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| Landscape Alert newsletter | |||||||
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| Vol. 23, No. 6, May 16, 2008 |
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| In this issue Landscape and nursery Four-year test shows that an annual basal drench with imidacloprid protects trees from emerald ash borer Trunk injections of imidacloprid or emamectin benzoate for emerald ash borer can be scheduled for late May or JuneTurfgrass Mid-May lawn activitiesChristmas trees and forestry Christmas trees and forestry pest update Managing grubs in Christmas trees Use copper-based fungicides in management of Dothistroma needle blight of Austrian Pine - correction from last week Gypsy moth spray window updateAround the home Obscure turf pest shows up again in Southwest Michigan Clover mites are on their spring rampageOther news Nightmare results for appliers of volcano mulch Pesticide residue testing Civil rights in employment decisions Weather news |
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| Four-year test shows that an annual basal drench with imidacloprid protects trees from emerald ash borer We began treating half of the ash trees at two golf courses with basal soil drenches of imidacloprid in 2004. After four years, the treated trees are healthy and nearly all of the control trees are dead. Treatment consisted of mixing Merit 75 (the homeowner product, Bayer Tree and Shrub Insect Control works just as well) in a bucket of water and pouring it around the base of each tree sometime in the month of May each year. The amount of Merit 75 used was determined by the diameter of the tree as specified on the product label. |
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| In tests at Bay Pointe and Barton Hills, all of the ash trees with less than 60 percent canopy thinning and dieback in July of 2004 (two months after the first basal drench) survived and looked very healthy by 2007. Many of the ash trees that had more than 60 percent canopy thinning and dieback in 2004 did not survive. Even though we have had excellent results in our research tests with basal soil drenches of Merit, we have still seen sites were imidacloprid soil treatments failed to save ash trees. Most of the failures are with very large ash trees growing in dry soils, where the imidacloprid was applied out to the drip-line instead of at the base of the tree, or when less than the maximum label rate was applied. The basal soil drenches are extremely reliable for small ash trees (less than 10” dbh) in good health, and for larger ash trees in good health and in moist soil (or watered during periods of dry weather). For heavily infested ash trees (but still with less than 60 percent dieback), you may want to consider a trunk injection with imidacloprid or emamectin benzoate and imidacloprid basal drench the first year followed by basal drenches in future years. BayPointe County Club (all green ash, dbh = 8 – 30 inches)
Barton Hills Country Club (mostly green ash, dbh = 8 – 25 inches)
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| Trunk injections of imidacloprid or emamectin benzoate for emerald ash borer can be scheduled for late May or June Valuable trees can be protected with trunk injections of imidacloprid or emamectin benzoate made by tree care professionals. Research tests with Merit Tree Injection (imidacloprid), ImaJet (Arborjet imidacloprid), and Tree-Äge (emamectin benzoate) have shown excellent results over a three-year period. Ash trees should be injected in late May or June (bidrin can be also be injected in July and early August) to prevent injury this year. Trunk injections made later in the summer or early fall may provide protection the following year. Below is a table of the products available for trunk injection and the suggested frequency of treatment on the product label.
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| Mid-May lawn activities Seeding turf The recent weather forecast indicates that it’s going to remain cool, cloudy and maybe rainy. If you’ve recently seeded turfgrass and are getting anxious to see results, remain patient. The cool temperatures are slowing germination and emergence. I seeded an area about two weeks ago with a mixture of turf type tall fescue and Kentucky bluegrass, and I currently need to take a gopher’s eye view to see the green fuzz of the new seeding. If you have any reseeding projects planned, I’d get rolling as the longer you delay, the closer we get to summer and with summer warmth comes crabgrass germination. Broadleaf weeds Dandelions have had their first flush of the bright yellow flowers in many areas of the state and are now in the puff ball stage. If you feel the need to burn down some dandelions, the puff ball stage is a good time to do it. Of course, the best time is in the fall. Usually, the turf areas that are really infested with dandelions are the thin areas. If you can simply improve the density of the turf with sound management practices such as mowing high, returning clippings, providing adequate nutrition, and improving the soil through core aeration, you will probably start to see the turf out compete the dandelions and other weeds for that matter. |
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| Managing grubs in Christmas trees |
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| Growers from around the state are reporting losses of young trees to grubs. The larvae of June beetles or European chafer will feed on the roots of Christmas trees killing many newly planted trees. Injury usually occurs during the first two growing seasons. To determine if your trees died from grubs, examine the roots of dead or dying seedlings or transplants. If it is damage from grubs, you will find little to no small feeder roots. With European chafer, we have seen some situations where grubs have fed on spruce tree roots causing small trees to die (about 75 percent of the trees in one field) and larger trees to fall over because they had no root system. Four grubs can kill a 2 to 3 foot tall tree. If you find grubs, you may want to take them to your local extension office or send them into Diagnostic Services to be identified. Here is a link to “Identifying Common White Grubs in Michigan” by Howard Russell, http://www.pestid.msu.edu/profiles/index.htm June beetle In May or June, the adult beetles emerge from the soil, feed on hardwood leaves near the field and mate. They return to the field to lay eggs in the soil. The newly hatched larvae burrow in the soil and feed on roots for two to five years. If you are finding grubs in a variety of sizes, you may want to treat the field now with Sevin ( carbaryl). Sometimes we find that populations may be synchronized to emerge every three years. If you have a big hatch (every three years) then make sure you are making an applicaion at those high years with imidacloprid (Admire) or thiamethoxam (Flagship) the end of May through June (adult flight through peak hatch). Rain or irrigation (a half to 1 inch) is needed to move the insecticide down to where the grubs are. European chafer European chafer may become more and more of a problem throughout the Lower Peninsula. European chafer has a one-year life cycle. They will be done feeding by the end of May. If you have European chafer, target your control for the newly hatched larvae in July (adult flight through peak hatch) with imidacloprid (Admire) or thiamethoxam (Flagship). Rain or irrigation (a half to 1inch) is needed to move the insecticide down to where the grubs are. |
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| Christmas trees and forestry pest update Gall rust On Scotch pine, gall rust can be found on branches and on the main trunk. Infection begins when spores infect green, succulent stems during wet springs. Symptoms rarely appear the year of infection, but galls on the twigs near the point of infection appear in subsequent years. The conspicuous, perennial, round-stem galls can be one to four inches in size. The galls are now beginning to turn yellow-orange due to the release of spores. This rust rarely kills mature Christmas trees, but it disfigures and severely reduces their quality. Pruning out these galls before they produce spores may help to reduce the spread of this rust. Cooley on Douglas fir Cooley's adelgids also feed on Douglas fir needles. They do not cause galls to form on Douglas fir, but they do cause the needles to become distorted, and at high densities, will reduce needle and shoot growth. You will usually find the adelgids on the undersides of the needles. They look like tiny, white cotton balls on the needles because the adelgids secrete white, waxy material as they feed. One stage of adelgid eggs often hatch in the spring, soon after buds break. The new nymphs will move onto the tender, succulent young needles. It often looks like someone has sprinkled black pepper on the new needles. If you need to apply an insecticide, this is a good time to do it. There is usually a second hatch of eggs later in the summer too. Pine tortoise scale Growers may have noticed pine tortoise scale on their Scotch pine because the overwintering female scales have begun feeding again. As they feed, they excrete amazing amounts of sugary honeydew that attract bees and ants. Pine tortoise scale is the reddish-brown, roundish scale that feeds on the woody part of pine shoots and small branches. Black sooty mold then grows on the honeydew that coats the needles and branches. Even though you have noticed them now, the timing for treatment is at the active crawler stage. Pine tortoise scale has a single generation per year. Eggs usually hatch around 400-500 GDD50. Spruce spider mite We have found spruce spider mites active on Fraser fir. You should be scouting for spider mites on firs, spruce, pines and even Douglas-fir trees, particularly those you plan to harvest this year. These cool season mite populations usually are highest in the spring and fall. 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. Don't be too gentle – go ahead and whack those shoots – you need to dislodge the mites from the needles so you can see them. Immature mites will be pinkish in color while adults are dark green or brownish. In one field that was heavily infested last year, we found more mites on the top third of the tree rather than in the low portion of the trees where we normally find them. Make sure to scout both areas of the tree for mite activity. |
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| Correction from last week - Use copper-based fungicides in management of Dothistroma needle blight of Austrian pine Last week, I wrote about this disease and made an error in the product that should be used in management of this disease. While chlorothalonil-based fungicides have been shown in research papers to be effective, they are not registered for use. Please disregard that information. A registered fungicide that should have been listed is Basicop, which should be applied as new needles emerge and repeated two or three times as needed at 7 to 10 day intervals. 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 and 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 copper-based fungicide. 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. Trees from a Yugoslavian seed source have been shown to be resistant |
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| Gypsy moth spray window update Recent cold weather patterns have resulted in the Upper Peninsula portion of Zone 5 being much colder than expected. Therefore, we are splitting Zone 5 up this season in respect to the Dimilin spray window. Growers should note that the Dimilin spray window open date for the Lower Peninsula counties of Zone 5 has been set for Friday, May 16. The Dimilin spray window open date for the Upper Peninsula counties of Zone 5 will be delayed until after May 25. 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 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.
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| Obscure turf pest shows up again in Southwest Michigan Back in 2006, we received a sample of sawfly larvae from a lawn care service located in southwest Michigan. I was able to identify them as grass sawflies, Pachynematus sp. (Hymenoptera: Tenthredinidae). Mature larvae can be distinguished by their solid green color, amber head with a brown band and many legs. This sawfly has been reported as a minor pest of grass seed fields in Oregon. The University of Delaware lists them as an occasional pests of small grains. Tom Dudek, MSUE educator, sent me another sample of the same sawfly that a client of his collected in his lawn in Hudsonville. Here is what is known about the grass sawfly. Its hosts include a number of grasses including wheat and barley, but they appear to favor the fine fescues over everything else. There is one generation per year. Adults emerge from the soil in late spring and lay eggs. The first larvae can be found by early May feeding on the lower leaf blades. Larval development takes approximately 21 to 30 days. By mid-June, larvae burrow into the ground and begin a period of summer hibernation in the prepupal stage. The larvae resemble Lepidoptera caterpillars or foliage feeding cutworms at first glance. There are two easily recognizable characters that separate sawfly larvae from true caterpillars. Sawfly larvae have eight pairs of abdominal prolegs (fleshly little pegs) as compared to caterpillars which have no more than five pairs of these prolegs. Also sawfly larvae have a single, easy-to-see, large ocellus or simple eye on each side of the head whereas caterpillars have up to seven, difficult-to-see, ocelli arranged in a semi-circle on each side of the head. Generally, these sawflies do not cause significant damage to crops or lawns because they are normally heavily parasitized by Icheumonid and Chrysidid wasps.
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| Clover mites are on their spring rampage I’ve had several calls and samples in from folks complaining about a tiny, unwelcome guest in and on their homes. Clover mites: Don’t ya just hate ‘em! |
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| Clover mites are among the smallest home invaders we have in Michigan. They belong to the spider mite family Tetranychidae and, as the name implies, they feed on clovers and grasses. People often mistake clover mites for minute, six-legged insects because their front legs are considerably longer than the others and are projected forward giving them the appearance of antennae (mites do not have antennae). Lush growing, well-fertilized lawns tend to produce the largest number of clover mites. For whatever reason, newly established lawns also seem to harbor large numbers of clover mites. When conditions are right, clover mites can invade homes by the thousands. This normally happens in the spring, but fall invasions also occur. They are small enough to crawl right through window screens and through cracks around windows, doors and other external openings. If they are crushed during attempts to wipe them up, they leave tiny red stains. Clover mites are usually a temporary nuisance. They appear suddenly and are generally gone a few days later. Household aerosol insecticides can be used to kill the mites indoors, if deemed necessary, but a soapy rag or wet sponge work just as well on indoor surfaces. A vacuum cleaner equipped with a hose and a soft brush attachment will also work. Wipe or brush carefully to avoid crushing the mites and causing stains. Mites can be removed from the outside of buildings with a garden hose. An insecticidal soap can be concocted by using regular liquid dish-washing soap mixed at the rate of 2 tablespoons per gallon of water. These water-based treatments will not provide any residual control. A more aggressive approach would be a perimeter treatment of a persistent insecticide along the outside walls and extending about 10 feet out from the foundation. Be sure to read and follow all instructions and safety precautions found on the label before using any pesticide. The best long-term method for reducing persistent clover mite invasions is by providing a grass-free band, 18-24 inches wide, around the house. This can easily be accomplished by open areas of course sand or pea stone, or by installing a plant bed. Removing clovers and other groundcovers from the lawn may also help prevent mite numbers from building up in lawns. |
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| Nightmare results for appliers of volcano mulch In response to our volcano mulch challenge, Mark Oomkes of Oomkes Landscape Management sent us something even better – pictures of what volcano mulching can produce. Oomkes writes, “This was an otherwise healthy ash that blew over during a relatively mild storm a few years back. Wind gusts were recorded at about 60 MPH in the area. There was no evidence of emerald ash borer or any other pests at the time. The ring around the trunk from the volcano mulch is very visible. I’m not sure how high the mulch was, but would estimate 8-10 inches.” Be kind to your trees – keep that mulch back off the trunk.
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| Pesticide residue testing Herbicides can injure desirable, non-target plants in a variety of ways, including drift, volatilization, carryover, tank contamination, misapplication or simply accidental or intentional exposure. In addition to diagnosing plant pathogens, nematodes and insect-related pests, all plant samples submitted to MSU Diagnostic Services – the multi-disciplinary plant health and pest diagnostic facility on campus – are visually inspected for pesticide injury. If warranted, samples can be tested for the presence of pesticide residue using appropriate analytical instruments and techniques. Sampling We urge clients that are interested in pesticide residue testing to contact the laboratory before collecting and submitting samples. Samples should be collected immediately if pesticide injury is suspected. If you suspect a drift event has occurred but are not positive, it may be wise to collect a tissue sample that day or the next and place the sample in the freezer. Glyphosate and 2,4-D, for example, can be very difficult to detect and quantify in the tissue once injury symptoms develop. Therefore, a little foresight in sampling may really help if injury symptoms do develop 7 to 10 days later. Collect enough plant tissue to fill a quart-size plastic bag; collect enough soil to fill a pint-size plastic bag. In general, samples should be frozen immediately and kept frozen until arrival at the laboratory. Fees Plant samples are visually inspected for pesticide injury for $20. Samples can be tested for pesticide residue on an individual basis or, if available, in multi-pesticide screens. Fees may vary depending upon number of samples, clientele location and numerous other special circumstances. Fees for individual pesticide residue screens are generally $90, $100 and $125 in water, tissue and soil, respectively. Fees for multi-pesticide residue screens are generally $125, $150 and $175 in water, tissue and soil, respectively. Questions regarding pesticide injury or pesticide residue testing should be directed to Steven Gower by phone at 517-432-9693 or email at sgower@msu.edu. |
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| Civil rights in employment decisions While many federal laws protecting equal employment opportunity exempt small businesses, Michigan laws do not. Michigan laws protect religion, race, color, national origin, age, sex, height, weight, marital status and disability. As long as the specific disability is unrelated to the individual’s ability to perform the duties of a particular job or position with or without reasonable accommodation. Whether an applicant is a union member or an applicant’s veteran status also are questions that should have no place in employment decisions. 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 Michigan, such as sexual orientation. Also, interview questions should be similar for all job applicants. 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. |
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| Weather news A significant change in the upper air pattern across North America is currently underway with the formation of a deep troughing feature across the Great Lakes region. This pattern is expected to continue for much of the next week and should lead to cooler and cloudier than normal conditions. In the short term, an area of low pressure and accompanying cold front will begin moving through the state from the northwest by late Friday, May 16. This weather system will bring a good chance for showers statewide late Friday continuing through much of the weekend. Rainfall totals through early next week are expected to remain light to moderate with most totals in the 0.25-0.5 inch range. High temperatures during the next several days will generally remain from the mid-or upper 50's north to mid- to upper 60's south with lows from the upper 30's to the low or mid-40's. While most nights during the next week are expected to be cloudy and with some wind, it is important to note that with relatively cold expected aloft, frost and even freezing temperatures are a possibility on any given night should clear, calm conditions develop. This would be especially true in inland northern sections of the state and in low-lying areas such as over muck soils where cold air tends to pond at night. In the medium‑range forecast period, outlooks for the Great Lakes region are related to the upper air pattern mentioned above with more cloudy and cool weather expected. Both 6-10 day and 8-14 day outlooks covering May 21-25 and May 23-31 call for precipitation totals to range from below normal levels across northwestern sections of the state to below normal levels in the southeast. Mean temperatures during the 6-10 day time frame are forecast to range from near normal over the Upper Peninsula to below normal levels over Lower Michigan. Below normal temperatures are forecast statewide during the 8-14 day period. Due to some disagreement between the various forecast models used to create the outlook, forecaster confidence is considered below normal. Enviro-weather update We are happy to report that six new automated weather stations have recently been added to the Enviro-weather network: Arlene, Berrien Springs, Coldwater, Hickory Corners (MSU Kellogg Biological Station), Keeler and Romeo. Many thanks to the sponsors of these sites and to local MSU Extension personnel for making this possible. On a related note, a new option is now available for downloading automated weather station data. Users may choose to download data in Comma Separated Value (CSV) format, which makes the transfer of data to spreadsheet-oriented software such as Microsoft Excel much easier. To use the new feature, go to the Michigan Automated Weather Network site at http://www.agweather.geo.msu.edu/mawn/ and select a station of interest. Next choose the Custom Reports (Data‑on‑Demand) function. Select your preference of data type: daily, hourly or five minute data (this feature will also be available for growing degree day totals within the next week or so). Finally, select your data output format in either ASCII/HTML (the only previous option) or CSV (comma‑delimited), which is the new option. |
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