Landscape and nursery
§ “Volcano” mulching challenge
§ Rhizosphaera or not?
§ Frost damage recovery Turfgrass
§ Weed identification guides for field and container nurseries
Turfgrass
§ Fertilizing and water smart formula
Christmas trees and forestry
§ Oak wilt infection time: Remember these three rules
§ Management of Douglas Fir and Colorado Blue Spruce needle cast diseases
§ Management of Diplodia/Sphaeropsis shoot blight of Austrian, Red and Scotch pine
§ Dothistroma needle blight of Austrian pine
§ Christmas trees and forestry insect update
§ Gypsy moth spray window update
Around the home
§ The elm flea weevil: A new pest found in Michigan
Other news
§ Civil rights in employment decisions
§ Weather news
Joy Landis, Editor
Each year, Landscape Alert readers see our articles bemoaning the use of too much mulch mounded up around trees. As horticulturalist Bert Cregg puts it, mulch should be applied in a “doughnut” shape in the drip zone of trees and shrubs, not a “volcano.”
Reader Jeff Granger suggests it is time to feature some of the biggest or tallest “volcanoes” around the state in the Landscape Alert. He sent the accompanying photo taken in Petoskey outside a popular home improvement store, and reports the mulch towers at 16 inches.
Send us a photo of your favorite
Jan Byrne, MSU Diagnostic Services
This time of year the lab frequently receives samples and
phone calls from clients concerned about blue spruce with needle drop symptoms.
Many of these are from home landscapes, occasionally they are from commercial
growers. Sometimes people jump to the conclusion that the needlecast was caused
by Rhizosphaera, a common disease seen on spruce in
Beginning in the spring, Rhizosphaera spores are released and spread in the tree canopy by splashing water (from either rain or irrigation). These spores infect needles beginning in the spring; first year needles on lower branches are most commonly infected. The infected needles remain on the tree, usually with no visible symptoms, throughout the growing season. Subsequently, in late winter or early spring these infected needles turn brown (Figure 1). Late in the summer or fall the needle drop phase begins. This creates a pattern where branches have needles on the outer most portion (newest growth) but are bare further back toward the center of the tree (on previous year’s growth). Note: for information on control of Rhizosphaera consult a previous article in the MSU Landscape Alert from May 4, 2007. (http://www.ipm.msu.edu/cat07land/l05-04-07.htm#7)
Rhizosphaera can be identified by the presence of fruiting
bodies emerging from the stomates of infected needles (bugwood image). However,
there are several other fungi that produce fruiting bodies on spruce needles
that can easily be mistaken for Rhizosphaera. These fungi include Stigmina
lautii, sometimes referenced as Stigmina needle cast and Setomelanomma holmii, more commonly referred to as spruce needle drop or
SNEED. At this time, experts disagree on whether or not these are
virulent pathogens that are capable of causing damage to spruce, or rather fungi
that colonize tissue on already weakened or stressed trees.
http://www.ipm.iastate.edu/ipm/hortnews/2008/2-6/Stigmina.html.
To distinguish Rhizosphaera from these other “look alikes” one must use good magnification and look carefully at structures emerging from the needles. Rhizosphaera pycnidia (fruiting structures) are rooted in the stomates, they protrude in rows. These structures are most readily found on brown needles. The pycnidia are spherical and have an even outer surface. If the outer surface of the pycnidia is not smooth, for example it has hair like appendages protruding from it, it is not Rhizosphaera.
There are other factors that cause needledrop on spruce. Some of the spruce samples we receive have signs of great growth but all the needles on the growth have dropped (Figure 2). On these samples, we generally are able to rule out the presence of insect pests and Rhizosphaera. The phenomonen is attributed to environmental or cultural causes. Environmental or cultural causes include a lot of things such as drought stress, extreme temperature fluctuations, poor site conditions, soil compaction, etc. We (and our clients) are commonly frustrated with our lack of ability to specifically identify a specific cause. From a diagnostic perspective, it is very difficult to go back in time, maybe as far back as a year, and pin point the specific cause.
Bert Cregg, Horticulture and forestry
With temperatures dipping well below freezing on April 30, it looks like we’re done with our annual bout of late frost. Now it’s time to set about cleaning up the damage. In the mid-Michigan area, most of the damage I’ve seen has been relatively mild. We lost some magnolia blossoms, and a few early flushing trees and shrubs were frosted back a bit. Often these situations aren’t as bad as they initially appear and plants will usually grow out of the damage. Some light pruning can help with aesthetics in the near-term and improve the overall re-growth of the plant in the long term. Tom Fernandez offered some pruning tips following last year’s late frost event. Read the Landscape Alert from April 13, 2007 (http://www.ipm.msu.edu/cat07land/l04-13-07.htm#2) to review these helpful tips.
Thomas Dudek, District Extension Horticulture and Marketing Educator
Nursery growers who need some resources for identification
of weeds that impact their production will find these two publications helpful.
"Weeds of Container Nurseries in the
When used in conjunction with the MSU publication E-2982 "An IPM Pocket Guide for Weed Identification in Nurseries and Landscapes" (available from the local Extension office or MSU Extension Bulletin Office at 517-353-6740) you should be able to identify most weeds that show up in the nursery container area. This guide is also available on-line at: http://www.ipm.msu.edu/weeds-nursery/contents.htm
Proper identification is the first step to controlling weeds in the nursery. Please contact your local MSU Extension horticulture educator for the latest weed control recommendations.
Kevin Frank, Crop and Soil Sciences
If you’ve been watching any TV lately you’ve probably seen the new Scotts fertilizer ad that discusses Scotts® Water Smart Formula. The first time this ad rolled past my somewhat disengaged eyes during a break from the weekend sporting broadcasts, I didn’t really catch what was being promoted. Overall, there hasn’t been a tremendous amount of innovation in lawn care product ads over the years. Each year, we see the typical RoundUp ready to use “quick draw” ads which look as though if you use this weed killer you won’t kill all the grass just the weeds. There are a wide variety of fertilizer ads with stereotypical families discussing the greenness of their lawn and how much they love having picnics on their green lawn early in the spring.
So, you can imagine my surprise when I viewed the most recent Scotts ad that talks about how Water Smart Formula will make your turf healthier and shows the animation of the turf throwing back water like a sprinkler system. The Water Smart Formula is not a new fertilizer product; instead the message is that fertilizing is part of the formula for a healthier turf. A well fertilized, healthy turf will actually result in water savings. If you think about this concept it makes sense.
Turfgrass management practices, including fertilizing, that result in a deeper, more extensive root system allow the turf to “gather” water from a larger soil volume. So when the weather dries out this summer, as it almost always does, if the turf has a more extensive root system you may even notice that if you’re not irrigating, the turf may hang-on to some of its green color longer into the drought and probably recover more quickly once the rainfall resumes.
1) Keep the fertilizer on the lawn and off paved surfaces.
2) Follow the directions on the bag.
3) Use a product designed for lawns not the “triple” products (i.e. 12-12-12)
4) Create an application buffer near any water body to minimize the risk of fertilizer particles moving or being directly applied to the water.
5) When it comes to phosphorus, don’t apply it if you don’t need it. Take a soil test to check the level of phosphorus in your soil.
Dennis Fulbright, Plant Pathology
Rule number 1: No pruning of oak trees in May, June or July. Wait until fall or winter.
Rule number 2: No pruning of oak trees in May, June or July. Wait until fall or winter.
Rule number 3: No pruning of oak trees in May, June or July. Wait until fall or winter.
Oak wilt is a devastating disease of northern red and white oak trees that kills oaks much the same way as Dutch elm disease kills elm trees. White oak is not as susceptible as red oak. A fungal pathogen, Ceratocystis fagacearum, colonizes the water conducting vessels of the tree, and through various mechanisms blocks water movement in the tree. Wilt symptoms rapidly develop and show up by July. Insects called nitidulids, the sap feeding beetles (also called picnic beetles), are responsible for moving spores of the fungus from one tree to another (long or short distance dispersal). Sap bleeding from wounds attracts these insects. If the insect is carrying spores of the oak wilt pathogen, an infection site can be initiated. Once the tree is infected, it can be a source of disease for future infections in the surrounding area. Since the fungus is in the water conducting vessels, the pathogen can make its way to the roots of the tree. Like many other trees, oak roots can graft to other oak trees and spread the disease underground to oaks in the area. Even after the top of the tree is dead, the roots remain alive and can continue to be a source of disease a few years after the tree has died or been removed.
Three important events occur for successful infection in May and June each year: 1) The insects are at their highest population level; 2) Last year’s oak trees that died of oak wilt are producing spores and attracting nitidulids beetles through the sweet smell of the spores; and. 3) Wounds on oak trees are weeping sap. These three events coincide during spring. Since you cannot control the beetle, and cannot find or remove all infected oaks, the only recourse one has to prevent oak wilt infection is to reduce the number of wounds on red and white oaks this time of year. Do not let anyone prune oaks in May, June or July, regardless of the price. That they just happen to be in the neighborhood and just pruned your neighbors’ trees, or that they use modern methods and clean tools should not sway your decision. Never let anyone climb your living oak trees with spikes, anytime of year.
If red or white oak trees begin dropping leaves in mid-July to mid-August, call your landscape advisor immediately. White oaks can be saved after infection, red oaks cannot be saved, but you will want to begin a program to reduce future infections. See MSU Extension Bulletin 2764.
Dennis Fulbright, Plant Pathology
Normally, I would be telling you that with all this spring rain you need to be concerned about needle cast disease. So far, this year seems to be different. Without all the spring rain, why should you be nervous about needle cast diseases that spread by rain? You should be concerned about needle cast diseases because it does not take much rain to activate spore release, spread and infection, and because there are so many infected needles from previous years that the trees will still have serious levels of disease pressure on them. Other reasons include the fact that spores can continue to spread well into June, and rain events in early to mid-June can still cause spore showers to rain on susceptible needles. If my reasoning still has not won you over, perhaps this final statement will. This is the first spring in many years that nature is on your side in the battle against needle cast diseases, so take advantage of it.
Needle cast diseases are the main reason for the casting of last year’s needles. If you did not get control of the needle cast diseases last year, you may begin to lose those needles soon. You can only stop needles from casting in 2009 if you get the diseases under control right now. Two events must occur before needle cast disease fungal pathogens begin to infect the needles. First, buds need to break, with needles becoming roughly half their final size, and second, the spores of the fungus must be released from last year’s infected needles. This latter event occurs when it rains. So bud break, spore release and rain lead to needle cast infections in Douglas fir and blue spruce. Since you can’t really tell when the spores release or if it rained enough for spores to release, the best bet is to assume that spores will be releasing about the time buds are breaking and take action. The most effective material for control of Swiss and Rhabdocline is chlorothalonil.
To put nature on your side plant disease resistant and
disease tolerant trees every year. The Douglas fir seed source Shuswap is
absolutely resistant to Rhabdocline needle cast and therefore, all you have to
manage is Swiss needle cast. To get the upper hand on spruce needle cast, plant
species of spruce other than Colorado blue spruce which is the most susceptible
spruce to Rhizosphaera needle cast. Shifting slowly to these disease resistant
or tolerant species will reduce pesticide use in the
It is important to monitor for the amount of needle cast in your plantings before initiating a spray program. To determine if your trees warrant chemical management, look for signs of the fungal fruiting bodies on the needles. These fruit bodies are producing the spores that will infect the new needles as they break bud. With a hand lens, scan the discolored needles. For Rhabdocline on Douglas fir, look for needles with elongated brown splotches and on the bottom side of the needle, look for areas where the outer portion of the needle’s epidermis (skin) appears raised. If you see these, then examine 2-year-needles on 50 or more trees scattered throughout your plantation. If you find fruiting bodies on 20 percent or more of the trees, consider treating the plantation.
In the case of Swiss needle cast of Douglas fir and Rhizosphaeria of spruce, randomly select 20 or more trees scattered around the plantation, and remove three sample branches from each tree. Examine the white rows of stomata on 2-year-old needles and if half of the branches have dark fruiting bodies on more than 10 percent of the needles, consider treating the entire plantation. Two sprays are more effective than one.
Here are some important things to consider when monitoring for needle cast diseases. For those of you with selective cuts on your farms, older trees can act as sources of disease for the younger trees. If you do not spray this year because you thought the trees were going to market in the fall, sometimes plans change and those trees can be points of infection. Also, survey the landscape around your plantation for old wind- and fence-row trees that will almost always carry spores of needle casting diseases. These “typhoid Marys,” from abandoned plantations may be contributing large amounts of disease to your plantations. We have observed spores blowing more than one half of a mile and it probably moves farther than that. So, if you monitor the trees within your fields, make sure you consider these other possible sources of infection.
A good spray program started or continued now will prevent poor looking diseased trees in 2009. At lease two sprays to cover the emerging needles should be considered and a third spray in June will provide added insurance.
Dennis Fulbright, Plant Pathology
This disease is different from the needle cast diseases in that it kills the current year’s infected needles and stems. The fungal pathogen, Diplodia sapinea, (use to be known as Sphaeropsis) will also kill seedling trees in nurseries, whereas the needle cast diseases do not infect seedling trees because their needles dry so fast. With Diplodia shoot blight and canker disease, mature trees usually require a stress event to trigger a susceptible reaction, but seedlings can be infected if a source of the pathogen is available. This fungus infects growing and elongating shoots in the spring and kills the main terminal of the seedlings. The black fruiting bodies are relatively large and can be seen easily with a hand lens and even the naked eye. These black dots will be on the needles, usually under the sheath, and on the stems.
With previous springs having been so conducive for disease, Diplodia shoot blight is currently widespread, ravaging many landscape pines. You should consider applying fungicides every two weeks, up to four times to prevent the spores that are now being produced, from infecting the succulent new growth. During rain and windstorms, these spores will disperse over long distances and conditions for infection will remain favorable during rainy and humid days. If you have severe shoot blight infection in a nursery this year, you may want to reduce the number of susceptible species, such as Austrian or red pine in the nursery for a couple of years, as this infection period will probably be extended, even with management. If you are planting mature Austrian and red pine, consider the fact that even though they have been inspected they may still have come from nurseries or plantations with latent infections, and more than likely, spores will have infected some of these trees. If the trees are stressed, shoot blight will appear and you should be ready to manage this disease next spring. If, later in the summer, more than 10 percent of the trees have severe shoot blight, begin a spray program next spring. Do not shear trees that have infections, or may have come from nurseries with infections, as the cutting shears will carry the spores to new plantations. Also, in landscape situations, consider raking up cones which also are a source of the spores.
Manage this disease with a package
of treatments including turf removal under the tree, apply mulch and water. By
eliminating the grass under the tree, it will remind you not to apply
fertilizer to the tree. Use no nitrogen fertilizer. Water during dry periods.
Prune out dead tips and clean pruners with bleach mixture. Use Cleary’s 3336
thiophanate methyl or chlorothalonil for chemical control if needed.
Dennis Fulbright, Plant Pathology
Editor's note: This article includes a correction from the May 16, 2008 issue and should now be accurate as stated here
This pathogen kills needles of all ages and can weaken or kill Austrian pine trees. The main symptom is dead needle tips beyond the yellow to tan needle spots that enlarge to form distinct brown to reddish-brown bands. The black fruit bodies can be seen in the dead spots or bands on the needles. The spores spread by wind and rain can infect needles throughout the growing season. New needles are susceptible once they emerge from the needle sheaths. The black fruit bodies appear in the fall and the spores are released the following spring and summer.
To protect all foliage from infection, apply a chlorothalonil-based fungicide in mid-June through
mid-July. Before spraying, check all trees in the plantation in the fall, and
if you find any needle blight consider spraying the following year. Help
yourself by not planting Austrian pines near windbreaks composed of Austrian
pine. Reports suggest that removal by pruning of infected branches helps reduce
disease. Resistant trees of a Yugoslavian seed source have been shown to be resistant.
Jill O’Donnell
Christmas Tree ICM educator
Growers in the southern portion of the
Spring generation eggs hatch in May or early June at roughly 300 GDD50. Usually, eggs hatch within about a week, and most crawlers should be in the hyaline stage by 400 to 500 GDD50. This is the ideal time to apply an insecticide. If the weather cools down, hatching may continue over two to three weeks. Good scouting will help you assess the size of the pine needle scale population in your field, determine whether control is necessary, and the best timing for control.
Don't forget, if you are in the Pine Shoot Beetle Compliance
Program, you must have your trap logs and piles of cull trees collected and
destroyed by May 20. All potential brood material
must be destroyed before May 20.
This includes any pine trees, branches, etc. cut since October 1 of last year.
The idea is to destroy the brood material before the new generation of beetles
can emerge next summer. Culled trees and other potential brood material can be
piled and burned, or chipped. Don't use a brush-hog; it leaves large chunks of
pine that are still suitable for
Stumps from trees harvested last
autumn will also need to be managed because they can be colonized by breeding
adults in the spring. You have some options for stump treatment.
First, stumps can be cut off very low - less than 4 inches or as close to the
ground as possible. The idea here is to limit the amount of brood material
available to the beetles. If you leave high stumps this fall, you can re-cut
the stumps and chip or burn the cut section by May 20. You can also spray the
stumps after May 1 but before June 1 (depending on location) with an USDA
approved pesticide to kill the new generation of beetles when they emerge from
stumps. The final option is to pull the stumps out of the ground and burn or
chip them by May 20.
Sawfly eggs hatch this week in
Mike Bryan, MDA
Growers should note that the spray window open date has been set for Zones 3 - all other compounds for Saturday, May 17. The spray window open date for Zone 4 – all other compounds has been set for Wednesday, May 21. Spruce, fir and Douglas-fir nursery stock being shipped to destinations outside the gypsy moth regulated area requires a new treatment once the spray window is open. The reason is that gypsy moth hatch is imminent, and nursery stock is at risk for infestation by larvae “ballooning” on their silk. Those who ship nursery stock outside the regulated area should consult with MDA staff for obtaining certification to meet the USDA Gypsy Moth Quarantine.
The following chart shows actual and projected open/close dates for application of the two groups of pesticides used for regulatory treatment of gypsy moth in nursery stock and Christmas trees. We are listing the projected dates as guidelines to help you plan your pest management program. Since gypsy moth development will vary by location, you will need to monitor development around your farm. Weather conditions will affect caterpillar development and may effect end date of the spray windows. Growers should watch the Landscape Alert for additional announcements.
|
Zone |
Open – Dimilin (150 DD*) |
Open – all other compounds
(200 DD) |
Close – Dimilin (700 DD) |
Close – all other compounds
(800 DD) |
|
1 |
May 1 |
May 6 |
June 9 (projected) |
June 15 (projected) |
|
2 |
May 1 |
May 6 |
June 15 (projected) |
June 20 (projected) |
|
3 |
May 6 |
May 17 |
June 21 (projected) |
June 27 (projected) |
|
4 |
May 10 |
May 21 |
June 28 (projected) |
July 4 (projected) |
|
5 |
May 20 (projected) |
May 27 (projected) |
July 3 (projected) |
July 11 (projected) |
* DD = Degree Days
at base 50 degrees F.
NOTE: Projections
are based on 30 year historical degree day data.
ZONE MAP – A list of counties comprising each zone and a statewide zone map
appeared in the April 18, 2008 edition of the Landscape Alert.
Howard Russell, MSU Diagnostic Services and Jim Zablotny, USDA/APHIS/PPQ
Dr. Jim Zablotny, the USDA/APHIS/PPQ Insect Identifier at
the
According to Ohio State University Extension entomologist
Curtis Young, the European elm flea weevil, is commonly found throughout
We would be very interested in knowing where
else in
101 Center for Integrated
Tel 517-355-4536
Vera Bitsch, Agricultural, Food and Resource Economics
While many federal laws protecting equal employment
opportunity exempt small businesses,
Most laws apply to all employment decisions, including hiring, training, evaluation, promotion, compensation, discipline and termination. But questions on how to treat everybody fair and equally often come up during the selection process. As a general rule, all questions during the selection process should be relevant to the job to be filled. On an application form such questions may include name, address, phone number, the job the applicant is applying for and a summary of the applicant’s background (e.g., education and training, work history, special qualifications and skills). Citizenship and ethnicity are not typically relevant to agricultural jobs and therefore need to be avoided on application forms. An employer concerned about hiring applicants who will later fail to provide the required documentation for the I-9 form, may include a question in the application form such as “Are you legally eligible to work in the United States?” It is important to remember that many questions, which must be asked after a job candidate is hired, need to be avoided before the job has been offered.
Everybody who participates in the hiring process must be familiar with the relevant qualifications, skills and experience of the job or jobs to be filled. Often times, small differences in how a question is asked differentiate a legitimate question from a discriminatory one. For example, “When did you attend college? When did you graduate?” could be construed as discriminatory on the basis of age; “How long did you attend college? Did you graduate?” are legitimate questions, if education is a relevant job qualification. By writing up questions before an interview, discriminatory practices can be avoided.
In addition, interviewers should take notes during the
interview in a neutral language. All interviewers must be trained how to ask
legitimate questions and what topics to avoid with job applicants. If an
applicant brings up any of these topics, such as family and children,
disability or religion, it is best to not dwell on such information and to not
ask any follow-up questions. The best practice is to follow the general rule to
only ask job related questions and avoid all others, even if they legally can
be asked in
This information serves educational purposes only and does not constitute legal advice. For more information go to www.msu.edu/user/bitsch, under “News” click on “Civil Rights and the Hiring Process” or click on “Agricultural Labor Issues in Michigan” for a list of available newsletters.
Aaron M Pollyea, Geography
A relatively zonal, west to east jet stream pattern is
expected across North America during the next one to two weeks, which should
lead to an unsettled weather pattern across the Midwestern United States
including
A low pressure system is expected to move over the state
late on Sunday bringing with it significant amounts of precipitation to
southern portions of the state, perhaps as high as an inch in some locations. Temperatures
will remain in the 50’s in the north to the upper 50’s in the south with
morning lows in the mid-30’s to mid-40’s. There will be slight warming by
Tuesday with temperatures reaching the upper 60’s in some portions of the
Current medium‑range forecast guidance suggests more
of the same recent pattern, with a series of upper air troughs moving eastward
across the
New NOAA long lead outlooks for the upcoming few months reflect a significant weakening of the La Niña event that has been in place across the equatorial Pacific region since last fall. The outlook for the month of May calls for a continuation of an active storm track across the western and Midwestern United States leading to a forecast favoring cooler and wetter than normal conditions for Michigan and the Great Lakes region. However, given the recent weakening of La Niña conditions in the Pacific, there have been additional changes in the longer lead forecast periods (mainly moderations in precipitation forecast).
For May through July, mean temperatures and precipitation
totals in