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Landscape Alert newsletter

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Vol. 23, No. 2, April 4, 2008

In this issue
Landscape and nursery

Salt damage to landscape trees and shrubs
Christmas trees and forestry

Will we have a big year for cones in Fraser fir this year?

Insect update: Take time now to examine your trees

Spring clean up

Is it winter damage or needlecast?
Around the home

Brown dog ticks, the other dog tick

Boxelder bugs, Asian lady beetles and cluster flies. Oh boy!

Flower hermit beetle grubs

Winter snows encourage rodent damage

Recycle your old plastic garden pots and containers
Other news

Update on new pesticide applicator core manuals

Department of Homeland Security plans I-9 audits in 2008

Weather news

Next issue April 18

Salt damage to landscape trees and shrubs
Bert Cregg
Horticulture and Forestry

As our landscapes slowly wake up from their winter slumber, we’ve been getting quite a few reports of plants suffering from apparent salt damage. Many parts of the state had record or near-record snowfall totals, which means road crews applied record or near-record amounts of de-icing salts. Where we live in Mid-Michigan most of our snow came in 2-4 inch increments, which meant the salt trucks were out like Chicago voters, early and often. This constant bombardment with sodium chloride can take a toll on a lot of landscape plants. Common signs of salt damage are scorched needles on conifers, especially on the side of the plants facing the road, witches brooms (clusters of irregular growth at the end of terminal shoots) and crown or branch die-back.

Dealing with winter injury
As with many environmental injuries, there is typically not a lot that can be done about salt injury after the fact except to keep the patient quite and comfortable and let nature take its course. For evergreen conifers, the initial damage, especially right about now, often looks worse than the final outcome. Needles can experience pretty heavy scorching, but as long as the buds are not damaged and the plants flush normally this spring, they will usually be OK. Branch die-back in deciduous trees and shrubs can be more problematic and may require some attention. Right now, we’re in a “wait and see” mode. As trees and shrubs begin to leaf out, salt damage or winter freezing injury will become apparent. Play close attention to recently planted (within the last year or so) trees and shrubs, which are often prone to die-back. Also bear in mind that salt exposure varies depending on type of road (four lane arterial road versus two lane county road); exposure (prevailing winter winds are from the north and west so trees on the east and south sides of road often receive a heavier salt load); and traffic speed and volume (increased traffic speed increases the distance salt spray will travel).

Road salt is a fact of wintertime in Michigan. Many road commissions have adapted strategies to optimize salt effectiveness and incorporate alternative de-icers into their snow and ice management. But the fact remains sodium chloride is the lowest cost option to for road deicing. As I’ve noted before, the best solution for long term management of salt damage is selection and protection. In salt-prone areas, select plants that are tolerant of salt exposure and where possible, use physical barriers such as burlap screens to prevent salt spray from reaching sensitive plants.

To view an article on salt tolerant trees, please visit the Landscape Alert issue from May 19, 2006 at: http://www.ipm.msu.edu/cat06land/l05-19-06.htm

Will we have a big year for cones in Fraser fir this year?
Bert Cregg
Horticulture and Forestry

In the last Landscape Alert, I mentioned that “Will we have lot of winter injury?” is one of my least favorite questions to face each year. “Will we have a lot of cones in Fraser fir?” is another dreaded question. In this case, however, we have a little better basis for making an assessment.

Fir cone buds are actually formed the year before the cones develop. So, the buds that will produce the cones we’ll see this May are already on the trees. Each year buds are formed along newly expanding shoots. As growth begins to slow in June and early July, the newly formed buds begin to differentiate; some become vegetative, others become cone buds. Stress, due to high temperatures or drought, promotes cone buds over vegetative buds.

Cone from Fraser fir.

The weather pattern we saw over much of the state last summer suggests we could be in for a major crop of cones this year. For example, at the Michigan Automated Weather Network site at Montcalm Research Center near Lakeview, Michigan, daily high temperatures were very warm in June 2007, averaging nearly 85ºF for much of the month. At the same time, rainfall was relatively scarce. If we compare rainfall for the summer with potential water loss from soil and vegetation (potential evapotranspiration or PET) we see that we experienced a rainfall deficit (rainfall less than PET) for 10 out of 12 weeks during the early summer (see figure). This resulted in a total rainfall deficit of about 10 inches for the period. Since much of this period corresponds to the time when cones are formed, we may be in for a lot of cones this year.

Table 1. Rainfall and potential evapotranspiration (PET), MSU Montcalm Research Farm: Summer 2007

Insect update: Take time now to examine your trees
Jill O’Donnell
Christmas Tree ICM educator

It has been cold, snowy and dreary, but it will soon be time to think about aphids, adelgids, borers, weevils and other pests! Take time now to walk through your fields and examine your trees carefully. What sort of insect damage is left from last year? Do you see galls on your spruce trees? Did white pine weevil kill the terminal leaders of some of your pine or spruce trees? How do the needles of your Douglas fir trees look – are they curled or bent from Cooley adelgid or browning from needlecast diseases? Maybe you see little white pine needle scales or maybe black sooty mold on your Scotch pine needles. Don’t forget to look at the stems of your trees. Big pitch globs on the stem usually mean that Zimmerman pine moth is present.

Good scouting is one of the most important parts of integrated pest management (IPM). It helps you get a jump on insect pests that may cause you problems this year, tell you if the problem is located in one spot or generally across the field, and whether the damage is enough to require treatment. Soon we will see some of our early season pests that are active between 25 – 100 GDD Base 50 begin their activity.

Zimmerman pine moth is an insect that can be a real problem if you have Scotch and Austrian pine. This insect overwinters as a tiny caterpillar and bores under the bark early in the spring. It will tunnel under the bark for several weeks during the summer causing large soft masses of pitch to flow from the tree. Zimmerman pine moth larvae usually bore into large branches or more commonly, into the stem of the tree, often right at the branch whorls. The tunneling can kill branches and tree stems may break off above the wound.

If you plan to use an insecticide to control this pest, the insecticide must be on the bark as the caterpillar bores in (mid- to late April.) Otherwise, it will be well protected under the bark for the rest of its life cycle. In addition to applying the insecticide early, it is also important to adequately cover the bark of the stem and large branches. If you are unable to get good coverage, then spraying will not be effective!

Also, we have found that trees attacked the previous year were more likely to be attacked again. This means you need to look for heavily infested, individual trees. Cut and destroy those trees by chipping or burning them as early in the season as possible. That should help remove the most attractive trees from the field and kill the developing larvae.

White pine weevil is another insect that becomes active early in April on warm spring days. Overwintering adults move from the litter to the treetops to mate and lay eggs. In the past few years, we have seen increasing damage (dead leaders on white pine, spruce and Scotch pine). Controlling this pest involves applying a registered pesticide to control the egg-laying adults. Make sure to thoroughly cover the leader and the upper part of the tree. Then in the growing season when you see leaders beginning to die, clip them out and remove them from the field. We will be setting out traps at several locations this year to monitor the emergence of the overwintering adults.

Be thinking about pales weevil if you have trees that have sustained damage in the last one to three years. These weevils overwinter as adults in the litter and duff. They are attracted to fresh pine stumps to lay eggs. The larvae feed around the root collar and in the big roots of the stump. That's not a problem – you don't sell stumps, right? The adult weevils actually cause the problem, as they will gnaw away on the bark of shoots, below the needles. This feeding causes the shoot to die and flag. They will feed on several different conifer species including white pine, Scotch pine, Fraser fir and Douglas fir.

If you have fresh pine stumps near or mixed in with live trees, and you have a problem with pales weevil, you can spray the bark area of the fresh stumps with a registered, persistent insecticide. This will need to be done in spring, usually sometime between early and late April, depending on your location and the weather.

Cooley's adelgids will also complete their life cycle on Douglas fir. They do not form galls on the tree. Instead, the adelgids appear to be small, white cottony balls, usually on the undersides of the needles. Their feeding can cause small, yellow necrotic spots on the needles. When populations are heavy, the needles will be distorted and appear to be "clenched" around the shoots.

Again, scouting is important. There are several windows in which you can control this pest. Watch for tiny black nymphs early in the spring. These are the overwintering females. The nymphs will cover their bodies with cottony-appearing white threads where they will lay 10 to 30 eggs. These will hatch around the time that buds are breaking and move to the newly formed needles to continue feeding. When the females and nymphs are out from under the cottony mass, is the best time to apply an insecticide. Another spray may be needed in mid-summer, when another generation of nymphs begins feeding on Douglas fir.

Spring clean up
Jill O’Donnell
Christmas Tree ICM educator

Now is a great time to walk through your fields and do a little spring “clean up” that you may not have gotten to last fall.
Some of the things to look for and correct or remove are:

Competing leaders.
Horns in Fraser fir.
Create new leaders on trees that have lost their leaders by tying up a lateral branch to create a new leader.
Stake crooked leaders.
Eliminating branches that are growing into the tree (shooters)


Competing leaders.	Horns in Fraser fir.	After some of the horns are removed from a Fraser fir.

Is it winter damage or needlecast?
Dennis Fulbright, Plant Pathology

Several problems that we are finding are winter damage, Swiss and Rhabdocline needlecast. To tell the differences, look on the underside of the needles. With winter burn you have a drying of the needles that causes the tips or the whole needle to be brown but the stomata (tiny pore-like openings) will be white. If you are seeing two rows of fuzzy, black fruiting bodies coming out of the stomata on green, yellow and brown needles, it probably is Swiss needlecast. Rhabdocline infected needles will appear as yellow to purple-brown splotches (mottling).

Of these two diseases, Rhabdocline is the more serious and can cause serious disease on seed sources San Isabel, Lincoln and Coconino; the seed source Shuswap is resistant to Rhabdocline needle cast. Left unchecked, Rhabdocline needle cast can cause devastating amounts of casting if not managed through genetic, horticultural and chemical programs. Rhabdocline is more severe along Lake Michigan and has recently become severe in inland locations where conditions favor moisture retention on needles in the spring. Swiss needle cast is more wide spread than Rhabdocline in Michigan, but less severe than Rhabdocline unless left unmanaged. Both diseases are currently managed with chlorothalonil-based materials after the new growth has expanded to to 0.5 to 2 inches in length, typically in May.

Brown dog ticks, the other dog tick
Howard Russell
MSU Diagnostic Services

If the ticks we most often encounter outdoors aren’t disgusting enough, then please consider the brown dog tick (Rhipicephalus sanguineus). This tick can infest homes by the thousands and is the only tick that occurs in Michigan that can complete its life cycle indoors. The only good thing about this tick is that it rarely, if ever, feeds on people.

The brown dog tick is probably the most widely distributed tick in the world and is found throughout the United States, though it is much more common in warmer areas in the country. Oddly, I received two samples of the brown dog tick this past March. One came from a lady in Haslett and the other from a vet clinic in Romulus. The lady in Haslett collected hers from her bed. Both samples included fully engorged females that were bursting with eggs. Yech!

A sample of brown dog ticks sent in by a vet clinic this past March.

Adult brown dog ticks are tear drop-shaped and resemble deer ticks in that they do not have white markings on their backs. The head and mouthparts are distinctive (see the accompanying drawings). These ticks will often emerge in great numbers from furniture, baseboards, moldings, electrical outlet boxes, curtains, etc. The brown dog tick has been reported to be a vector of Rocky Mountain spotted fever in the western hemisphere. After mating, females drop from the host and seek out sheltered areas where they lay 1,000-3,000 eggs. Double yech! The female dies soon after laying her eggs. The eggs hatch in 19-60 days depending on temperature and humidity. The microscopic 6-legged larvae attach to a dog at the first opportunity, but if they cannot find a host, will survive for eight months without a bloodmeal.

After feeding, a larva drops from the host and seeks a sheltered area to molt into an eight-legged reddish-brown nymph. The nymph seeks out and attaches to the poor dog again to take another bloodmeal, but if they can’t find a host they too can survive for extended periods without food or water. Once engorged, the nymph drops from the host and hides once again to molt into the adult stage. Adults then seek out and attach to the poor dog again to take yet another bloodmeal and mate. Adults can survive for 18 months without food! Under normal environmental conditions and host availability, there may be up to four generations per year.Control of the brown dog tick requires extreme persistence by the pet owner and may require the services of professional pest control operator. If the infestation is throughout the residence, the dog, home and yard will need to be chemically treated at the same time. The primary objective when applying a pesticide to control this pest is to concentrate on those areas which are frequented by the dog. Incomplete treatments will prolong the infestation and result in an over use of pesticides. Insecticides to control this pest should have a reasonable residual efficacy. Products like Bayer Advanced Home Insect Control (cyfluthrin) or Othro’s Home Insect Defense (bifenthrin) are long-lasting and registered for use inside homes. Be sure to read and follow all instructions and safety precautions found on the label before using any pesticide.

Male brown dog ticks	Female brown dog ticks

Line drawings of a female and male brown dog tick showing their tear drop shape, deeply cleft first coxae and distinctively shaped heads. The dorsal view is on the left. Drawings taken from Ticks of Veterinary Importance, USDA Handbook No. 485 (out of print).

Boxelder bugs, Asian lady beetles and cluster flies. Oh boy!
Howard Russell
MSU Diagnostic Services

Finally the weather is warming, but warmer temps are bringing the bugs out. Already the telephone calls have started. People have bugs literally coming out of the wood work. Boxelder bugs, cluster flies and Asian lady beetles are awakening and looking to move out from their overwintering sites in our homes. At best, they will only clump up outside on the sun drenched sides of buildings. At worst, they will clump up inside our homes. And since they gained entry last fall, there is not much we can do about it now.

Most calls have been about boxelder bugs, but a few folks have also called to complain about cluster flies and the ever popular Asian lady beetles. These insects enter homes and other structures by squeezing

A large group of boxelder bugs sunning themselves on a house.

through cracks around windows and doors, loosely hung siding, soffit vents, louvers and other similar entry points. In heated structures, they may remain active during the winter months and may continually emerge from their hiding spots and find their way into living areas. Their presence is usually not appreciated by other residents of the home. Aside from being a tremendous annoyance, they are harmless; they do not feed or lay eggs during the winter months. They do not harm woolens, fur or feathers, nor do they infest foods in kitchen cupboards. Asian lady beetles may bite and boy, do they stink. Boxelder bugs and cluster flies are more considerate of their human hosts and keep pretty much to themselves. None of the three is known to transmit disease.

Cluster flies resemble the common house fly, but differ in that they have a patch of yellow hair under their wings. The cluster fly maggot is an internal parasite of earthworms and the flies are among the first to be active in the spring. They can be observed buzzing around yards just above the ground. They lay their eggs in cracks in the soil and the eggs hatch in about three days. Newly hatched maggots grab onto earthworms as they slither by and burrow into the worm to feed. Four to five weeks are required to complete a life cycle. The worm does not usually survive the experience. There are up to four generations of cluster flies in Michigan each year.

During the summer, boxelder bugs are black with red markings. They feed on the flowers and seed pods of female boxelder trees. The developing nymphs are bright red in color and are quite nomadic. They can be seen roaming about yards and gardens throughout the summer months. They are two generations of boxelder bugs each year in Michigan.

There is no easy remedy for these insects. It is practically impossible to kill enough of them to make a difference once they have found their way into wall voids, ceilings voids and attics. Once they’re in, they’re in and there is not much we can do about it. Sealing exterior cracks and holes with caulk may help reduce the number of bugs that find their way into older homes with clapboard siding. But no amount of caulk will help keep them out of newer homes with vinyl siding and soffits. Vinyl siding and soffits are “hung” when installed and not tightly nailed to allow the panels to expand and contract with changing temperatures. This allows insects to get around the panels and gain entry into the house.

Spraying the outside walls of homes with soapy water or a persistent insecticide, especially the south and west facing walls, when the insects begin to appear in the fall may help reduce the number entering the home. Another option is to hire a professional pest control operator to provide this service, but they can be expensive. And don’t expect miracles. Chances are you will continue to see flies even after “professional treatments.”

A top view of a cluster fly. From the top, they look pretty much like a house fly.

A closer look at the side of a cluster fly reveals the long golden hairs that are characteristic of this home invader.

Flower hermit beetle grubs
Howard Russell
MSU Diagnostic Services

The hermit flower beetle, Osmoderma eremicola (Coleoptera: Scarabaeidae), is one of the largest beetles found in Michigan. The larvae or grubs are very impressive. The grubs are giant white grubs like the ones that feed on our lawn. But hermit flower beetle grubs live in decaying trees. They are often discovered when old rotted trees or limbs are removed or cut up. This usually leads the owner of the tree to believe the grubs are responsible for the demise of the tree or portion of the tree. Not true. These large scarab beetle grubs are secondary invaders, that is, they are in the wood because of the presence of wet and rotting wood in the tree. Adult beetles emerge in mid-summer and females soon begin to lay eggs in hollow trunks, tree holes or other wet and decayed portions of the tree. There the larvae feed for three years on the wet, decaying wood. Both standing and felled trees, and occasionally stumps, serve as larval food. Just before the larva is ready to pupate (change into the adult), it constructs an oval pupal cell by cementing together small wood particles around itself. When completed, it then transforms into the adult.

An impressive sample of Osmodera grubs that were sent to the lab this past March. The Petri dish is approximately 3 ½ inches in diameter.

Adult beetles are large, black beetles that resemble June beetles. They are nocturnal and spend the day hiding in nooks and crannies in trees. Larvae have been found in several species of hardwood trees including beech, hickory, boxelder, elm, ash, hackberry, apple, cherry, oak, maple and cottonwood. There is no need to attempt to control the larvae with insecticides when they are discovered in a tree. They are harmless and probably make great fish bait.

To view an image of an adult flower hermit beetle, click here.

Winter snows encourage rodent damage
Rebecca Finneran, Kent MSU Extension educator

The Easter Bunny may not be so fondly remembered this spring as the snow piles melt away from our landscape trees and shrubs. Heavy and consistent snow cover is the perfect recipe for chewing damage by a variety of rodents, especially rabbits. The snow cover keeps rabbits from being able to forage what little green is available underneath and makes a natural ladder for climbing into the crown of shrubs like burning bush and others. One year while at college, I remember when the snow was piled so high along the main street that the following spring, rabbit damage to the dozens of flowering crabs was actually at eye level.


Chewing damage cause by rabbits during the winter.

Underneath the canopy of stems, check for twigs that appear white instead of dark gray. Rabbits, mice and other varmints love to gnaw off the outer bark in search of the tender green cambium just beneath. If the chewing damage completely encircles the twig, the top portion is history and will begin to die back in early summer.

Mouse damage, essentially has the same result but the girdling typically will be found much lower on the trunk. My observation is that mice have a much greater range of plants they will chew and damage is often more irregular, not girdling the whole way around, giving the plant at least a fighting chance to survive. One often finds mature pines or fruit trees completely girdled at ground level where mice have over-wintered. Mice can also chew into the upper canopy of twigs such as in the case of a dense juniper, covered by snow. The branches become a super highway for their movements and the snow cover protects them from predators such as hawks.

Your best defense here is a good offense, so go ahead and get the pruning equipment out and sharpen the blades. On a burning bush, you can cut off the twigs just beneath the girdled portion and the plant will sprout back new shoots all along the stems that are left. If you leave a few long stems that were not fed upon, the plant is likely to look lopsided come next summer. You can expect a mature and healthy burning bush to regrow quickly back into what it was in about two seasons. Some folks actually look at the girdling damage as nature’s pruning.

Next fall
If you have high populations of rabbits in your area you will certainly want to take some precautions for protecting woody plants next winter. Chicken wire (a fine mesh) can be your best friend when it comes to keeping hungry varmints away from valuable specimens. You may only need to encircle the trunk of a tree to about two feet or you can make a cage to encircle a shrub or specimen conifer.


Pruning after rabbit damage.

The other thing you should think about is habitat. Leaving large brush piles near by, low hanging limbs of conifers and tall grass are all encouraging factors for small rodents. One year I found a perfect bunny nest in a large bag of potting soil I had left out all winter. I will bet they enjoyed a well-insulated winter slumber just before they annihilated my shrubs.

If you live in the country, be observant of natural predators in the area such as hawks, owls and fox. If you can create a perch for predacious birds, such as leaving a dead tree standing, you will invite them to patrol your area. It is surprising how one nice hawk family can keep a rodent population from exploding.

Recycle your old plastic garden pots and containers

Join us for a one-time opportunity to recycle your old plastic flower pots, tree and shrub containers, plastic trays and labels. Clean out your garage or garden shed and bring as many old flower pots and plastic trays, even plastic buckets that you can find.

When: Saturday, May 31 from 8:00 AM to 2:00 PM

Where: Watch for the signs posting the location behind the Plant Biology building off Wilson Avenue (parking lot 46). Michigan State University campus

What can be recycled?
All pots and containers that have recycle numbers on the bottom as follows: #2 HDPE, # 5 PP, #6 PS. We can also take tray flats, plastic buckets and tags.

How to prepare
It is not a requirement to wash your items before you bring them, but make sure as much dirt as possible is knocked out of the container. Please check that there are no stones or any other contaminants, since these will eventually be melted down by a local Michigan company.

All containers and tags should be sorted before you bring them to campus. Please sort by recycle number and size and nest containers tightly. Please view the website for more details: http://www.hrt.msu.edu/RecyclePlasticPots/Default.htm

Update on new pesticide applicator core manuals
Carolyn Randall, Coordinator Pesticide Safety Education Program

There is a new delivery date for the new pesticide applicator core training manuals. The private applicator manual (MSUE Bulletin E3007) and commercial applicator manual (MSUE Bulletin E3008) are expected to be delivered to the MSUE Bulletin distribution center by mid-April. The new cost of the manuals is $30 each. There is still a cut-off date of August 1, 2008 for taking the old core exam.

Department of Homeland Security plans I-9 audits in 2008
Vera Bitsch, Agricultural, Food, and Resource Economics

The Department of Homeland Security (DHS) has posted a revised I-9 form on its website for employers to use with new employees (http://www.uscis.gov/files/form/I-9.pdf). To order forms, call toll-free at 1-800-870-3676. For forms and information on immigration laws, regulations and procedures, call the National Customer Service Center at 1-800-375-5283. In 2008, industries targeted for random audits are agriculture, restaurants, and janitorial/cleaning services. Ways to be included on the audit list include having been complained about on the national hotline, having been referred by another auditing agency, such as the Department of Labor (DOL), or having been audited before by Immigrations and Customs Enforcement (ICE).

Audits can take a number of different forms and be done by mail or in person. For a mail audit, employers will need to send in their I-9 forms to the ICE office. Certified mail and return receipt requests are the recommended way to mail original I-9 forms. Employers should also make copies of the original I-9 forms to keep on file for the duration of the audit. During the audit, each employee for whom an I-9 form is submitted will be subjected to a full background check and each form is carefully evaluated. Civil monetary penalties are $375 to $3,200 for the first violation; $3,200 to $11,000 for the second violation; and $4,300 to $16,000 for subsequent violations on a per-alien basis. Fraudulent I-9 forms constitute a felony and are likely to be prosecuted. When the need arises to correct an I-9 form, employers should use a single line strikethrough, initial it, if necessary attach an explanation, and also attach an additional I-9 form with the correct data. White-out and similar alterations to I-9 forms are strongly discouraged.

Different from a random audit, the typical worksite enforcement targets specific individuals, e.g., fugitives or criminal aliens, or looks for evidence in a crime, and is based on prior information. A common reason for worksite enforcement in Michigan is identity theft. Providing access to the individual in question is likely to be less disruptive than a search of the farm premises. If ICE officers take I-9 forms during a search, the employer should make copies and request the officer to certify the copies. If the original I-9 forms are evidence in a crime, they will not be returned to the employer.

When the Immigration Reform and Control Act was created in 1986 a concern for resulting unfair employment practices led to founding the Office of Special Counsel (OSC) as part of the U.S. Department of Justice. In a 1990 report, widespread employment discrimination against citizens and legal workers, against persons who appear foreign, and against persons with a foreign accent were indeed found. With increased enforcement, an increase in discriminatory practices is expected. The OSC operates a hotline for employers, which may be contacted, even anonymously, at 1-800-255-8155.

This article serves educational purposes only and does not constitute legal advice. For more information go to www.msu.edu/user/bitsch, under “News” click on “Department of Homeland Security Plans I-9 Audits 2008” or click on “Agricultural Labor Issues in Michigan” for a list of available newsletters.

Weather news
Jeff Andresen
Agricultural Meteorology
Geography

An upper air troughing pattern across the central and eastern United States has been persistent for much of the past winter, leading to a very active storm track from the southern Great Plains through the Ohio Valley and to a very long and snowy winter season in Michigan. Forecast guidance for the upcoming week suggests that we will experience more of this pattern, but with some moderation of temperatures to near or even slightly above normal levels. In the short term, the area of low pressure that brought light rain to southern sections of the Lower Peninsula Friday, April 4, will move east of the region and be followed by high pressure, clearing skies and fair weather for most of the state Saturday. A slow-moving frontal boundary will approach the state by late Saturday, bringing a chance for rain or snow to mainly western sections of Upper Michigan persisting into Sunday. The remainder of the state should remain fair and dry through Sunday afternoon.

The frontal boundary will move through the Lower Peninsula Monday, bringing the chance for rainfall to most areas of the state. Look for a continuing chance for showers Tuesday and Wednesday of next week, followed by dry weather Thursday and yet another weather system and more precipitation by late in the week. Temperatures will moderate to above normal levels during the next few days, with highs ranging from the upper 30's far north to near 60ºF south and lows generally falling into the upper 20's north to the upper 30's to low 40's south.

Current medium‑range forecast guidance suggests more mid-continent troughing for the first two weeks of April, with a continued active storm track through the Midwest. The official NOAA 6-10 day and 8-14 day outlooks covering April 9-13 and 11-19 call for above normal precipitation totals. Mean temperatures during the 6-10 day period are forecast to range from near normal in the western Upper Peninsula to above normal elsewhere across the state. Temperatures are expected to fall back to below average levels state- and region-wide during the 8-14 day period. As of the first week of April, seasonal growing degree day totals (since March 1) are lagging at least one calendar week behind the climatological normals, which is not a surprise given the recent cooler than normal weather pattern.

Long lead outlooks
Forecast guidance for the next few weeks suggests more of the same upper air pattern across the Midwest, which would lead to normal to below normal mean temperatures and normal to above normal precipitation totals in Michigan. With the stronger sun of the season, the majority of any precipitation that occurs will likely be the form of rain. An active storm track across the Midwest would also suggest the potential for severe weather outbreaks, most of which will remain in areas to our south, but could reach into southern portion of the Great Lakes region. In the longer term, outlooks are largely dependent on the longevity of a La Nina event currently in place across the equatorial Pacific region.

For the April through June period, mean temperatures and precipitation totals in Michigan are forecast to remain in the “climatology scenario” with near equal odds of below, near and above normal values. However, milder and drier than normal conditions are forecast across much of the central United States for the upcoming summer months, including portions of Michigan. This outlook is associated with expectations that the current La Nina event will persist into the summer season, as La Nina events are statistically linked to drier than normal conditions in the Midwestern United States.

On the other hand, drought was a serious problem across many sections of Michigan during the 2007 growing season, and back to back growing season droughts in Michigan are very rare climatologically. At the least, the 2008 growing season will begin with a rooting zone at near field capacity in terms of soil moisture, which reduces the risk of vegetation running out of moisture later in the season.

The MSU IPM Program maintains this site as an access point to pest management information at MSU. The IPM Program is administered within the Department of Entomology, fueled by research from the Michigan Agricultural Experiment Station, delivered to citizens through MSU Extension, and proud to be a part of Project GREEEN.
Email the web developer.

04/04/08