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Showing posts from September, 2010

Brown Marmorated Stink Bug: The Next Invasive Insect Pest in Minnesota?

Jeffrey Hahn, Asst. UMN Extension Entomologist

Gypsy moth, Japanese beetle, multicolored Asian lady beetle, soybean aphid, emerald ash borer. There is a long list of invasive insect pest species that have entered the U.S. and Minnesota and have caused significant problems to crops, landscape plants, or even just as nuisances. An insect that should be on our radar screen that is present in the U.S. but has not been discovered in Minnesota yet is the brown marmorated stink bug (BMSB), Halyomorpha halys. It was introduced from Asia and was first found in the U.S. in Pennsylvania in 2001. It is now known in most mid-Atlantic states as well as in Oregon.

This is a moderate-sized insect, measuring about ½ - 3/4 inch long. Like other stink bugs, it has a shield-like or triangular shaped body. The BMSB is brown with whitish mottling on its body. There are native stink bugs in Minnesota that are also brown and a similar size. The best way to distinguish between them is BMSB has alterna…

Pollinator Blues - Part I

Karl Foord, UMN Extension Educator

The Native Wild Pollinator's Perspective

Photo 1: Bumblebee on Cosmos. Karl Foord. Most everything we do cuts into their territory. We make roads, houses, cities, and factories. We plant grass athletic fields, home owner lawns, double flower sterile plants, and we plant large agricultural fields of corn and beans all of which are in essence deserts for them. We use insecticides targeted for other critters and sometimes damage them in the process. We even mulch our gardens making it difficult for them to find ground based nesting sites. I can hear them singing the Jim Croce song 'Car Wash Blues' and changing some of the lyrics. "I got them steadily depressing low down mind messing 'I can't find no pollen' blues".

Short History of Insect Pollinators

Most animals and birds depend on flowering plants for food or shelter. Most plants depend on pollinators to complete their reproduction cycles. This makes pollinators…

New Oak Leaf Blight Confirmed in Minnesota

Michelle Grabowski, UMN Extension Educator

A new fungal leaf blight of bur oak (Quercus macrocarpa) trees has been confirmed in Minnesota. Bur Oak Blight, also known as BOB, was collected by Jill Pokorny of the USDA Forest Service in several central Minnesota counties and confirmed by Dr. Harrington of Iowa State University.

How to Recognize BOB

• Bur oak blight only infects bur oak trees. Leaf spots or blights on other types of oak tree are caused by different pathogens.
• On bur oaks, symptoms first appear in July or August.
• Infected leaves have brown angular or wedge shaped lesions. Leaf veins turn brown and small black spots (fungal spore producing structures) can be seen with a magnifying glass within the brown lesions.
• Infected leaves are often found first on the lower branches. After many years of infection, however, the entire canopy can be infected.
• Healthy bur oak trees typically drop all of their leaves in the fall. Trees infected with BOB, however, often have many leaves t…

Damage Assessment and Repair Options for Late September flooded lawns.

Bob Mugaas, UMN Extension Educator - Horticulture U of MN Extension and Brian Horgan, PhD. Associate Professor, Extension Turfgrass Specialist U of MN Department of Horticultural Science

Flooding is not uncommon during spring and summer here in MN. Yet residents of southern MN are experiencing significant flooding this fall. Justifiably, repairing lawns and landscapes is probably not the highest priority. However, should attention turn to wanting to do 'something', here are a few tips regarding the assessment of potential lawn damage and options for repairing them, even yet this fall.
Have flood waters actually done any damage to my lawn? In general, where flood waters have risen quickly to cover the lawn area but also receded quickly (within 2 or 3 days), there has probably been little permanent injury to the lawn. With shorter days and cooler temperatures in fall, lawn grasses are usually able to remain green and alive through brief periods of being submerged. Picture 1…

Lawn Care Tips for October - Yes, Really, Lawn Care in October.

Bob Mugaas, UMN Extension Educator

Photo 1: Healthy, vigorous late summer lawn. Bob Mugaas. Even though much of the month of October can be one of the best times for grass growth and recovery, it's tempting to put away our thoughts, practices and equipment used to care for our lawns by the middle to end of September. The reason for this active period of growth is that the lawn grasses adapted to this area (e.g., Kentucky bluegrass, the fine fescues and perennial ryegrass) are best adapted to the cooler and usually moist conditions of spring and fall. See Picture 1. So, with that in mind, here are a few end-of-season lawn care practices that help support actively growing grass plants.

1. Mowing. So long as our grasses continue to grow, we should be continuing to mow as needed. With cooler temperatures and shorter days, mowing intervals usually become longer the later we go into the month. A common question at this time of year is "Should I cut my lawn shorter the last m…

Garden Calendar: October 1, 2010

Starting this month, the Yard and Garden News will move to publishing just once per month for the winter. We'll return to twice monthly in the Spring!

Watch November 1 for an article on the challenges facing honey bees by UMN Bee Researcher, Marla Spivak. Spivak, a nationally and internationally respected entomologist, recently won a MacArthur Foundation Genius Grant for her work on the health of honeybees!

Garden Calendar:

The first frost in the Twin Cities Metro area is expected Sunday! Be sure to cover any tender annuals, and keep an eye out for frost damage! Wondering what the historic frost dates are for your area? Look up your city in this handy table from the Minnesota Climatology Working Group!
Be sure to protect hybrid teas and other roses that aren't winter hardy here, around mid-month. It's a gamble when canes are damaged when temperatures drop below 20 degrees F. Mounding soil over over the crowns or tying canes is more work, but much more effective than just …

Pumpkins are Too Cool!

Karl Foord, UMN Extension Educator

The word pumpkin originates from the Greek word pepon or "large melon". The French changed this to pompon, the British to pumpion, and the American colonists to "pumpkin".

Pumpkins (cucurbits) originated in Mesoamerica, and many of the wild species are found in the area south of Mexico City to the Guatemalan border. There are three species of interest: Cucurbita pepo, C. maxima, and C. moschata. The terms squash and pumpkin have no botanical meaning because as you will see each species has produced both squash and pumpkins. This article will mention the squash but focus on what we traditionally call pumpkins.

All species are monoecious having separate male and female flowers. The pollen is heavy and must be transferred by a pollinator. Two bee genera evolved to become efficient pollinators of cucurbits (squash bees, Peponapis spp. and Xenoglossa spp.). Interestingly enough pollination seems to be a morning phenomenon as breed…

What Naked Crabapple Trees Tell About Apple Scab - This Year and in the Coming Year

Michelle Grabowski, University of Minnesota Extension Educator

Photo 1: crab apple infected with apple scab M.Grabowski, UMN Extension.
Across Minnesota, crab apple trees are nearly leafless due to high levels of apple scab this year. Apple scab is a common fungal disease caused by Venturia inaequalis. In the landscape, apple scab can infect flowering crab apple (Malus sp.), hawthorn (Crataegus sp.) and mountain ash (Sorbus sp.) trees.

Apple scab infects leaves and fruit of susceptible trees. Leaf infections are olive green to black spots with feathered edges. Severely infected leaves or leaves with an infected petiole, yellow and fall off prematurely. This early defoliation not only reduces the ornamental value of the tree in the landscape but weakens the tree. Severely defoliated trees are likely to have fewer blooms the following year. Repeated years of defoliation can predispose a tree to winter damage.

Although many Minnesotans don't notice apple scab until July when leaves s…

Nuisance Insects In Fall

Jeffrey Hahn, Asst. UMN Extension Entomologist

As the days get shorter and the days and nights get cooler, this is a cue to people that summer is ending and fall is upon us. That is also a sign for insects, signaling them that they need to prepare for winter. For some insects and related arthropods, this means finding sheltered places to overwinter which unfortunately can mean our homes.
Some insects, particularly boxelder bugs, multicolored Asian lady beetles, cluster flies, and hackberry psyllids, will fly to buildings and congregate on the outside, especially on the south and west facing exposures where it is the sunniest. As they find spaces and cracks to get inside, some end up in attics, wall voids, and other spaces (where they remain until a mild winter day or spring) while others find their way into the interior part of homes. Yet other arthropods, such as sowbugs, millipedes, and crickets, don't fly but crawl to buildings and find their way indoors at ground level.