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Showing posts from May, 2016

Mosquitoes and Zika virus: What you should know

Jeffrey Hahn, Extension Entomologist

Mosquito season is just around the corner for us here in Minnesota. Most of us know the drill when mosquitoes arrive; wear protective clothes and use repellents to protect ourselves from these biting menaces.

There is added concern this summer as we not only worry about mosquitoes but are also anxious about the Zika virus (Zika). Zika has been talked about a lot in the media especially with the upcoming summer Olympics in Brazil. People want to know whether they are at risk here and what can they do to protect themselves.

Fortunately, the threat of Zika in Minnesota right now is negligible. In fact Zika has not been found locally in any state in the U.S so far. However, the potential does exist for the virus to be a problem in this country. The mosquito primarily associated with transmitting Zika, the yellow fever mosquito, Aedes aegypti, is found in the southern and eastern areas of the U.S. but is not known in Minnesota. A second specie…

Design for U: Protect tree roots and create great garden spaces

Julie Weisenhorn, Extension Educator

Q: The roots of our shade trees are becoming more exposed as they age and the grass is is not growing well beneath the trees. What can we do to take care of the trees and avoid damaging the roots with the lawn mower?

A: Protecting the roots of mature trees is important. Mowing and other activities may potentially wound these roots exposing them to pests and disease. Likewise, grass can be difficult to grow under trees as it is often shaded out and becomes thin. Grass also competes with tree roots for moisture and nutrients, and - as you know - can be challenging to mow properly.

Protect the roots by mulching them with wood mulch. Remove any lawn grass growing between / over the roots. The minimum recommended diameter of a mulch ring is 6-feet, but you may certainly go larger. Likewise, a kidney-shaped form or some other unique shape may better fit your site and aesthetic. You might also choose to plant shade-loving plants in the mulch …

Clavate tortoise beetles in gardens

Jeffrey Hahn, Extension Entomologist

An interesting insect has been found in some gardens recently. The clavate tortoise beetle, Plagiometriona clavata, is about a ¼ inch long or a little smaller, mostly round, and turtle-like. A thin, opaque, shield-like structure extends from the body and covers the head. There is a distinct brown figure on its back that somewhat resembles an animal.

This tortoise beetle has been reported this year feeding on tomato and eggplant. They can also feed on other Solanum spp., such as potatoes. In the past, the clavate tortoise beetle has been found on Chinese lantern. The literature also records this insect on jimson weed Datura stramonium and ground cherries, Physalis spp. When these beetles feed, they create roundish holes in the interior of the leaves.

Fortunately, this beetle typically occurs in just small numbers and rarely, if ever, causes significant defoliation to plants. If these beetles are found in your garden, physical removal shoul…

Nuisance forest tent caterpillars

Jeffrey Hahn, Extension Entomologist

People in some parts of central and northern Minnesota have been finding themselves inundated by forest tent caterpillar, also called armyworms. The caterpillars feed during May on a wide variety of trees and shrubs, especially aspen, birch, linden, and oak. As they become fully grown, they move down the trees and start crawling on the ground to do some last minute feeding and looking for places to pupate.

This brings them onto lawns, gardens, homes and other building, and essential any object they encounter. Interestingly while people generally did not notice forest tent caterpillars feeding in trees this year, it is hard to miss large numbers moving across a property. Unfortunately, a resident’s options are limited. For those found in lawns, they are not injuring the grass and treatment is not necessary.

However, when they get on buildings, people can try physical removal, e.g. taking a broom and sweeping them off and/or spray the exterio…

MDA Weed of the Month: Multiflora Rose

From the Minnesota Department of Agriculture Minnesota Noxious Weed Program

May’s weed of the month is an aggressively spreading, thorny plant. Multiflora rose (Rosa multiflora) is native to eastern Asia. It was introduced to North America as a rootstock for ornamental roses, and for erosion control, living fencerows, and wildlife habitat. Because of its highly invasive nature, it escaped cultivation and has become a serious threat to habitats where it outcompetes native plants and desirable agricultural forages. Read more ....

Spring leaf drop and anthracnose

M. Grabowski, UMN Extension Educator

Lawns scattered with fallen tree leaves in spring and early summer often point to infection of shade trees by anthracnose. Many common shade trees can be infected with anthracnose including ash, oak, and maple. Anthracnose is caused by several different fungi. Each fungus infects a particular type of tree. The fungal pathogens that cause anthracnose infect young developing leaves during cool wet weather. Symptoms include dark brown to black water soaked spots on leaves, curled or cupped leaves, and leaf drop in spring and early summer.

There is no management needed for trees suffering from anthracnose. Although the disease can be somewhat unsightly, it is only a minor stress on the tree. As the weather becomes warm and dry, tree leaves are able to mature without infection. Once leaves are mature they are largely resistant to the anthracnose fungi. Even trees that have dropped many leaves due to infection will produce a new flush of leaves and recov…

Four-lined plant bugs are now active

Jeffrey Hahn, Extension Entomologist

If you have perennials in your garden, start monitoring for four-lined plant bugs now, especially if you have had problems with them in the past. These insects are bright red and 1/16th inch long when they first hatch. The immature nymphs and adults feed with piercing-sucking mouthparts which creates small, dark, circular, sunken spots on leaves. To determine whether these insects are present in your garden, watch for both four-lined plants bugs and their damage.


Fortunately, while four-lined plant bug damage can affect the plant’s appearance, it normally does not seriously injure them. How much damage is deemed unacceptable is subjective and will vary with different gardeners.

Early detection is crucial for effective four-lined plant bug management. It is easy for gardeners to overlook the damage until it becomes too severe. Your goal should be to find the insects before they cause unacceptable damage. As you long as you do not find the…

The value of lawn weeds for pollinators: not all weeds are created equal

Karl Foord, Extension Educator


In my travels around the state of Minnesota regardless of rural or urban, I have encountered a significant lack of flowers. Because pollinators rely on flowers for sustenance, this lack can lead to nutritional problems for pollinators. This is why Dr. Marla Spivak is always encouraging people to plant flowers as part of the solution to the “pollinator crisis”.

The lawn is practically omnipresent in the landscapes of any building be it home residence, public, or commercial. As a culture, we have evolved into thinking that one’s lawn should be maintained in such a way that it is of playing surface quality meaning there are no broadleaf weeds present, and that the lawn is continuously verdant as a result of the choice of grass varieties, as well as fertilizer and irrigation regimens.

One potential way to address the “pollinator crisis” personally is to accept broadleaf plants (perceived as weeds) to establish in one’s lawn. Given the mindset, this creates…

Wild parsnip

From the Minnesota Department of Agriculture Minnesota Noxious Weed Program

Wild parsnip (Pastinaca sativa), is a toxic plant with an edible root. Native to Eurasia, it escaped cultivation and is commonly found throughout Minnesota and North America. Wild parsnip is a member of the carrot family. It produces a sap that can cause blistering, swelling, and discoloration of the skin when in the presence of sunlight. Protective clothing should be worn when working with this plant. Animals, including livestock, can also be burned by the sap in combination with sunlight. Read more...