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Showing posts from June, 2017

Gypsy moth quarantine established in Minneapolis

Jeffrey Hahn, Extension Entomologist

The following information was slightly edited from a Minnesota Department of Agriculture news release.

The Minnesota Department of Agriculture (MDA) is placing a gypsy moth-infested area in the Lowry Hill Neighborhood of Minneapolis under quarantine beginning July 1 after a neighborhood resident reported a large insect population. The quarantine will be in place until early next summer.

The MDA was contacted earlier this month by a resident in the neighborhood who suspected a gypsy moth infestation after he noticed caterpillars on trees. MDA staff conducted a survey and found thousands of gypsy moth caterpillars that had already started defoliating trees.

Gypsy moths have caused millions of dollars in damage to forests in the eastern United States. The moths are common in Wisconsin and are now threatening Minnesota. If present in large numbers, gypsy moth caterpillars can defoliate large sections of urban and natural forests. They feed o…

Look for Leaf Spots

M. Grabowski, UMN Extension Educator
Recent rains and warm weather has provided ideal conditions for many leaf spot plant pathogens to spread and infect young vegetable plants. Leaf spot diseases are caused primarily by fungi and sometimes by bacteria. These plant pathogens survive from one season to the next in previous years infected plant debris and garden soil. Rain splashes fungal spores or bacteria from the soil onto the lower leaves. If the conditions are favorable (typically warm and wet) the pathogen infects and a leaf spot forms.
Leaf spots will soon produce a new set of fungal spores or bacteria that will spread to form new leaf spots. This cycle can continue throughout the summer as long as weather conditions are favorable. By August, entire leaves or plants are blighted brown and some leaf spots have become fruit spots or rot. What’s a gardener to do? Inspect plants now. Look at the lower leaves that are closest to the soil.Pinch off leaves with leaf spots and remove the…

Grasses that self-seed

Mary H. Meyer, Extension Horticulturist and Professor, University of Minnesota

Is a plant that grows easily from seed a good thing or a bad thing? Perhaps it depends on how much you like the plant! Grasses that self-seed and come up throughout the garden can be an asset or a liability. Listed below are native and non-native grasses that I have seen self-sow in Minnesota growing conditions.  I have noted which are native and ranked them in two categories: very likely (VL) to seed and somewhat likely (L), because to make this list, they all sow seeds.

The worst offender across the U. S. is Miscanthus sinensis, which is listed on many state’s invasive plant lists, and in 2015 New York state regulations started requiring these plants for sale be labeled as invasive plants using specific language. Along a shoreline, it may be advantageous to have native sedges like porcupine and palm sedge that self-sow. I find river oats is marginally hardy so the mother plant may die, but seedlings come …

Watch your garden for squash vine borers

Jeffrey Hahn, Extension Entomologist

If you are growing squash, pumpkins, cucumbers, or melons in your garden this year, now is a good time to start monitoring for squash vine borers. Squash vine borer larvae bore into the stems, causing plants to wilt and eventually die. The best management is well timed insecticide treatments when adults are active and laying eggs.

Adult squash vine borers are day-time flying moths that resemble wasps. They are about 1/2 inch long with an orange abdomen with black dots. The first pair of wings is an iridescent green while the back pair of wings, which may not always be seen, is clear.

There are a couple of methods for detecting them in your garden. You can watch for them flying around while you are in your garden; they are conspicuous and easily noticed. You can also place yellow containers (like pans or pails) half filled with soapy water. These moths are attracted to yellow; when they fly to the container, they will fall in to the water. …

Jumping worms in Minnesota

Lee E. Frelich, Director of the University of Minnesota Center for Forest Ecology and Laura Van Riper, Terrestrial Invasive Species Program Coordinator, Minnesota Department of Natural Resources

The arrival of jumping worms in the Midwest has made news headlines during the last 2-3 years. Native to Asia, jumping worms have the ability to infest soil at high densities, change soil structure and chemistry, and damage roots of plants in nurseries, gardens, forests, and turf grass. Relatively little is known about them compared to the European earthworms that have been present since European settlement, and the following summarizes the state of knowledge at this time.

Jumping earthworms are more properly known as Pheretimoid worms. Sixteen species originally
from Japan and Korea are known in North America north of Mexico, in four genera Amynthas (10 species), Metaphire (4 species), Pithemera (1 species), and Polypheretima (1 species). The taxonomy of these genera is in a state of flux an…

SWD out now!

Jeffrey Hahn, Extension Entomologist

The first spotted wing drosophila (SWD) adults were detected in Minnesota last week, collected in
traps at the Rosemount Research and Outreach Center. If you are growing susceptible fruit in your gardens, including raspberries, blackberries, blueberries, cherries, strawberries, or grapes, be sure to set out traps to determine when SWD is first active in your area. SWD is a very destructive invasive insect pest that can severely damage untreated susceptible fruit crops.

The best approach to managing SWD is through detection, sanitation, and insecticide treatments. For more information on SWD see Spotted wing Drosophila in home gardens.

Dutch elm disease active now

M. Grabowski, UMN Extension
Although not as common as they once were, many American elm trees can still be found throughout Minnesota.  In late spring and early summer the first symptoms of Dutch elm disease begin to appear. Gardeners with elm trees on their properties should watch for leaves that wilt, turn yellow, and then brown. This may happen to leaves on just one branch or on multiple branches throughout the canopy. Leaves may fall off the tree and be scattered on the lawn below.
It is important to react quickly if symptoms of Dutch elm disease appear. The infection can be pruned out if the fungus has not yet reached the main trunk of the tree. This requires pruning out the infected branch 5 to 10 feet below symptoms of the infection to be successful. Gardeners that suspect Dutch elm disease should contact a certified arborist to inspect the tree and submit a sample for diagnosis to the UMN Plant Disease Clinic.

There are many varieties of elm that are resistant or tolerant of…

After the storm

M. Grabowski, UMN Extension Educator

Strong winds and hail have caused significant damage to plants large and small in Minnesota landscapes. Here's what gardeners need to know about treatment and recovery of storm damaged plants.

Storm damaged trees may be unstable and can be a hazard to people and property. Contact a certified arborist to evaluate and treat large trees that have suffered from storm damage.

Smaller branches that have been damaged by the storm, are low in the canopy, and accessible from the ground can be treated by the gardener. Prune off branches that are split, cracked, or torn at a point where the wood is undamaged. A tree will heal over small scattered wounds from hail but severely hail damaged branches should be pruned out. A clean pruning cut at a branch union allows the tree to naturally heal over the wound site. A proper pruning cut does not leave a branch stub or remove bark beyond the branch collar. Painting over pruning wounds is unnecessary unless the…

Creeping charlie: Management and value to pollinators

By: James Wolfin and Phoebe Koenig, University of Minnesota Bee Lab 
Creeping charlie (Glechoma hederacea L.), also called ground ivy, is an herbaceous perennial native to the British Isles and present in North American landscapes for nearly 200 years. While some consider creeping charlie to be a weedy species, others consider it to be naturalized, and some seed providers will sell this flower as a form of ornamental ground cover. Creeping charlie is in the Mint family and an early spring bloomer (April-May) easily recognized by its small, pale violet flower. It grows well in shaded areas with fine-textured soils that are damp and slightly acidic to slightly alkaline (pH 5-7.5). Like other mints, creeping charlie spreads rapidly through stoloniferous growth, where stems grow at the soil surface and spread laterally. These stems are commonly referred to as “runners” and allow creeping charlie to grow in its easily identifiable mat-like form of ground cover (Hutchings and Price 1999).