Posts Tagged ‘Michigan State University Extension’

Pesky Little Bugs

Every year is the same thing. Brown bugs covering garages, getting inside sheds and houses, and making their way into window frames. It seems like an invasion in certain parts of the country.

Here in Michigan, we have no shortage of invasive brown marmorated stink bugs. Fortunately, they haven’t reached plague proportions, but they are still a nuisance. And thanks to the citizen scientists across the state, we now have a good idea of where they are! Thanks to regular residents reporting sightings, Michigan State University Extension has a better idea of the population of brown marmorated stink bugs and how they are distributed.

But there’s still more work to be done.

Most of the reports came from the southern part of the Lower Peninsula. That makes sense since that’s where most of the people are. So if you live (or visit) the Upper Peninsula or the northern Lower Peninsula, we still need your data! Read the article below to find out how.


Why and how to report sightings of brown marmorated stink bugs in your home or business

September 2017 update on why and how to report sightings of brown marmorated stink bugs to the Midwest Invasive Species Information Network.

Posted on September 18, 2017 by Julianna Wilson, Michigan State University Extension, Department of Entomology

Adult brown marmorated stink bugs like to move into homes in the fall to take shelter for the winter. They are harmless to humans and pets, but are on the verge of being an important pest in fruit and vegetable crops in Michigan. Photo by Jim Engelsma.

Adult brown marmorated stink bugs like to move into homes in the fall to take shelter for the winter. They are harmless to humans and pets, but are on the verge of being an important pest in fruit and vegetable crops in Michigan. Photo by Jim Engelsma.

When we first published this article in September 2015, we knew very little about where the brown marmorated stink bug (BMSB) would be found in Michigan. Now, thanks to the eager reporting by many hundreds of people who saw that first article, we now know it is well-established across most of the southern half of the Lower Peninsula (see map below). If you live outside of this area, especially in the northern half of the Lower Peninsula or in the Upper Peninsula, and would like to submit a report, please follow the instructions below. Otherwise, please check out the resources at the end of this article for more information on what BMSB is, what it is doing in homes and what to do about it.

What is the brown marmorated stink bug (BMSB)?

The brown marmorated stink bug (BMSB) is a 0.5- by 0.625-inch shield-shaped insect that uses its piercing mouthparts to suck plant juices from fruits, seed pods and nuts on a wide variety of wild and cultivated plants. It was accidentally brought to North America from Asia sometime before 1996 and was first detected in Michigan in 2010. Also known by its scientific name, Halyomorpha halys, BMSB adults and nymphs – the immature stages of the bug – feed on a number of important fruit, vegetable and ornamental crops. Where it has been established for some time, it is now a major pest for growers of susceptible crops.

BMSB body parts

Brown marmorated stink bugs have dark and light banding along the margin of the insect’s body and white bands on its antennae and legs. Photo by Jeff Wildonger, USDA ARS BIIR

Part of the pattern of establishment by this pest is that it starts out as a nuisance pest in homes and businesses and then a few years later it becomes an important agricultural pest for neighboring growers. At this time of year in their native habitat, BMSB would normally look for shelter in south facing rocky outcroppings and other protected areas. The perfect surrogate turns out to be south-facing walls of man-made structures. It is important to note that BMSB do not bite humans or their pets – they are strictly plant-feeding insects. Also, they do not nest or reproduce in homes, they are simply finding a place to take shelter from the cold and will atempt to find their way out again when spring returns.

For information on how to prevent or get rid of this pest in your home, plus how to distinguish it from other common insects that are occasional home invaders, see this tip sheet from Michigan State University Extension: “The Brown Marmorated Stink Bug (BMSB): Information for Michigan Residents on a New Home Invader.”

Who should report seeing BMSB?

If you or someone you know has seen this pest in or on the outside of your home or place of business, and you are outside of the area in which we now know it is well-established in Michigan (see map below), we want to hear from you! Go to the Midwest Invasive Species Information Network (MISIN) website or mobile app, register as a user (it’s free) and follow the instructions for submitting a report. A few minutes of your time can be incredibly helpful in officially cataloging and tracking this invasive pest.

The MISIN website and the app are free to use – you simply register and log in, verify you do indeed have BMSB (by either comparing the bug or bugs you see with the photo in this article, by looking at the Species Factsheet provided by MISIN for BMSB or downloading the new tip sheet on brown marmorated stink bugs for homeowners), and then report the sighting or sightings. Users can also submit up to two images with every report if they are uncertain as to whether what they are seeing is BMSB. By reporting sightings of this pest, you will be helping growers in your area prepare for this pest by identifying potential new hotspots.

If you have trouble registering with MISIN and would like to report a sighting, email Julianna Wilson at with your nameaddress (or nearest crossroads), the date you saw them and how many you have seen. Again, if you have already reported from a particular address or live within the area where we know BMSB is well-established (see map below), we do not need to hear from you. Thank you!

BMSB 2017 Map

View larger image. As of September 2017, more than 12,000 reports have been submitted to MISIN from all but five Michigan counties. From these reports, we know BMSB is well-established in counties colored in red (darkest color), and we do not need any more reports if you see BMSB in these areas. Outside of the counties in red, we are interested in hearing where BMSB is being found. Reports should be submitted through the MISIN website.

Where to find more information about BMSB


*Original Article Published HERE.


Gypsy Moth Attacking Michigan Trees…Again

Ugh, they’re back! Or maybe it’s more accurate to say they never left.

Gypsy moth has been a pest to Michigan trees for decades, ever since it was introduced to the state in 1954. While the invasive pest has never been eliminated, some years seem to be worse than others? This year seems to be particularly bad. Why? One word: drought.

Read the below article by Michigan State University Extension to find out how drought can cause booms in gypsy moth populations.


Gypsy moth caterpillars once again attacking trees in Michigan

Large numbers of gypsy moth caterpillars strip trees in Mid-Michigan as drought hampers fungal controls.

Barrier band for gypsy moth larva control. Photo by Pennsylvania Department of Conservation and Natural Resources - Forestry,

Barrier band for gypsy moth larva control. Photo by Pennsylvania Department of Conservation and Natural Resources – Forestry,


They are back! A Clinton County resident contacted the Michigan State University Extension Lawn and Garden Hotline to report heavy caterpillar feeding in maples, pines and apple trees. A few trees had lost much of their foliage. A photo of the caterpillars confirmed it is gypsy moth, Lymantria dispar. For Michigan residents that have dealt with gypsy moths in the past, it is an unwelcome sight but one that is not unexpected.

Twenty to 30 years ago, gypsy moth was a plague across Michigan, defoliating thousands of acres of trees each year. Without many natural controls, it wreaked havoc on oaks, pines, maples, birches, apples and many other species. In 1989, a fungal pathogen was found killing off large populations of gypsy moth caterpillars in Northeastern states. This fungus was identified as Entomophaga maimaiga, a natural biological control of gypsy moth in Japan.

Brought to Michigan in 1991, E. maimaiga quickly became a key factor in suppressing gypsy moth across the state. Naturally occurring in soils, it spreads to young caterpillars as they move from tree to tree. Caterpillars begin to die as the fungus grows inside them. The spores from these dying and dead caterpillars spreads by wind infecting other caterpillars. As the season progresses, large infected gypsy moth caterpillars are found dying on tree trunks. Dead caterpillars remain attached to trunks and branches, hanging straight down. E. maimaiga is so effective that areas of the state often go for years without any noticeable damage from this ferocious defoliator.

So why are gypsy moths back in large numbers and feeding on trees? Drought! The fungus cannot effectively reproduce during times of drought. A year ago much of Michigan was in a serious drought from spring to early summer.  This is the time the fungus is dependent on moisture for its development and of course it is also the time gypsy moth caterpillars begin to feed on trees. Callers to the MSU Extension state hotline in 2016 confirmed that more caterpillars were feeding on trees across southern Michigan. Without consistent moisture in the spring, more gypsy moth caterpillars survived into the moth stage to produce larger numbers of egg masses. It was not unexpected to see growing populations of gypsy moth caterpillars this year.

gypsy moth larva

Gypsy moth caterpillar. Photo by Bill McNee, Wisconsin Dept of Natural Resources,


Drought is the weak link for the Entomophaga maimaiga fungus and in years when this occurs gypsy moth populations begin to grow and impact landscapes and forests. Spring droughts in 2007 and 2012 led to higher population of gypsy moth the following years. The good news is that in most years we do have adequate rainfall in the spring. Many areas in southern and mid-Michigan had consistent rain this past May, allowing for good development of the fungal pathogen.

Inspect plants now for gypsy moth caterpillars and damage. Trees that lose a large percentage of leaves to gypsy moth feeding can become stressed as energy reserves are used to produce a second set of leaves. Conifers may be permanently damaged if totally defoliated, especially pines. Valuable pines and hardwoods in the landscape can be sprayed with insecticides labeled for caterpillars, or trunks of trees can be banded with a sticky material to trap caterpillars as they crawl up and down trees. This may help on individual trees that are out in the open but may have little effect on trees in the woods where insects can move between adjacent trees.

If valuable trees are infested, you can contact an arborist to spray for the caterpillars. You could also choose to let nature take its course.  In my conversation with the gentleman from Clinton County, we discussed how wet conditions in most of mid to southern Michigan this spring should lead to development of the fungus E. maimaiga. He observed that he was already seeing dead caterpillars hanging straight down, which is a symptom of the effect of the fungus on gypsy moth caterpillars. These dead caterpillars infested with E. maimaiga now become the future source of the fungus in this area protecting trees for years to come.

Michigan is a large state with different weather patterns. While one area is in a drought, another site can be experiencing heavy rains. Awareness of where spring drought occurs can provide an early indicator for possible gypsy moth outbreaks. Nature provides many clues if we pay attention.

New Hemlock Quarantine Possible

It’s a tiny forest pest that is wreaking havoc across the Appalachian Mountain region and one that could cause the same kind of devastation in Michigan if we’re not careful.

It’s called the hemlock woolly adelgid (HWA), a small aphid-like, sap-sucking insect that is responsible for killing thousands of hemlock trees. It’s difficult to find due to its small size, but can begin killing trees as early as 4 years after infestation. The first reported sighting was near Richmond, VA in 1951. By 2005 it had spread to 16 states from Maine to Georgia.

It has been recently identified in west Michigan; first noticed in Muskegon county, but has also been found in nearby Allegan and Ottawa counties. An import quarantine is already in effect for Michigan, meaning that hemlock cannot be brought into Michigan from an infested state. However, since it has been determined that HWA is in several Michigan counties, an in-state quarantine is being considered. This would mean that movement within Michigan would be regulated, especially within the quarantined counties.

With the estimated 170 million hemlock trees in Michigan, including the virgin hemlock forest at Porcupine Mountains State Park, extra caution is a good thing.


Michigan is preparing to enact interior quarantine due to invasive hemlock tree pest

A recent outbreak of the pest within the state has prompted new legislation which will restrict the movement of hemlock products within Michigan in an effort to control this invasive pest.

Adelgid infested hemlock branches. Photo credit: USDA Forest Service - Region 8 - Southern, USDA Forest Service,

Adelgid infested hemlock branches. Photo credit: USDA Forest Service – Region 8 – Southern, USDA Forest Service,


Over the last several years, in reaction to the outbreak of hemlock wooly adelgid in forest stands across the eastern U.S., Michigan banned the shipment of hemlock trees and wood with bark into the state. However, a recent outbreak of the pest within the state has prompted new legislation which will restrict the movement of hemlock products within Michigan in an effort to control this invasive pest.

The exotic hemlock wooly adelgid insect was first identified in the eastern U.S. in early 1950s. It has systematically spread throughout the Appalachian region and is devastating the hemlock tree forest resource by the thousands. In an effort to help protect the estimated 170 million hemlock trees in Michigan, a ban or quarantine on bringing hemlock nursery stock and wood products with attached bark into the state has been in place for some time and was last revised in 2014.

In spite of the efforts to keep this destructive forest pest out of the state, an infestation has been identified in central West Michigan. First noticed in Muskegon County, closer inspection has identified colonies of the tiny sap feeding pest in neighboring Ottawa and in Allegan Counties as well.


Pale crown appearance with no new growth indicates this tree is under severe attack from Hemlock Woolly Adelgids. Photo credit: James Johnson, Georgia Forestry Commission,

In an effort to control or slow this tree-killing pest, the Michigan Department of Agriculture & Rural Development (MDARD) solicited public comment on a proposed hemlock woolly adelgid interior quarantine. The original draft stated that “the proposed quarantine, movement of hemlock nursery stock, branches, boughs, uncomposted chips, logs and firewood would be regulated. Specifically, movement out of, or within, the three county area would be prohibited except under compliance agreement issued by MDARD. The proposed regulated area includes Allegan, Muskegon and Ottawa counties.” Other counties may be added as the need arises to further limit the spread of hemlock woolly adelgid.

If the quarantine is enacted, the movement of hemlock trees, boughs, firewood, logs or limbs will be prohibited without a compliance agreement. This restricted movement would include movement within these counties from site to site. (Note: A compliance agreement are actions jointly taken by both producers and the State of Michigan to ensure hemlock nursery stock and wood products are free of the adelgid insect.)

For more information on the hemlock wooly adelgid, Michigan State University Extension has a bulletin available. Extension Bulletin E-3300  details the life cycle and highlights the negative impacts from this invasive killer with some available treatment options should landowners identify adelgid colonies in their trees.

In addition, people interested in becoming actively involved in identifying new infestations of this and other potential forest pests are encouraged to become involved in the MSU Extension Eyes on the Forest program by becoming a sentinel tree volunteer.

The Stink Bugs Are Back

They’re brown, numerous, and annoying. And right now they’re trying to make their way into your homes. Brown marmorated stink bugs.

Every year people are plagued with these pests as they look for warm places to hide for the winter. Unfortunately for us, we’ve made lots of them with our obsession for cozy homes, insulated garages, even storage sheds and barns. All of these provide great protection for these insects during the harsh temperatures of winter.

If you find yourself infested, don’t panic. While irritating, they’re harmless. And there are ways to keep them out of your house.

The article below from Michigan State University Extension gives you a few tips and resources to help.


Brown marmorated stink bugs are moving into Michigan homes again

What they are, why stink bugs are entering houses, and what you can do about them.

The brown marmorated stink bug is a shield-shaped, plant-feeding bug native to Asia. It has distinctive banding on its antennae and around its abdomen. Photo: Jeff Wildonger, USDA-ARS-BIIR.

The brown marmorated stink bug is a shield-shaped, plant-feeding bug native to Asia. It has distinctive banding on its antennae and around its abdomen. Photo: Jeff Wildonger, USDA-ARS-BIIR.

It’s that time of year again when brown marmorated stink bugs invade structures humans create looking for a place to hunker down for winter. Since last fall when Michigan residents were asked to report brown marmorated stink bugs in their homes, we now know that brown marmorated stink bugs are well-established as a nuisance pest in homes in the southern Lower Peninsula of Michigan.

What are they doing?

Brown marmorated stink bugs are looking for a protected place to hibernate over winter. They will leave your house again in the spring – if they can find their way back out – to look for plants to feed on and lay their eggs outside.

What are they NOT doing?

They are NOT nesting, laying eggs or feeding on anything or anyone in your house. These are plant-feeding insects with straw-like mouthparts for drinking plant juices – they are harmless to humans and pets.

What do you need to do?

  1. Don’t panic.
  2. Look for gaps around window air conditioners or holes in window screens and block them off – these are easy access points for brown marmorated stink bugs to enter houses.
  3. The easiest, non-toxic way to dispose of them is with a couple inches of soapy water in a bucket – the soap prevents them from escaping the water. Sweep them into the bucket and they will drown in the soapy water, which you can then dump outside. Or you can do the same with a Shop-Vac – add the soapy water to the canister before vacuuming them up with the Shop-Vac.
  4. Report how many you’ve seen at a given location using the Midwest Invasive Species Information Network. If you have trouble entering the information on the Midwest Invasive Species Information Network website, leave a message for Julianna Wilson via email at or by phone at 517-432-4766 with your name, address (or nearest crossroads), the date you saw them, and how many you have seen.

The map below shows where we have received reports to the Midwest Invasive Species Information Network of brown marmorated stink bugs in the Lower Peninsula since Sept. 25, 2015.

Map of Michigan counties that have received brown marmorated stink bugs reports

Biology and other tips for managing them in your home: download the free Brown Marmorated Stink Bug (BMSB): Information for Michigan Residents tip sheet from Michigan State University Extension.

Prevent them from entering your home: see “Managing brown marmorated stink bugs in homes.”

Report sightings of brown marmorated stink bugs: see “Report sightings of brown marmorated stink bugs in your home or business.”

Visit MSU’s Brown Marmorated Stink Bug website for 2016 monitoring network reports and additional information.

Be Careful with Water Gardens

You see them all the time, people adding ponds and other water features to their yards or gardens. Done correctly, water gardens are a great way to attract wildlife, create habitat, and add beauty to your property.

Yet there should be caution to this tale. Your choice of plants and animals when planning these features is key. If you’re not careful, your innocent plant purchase might just take over your neighboring lake or river. Please take the proper precautions when choosing plants and animals and when in doubt, choosing native species is always the safest bet.

Learn more about keeping non-native aquatic plants and animals contained in the article below. There’s also some great information in it about the new RIPPLE project, an education program created by Michigan State University Extension and the Michigan Department of Agriculture and Rural Development.

Is your water garden having a RIPPLE effect on Michigan’s waterways?

While water gardens add beauty to backyards, it is important to be aware of the risks associated with aquatic invasive species and to prevent escape.

Build water gardens away from other waterbodies to prevent escape of non-native animals and plants during flooding events. Photo credit: Paige Filice

Build water gardens away from other waterbodies to prevent escape of non-native animals and plants during flooding events. Photo credit: Paige Filice

Wildlife habitat, soothing sounds and scenic beauty are just a few of the benefits of having a backyard pond. Exotic fish such as koi can be attractive additions to your pond, and non-native ornamental plants such as water hyacinth can add beauty. But if let loose, these species can have long-lasting, detrimental effects on Michigan’s lakes and streams. Water garden fish and plants are commonly selected for their hardiness and rapid growth, but these characteristics also contribute to the species’ ability to become destructive and invasive if they escape.

Invasive water garden plants and fish can enter Michigan’s lakes and streams a variety of ways. One of the most common practices is the intentional release of unwanted pets, such as koi and goldfish. This happens most often during the breeding season when fish reproduce rapidly and in the fall when homeowners are preparing their water gardens for winter weather. While releasing unwanted fish and plants into natural waterbodies may seem humane, the consequences to the environment can be devastating. More environmentally friendly alternatives include giving to or trading with another hobbyist, environmental learning center, aquarium or zoo. Some local pet stores will take back unwanted fish and plants. Invasive fish and plants can also escape water gardens during heavy rain events if the pond overflows, so the best location for a backyard pond is well away from other waters.

Aquatic Species of Concern

One common water garden plant of particular concern is water hyacinth. While beautiful with light purple flowers and glossy leaves, it can become very invasive and is on the International Union for Conservation of Nature’s list of 100 of the world’s worst invasive alien species. It can form dense mats on the surface of the water, impeding boat traffic, clogging waterways and interfering with wildlife. Due to its free-floating nature, water hyacinth prevents sunlight from penetrating the water, reducing the growth of native submersed aquatic plants, which many aquatic organisms rely on for shelter and food. Water hyacinth was first introduced to the United States in the late 1800s from South America and has since invaded much of the southern United States. It has been found in southeastern Michigan, including Lake Erie Metropark, where it has persisted for years even though it was commonly believed to be unable to survive Michigan’s winter temperatures. When choosing plants and fish for your backyard pond, consider asking your local retailer for native species. There are many varieties of native aquatic plants that can add great beauty to backyard ponds without as many risks.

Tips to reduce the risk of invasion

Follow the RIPPLE: Reduce Invasive Pet and PLant Escapes program guidelines to prevent escapes. If you have water hyacinth, or any other potentially invasive plant or fish in your pond, and would like to get rid of it, remember to never release it into waterways. It is also important to not compost it, as the seeds can still be viable.

  • Inspect and rinse any new plants to rid them of seeds, plant fragments, snails and fish.
  • Build water gardens well away from other waters.
  • Seal aquatic plants for disposal in a plastic bag in the trash.
  • Give or trade unwanted fish or plants with another hobbyist, environmental learning center, aquarium or zoo.
  • Contact a veterinarian or pet retailer for guidance on humane disposal of animals.

The State of Michigan has laws restricting and prohibiting the sale of some organisms, including plants and fish in the water garden industry. However, it does not include all potentially harmful invasive species such as water hyacinth.

Michigan State University Extension teamed up with the Michigan Department of Agriculture and Rural Development to create the RIPPLE education campaign. It is used to educate Michigan retailers and residents about proper inspection and disposal techniques to keep non-native plants and animals contained and out of Michigan’s lakes and streams. To learn more about invasive species and to report sightings in the wild, visit

What is Spruce Decline & What to do about it?

Many Michigan residents have reported that their spruce trees are looking a little…ragged, to say the least. Most are seeing branches dying, starting at the bottom and moving up the tree.

There are several reasons for this, but the most common ones in Michigan are due to fungal infections or insect infestations. The following article by Michigan State University Extension lists several of the ones we typically see.

Do you have a spruce that’s not looking so hot? It might be because of one of these.


What is spruce decline and what should you do about it?

Frequently asked questions about spruce decline.

Photo 1. Declining spruce trees. Photo credit: Bert Cregg, MSU

Photo 1. Declining spruce trees. Photo credit: Bert Cregg, MSU

What’s wrong with the blue spruce trees in my neighborhood?

Colorado blue spruce trees have long been among the most popular conifers for landscaping in Michigan and the upper Midwest. Blue spruce trees are widely planted due to their good growth rate, stately form and, of course, their blue foliage. Unfortunately, blue spruce trees are subject to a wide range of insect and disease problems that can impact their growth and aesthetic appeal.

The prevalence of diseases on blue spruce trees has intensified in recent years and trees are declining rapidly in many areas (Photo 1). The key symptom of spruce decline is branch dieback, which progresses over two to four years and renders the plant’s appearance unacceptable for most homeowners (Photo 2). The rapid decline of many spruce trees in Michigan and surrounding states appears to be related to an increase of canker diseases coupled with other disease and insect problems that plague the species.

Decline starts on lower branches
Photo 2. Decline usually starts on lower branches. Photo credit: Dennis Fulbright, MSU

What kind of diseases affect blue spruce trees?

There are three principle types of diseases that affect blue spruce trees: needlecasts, tip blights and canker diseases. All of these diseases are caused by fungal pathogens and each produce specific symptoms that can be useful in diagnosing the problem.

1. Needlecasts. As the name implies, trees with needlecast diseases shed needles. Needlecast fungi often infect needles on the current year’s shoots. As the disease progresses, the needles die, usually the year following the infection. As a result, trees affected by needlecasts often have an outer “shell” of live needles on current shoots and dead needles on older shoots (Photo 3). The two most common needlecasts we find in spruce are caused by the fungal pathogens Rhizosphaera and Stigmina/Mycosphaerella.

2. Tip blights. Tip blights are fungal diseases that typically cause dieback to new, emerging shoots (Photo 4). Tip blights are most common on pines, especially Austrian pines, but can also occur on spruces.

3. Canker diseases. Canker diseases are caused by fungi that infect branches or the main stem of trees. Typical symptoms of cankers are sunken areas along a stem that may ooze resin (Photo 5). Trees may produce ridges of wound tissue around older canker infections as the tree attempts to restrict the fungus’ growth. As cankers develop, they can interfere with the branch’s ability to transport water and nutrients, resulting in the death of individual branches often referred to as “flagging.”

Needlecast disease on spruce New shoot tips Canker disease on branch
Photos 3-5. Left, Needlecasts kill older (inner) needles, but leave newer needles unaffected. Middle, New shoot tips killed by Phomopsis tip blight. Right, Resin oozing from a branch canker caused by Cytospora. Photo credits: Left and middle photo, Dennis Fulbright, MSU; right photo, Michael Kangas, NDSU,

What kinds of insects affect blue spruce trees?

Numerous insect pests can impact spruces in Michigan’s landscape, but the two most common are gall adelgids and spruce spider mites. In both cases, the insect pests are tiny and you may need a hand lens to see them. Often times, people are more likely to see the damage as opposed to the insect pests themselves.

1. Gall adelgids. Adelgids are small insects that feed on shoots by sucking plant sap. As they do so, they cause the shoots to deform and produce galls that resemble cones (Photo 6). Damage from gall adelgids is mainly aesthetic.

2. Spruce spider mites. Spruce spider mites cause needle discoloration and eventually kill needles, which can be mistaken for a needlecast disease (Photo 7). Technically, mites are not insects, but are related to spiders. This distinction is important since not all insecticides will control mites.

Cooley spruce adelgid gall Mite needle damage
Photos 6-7. Left, Gall caused by Cooley spruce adelgid. Right, Needle damage caused by mites. Photo credits: Jill O’Donnell, MSU

Why are we seeing increased decline in blue spruce trees?

There are a number of factors contributing to the decline we see in blue spruce trees, including environmental changes, poor site conditions and new pathogens. Colorado blue spruce is native to arid regions in the Rocky Mountains. Michigan’s climate is generally more humid, especially in the summer, which is ideal for fungal pathogens to thrive. In landscapes, Colorado blue spruces have been planted on some sites that are marginal for their success. As a result, they are stressed and more susceptible to fungal pathogens.

Finally, for decades the default diagnosis for most problems with blue spruce has been Rhizosphaera needlecast or Cytospora branch canker. However, a recent survey by Michigan State University researchers suggests two other fungal pathogens, Diplodia and Phomopsis, were much more commonly associated with branch death and tree decline than Cytospora (Photos 8-9). Diplodia and Phomopsis are both considered weak or secondary pathogens, so it is unclear at this point why they appear to cause major disease problems for spruce. Also, in many cases there may be more than one issue that is affecting your tree’s health.

Spruce decline symptoms  Phomopsis canker on branch
Photos 8-9. Left, Decline symptoms moving upward. Right, Wood staining on branch with Phomopsis canker. Photo credits: Left photo, Christine McTavish, MSU; right photo, Dennis Fulbright, MSU.

Can I do anything about these spruce problems?

As with any tree health problem, the first step in dealing with declining spruce trees is to diagnose the problem and identify the cause. For large or important landscape trees, homeowners should contact a professional arborist or tree care company.

For some disease issues, such as needlecasts, fungicides may be effective in preventing or controlling the disease. It is important to note that fungicide treatments for needlecasts only protect new growth. For control to be fully successful, it may take two to three years of yearly fungicide applications. For canker diseases, the effectiveness of fungicides is usually limited. Removing affected branches is usually the best action to improve the tree’s appearance and slow the spread of disease within the tree.

For insect or mite issues, insecticides or miticides can be effective, however selection of the proper product and timing are critical.

Should we continue to plant blue spruce trees?

This is a difficult question. Although spruce decline is widespread and appears to be increasing, it is not a certainty that all trees will be affected. In fact, it is not uncommon to see healthy, thriving spruce trees near or adjacent to trees that are in severe decline. Another complicating factor is that trees may be healthy for a number of years and then begin to decline as they mature and are more difficult and costly to remove.

The likelihood of having success can be improved by planting blue spruce trees on sites with conditions they favor. Key site factors for blue spruce trees are full sunlight, good air movement and excellent soil drainage. Michigan State University Extension recommends homeowners diversify their landscapes to help make their landscapes more resilient to pest and environmental changes, and seek to plant a variety of species wherever possible.

Healthy blue spruce tree
Blue spruce does best on exposed sites with good soil drainage. Photo credit: Bert Cregg, MSU

Additional resources

Print a PDF of this article.

How to Protect Pollinators

With collapsing populations of honeybees all over the country, pollinators are big news right now. There have been several articles and media campaigns lately that all promote what individual citizens can do to help them out. That’s where it all starts right? At home. People may think that what they’re doing is small, too small to make a difference, but when you add up all of those small individual actions throughout a neighborhood, a city, a state…that’s a BIG difference if you ask us.

Even if you don’t have a lot of land you can still help out your local pollinators. This new publication from Michigan State University Extension has everything you will ever need to know about how to make your yard as pollinator friendly as possible.


How to protect pollinators in urban landscapes and gardens

A new PDF publication is the complete guide to protecting pollinators while gardening, growing flowers or managing trees, shrubs or turfgrass in urban areas.

How to protect pollinators in urban landscapes and gardens

Many people are concerned about declines in the number of bees and butterflies, especially honey bees and monarchs. To help gardeners and others in urban settings identify how they can protect and increase populations of pollinators, I worked with a team of my fellow entomologists to write a guide full of resources and recommendations. “Protecting and enhancing pollinators in urban landscapes for the US North Central Region” is available online in PDF format for free viewing and downloading.

This online publication includes:

  • The principles of integrated pest management (IPM) for dealing with pest problems while protecting pollinators.
  • Factors that threaten pollinator health.
  • Detailed recommendations for selecting annuals, perennials, shrubs and trees that support pollinators.
  • Unique to this publication, best management practices for managing devastating exotic pests, or troublesome outbreaks of native pests, while minimizing impacts on pollinators. These practices include trunk injections and the use of low-impact pesticides.
  • A detailed phenological table that tells when the most common trees and shrubs bloom so that sprays can be avoided until they are done blooming.
  • A list of 55 references for those that would like to read more on this subject.

Pollinator coverThis resource is a 30-page PDF and will answer nearly every question that gardeners, landscapers and tree care professionals may have about protecting pollinators. The plant material listed and discussed are for the north central region of the United States, but other versions of this bulletin are in progress now to provide lists of plants for other regions of the country.

The title and complete list of authors is: Protecting and enhancing pollinators in urban landscapes for the US North Central Region (Michigan State University Extension bulletin E3314), by David Smitley, Michigan State University Department of Entomology; Diane Brown and Erwin Elsner, Michigan State University Extension; Joy N. Landis, Michigan State University IPM; Paula M. Shrewsbury, University of Maryland Department of Entomology; and Daniel A. Herms, The Ohio State University Department of Entomology.

Dr. Smitley’s work is funded in part by MSU’s AgBioResearch.