski, UMN Extension Educator
As the buds of trees and shrubs open and young shoots begin to grow, some will emerge already infected with powdery mildew. Powdery mildew, a common fungal disease of many garden plants, is easily recognized by powdery white growth on the surface of infected leaves, shoots, and other plant parts. Gardeners often describe infected plants as dusted by flour or having cobweb like growth on leaves.
Some powdery mildew fungi survive Minnesota’s harsh winter by colonizing young plant tissue within dormant buds. When the buds open in spring and the new shoot emerges, it will be covered by the characteristic white growth of powdery mildew. From that one severely infected shoot, spores are blown throughout the plant canopy starting new infections on healthy leaves from neighboring shoots.
This type of winter survival is common on woody ornamental plants like ninebark, hawthorn, currant, and rose. Gardeners should carefully inspect young shoots of woody shr…

Clover mites in homes

Jeffrey Hahn, Extension Entomologist

Clover mites are tiny arachnids, about the size of a pinhead, that are reddish or brownish in color. The first pair of their eight legs is particularly long and noticeable even at their size. People have been finding clover mites this spring on the outside of their homes, especially around windows, as well as indoors.

During summer, clover mites feed on grass and clover (they are not pests on these plants). They can occur in 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 most common on the south sides of homes. Fortunately, clover mites are not harmful to people or our property.

Physically remove small numbers of clover mites, e.g. with a vacuum or gently wipe them up with a damp cloth. Be careful to avoid crushing them as the can stain surfaces. Clover mites are a temporary problem that will go away on its own when the weather b…

Clouds of chironomids (midges)

Jeffrey Hahn, Extension Entomologist

People in many parts of Minnesota have noticed this month large swarms of small, dark insects close to sources of water, especially lakes. These abundant insects are called chironomid midges. The larvae are usually aquatic and can feed on a variety of foods, such as algae and tiny bits of decaying plant matter. They are important food sources for fish and other aquatic animals.

Different midge species emerge as adults at different times during the spring and summer. Emergence typically occurs in large numbers, especially during the evening. They are weak fliers and generally do not move far from the water. Midges vary in color from brown, gray, or green.

Chironomid midges are mosquito-like but unlike mosquitoes lack scales on their wings and a long proboscis (mouthparts). Their first pair of legs is longer than the others. Males usually have feather-like antennae.

Despite their similarity to mosquitoes, they do not bite people. But they …

Cedar apple rust is active

M. Grabowski,  UMN Extension Educator 
Gelatinous, orange fungi can now be found on junipers in Minnesota on rainy days. Cedar apple rust, cedar hawthorn rust, quince rust,and juniper broom rust are caused by a group of related fungi that spend half of their life on juniper trees and shrubs and the other half infecting members of the Rosaceae family, including crabapple, serviceberry, and hawthorn.  Despite their eye catching symptoms, these rust fungi do not seriously affect the health of either host plant.
These rust fungi overwinter as infections in woody branches of junipers. Cedar apple rust and hawthorn rust result in round woody galls. Juniper broom rust causes a cluster of small branches, or a broom, to form, and quince rust directly infects the branch.  In wet spring weather, these rust fungi come out of dormancy and produce gelatinous orange spore producing structures on rainy days. Spores released from these strange orange fungi are carried by wind and rain to infect near…

Selecting healthy plants

M. Grabowski, UMN Extension Educator


Starting out the growing season with healthy plants can be the key to a beautiful and productive garden. Plant pathogens can devastate a gardener’s dream of beautiful blooms or ripe red tomatoes. One key strategy in preventing plant disease problems is to purchase healthy transplants.

When visiting the garden center this spring, be a smart and selective consumer.

Read plant labels and choose plants that will thrive in the conditions of your garden. Think about the amount of sun the garden receives, soil type, and your ability to provide irrigation if Mother Nature does not.Look for disease resistant varieties for common disease problems like powdery mildew or rust. Mix and match plants from different plant families. Many plant pathogens can only cause disease on one type of plant. Planting a diverse mix of plants reduces the pathogens ability to spread. Check how big the plant will get when fully grown. Space plants so that there is room for air flo…