Vol. 19, No. 2, July 30, 2004

In this Issue
Landscape and nursery
Magnolia scale outbreak
Potato leafhopper on red maples
Japanese beetles will be active for another 4 to 6 weeks
Fall webworm appearing
All miticides are not created equal
Control of downy mildew in perennials
Phenology table
Consider herbicide resistance screening
Confirming herbicide resistance in weeds
The Michigan Garden Plant Tour
Turfgrass
Wet year equals nutsedge year?
Christmas trees and forestry
Lophodermium needlecast (Dennis Fulbright)
Spruce needle rust
Lophodermium needlecast (Jill O'Donnell)
Spider mites
Douglas-fir needle midge
Other news
News update from Pesticide Education
Weather news

Next issue August 13
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Magnolia scale outbreak

Dave Smitely
Entomology

Several people have reported outbreaks of magnolia scale on magnolia trees. These scales produce lots of honeydew that drips down on the leaves below. A black fungus called sooty mold grows on the honeydew. If there is enough scale, the upper side of the lower leaves start to turn black. Adding to the problem is the attraction of bees and wasps to the honeydew.

Oil sprays have not worked real well for magnolia scale, although repeated sprays with a 2 percent horticultural oil has worked for some. Merit as a soil injection or soil drench has also been inconsistent. Some say it works well, and others say it doesn't work. The best options for insecticide treatments are probably using Flagship now as a soil drench or soil injection, or spraying with Talstar, Tempo, or Scimitar now and again in late September to catch the next generation of crawlers. Sprays can also be used in spring or early summer for the developing scales. Flagship may be a good choice, because in some research tests on Lecanium-type scales it has worked very well as a systemic insecticide. We need some more testing on magnolia scale to see what works best. but where can you find 50 infested magnolia trees for a good test?

Potato leafhopper on red maples

Dave Smitely
Entomology

This seems to be a big year for potato leafhopper. And that means some red maple trees, especially those in rural areas near meadows, are starting to show curling and puckering of the growing tips that sometimes even turn black. Leafhoppers can be curbed on red maples by spraying with Talstar, Tempo, Scimitar, or Sevin. One spray should protect trees for several weeks. Growers can also try Flagship as a soil injection or soil drench. Allow two to three weeks for the Flagship to be absorbed by the roots and moved up into the foliage.

Japanese beetles will be active for another 4 to 6 weeks

Dave Smitely
Entomology

In some places, linden trees and other trees and shrubs have been stripped from Japanese beetle feeding. Spraying the foliage with Sevin, Tempo, or Discus will protect them from additional feeding damage. Expect the beetles to remain active until early September this year.

Fall webworm appearing

Dave Smitely
Entomology

Tents are starting to appear on the branch tips of walnuts, crabapples, and a few other types of trees that fall webworms love. Remove the webs by pruning whenever possible, or spray the branches around the webs with an insecticide to kill the caterpillars before the webs become larger. Fall webworms don't usually cause enough defoliation to hurt the trees, but the webbing can be unsightly. B.t. products provide a good alternative to conventional insecticides for fall webworm and other caterpillars.

All miticides are not created equal

Raymond Cloyd
Extension Specialist in Ornamental Entomology/IPM
University of Illinois

Editor's note: This article is being reprinted with permission from the University of Illinois Extension. The original article was published in Home, Yard, and Garden Pest Newsletter: Number 10.

When it comes to selecting a miticide to control spider mites or "mites" in landscapes and nurseries there is sometimes confusion that all miticides are similar in terms of their use and the range of mites they control. However, miticides are not all created equal because miticides may vary in where they can be used and the target mites on the label. Below are detailed descriptions of miticides generally recommended for controlling mites both indoors and outdoors.

Avid
Avid, which contains abamectin as the active ingredient, is an effective insecticide/miticide for many different mite species and is typically recommended for control of mites both indoors and outdoors. The active ingredient, which occurs naturally, is derived from the soil micro-organism, Streptomyces avermitilis. Avid is labeled for control of twospotted spider mite, European red mite, carmine spider mite, Southern red mite, spruce spider mite, cyclamen mite, broad mite, and rust and bud mite. The product can be used to control mites in greenhouses, shadehouses, on field-grown ornamentals, Christmas tree plantations, and on woody ornamentals. Avid is a contact and translaminar miticide. Translaminar is a term that refers to insecticides/miticides that penetrate the leaf tissue and form a reservoir of active ingredient within the leaf. Avid generally provides up to 28 days of residual activity. The label rate for all mite species is 4 fl oz per 100 gallons. Avid is active on the mobile life stages of mites with no activity on eggs. Although slow acting, mites treated with the insecticide/miticide are immobilized after exposure.

Talstar
Talstar is a pyrethroid-based insecticide/miticide with the active ingredient - bifenthrin. The product is labeled for control of the following mites: twospotted spider mite, broad mite, clover mite, and European red mite. There are a number of different formulations and each has certain use requirements. However, in general, Talstar is registered for use on indoor and outdoor ornamentals. This includes greenhouses, lathhouses, shadehouses, outdoor nurseries, and ornamental trees. Talstar is a contact insecticide/miticide so it is important to do a thorough cover of all plant parts during application. The product provides between 7 and 21 days of residual activity. Talstar is a restricted use pesticide and rates vary depending on the formulation - so be sure to read the label prior to use. This insecticide/miticide has the same mode of action as lambda-cyhalothrin (Scimitar - see following section) so avoid using these two products in succession in a rotation program.

Scimitar
Scimitar is a pyrethroid-based insecticide/miticide with the active ingredient lambda-cyhalothrin. This product has a very general label stating control of "mites" and broad mites. It can be used to control mites on ornamentals in greenhouses, shadehouses, nurseries, and outdoor landscapes. Scimitar is a contact and stomach poison (when ingested) insecticide/miticide providing up to 14 days of residual activity. The label rate for control of mites is 1.5 to 5.0 fl oz per 100 gallons. Scimitar has the same mode of action as bifenthrin (Talstar - see previous section) so avoid using these two products in succession in a rotation program. Scimitar, like many pyrethroids, is a restricted use pesticide.

Hexygon
Hexygon contains the active ingredient hexythiazox and is labeled for control of the following mites: twospotted spider mite, arborvitae spider mite, European red mite, honey locust spider mite, Pacific spider mite, Southern red mite, spruce spider mite, strawberry spider mite, and Willamette mite. Hexygon is registered for use on ornamental plants grown in nurseries, greenhouses, shadehouses and Christmas tree plantations. In addition, it may be used on established ornamental landscape plantings, interiorscapes, residential areas, public areas, and commercial areas. Hexygon is a contact and stomach poison miticide so thorough coverage of all plant parts is recommended. The product can provide 30 to 45 days of residual activity. The label rate is 1 to 2 oz per 100 gallons. Hexygon is active on mite eggs and the immature stages. In fact, eggs deposited by adult females that contact treated surfaces will not be viable. The product has no activity on adult mites. Hexygon has the same mode of action as clofentezine (Ovation - see following section) so it is important to avoid using these two miticides in succession in a rotation program.

Ovation
Ovation contains the active ingredient clofentezine and is labeled for control of the following mites: twospotted spider mite, Pacific spider mite, McDaniel spider mite, European red mite, and yellow spider mite. The product is registered for use in greenhouses, saranhouses, shadehouses, outdoor containers, and field-grown nursery stock. Ovation is a contact miticide so thorough coverage of all plant parts is critical during application. It is active on mite eggs and the immature stages. The product has no activity on adult mites. Although Ovation is slow acting, it may provide up to 45 days of residual activity. The label rate is 2 fl oz per 100 gallons. Ovation has the same mode of action as hexythiazox (Hexygon - see previous section), which means that the two miticides should not be used in succession in a rotation program. Ovation is toxic to fish.

Floramite
Floramite, which contains the active ingredient, bifenazate is labeled for control of a wide-range of mites including twospotted spider mite, Pacific mite, strawberry mite, European red mite, citrus red mite, clover mite, Southern red mite, spruce spider mite, and bamboo spider mite. It is not active on rust, broad or flat mite. Floramite is labeled for use in greenhouses, shadehouses, nurseries, Christmas tree plantations, landscapes, and interiorscapes. This is a contact miticide so thorough coverage of all plant parts is essential. This miticide is active on all mite life stages including eggs. Floramite is fast acting and provides up to 28 days of residual activity. The label rate is 4 to 8 fl oz per 100 gallons.

Sanmite
Sanmite, which contains the active ingredient pyridaben, is labeled for control of the following mites: twospotted spider mite, broad mite, European red mite, Southern red mite, and tumid mite. The material is registered for use on ornamental plants grown in greenhouses or outdoors. Sanmite is a contact miticide so thorough coverage of all plant parts is important. It has activity on all mite life stages including eggs, nymphs, larvae, and adults. Sanmite is fast-acting on the mobile stages and will provide up to 45 days of residual activity. The label rate is 4 oz per 100 gallons. Sanmite has the same mode of action as fenpyroximate (Akari - see following section) so these two miticides should not be used in succession in a rotation program.

Akari
Akari contains the active ingredient fenpyroximate. The product has a very general label stating control of "spider mites." Akari is labeled for use on greenhouse ornamental crops and indoor ornamental plantings and plantscapes. This miticide is a contact and stomach poison so thorough coverage of all plant parts is essential during application. The product is effective on all spider mite life stages including eggs. Akari works very fast with rapid knockdown. In fact, treated mites immediately stop feeding and females fail to lay eggs. This miticide provides up to 21 days of residual activity. The label rate is 16 to 24 fl oz per 100 gallons. Akari has the same mode of action as pyridaben (Sanmite - see previous section) so these two miticides should not be used in succession in a rotation program.

TetraSan
TetraSan contains the active ingredient etoxazole and is actually a growth regulator for mites inhibiting the molting process. TetraSan is labeled for control of the following mites: twospotted spider mite, citrus red mite, European red mite, lewis spider mite, Pacific spider mite, Southern red mite, and spruce spider mite. TetraSan can be used to control mites in greenhouses, lathhouses, shadehouses, interiorscapes, and on outdoor ornamentals. Similar to abamectin (Avid), TetraSan is a contact and translaminar miticide providing up to 28 days of residual activity from a single application. The label rate for controlling mites is 8 to 16 oz per 100 gallons. The product is active on the egg, larvae, and nymphal stages. It has minimal effect on adult mites. However, adult female mites that are treated will not produce viable eggs.

Pylon
Pylon is a miticide that is can only be used in greenhouses. It contains the active ingredient chlorfenapyr. Pylon is labeled for control of various mites including twospotted spider mite, broad mite, cyclamen mite, citrus bud mite, and rust mite. Pylon is a contact and translaminar miticide. In addition, it works as a stomach poison when ingested. Pylon is only active on the mobile life stages including larvae, nymphs, and adults. It has no activity on mite eggs. The product can provide up to 28 days of residual activity. The label rate is 2.6 to 5.2 fl oz per 100 gallons.

Vendex
Vendex is one of the older miticides and contains the active ingredient fenbutatin-oxide. The miticide is labeled for control of twospotted spider mite, clover mite, Southern red mite, and spruce spider mite. Vendex can be used in greenhouses, on outdoor ornamentals, on established landscape ornamentals and nurseries. This is a contact miticide so it is important to thoroughly spray all plant parts during application. Vendex is slower acting than most miticides taking 7 to 10 days to eventually kill mites. However, it provides long-lasting control, approximately 30 days of residual activity. The label rate is 8 to 16 oz per 100 gallons. Vendex is a warm weather miticide providing better control when the ambient air temperature is above 70°F. This product is a restricted use pesticide.

For more information on the above products mentioned be sure to consult the label or the manufacturer.

Control of downy mildew in perennials

Willie Kirk
Plant Pathology

Downy mildew has been a problem in certain species of perennials this year due to conducive weather conditions and survival of innoculm from previous years. Research at MSU has shown that products such as Banner Maxx provide good control but efficacy declines 21 days after application. This means further applications of effective fungicides are required. Such fungicides include strobilurins (Headline, Cygnus, and Heritage). Another product that can be used is Stature. For protecting unaffected foliage, use products that contain Chlorothalonil. Plants already infected should be destroyed and removed from the growing area.

Phenology table

Diane Brown-Rytlewski
MSU IPM Program
Nursery & Landscape ICM Integrator

As of July 28 at noon, temperature accumulations for the Horticultural farm were 1426.3 GDD50 and 1578.4 GDD50 for the perennial garden. The GDD accumulation for July 28 is 1522.5 GDD50 for the Lansing area. Japanese beetle adult emergence continues; numbers are still light. Early instar larvae of fall webworm larvae are still appearing; and seem more numerous than usual. I have noticed it on pear, walnut, birch, corneliancherry dogwood, and crabapple so far.

Elsewhere in the state
More reports of the Tarspot fungus on maples have come in; in Kalamazoo County there seems to be a Tarspot epidemic. Reports from Ottawa County indicate lower than usual numbers of adult Japanese beetles and European chafers. Potato leafhoppers are still damaging shade trees, especially red maples. Powdery mildew is still occurring on herbaceous perennials, downy mildew is still a concern. In Oakland County, emerald ash borer adult emergence continues to trail off - four new emergence holes in the trees at the Novi location, and only two emergence holes at the site in Troy. Rose of Sharon, liatris, purple coneflower, bee balm, and Itea are at full bloom. In Genesee County, only one new EAB adult emergence hole was reported for the trees being monitored; Rose of Sharon, purple coneflower, liatris and bee balm are at full bloom as of July 28. At Applewood garden in Flint (1484.7 GDD50 as of July 22), Culver's root and Queen of the prairie are at late bloom, bee balm, gooseneck loosestrife, liatris and purple coneflower are at full bloom. Sweet pepperbush (Clethra alnifolia) is at first bloom. From Wayne County and surrounding areas, there seems to be an increase in the occurrence of magnolia scale this year. Thanks to county Extension agents and Mike Belco from Applewood Garden for contributing information.

MSU Diagnostic Services
Jan Byrne reports that a number of samples with disease caused by Phytophthora spp. are coming into the clinic on a number of hosts including holly, azalea, rhododendron, and forsythia. Over 1,000 samples from several states have been tested for Phytophthora ramorum (sudden oak death or SOD). None of the Michigan samples has tested positive.

What's being found elsewhere - reports from other states
At the Morton Arboretum in Lisle, Illinois, (1617 GDD50 as of July 20) 'Sunny Honey' daylily is at full bloom. Fall webworm (Hyphantria cunea) caterpillars have just started feeding on bitternut hickory. Recently emerged arborvitae leafminer (Argyresthia thuiella) larvae are active and were found mining Eastern arborvitae. Woolly alder aphid adults (Paraprociphilus tessellates) are migrating from maple trees to their alternate hosts - alders. Masses of these aphids can be found on the branch undersides of common alder, along with copious amounts of sooty mold growing on the honeydew the aphids produce. Disease reported include: Botryosphaeria canker caused by the fungus Botryosphaeria quercuum, girdling twigs and branches of several species of oaks; Septoria leafspot on dogwood; Tarspot fungus on maple; and Anthracnose on yellowwood. There also reports of oaks infected with oak wilt, and Armellaria root rot. To read the complete report go to: http://www.mortonarboretumphc.org/

The Ohio Buckeye Yard and Garden OnLine of July 20 indicates that agents have been getting calls about dying white pines, the cause of death as yet undetermined. Late season conifer sawflies, including redheaded pine sawfly, introduced pine sawfly and white pine sawfly are showing up. Yellownecked caterpillars (Datana ministra) are feeding on crabapple leaves in Southwest and Central Ohio. These caterpillars feed as a group and defoliate one branch before moving on to another; they have a wide host range, including walnut, hickory, oak, crabapple, cherry, maple, and others. Diseases showing up in their plant clinic include blackspot and downy mildew on rose and verticillium wilt on smokebush and sugar maple. For the complete report go to http://bygl.osu.edu/search.lasso

Consider herbicide resistance screening

Rob Richardson
Horticulture

Weeds can develop resistance to herbicides after repeated exposure to the same herbicide mode of action. This has happened in many instances including common lambsquarters resistance to triazine herbicides (atrazine and simazine), marestail resistance to glyphosate, and resistance in pigweed species to ALS inhibiting herbicides. Knowing whether or not resistance is present is very important for planning future weed management programs.

In a recent screen of a Christmas tree field, triazine-resistant marestail and ALS-resistant common ragweed were both present. The presence of two weed species resistant to two modes of action will severely restrict the weed control programs that may be used. This is also cause for concern as simazine has historically been the most commonly used preemergence herbicide and ALS-inhibiting herbicides are not labeled for Christmas tree applications. Other instances of resistant weeds in Michigan Christmas trees and nurseries need to be documented so that sustainable weed management programs can be developed.

Possible signs of resistance
There are some warning signs that may signify when resistance is present. With postemergence applications, look for areas where some plants die, while adjacent plants of the same species survive. In other situations, look for surviving weeds of a species that should be controlled by the herbicide used. Also take note if the same herbicide has been applied to the same field for several years or if the weed species of concern has already developed resistance in other areas. Certain weeds are more likely to develop resistance than other weeds due to factors including population numbers, genetic plasticity, and prolific seed production.

Resistant weeds of note
Some important herbicide resistant weeds that have been documented in Michigan or other parts of the U.S. include:

§      Marestail: triazines, glyphosate (Roundup, Touchdown, others), ALS inhibitors (Manage, others), other modes of action
§      Common ragweed: triazines, ALS inhibitors
§      Common lambsquarters: triazines, ALS inhibitors
§      Common purslane: triazines
§      Pigweed or Amaranth species: triazines, ALS inhibitors
§      Goosegrass: Seedling root inhibitors (Surflan, Treflan, Pendulum, Barracade, etc.)
§      Large crabgrass: ACCase inhibitors (Fusilade, Envoy, etc.)
§      Wild carrot: Synthetic auxins (2,4-D, etc.)

Confirming herbicide resistance in weeds

Steven Gower
MSU Diagnostic Services

Herbicide-resistant weed species have been documented throughout Michigan. There are currently 11 weed biotypes resistant to one or more herbicides in the state. If you suspect resistance in any weed species and would like to confirm this, seedheads can be collected upon maturity and submitted to MSU Diagnostic Services for an herbicide resistance screen.

The next several weeks prior to harvest are perfect for collecting mature, viable weed seed. Select plants definitely sprayed and not from field edges or sprayer skips. Harvest seedheads by cutting the stem just below the seedhead. Place seedheads into a brown paper bag or collect seed in a small envelope or container. Never seal plant or seed in plastic! If possible, include a list of herbicides applied in recent years.

Fees associated with herbicide resistant weed testing are generally $20 to $30 per sample (a sample could include multiple plants of the same species from one field). Please contact Steven Gower (517-432-9693, sgower@msu.edu) with any questions regarding sample collection. Send samples to: Diagnostic Services, 101 Center for Integrated Plant Systems, East Lansing, MI, 48824-1311, Attn: Steven Gower

The Michigan Garden Plant Tour

Mark your calendar and plan to attend the first Michigan Garden Plant Tour August 2-13, 2004. This is the first year for a coordinated open house program among five Michigan plant producers in cooperation with Michigan State University. The tour is for retail garden center owners, landscapers, grounds maintenance, and greenhouse growers who either grow or plant annuals or perennials in commercial settings only.

You are invited to visit each of these six sites during the two-week period August 2-13 to view their trials and display gardens. For the individual summaries for days and hours on the web site go to: http://www.hrt.msu.edu/planttour/ - Glass%20Corner%20Greenhouses,%20Inc.al/

Take a day trip to catch a couple of them or complete the full tour. The Michigan Garden Plant tour is completely free, but growers would appreciate a call in advance to know you will be coming.

You will see new varieties, commercial brands, and the latest colors and plant combinations all performing under Michigan conditions.

On August 3 a one-day event at Michigan State University called the MSU Garden Plant Showcase is planned. See and hear the latest on the new varieties available and view the annual and perennial trials. You will be able to attend any of four exciting short presentations that will help you sell even more plants! This program will appeal to both retail and wholesale growers.

The MSU Garden Plant Showcase event requires advanced registration. A form is available at:
http://www.hrt.msu.edu/planttour/registration.htm

Have a great summer, but be sure to attend the Michigan Garden Plant Tour and the MSU Garden Plant Showcase to complete your summer activities.

Wet year equals nutsedge year?

Kevin Frank
Crop & Soil Sciences

Every now and then it's helpful to look back in the books a couple years to see what problems occurred in years where the weather was similar to this year. Since my books only go back so far, it was easy for me to equate the cool and wet summer of 2000 with this year. As in 2000, it seems that 2004 is also a year where many questions are popping up about yellow nutsedge (Cyperus esculentus). Yellow nutsedge is enjoying the abundant rainfall this year and has taken advantage of the moisture to produce a bumper crop in many turf areas. Yellow nutsedge is often called nutgrass or swampgrass. It's not a broadleaf, it's not a grass, it's a sedge and is easily identified by the triangular shape of the stem. If you roll the stem between your fingers you should be able to feel the triangular shape. Other distinguishing characteristics of yellow nutsedge include leaves that are light green to yellowish in color and waxy or slick to the touch. Yellow nutsedge grows rapidly and the leaves are often seen several inches above the turfgrass canopy.

Nutsedge produces tubers or nutlets underground that really make controlling this weed difficult. These tubers can remain dormant in the soil for several years and sprout new plants when moisture becomes available. Nutsedge might not have been a problem in the relatively dry last couple years, but with the rains of this year, all of the sudden you might have a nutsedge problem. Nutsedge is also a prolific seed producer with each plant potentially producing 2400 seeds. The old saying of one year's seeding is worth seven years weeding would probably be adapted to 20 years weeding for nutsedge. Nutsedge is definitely a weed that will challenge even the most diligent and knowledgeable turf weed eradicator.

Fear not, there are options for controlling and eliminating nutsedge from turf. The first step is to keep up on your mowing schedule to prevent seed production. Hand weeding may be effective but remember that those little tubers under the surface will simply sprout a new plant, so if you like pulling weeds this may be your dream weed, it'll come back time and time again. Correcting drainage problems could help in the future but with a year like this, even great drainage isn't going to slow down nutsedge. For the serious infestations an herbicide application may be necessary.

Homeowners can apply repeat applications of the organic arsenicals, MSMA or DSMA, for control. The effectiveness of these herbicides on nutsedge will depend on your persistence. It may take 3 to 4 applications 7 to 10 days apart to achieve control. Another option for homeowner is to consider hiring a profession applicator to apply either Basagran (bentazon) or Manage (halosulfuron) for nutsedge control. These herbicides will control the existing nutsedge plants but will not be translocated to the underground tubers; therefore multiple applications are often necessary to reduce the nutsedge infestation.

Lophodermium needlecast

Dennis Fulbright
Plant Pathology

Management of Lophodermia needlecast disease of Scotch and red pine, caused by the fungal pathogen Lophodermium seditiosum, is slightly different than the needlecast diseases found on Douglas fir and spruce that I have written about in other reports. This disease can kill red pine seedlings and causes browning and massive amounts of needle loss on Scotch pines. Scotch pines infected with this disease have needles with brown spots surrounded by yellow margins, yellow needles, or brown needles, especially at the bottom of the tree.

If you see Lophodermia needlecast on your trees right now, you must remember that what you are seeing is from infection events that took place last summer or fall. Therefore, now is the time you can begin managing this disease to prevent or lower the amount of disease you will see next summer. You cannot do anything about the amount of disease you see this year. In fact, the dead needles currently falling off the trees this summer (June, July, and August) will be providing the inoculum (spores) that will spread throughout the trees in your plantation or nursery. These spores will infect this year's crop of needles from August to October. And, even though you won't see the result of those infection events until next year, the fungus will stay in those healthy looking needles all winter until spring, when, again, those needles will begin the process of yellowing, browning, and dropping off. To break this disease cycle, the time to manage this disease is in late July and throughout August, even into fall, if it stays warm and moist.

To initiate control, you must begin now. Look for needle spots and brown foliage on the lower branches of 50 or more trees scattered throughout the plantation. If ten percent of the trees are infected, consider treating the entire plantation by the first week of August. To reduce Lophodermium needlecast, remove the branches of pine from cut stumps where spores are likely to be produced. Apply a registered, preventative fungicide three or four times, once every two to three weeks from late July through October. This year, you may have to do this more often due to the likelihood of a continuing wet summer. Next time, plant long needle Scotch pines more resistant such as those from Germany, Belgian, Poland, and Czechoslovakia. Make sure all the older pines have been removed from windbreaks near nurseries or plantations. These pines can serve as sources of fungal spores.

Spruce needle rust

Jill O'Donnell
Christmas Tree ICM Agent

Spruce needle rust is showing up now in Christmas tree fields and blue spruce in the landscape. The needles will have yellow bands with small yellow-orange dots (pustules) on them. Like other rust fungi, spruce needle rusts need an alternate host to complete their life cycles. Spruce needle rust overwinters on Labrador tea and leather leaf. Spores from those alternate hosts will infect spruce trees. In July and August, yellow current-year needles with whitish blisters filled with yellow spores on Colorado blue, black, and white spruce will appear. This will be followed by shedding of infected needles. These alternate hosts are members of the Heath family and are found in bogs and damp thickets. Care should be taken to plant spruce away from wetlands especially the rust-susceptible Colorado blue, black, and white spruce. Norway spruce is more resistant. No fungicide is specifically labeled for this disease.

Lophodermium needlecast

Jill O'Donnell
Christmas Tree ICM Agent

Lophodermium is a severe needlecast of Scotch pine, which in some cases can cause the entire tree to brown in the spring. The infected needles are cast in June and July. In severe infections, only the current year's needles remain by late fall. Even though we see the symptoms of Lophodermium in the spring, the most important time to protect trees is from the end of July through September. This is when needles are infected from spores being released by the small, shiny, football-shaped, black fruiting bodies that form on the fallen needles. Fungicide applications should begin now and be re-applied every three to four weeks.

Spider mites

Jill O'Donnell
Christmas Tree ICM Agent

We continue to find spruce spider mite on Fraser fir, spruce and arborvitae. Growers should still be scouting for these. Pay particular attention to the trees you plan to harvest this year. Check for mite activity by closely inspecting the older needles near the tree stem or by sharply rapping shoots over white cardboard or a notebook with white paper.

Douglas-fir needle midge

Jill O'Donnell
Christmas Tree ICM Agent

Last year we found Douglas fir needle midge in two locations in Michigan, but may be more widespread than we realize. You will find a yellow band on the needle. The damaged area is initially pale in color but as the season progresses, will darken and eventually turn brown. In late summer, larvae emerge from the undersides of the needle and drop to the soil. We are interested in determining the distribution of this pest in Michigan. If you think you have the midge, please contact Jill O'Donnell, at 231-779-9480

News update from Pesticide Education

The following information is from the MSU Pesticide Safety Education Program's newsletter published by Christina DiFonzo and Carolyn Randall.

Teens and Ag
An OSHA web page about employing teenagers in agriculture has safety tips you can use to keep your teen employees safe: http://www.osha.gov/SLTC/youth/agriculture/other.html
The web site identifies hazards presented by working with machinery, the potential for falls or electrocution, precautions around farm chemicals, and other farm safety topics that might not be evident to teens.

The latest on West Nile Virus in Michigan
§      Number of counties with crows testing positive for WNV: 31
§      Number of states with bird or animal positives: 34
§      Number of counties with mosquitoes testing positive for WNV: 5 positive tests from 3 counties (Saginaw, Bay, Midland)
§      First human case this year in Michigan: June 26, 2004
§      Number of states with human cases: 10 (108 cases, concentrated in Arizona, California, and Colorado)

The latest on emerald ash borer
Thirteen counties are now part of the EAB quarantine zone: Shiawassee, Genesee, Lapeer, St. Clair, Ingham, Livingston, Oakland, Macomb, Jackson, Washtenaw, Wayne, Lenawee, and Monroe. In addition, there are a number of sites outside of the quarantine zone where EABs have been found. These sites are under eradication or containment (a ring of trees removed from a prescribed distance from the initial infestation). Also, a trap-tree program has been implemented across the state. The number of trap trees per township depends on the proximity to a known EAB infestation. Trees will be checked throughout the summer.

Buyer beware of the Love Bug!
A battery-operated device designed to protect babies in strollers from mosquitoes was recently dinged by the Federal Trade Commission. The device is called the Love Bug. It clips to a baby strollers and allegedly emits an ultrasonic tone that mimics "the wing-beat of the dragonfly - the mosquito's mortal enemy!"

The marketer, Prince Lionheart Inc, has been required by the FTC to prove its claims, which also include "protecting infants from West Nile Virus." Read more from the FTC at: http://www.ftc.gov/opa/2004/06/lionheart.htm. Incidentally, ultrasonic insect repellers in general do not stand up to scientific scrutiny. 

Weather news

Jeff Andresen
Agricultural Meteorology
Geography

A relatively benign weather pattern is setting up for Michigan and the Great Lakes region for the next several days as we enter the climatologically warmest stretch of the year (The last week of July through the first few days of August.). A cool front is expected to very slowly move across the state from northwest to southeast during the day Friday (July 30) before stalling out over the Lower Peninsula, resulting in a chance for showers and thundershowers Friday through the first half of the day Saturday. At the present time, this system is forecast to be weak, with only scattered-type rainfall expected (i.e. about a 30 to 40 percent chance of precipitation). Best chances for rainfall through Saturday will be in the southeastern Lower Peninsula and across far northern sections of the state where some 0.50" rainfall totals will be possible.

Temperatures during the next few days and continuing into the weekend should increase to near climatological normals with daytime highs ranging from the upper 70's north to the mid 80's south and low temperatures between the upper 50's to mid 60's. Some upper 80's are possible in southern sections of the state by early next week. Another frontal system will bring the next chance for rainfall to the state beginning in the Upper Peninsula late Sunday spreading southward to the remainder of the state Monday into Tuesday.

In the medium range time frame, forecast guidance suggests the return of a more active type of weather pattern across the region with a broad upper air ridge expected across the central US and an upper air troughs across the east and far west. The NOAA 6-10 day medium-range outlook, covering August 4-8 calls for near normal temperatures in eastern sections of the state and above normal temperatures in the west with precipitation totals forecast to range from near normal in northern sections of the state to above normal levels in the south. In the 8-14 day period covering August 6-12, above normal temperatures and near normal rainfall totals are forecast statewide.