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Monday, December 18, 2017

Houseplants make great gifts!

Moth orchid
Julie Weisenhorn, Extension Educator

Live plants are great gifts for friends and family, colleagues and the host of your next holiday party. Favorite plants like holiday cacti, amaryllis and poinsettia are great choices. Other plants that make great, easy-to-grow gifts are moth orchids (Phaleanopsis), amaryllis, and succulents.

Here are some tips for selecting a healthy plant for your favorite plant lover:
  • Look for plants with an overall healthy, vigorous appearance: clean foliage, bright green leaves, buds and/ or flowers, upright form, and new growth. Soil should be dark, moist and rich looking. The plant should not be overly wet or sitting in
    water which can lead to root rot.
  • Avoid plants with leaf spots, discoloration, or dead leaves as well as signs of insects such as webbing, chewing or honeydew (sticky, shiny areas on leaves). Check the underside of leaves for insect pests in hiding. If any of these are found, choose a different plant.
  • Moth orchids may have air roots protruding from the base of the plant and / or right out of the pot. This is a good sign! Roots should be firm, silvery and have a bright green tip, leaves should be bright green and firm.
  • Amaryllis are grown from tender bulbs that can kept from year to year. Allow soil to dry out before watering and be sure the pot drains well. 

Friday, December 1, 2017

Our experts' favorite gardening books for holiday gifts

By Extension Communication Specialist Gail Hudson

December and cold weather arrives quickly in Minnesota (surprise!), and with it comes that perennial question: what gift can I buy the family member or friend with a green thumb? We’ve tapped our gardening experts for their favorite books to read over the winter months. (And please note—we’ve included links to the publishers. You’ll find them for sale in a number of places.)

Courtesy: Princeton University Press
Learn about Bees in Your Backyard
Since the “buzz” in the gardening world these days is all about pollinators, Extension Educator Elaine Evans, whose research concerns wild bee diversity, the rusty-patched bumble bee and bee conservation and is an author in her own right, has this book at the top of her list: The Bees in Your Backyard: A Guide to North America’s Bees, by Joseph S. Wilson.
Elaine says it’s a great introduction to the fascinating world of bees through beautiful photos along with accurate, accessible information.  She says once you learn what you are seeing, you’ll be able to discover the rich diversity of bees, many of which you can find in your own back yard. 

Courtesy: Wicwas Press
Want to help pollinators in your garden next year? Extension Educator and the U’s Bee Squad Associate Program Director Rebecca Masterman recommends this excellent resource: Pollinator Friendly Gardening by Minnesota author Rhonda Fleming Hayes. She says the photographs and text will help you learn about pollinators, which plants support them and what things you can do in the garden to “bee friendly”! 

Thursday, November 30, 2017

Watch out for food infesting beetles

Jeffrey Hahn, Extension Entomologist

This is a time of year when beetles, like flour beetles, sawtoothed grain beetles, drugstore beetles, and
Cigarette beetles.  Photo: Jeff Hahn, U of M Extension
cigarette beetles, can infest a wide variety of dried food products, including (but not limited to) flour and other grain-based products, dried fruits, nuts, spices, such as dried red pepper, as well as dry pet food. These beetles are small, 1/10th - 1/8th inch long, and brown. They can range in shape from slender to stout and oval.

When these beetles are found in a home, the best control is sanitation. First find out what
Sawtoothed grain beetles. Photo: Jeff Hahn, U of M Extension
they are infesting. Because they are able to feed on many items, be sure to make a thorough inspection. Start in the kitchen and check all food items for their presence. However, don’t forget about any susceptible items that may be stored in other areas on your home, e.g. pet food. Throw out any infested food material that you find. Keep in mind that there can be more than one infestation source so don’t stop looking after you find the first one.

For more information, see Insect pest of stored foods.

Friday, November 17, 2017

From the MDA: Update on Palmer amaranth

Reprinted from Minnesota Noxious Weeds - Palmer Amaranth

Palmer amaranth plant in western MinnesotaIn September 2016, Palmer amaranth (Amaranthus palmeri) was initially discovered and confirmed in Minnesota. To date, isolated populations have been documented in first year conservation plantings in Yellow Medicine, Lyon, Douglas and Todd Counties. The Minnesota Department of Agriculture (MDA), University of Minnesota Extension, USDA, landowners and other partners are working to eradicate these infestations before they can spread to new areas.  Efforts to this point have been very successful.  MDA is also working closely with other state, county and federal agencies, the MN Native Seed Industry and several non-profit organizations to regularly sample and test seed sold in the state for presence of Palmer amaranth.

Why the concern? 

Palmer amaranth is a fast growing weed native to the southwestern United States and northwestern Mexico, and has spread east and north through a variety of pathways including contaminated seed, hay, livestock feed and agricultural equipment. It has developed resistance to multiple classes of herbicides and their different modes of action, making it very difficult and expensive to control. Palmer amaranth is a prolific seed producer. Up to 250,000 seeds can come from one plant. It is also highly competitive.

It has a fast growth rate of 2- 3 inches per day and commonly reaches heights of 6- 8 feet, greatly inhibiting crop growth. Reported yield losses have been up to 91% in corn and 79% in soybean in some states. The weed can also significantly increase production costs for corn, soybean, and other crops. 
Arrest the Pest icon, report sightings by emailing or call 888-545-6684Read  more about Palmer amaranth on the MN Department of Agriculture webpage

Wednesday, November 15, 2017

Pollinator-friendly landscape? Share on Instagram!

Do you have a pollinator-friendly landscape? Did you see a plethora of honeybees, native bees, flies, butterflies and other pollinators in your yard and garden this past summer? Share pictures of your landscape with other pollinator enthusiasts on Instagram @flowers4pollinators

Not sure how your yard and garden measure up for pollinators? Take the survey "How Pollinator-friendly is your landscape?" and find out!

Tuesday, November 7, 2017

MDA Weed of the Month: Oriental bittersweet

By Emilie Justen, Minnesota Department of Agriculture, 11/07/2017
Oriental bittersweet (Celastrus orbiculatus)

November’s Weed of the Month, Oriental bittersweet (Celastrus orbiculatus), is a woody vine with colorful red fruit. It was brought to North America from the Asia and used as an ornamental plant. The attractive vines have been used for wreath decorations and in floral decorations; unfortunately, the plant has escaped cultivation and has become invasive in residential and natural areas in Minnesota.

Oriental bittersweet spreads by several means. The persistent red fruit is consumed by birds, which spread the seed to uninfested areas. People trained to look for Oriental bittersweet may look for places where birds perch. The areas beneath the perches may have Oriental bittersweet seedlings, juvenile vines, or mature woody vines and would be a place to target control efforts. Humans also spread Oriental bittersweet infestations by physically moving the plants. Oriental bittersweet was commonly propagated and sold in Minnesota through nurseries and retail garden centers before 2010. Its use in floral arrangements and wreaths also increased its spread.

Despite its ornamental characteristics, Oriental bittersweet is an ecological threat to forests, grasslands, and parks in Minnesota. The vines twine around trees, girdling them in a snake-like fashion. Though it prefers forest edges and sunlight, Oriental bittersweet can grow in forest understories, eventually reaching forest canopies, shading the trees and understory and preventing native plant species from flourishing. Infestations can become so thick that wildlife, such as deer, can have difficulty navigating through wooded areas filled with Oriental bittersweet.

Read more how you can help ....  MDA Weed of the Month

Tuesday, October 10, 2017

30th Anniversary highlights ornamental grasses trend for low-maintenance gardens

By Gail Hudson, Horticulture Extension Communications Specialist

As summer flowers fade and the leaves turn fall colors in Minnesota, many varieties of ornamental grasses are at their majestic peak and in full flower.  They stand from 3 feet to as much as 12 feet in height (although some are shorter), as vibrant kings of the perennial garden with their jaunty, yet graceful looks. Ornamental grasses have not only become key components in the driving trend toward sustainable and low-maintenance landscapes, but their strong vertical lines offer living sculpture in today’s native gardening mix.

 Mary Meyer, U of M Extension Educator
“Today there’s a real interest in native grasses and using native cultivars in the garden,” said Mary Meyer, the University of Minnesota Extension professor and educator who maintains the only collection of ornamental grasses accredited by the American Public Garden Association in the U.S. “We went from having exotics from the non-natives and huge numbers of Miscanthus [in the collection] to more and more North American native species. And really the grasses that are native in the prairie.”

Tuesday, October 3, 2017

From our Turf blog: November is the time to dormant seed

November dormant seeding helps promote
a healthy lawn next spring.
By Sam Bauer, Turf Extension Educator

The optimal lawn seeding window is mid-August to mid-September. If you missed that time frame, but you still want to seed this fall, my recommendation is to wait until November to seed. This practice is called dormant seeding and is certainly an effective way to introduce new species and/or varieties of turf into your existing lawn.

By far our most popular post on this site has been the one on this topic, so we are re-posting an article originally published on November 1, 2013.

If you are considering dormant seeding, read on to start planning for November: There’s Still Time to Dormant Seed Your Lawn.

Friday, September 29, 2017

Maple tar spot strikes again

M. Grabowski, UMN Extension Educator
Tar spot may look different on different
species of maple. M. Grabowski, UMN

For the second summer in a row, tar spot, a fungal leaf spot disease is showing up in large numbers. Tar spot causes large black raised spots on leaves. Black spots are often shinny and look like wet tar. Although the symptoms of tar spot are most dramatic in the fall, the fungus actually infects the leaves early in spring when wet weather coincides with spore release. The fungus can only infect leaves, and will survive Minnesota’s winter in fallen leaves within leaf spots.

M. Grabowski, UMN Extension
Tar spot is not a serious threat to the health of the tree. The leaf spots may cause leaves to drop a bit early but not early enough to do significant harm. Gardeners interested in reducing problems with tar spot in the following year should rake up leaves and place them in a back yard or municipal compost pile.

Thursday, September 28, 2017

Prepare for boxelder bugs

Jeffrey Hahn, Extension Entomologist

Boxelder bugs are starting to congregate around the outside of buildings. Take action now if you wish to minimize problems with them later, especially if you have had a problem with them in the past. Although boxelder bugs are just a nuisance, they can potentially enter homes in large numbers. People can see them in their homes not only in the fall, but also during the winter and early spring.
Watch out for boxelder bugs trying to get into your home. 
Photo: Jeff Hahn, University of Minnesota Extension

It is not effective to spray the boxelder bugs found in the landscape. Adults have wings and can easily fly onto your property from adjacent areas. It is much more effective to take steps to help prevent boxelder bugs from entering a home to begin with.

There are two basic ways for dealing with boxelder bugs (and other insects, like lady beetles) that try come into your home seeking sheltered areas for the winter: sealing cracks and spaces and timely insecticide sprays. These are steps you can take yourself or hire a professional to do for you.

For more information on boxelder bugs, including control, see Boxelder bugs.

Tuesday, September 26, 2017

Plant hardy bulbs now for early spring pollinators

Honey bee on crocus
By Julie Weisenhorn, Extension Educator - Horticulture

Pollinators need pollen and nectar as early as April in some parts of Minnesota. Hardy spring-blooming bulbs such as scilla, allium, daffodil, fritillaria, and crocus provide this much needed early season nutrition. These bulbs require a cold period in order to flower successfully and therefore must be planted in fall (September - October) - in other words: right now!

Bee inside a daffodil flower
Bulbs are relatively inexpensive and easy to plant. Bulbs may be purchased locally or ordered from suppliers either through a catalog or online. Most bulbs require warm, sunny locations. Tip: Sun-loving bulbs can be planted underneath deciduous shade trees because they will bloom before the tree leafs out.

Follow planting instructions on the bulb package for depth and site specifications. Make you mark your planting location with a plant label so you remember what you planted next spring. After planting, soak the soil with water. If conditions are dry (little rainfall), soak the soil with water when dry until the soil freezes.  
Bee on Scilla siberica

Read more from Extension about spring flowering hardy bulbs.

Japanese beetles: Aftermath

Jeffrey Hahn, Extension Entomologist

Now that we are safely past the bump in the road called Japanese beetles (JB), it is time to take stock in what happened this year, whether we should be doing anything now, and even what to expect for 2018. Clearly, 2017 was a year of above average numbers of JB. However, this is not the first time we had high numbers of JB in Minnesota and it is unlikely to be the last. So why did we have so many Japanese beetles this year?
Japanese beetles were bad this year.  However, most plants
will survive this damage just fine.  Photo: Jeff Hahn,
University of Minnesota Extension

Although it might appear that JB occur in cycles (like forest tent caterpillars), in fact their numbers are driven by weather. The most important factor influencing their abundance is a lack of soil moisture. JB eggs and newly emerged grubs are very susceptible to dry soils so during years when we experience drought we typically see relatively fewer JB.

This was true about three to five years ago when we had some very dry summers. However starting in about 2014/2015 we started receiving more normal rainfall and JB numbers responded by becoming more numerous.

There has been a lot of concern by residents as to whether JB feeding would kill plants, especially trees.  While JB feeding definitely affects the appearance of plants, as long as (deciduous) trees and shrubs are healthy and mature, they can tolerate severe, even complete, defoliation.  However, if trees and shrubs are severely damaged for several consecutive years, they can sustain more lasting injury.  Maintain normal care for trees and shrubs to keep up their health.  Herbaceous plants are more vulnerable to JB feeding but also are able to tolerate some damage.  Look for most plants to rebound and be fine next spring.

Many residents also wanted to know about treating grubs to reduce the number of JB numbers on a person’s property. While it makes some sense to try to kill the grubs in your lawn so the adults don’t emerge and find your plants, the reality is that treating the grubs has no impact on how many adults you will find on your property next summer. The reason is that adult JB are good fliers and can fly from as far away as several miles.

If you have plants that are attractive to JBs, the adults will find them regardless of whether you treat for grubs or not. Only treat your turf if grubs are found damaging the grass. This is best done in July and August and into early September. By fall, the grubs are getting too large to effectively treat. They are definitely too large to treat the following spring.

So what about next year? We received pretty regular rains in 2017 throughout areas where JB is common. That strongly suggests that if you saw a lot of JB this year, you most likely will see at least similar numbers next summer. Stay tuned!

2017 Flowers for Pollinators: Which annuals attract pollinators?

By Julie Weisenhorn, Extension Educator - Horticulture

Honey bees on Music Box Mix sunflower, one of the annual flowers in this study

Planting for pollinator health is on just about every gardener’s mind these days.

Bumble bee on Envy zinnia
While there is a lot of research on how native plants help pollinators, there’s not much on the interaction of pollinators and annual flowers. Many people want to do their part, but may only have space for annual plantings. There are conflicting references to the value of annual flowers as pollinator-friendly plants. Which annual flowers attract pollinators? We want to find out, so we designed this study to address how home gardeners might help reverse pollinator decline. Pollinators are attracted to such plant features as flower form, color, size, and pattern. We've been counting pollinators that visit selected varieties of annual flowers like Salvia, Zinnia, annual Rudbeckia, sunflowers, marigolds, cosmos, snapdragons, hyssop, etc. Read more: Flowers for Pollinators

Wonder how your own yard and garden measure up when it comes to pollinator-friendly habitat? Take the eight-question survey that asks "How pollinator-friendly is my landscape?" Are you a "Wanna Bee Pollinator Gardener", a "Bee Benefactor" or a "Pollinator Protector"? Find out!

From our Turf Blog: Q&A on Fall Lawn Care

Fall is the best time to perform many of our lawn care tasks. Our cool season lawn grasses are
actively growing again after warm summer months, and people want to do want they can now to ensure we have a healthy start to our lawns next spring. Here's a helpful post from turfgrass extension educator Sam Bauer that addresses some current questions about fall lawn care: U of M Turf Blog

Thursday, September 21, 2017

Ground beetles are only nuisances

Jeffrey Hahn, Extension Entomologist

Some residents have been finding ground beetles in their homes lately. Ground beetles are a common group of beetles that are usually medium sized and dark-colored. As their name suggests, they are typically found on the ground where they hunt other insects. Because of their predaceous activities, they are considered to be very beneficial.
Ground beetles captured in a stick trap.  Ground beetles are
just nuisance and should be tolerated when possible.  Photo:
Jeff Hahn, University of Minnesota Extension

Occasionally in August and September, ground beetles can be found entering homes. Fortunately they are harmless to people and do no damage to property. Some people mistake them for cockroaches which is an insect that can infest homes so it is important to correctly identify any insects that are found. Ground beetles are short-lived and do not reproduce indoors.

Tolerate ground beetles when found in homes as much as possible. The only necessary control is physical removal, especially when only a few are seen. An option for controlling ground beetles is the use of sticky traps. Set out the traps in areas where ground beetles are being found; it is then an easy matter to remove the traps when they have captured ground beetles.

Regardless of what is done, ground beetles are a temporary problem that will go away on their own by the time the weather starts to cool off.

For more information, see Ground beetles in homes.

Monday, September 11, 2017

Late summer butterfly explosion

Photo: Britt Forsberg
Elaine Evans, Extension Educator

If you have been spending time in your flower gardens recently, you may have noticed many brown and orange butterflies visiting plants to drink nectar. Adults of the Painted Lady butterfly, Vanessa cardui, are gathering at flowers in unusually large numbers to prepare themselves for migration down to the southwestern U.S. and northern Mexico. The Painted Lady butterfly is one of the most widely distributed of all butterfly species, but is not frequently seen in Minnesota most years. According to Chip Taylor, director of Monarch Watch at the University of Kansas, this is probably the largest migration he has seen in over 30 years ( September 8, 2017). These larger migrations often follow rainy periods in their wintering grounds. 

You can help these butterflies on their journey south by making sure that you have flowers to provide them with the nectar they need to fuel their long journey and keeping these flowers free of pesticides. According to these butterflies prefer nectar from composites 3-6 feet high, especially thistles; also aster, cosmos, blazing star, ironweed, joe-pye weed, red clover, and milkweeds. Many of these plants can also serve as food for the caterpillars if the adults make it this far north again next year. Unlike monarch caterpillars, which require milkweed, the painted lady caterpillars have been found on over 100 different host plants, but favorites include thistles and legumes.
Photo: Britt Forsberg

If you have not already seen them, a visit to a pollinator garden planted with a variety of blooming flowers is likely to reward you with a stunning showcase of insect beauty.

Here are a few links with more information about Painted Ladies.

Friday, September 8, 2017

Late blight takes out tomatoes

M. Grabowski, UMN Extension Educator
Late blight symptoms on tomato leaves.
M. Grabowski, UMN Extension 

After carefully cultivating tomato plants throughout the summer, many Minnesota gardeners have been shocked to see their plants devastated by blight and fruit rot in a matter of days. The culprit is late blight, a disease of potato and tomato plants. Late blight does not cause significant damage every year in Minnesota but prolonged cool wet weather this year has created ideal conditions for disease.

Late blight is cause by the pathogen Phytophthora infestans, a fungus like organism that thrives in wet conditions. The scientific name of the pathogen translates to ‘plant destroyer’ and the pathogen lives up to its name.  Late blight is the plant disease that ruined the potato crop in the infamous Irish potato famine of the 1840’s and the disease has been responsible for numerous epidemics since then.

How to identify late blight

  • Leaves have large, dark brown blotches with a green gray edge.
  • Stem infections are firm and dark brown.
  • Disease progresses very rapidly in cool wet weather and the entire plant may turn brown and collapse in just a few days.
  • Fruit have firm dark brown blotches. If the tomato is cut open, dry brown rot can be seen extending into the fruit. Fruit only become soft and mushy when bacteria invade after the initial infection.
  • In high humidity, thin powdery white fungal growth appears on infected leaves, fruit, and stems.

Late blight on tomato fruit. Mold appears in high humidity.
M. Grabowski, UMN Extension 

Management options for home gardeners

Once late blight has been found in a garden, there is little that can be done to help the plant. The disease simply moves too quickly. Harvest any tomatoes that are not showing symptoms and keep them in a well ventilated area to ripen. It is likely that a few are infected but not showing symptoms at the time of harvest, so check on tomatoes regularly and discard any infected fruit. Potatoes from infected plants should be dug up as soon as possible. Uninfected tubers can be eaten but should be checked regularly for rot during storage. Discard infected tomato fruit and potato tubers along with infected plants.

Infected plants should be removed or destroyed as soon as possible to prevent the thousands of airborne spores forming on the leaves from spreading to neighboring plants.
  • Infected plants can be placed in a plastic bag or under a plastic tarp and left to cook in the sun for several days. Once all of the plant material is killed, the plant can be composted or buried.
  • Plants can also be shallowly buried in soil, as the freezing winter temperatures will kill both the plant and pathogen.
  • Infected plants can be placed in a compost pile that completely heats up and breaks down all plant material. Do not use a compost piles that does not thoroughly heat up or completely break down plant material. These mildly warm piles can sheltered infected plant material from the freezing cold and allow the late blight pathogen to survive from one season to the next. If you are unsure how hot your compost pile gets, heat infected plant material in a plastic bag before placing it on a compost pile.   

Can fungicides help?

Fungicides are not effective once a plant has become infected with late blight. For many gardeners, it is too late to apply fungicides. Fungicides only work to protect healthy plants and prevent new infections. Gardeners that have not yet seen late blight may choose to protect their tomato or potato crops with a fungicide that has copper as the active ingredient. The product MUST list tomato and/or potato on the label and the gardener MUST follow all label instructions to use the pesticide safely. There are a number of copper fungicides registered for use in home gardens. Some are certified for organic use.

Will late blight come back next year?

The late blight pathogen can only survive Minnesota’s winter if sheltered from extreme cold in infected plant material. This typically only occurs in large piles of unmarketable potatoes that are sometimes left on field edges or in infected potatoes that are buried deep enough to survive the winter. Most years the late blight pathogen must be brought into the state on infected potato seed, infected tomato transplants, or as windblown spores from other areas. Once the pathogen arrives, the right weather conditions (cool and wet) must be present for the disease to become established and spread.

There are a few tomato and potato varieties with resistance to late blight. Look for resistant varieties in your seed catalog for next year. 

Thursday, August 24, 2017

EAB found in Martin County

Jeffrey Hahn, Extension Entomologist

The Minnesota Department of Agriculture (MDA) reported earlier this week that emerald ash borer (EAB) was confirmed in Martin County in the south central area of the state on the Iowa border. Because the nearest infested areas in either Minnesota or Iowa are several counties away, the infestation is the result of someone moving infested ash into the county.
Watch for EAB galleries and other
symptoms of their presence.  Photo: Jeff
Hahn, University of MN Extension

EAB was first found in Minnesota in 2009. Since then, it has spread and is now found in 16 counties.  EAB is a very destructive invasive insect that threatens all native ash in the U.S. Ash is a very important resource in Minnesota where about 1 billion ash trees occur, one of the highest numbers of ash trees in the country.

People can greatly reduce the chance for EAB to spread by buying their firewood locally and avoid transporting it. Burn it where you buy it. It is equally important to observe any quarantine restrictions for the movement of any ash products that may occur in your county. Be aware of the symptoms of EAB and report any suspicious infestations to the MDA’s Arrest the Pest line at 1-888-545-6684 or

For more information about EAB, including symptoms of infestations, see Emerald ash borer in Minnesota.

For the original MDA news release, go here.

Wednesday, August 23, 2017

Add fall color and benefit butterflies by planting native grasses

Contact: Diane Narem, Horticulture Researcher,

Although summer may be coming to a close, it’s not too late to add some charm and color to your
Little bluestem Blue Heaven™
garden this fall with some perennial native grasses. Native grasses can liven up a planting with their interesting shapes and seasonal color changes and benefit multiple types of wildlife, including butterfly and moth species.

According to U of M Extension Horticulturalist Mary Meyer, native grasses require one month of good growing conditions to establish in the fall. This means you can safely plant grasses until mid-September. Extra watering may be necessary during hot or dry spells in the fall. Container plants with well-established root systems are the best choices for fall plantings.

“Many grasses are just beginning to flower in August," Meyer said. "They will soon start their fall color change, so August and early September can be peak season for native grasses".

Not only do they add beauty to your landscape, but grasses are also low maintenance and provide benefits to the environment. Once established, native grasses need little additional water because they are naturally drought tolerant. They also do not require fertilizer or added nutrients. They minimize soil erosion and increase organic matter, creating better soil conditions.

Native grasses provide habitat for wildlife, such as birds, native bees, and butterfly and moth larvae. Many species of butterflies and moths use native grasses as host plants during their caterpillar stage. The larva feed on native grasses, and some build shelters in the leaves and stems, while others hide at the base of the plant. Many of these species survive winter as larva and take shelter within grass plants or burrow just below the soil surface.

Native grasses that provide fall color and food for butterfly and moth larva include little bluestem, big bluestem, switchgrass, and Indiangrass. You can find these plants and others at garden centers throughout Minnesota. For more information on native grasses from the University of Minnesota Extension: Ornamental Grasses for Cold Climates

Friday, August 4, 2017

Cicada killers common now

Jeffrey Hahn, University of Minnesota Extension

A large solitary wasp called a cicada killer, Sphecius speciosus, is common in many areas of Minnesota now. It ranges in size from 1 – 1 ½ inches long. It has a black abdomen with yellow bands, a reddish brown thorax with reddish brown legs and amber colored wings.
Cicada killer with a captured cicada.  Jeff Hahn, U of M Ext.

Some people mistakenly believe they have found a European hornet which is also a large wasp. However, European hornets are social insects living in nests they usually build in tree cavities; they can also be found within homes and other buildings. European hornets do not occur in Minnesota.

Cicada killers nest in the ground, typically in well-drained, light soil exposed to full sun. They are a solitary wasp, meaning that there is only one wasp per burrow. However, cicada killers are gregarious, so there are typically many of them in a small area.

These wasps prey on cicadas. Cicadas are stout, winged insects that are common during the summer. A cicada killer uses her stinger to paralyze a cicada she captures. She carries it back to her nest where it is food for her young. Once the larvae are full grown, they pupate and remain in their burrows until next year.                    

Despite their size, cicada killers are not dangerous to people. Females have stingers but they are not aggressive and ignore people. They do not have an instinct to protect their nests (like yellowjackets and honey bees) and you can walk among them with little worry. Of course, if you provoke a cicada killer or it feels threatened, it can sting to protect itself.
Cicada killer nests can become very abundant in a small area. 
Jeff Hahn, University of Minnesota Extension

Fortunately, cicada killers are just annoying. Their tunneling can be unsightly but does not kill lawns. It is not impossible for their burrowing activity to undermine patio bricks but that is not common.

If you have cicada killers nesting on your property, there are a couple of options to consider. The first is to ignore and tolerate them and let them run their course. Remember, there is very little risk of stings and they will go away on their by the end of the summer. The area can be roped off, in necessary, to keep people away from the nests.

Another option is to treat the nests. Treating the general area is not very effective. Instead, apply an insecticide into each individual nest entrance. Dusts are most effective, although sprays can help reduce numbers. Be sure the product you use is labeled for you use on turf. Effective active ingredients include permethrin and carbaryl. You can also hire a lawn care company to treat the cicada killers.

Wednesday, July 5, 2017

Dealing with Japanese beetles

Jeffrey Hahn, Extension Entomologist

If you had problems last summer with Japanese beetles on your property, the odds are very good they will be pests again this year. In fact some people are already seeing them in high numbers. So the question is what can a gardener do?

Killing individual Japanese beetles is actually easy but the problem is what to do when there are a lot of them. There is no one guaranteed method for treating Japanese beetles. It is best to use as many different management steps as possible to improve your chances of keeping Japanese beetle feeding to tolerable levels.

Have you checked your garden recently for Japanese beetles?
  Photo: Jeff Hahn, University of Minnesota Extension
If you have a small garden, physical removal can be a good option, especially when only small numbers are present. However when Japanese beetles are numerous, it becomes impractical to handpick them every day. Another non-chemical option is to place a cheese-cloth, or similar type of fabric, around valued plants to exclude the beetles.

There are a few low impact insecticides available. Pyola is effective but this product is short-lived and repeat applications are necessary. Neem oil is also an option. It helps deter Japanese beetles but is less effective when large numbers are present. Both of these products can be toxic to pollinators so be sure to apply them when bees are not active.

Thinking of using traps to control Japanese
beetles? Save your money, they are not
effective.  Photo: Jeff Hahn, U of M Ext.
There are a variety of residual insecticides that you can use, like permethrin or carbaryl (Sevin). To protect bees, apply insecticides during late evening after bees are no longer active. The products should be dry by morning when bees become active again. If you are trying to protect a large tree, you may need to have it treated by a landscape or tree care company.

Deciding whether to treat trees and other plants will depend on how many of the leaves are still intact. If nearly all of them are already chewed up, then spraying does not help protect the plants. If there are still a lot unaffected leaves, then it is worth your while to treat them.

Keep in mind that trees that are healthy and mature are not going to be killed from just one year of feeding. Trees are quite resilient and can tolerate a lot of defoliation. If trees has been recently transplanted or are already under stress, it is a good idea to protect them from any additional damage.

What you don’t do is just as important as what you do try. Some people like the idea of using Japanese beetle traps to protect their plants. While these traps can capture an impressive number of beetles, the traps are attracting more beetles than they catch. Research has shown that when these traps are used in home gardens, damage is not reduced but in fact is likely to increase. Likewise, companion planting has been demonstrated to be ineffective in protecting plants from Japanese beetle feeding.

 For more information, see Japanese beetle management in Minnesota.

Poison hemlock: Highly toxic - use caution


Poison hemlock (Conium maculatum) is an invasive plant native to Europe and North Africa. It is highly toxic (i.e., fatal) to humans and animals. Poison hemlock requires considerable sunlight to flourish and is found often near railways, rivers, ditches, field edges, farms and bike paths. It is a biennial plant (having a two year life cycle), and is unlikely to grow in very shady areas or places that are frequently mowed. Read more...