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| Landscape Alert newsletter | ||||
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| Vol. 22, No. 9, June 8, 2007 |
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| In this issue Landscape and nursery  Trees and lightning Wind injury to tree shrubs and perennials Late frost damage on conifers Managing fire blight on ornamentals Managing botrytis blight on Hosta Controlling juniper scale Scouting for insects: Juniper scale Scouting for disease: Cytospora canker Last call for spring basal soil drenches and trunk injections for emerald ash borer Cottony maple scale and Lecanium scale on silver maple, honeylocust, oak, and some ornamental Prunus spp. Honeylocust plant bug injury continues for another weekTurfgrass Clover, medic, and fertilizingChristmas trees and forestry Christmas tree update Gypsy moth spray window datesAround the home Powderpost beetles – The other, other wood destroying insects Confused Cooley spruce adelgids in Jackson CountyOther news Weather news |
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| Trees and lightning Summertime thunderstorms can cause problems for trees in a variety of ways. High winds and soaking rains can cause major limbs or entire trees to fail. Thunderstorms can also damage trees by lightning strikes. Lightning tends to hit tall objects. (Contrary to the light never strikes twice myth, lightning usually strikes the Empire state building 20 times a year.) Lightning contains an incredible amount of energy – often hundreds of millions of volts. Damage from lightning can range from relatively minor to total devastation. Paul Dykema, city forester for the city of Lansing, and I visited a tree in a school yard in Lansing a few years ago that literally exploded when it was hit by lighting (Photo 1 & 2). Shards of the trunk were thrown hundreds of feet from the base of the tree. Obviously this tree is toast, but trees can survive less severe lightning strikes. Several factors need to be considered in assessing lightning damage and whether or not a tree can be saved. |
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| Extent of damage Lightning often strikes near the top of a tree and then follows the trunk to the ground. The energy released by the strike and rapid expansion of vaporizing water in the trunk commonly results in splits in the trunk (Photo 3). Many trees are often able to recover from this damage which, when minor, may look similar to a frost crack once the trunk has healed over. Kim Coder, urban forestry specialist from the University of Gerogia, suggests that if less than 20 percent of the circumference is damaged (measured at the widest split) the tree has a good chance of recovery. Trees with deep splits or major limb breakage are candidates for removal. It should also be noted that lightning damage assessment takes time. Lightning can travel through the tree into the roots and result in damage that may not be immediately evident. Lightning-struck trees should be monitored for at least a year to observe signs of decline. Species Species influences the assessment in a couple of ways. First is value. We may be more likely to have less patience with the cottonwood in Photo 3 than we would with a maple with similar damage. The species of tree struck also influences the likelihood of subsequent insect or pathogen problems. For example, a red oak with a major lightning-caused trunk split during the warm, humid thunderstorm season may become a likely candidate for oak wilt infection. Likewise bark beetles and other opportunistic insects may infest lightning damaged trees. Likelihood of becoming a hazard tree There are two components to a hazard tree. One is a defect in the tree (e.g., major limb damage, trunk split). The second is a target. If the tree or limb were to fail, what would it hit? If a tree is in the middle of a woodlot and is struck by lightning, it may not require any action since it would not pose a risk to people or property if it failed. The same tree with the same damage could pose a major risk if it were next to a house or overhanging a playground. Not for the do-it-yourselfer The likelihood of tree recovery after lightning strike is difficult to predict: trees with relatively little damage may fail, while trees with major cracks survive and grow. For homeowners, the best course of action is to contact an arborist certified by the ISA (International Society of Arboriculture). Most veteran arborists in Michigan have seen a range of lightning damage in trees and can assess the situation and propose the best course of action to protect lives and property. Many arborists are also trained in lightning protection systems. These are grounding systems, similar to lightning rods used to protect homes and buildings, that can reduce the potential for lightning damage to especially valuable or specimen trees. To find a certified arborist in your area, contact the ISA at: http://www.treesaregood.org/findtreeservices/TCSHome.aspx For more information on trees and storm recovery, visit the National Arbor Day Foundation at: http://www.arborday.org/media/stormrecovery/?CFID=19497600&CFTOKEN=26030518 |
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| Wind injury to tree shrubs and perennials Nursery growers should be aware that the strong winds that occurred on Thursday, June 7, will cause some sand blasting of plants in both container and field growing systems. This sand blasting will open up wounds where both bacterial and fungal diseases can enter the plants. Foliar pathogens such as leaf spots, like Alternaria and Septoria and bacterial pathogens like bacterial leaf spots, can be a concern following these winds. Tender newly emerging leaves can be severely tattered and deformed also. Stem infections on smaller plants can result from abrasion due to blowing soil particles. This can lead to infections from Rhizoctonia, Fusarium and Colletotricum fungi. Growers should consider starting a fungicide program to prevent the spread of plant pathogens and to protect wounded tissue as soon as possible after the winds subside. I would suggest including both a copper material and a protectant fungicide for any applications that you use. Consult the Cornell Pest Management Guides for both Tree and Shrub and the Perennial Guide; E-2782 and E-2783, which are available from your local MSU Extension office. If you applied a preemergent herbicide prior to the wind event, there is a good chance that the soil may have blown enough to move the herbicide off the field or to cover it up with soil from adjacent fields. If your containers had soil deposited on them, the herbicide may be covered up and new weeds could sprout from the blown in sand. The bottom line is to watch your fields and be ready to reapply herbicides if necessary. Any post emergent herbicides applied prior to the wind should not be affected. We have also received reports of large numbers of leafhoppers showing up on plants in the area as a result of the strong southerly winds. Leafhoppers can carry aster yellows micoplasma, and they can also cause hopper burn on a wide variety of trees. Note June 1, 2007 Landscape CAT Alert articles on these issues. |
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| Late frost damage on conifers We have received some reports of frost damage to conifers in mid-Michigan associated with a freeze in mid-May. At the MAWN weather station at the MSU Horticulture farm south of campus, we recorded a low temperature just below freezing (30.7ºF) on May 18. In some low areas or frost pockets, it is likely that temperatures dropped a couple degrees colder; just enough to cause problems for newly emerged spruce, fir and Douglas-fir shoots. We observed some damage in our exotic fir block at the Hort farm that is typical of this type of injury (Photo 1 & 2). The damage occurred only on new growth, occurred on the bottom of trees and was most evident at the lowest point in the field where cold air had settled. Jan Byrne, from Diagnostic Services, received spruce samples with similar damage (Photo 3). Unfortunately, like many abiotic problems, there is little that can be done once the damage has occurred. Most trees will grow through the damage. If a terminal leader is damaged, some corrective pruning may be necessary to prevent the development of multiple leaders. |
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| Managing fire blight on ornamentals Several landscape professionals are reporting damage caused by fire blight. Fire blight is caused by Erwinia amylovora, a bacterial pathogen. The disease is best known for the severe damage it causes in fruit orchards, but several common landscape plants are also susceptible. Cotoneaster, flowering crabapple, flowering pear, hawthorn, photinia, pyracantha and mountain ash are all susceptible. Blossoms are particularly susceptible to infection; infections initiated in the blossoms can move into the woody tissue, causing shoot damage. Disease is commonly spread by insects and splashing rain or irrigation. Infected plants have a scorched appearance with young shoots wilting and turning brown. The shepherd-crook shaped dead tips are a good diagnostic symptom of this disease. Samples of live, symptomatic tissue can be submitted to MSU’s Diagnostic Services for confirmation. Diagnosis can be performed with a molecular based test (PCR), which is very sensitive. The disease is favored by excessive nitrogen fertilizing and heavy pruning, which both lead to more succulent growth. Tolerant or resistant cultivars of some the above mentioned plants are available. Results of studies on resistant species across the United States are inconsistent, therefore, nursery growers need to do some cultivar evaluations to determine the best ones for their area. To manage this disease sanitation is the best strategy. If your nursery is located near old pear, apple or quince trees, these abandoned trees can be a reservoir for the inoculum. You should consider removing them. Where low levels of infection occur, the infected tissue should be pruned out, make pruning cuts several inches below the edge of the infected area. If pruning is not possible, affected plants should be removed from the nursery and destroyed. Sterilize pruning tools or shears between cuts with either 10 percent household bleach or 70 percent alcohol. Copper-based bactericides like Phyton or Kocide may be helpful. These materials limit the amount of bacteria on the plant surface, but should not be relied upon as the sole management strategy. Efficacy of applications can be maximized by using predictive models. The commercial fruit industry uses predictive models that are based on recent environmental factors, and the biology of the pathogen to optimize the timing of chemical applications. One such predictive model (derived from the Maryblyt model) is available online at MSU’s Enviro-weather site. Users must regularly monitor the predictive results during bloom time, but landscape managers looking for a more inclusive management program may benefit from the information provided by the model. Additional information about fire blight is available on the MSU IPM web site at: http://www.ipm.msu.edu/fruitpests/fireblight.htm |
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| Managing botrytis blight on Hosta This year, the weather has been conducive for infection with the common plant pathogen Botrytis cinerea (view photos). In commercial nursery fields and shade houses, the practice of growing plants close together creates a humid environment, which is ideal for the development of botrytis blight. In the presence of inoculum, when conditions are favorable for development of Botrytis and the plant is susceptible, botrytis blight can occur. In hostas, immature lesions appear mostly as water-soaked spots that increase in diameter to become circular spots with dark halos around the outside. As the lesions mature and increase in size, rings can be seen within the lesions, which appear cinnamon to dark tan in color. The dark fungus often can be seen on the underside of the lesion, especially early in the morning when the leaves are still wet. The lesions can spread down the leaf petiole and sometimes can be found beneath the soil surface. In hostas, it appears the age of plants is not a factor in Botrytis infection. There clearly are differences in susceptibility among varieties, but these do not follow any particular characteristic of the plant, such as leaf texture, variegation or leaf size. Botrytis reproduces asexually by conidia (spores) that can be released and dispersed by plant agitation, such as wind, grower activity, irrigating, spraying pesticides and during harvest activities. In both fields and shade houses, Botrytis conidia are released in the atmosphere from mid-morning to mid-afternoon, coinciding with a rapid decrease in relative humidity. If conidia land on a leaf of a susceptible species of Hosta, but the environment is not favorable for infection, they may survive for up to three weeks and potentially infect and cause lesions even after the plants have been sold. Like many other plant diseases, botrytis blightrequires free moisture on the leaf surface to proliferate. Therefore, preventing the accumulation of free moisture for extended periods on leaves is critical to Botrytis management. Relative humidity should, if possible, be maintained below 85 percent by promoting conditions that enhance air circulation to prevent the formation of condensation on leaf surfaces. In shade houses, if plants are being watered overhead, the irrigation should be timed to allow plants to dry before evening. In addition, containers should be spaced far enough apart to promote air circulation and allow leaf drying to occur. Botrytis conidia will not germinate on dry leaves and will be unable to infect plant tissue and reproduce. Sanitation practices are important management techniques for the control of botrytis blight. Plants that already are affected should be isolated from tolerant varieties to reduce the amount of inoculum exposure to these plants. This should be done on calm days to avoid excessive agitation of diseased leaves. Botrytis can thrive on living and dead tissueand it is therefore important, where practical, to remove leaves that are diseased or senescent (mature). If leaves fall to the ground of the shade house or onto the potting medium, these should be removed, as this tissue is still a suitable host for infection if the environment is wet and humid. Diseased and senescent leaves should be collected and put into an enclosed trash container, as Botrytis still can produce conidia on dead tissue. Dead tissue should be disposed of at a landfill. Hostas that have severe cases of disease (lesions covering 50 percent of the leaves and with lesions all the way down the petioles) should be discarded. These plants should not be moved from their initial location, but should be placed gently into bags and sealed to prevent conidia from being released. Several fungicides have good efficacy, but must be chosen carefully as some strains of Botrytis are resistant and can grow and reproduce in the presence of some of the fungicides that had been effective. Protectant fungicides include chlorothalonil (Daconil), mancozeb (Dithane, Penncozeb, Manzate), fenhexamid (Decree), iprodione (Chipco 26019) and some strobilurins, such as azoxystrobin (Heritage). Ideally, fungicides should be applied as preventive controls. However, as many hosta growers may be unaccustomed to protecting their plants against Botrytis, curative strategies should include the cultural and sanitation practices described earlier. Heritage, if used, should be tank-mixed with one of the protectant fungicides, such as Daconil or Manzate, and used in alternation with a protectant fungicide every 14 days where botrytis blight has appeared. Because there are no documented cases of resistance to protectant fungicides,they should be used as the cornerstone of any crop protection strategy. Chlorothalonil products and Decree are the most effective protectants. In situations where Botrytis is a problem, full label rates should be applied at the minimum labeled frequency in enough water to attain effective cover to the foliage yet still allow some drying time. In situations where there is a history of botrytis blight, the protection program for hostas should be started approximately seven days after leaf growth resumes in the spring and continue through fall when the plants become senescent. The following bullet points summarize the steps that should be taken to prevent the establishment of Botrytis in hostas. Field-grown hostas
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| Controlling juniper scale Juniper shrubs can be sprayed for juniper scale in the first two weeks after crawler emergence, which will be sometime in June for most people. Horticultural oils work very well for armored scales like juniper scale when they are applied as a crawler spray. Choose a well known horticultural oil that can be used all summer long. Mix the oil in water at a 2 percent concentration and spray the junipers thoroughly for good coverage. One spray per year should keep juniper scale under control. |
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| Scouting for insects: Juniper scale Juniper scale: Carulaspis juniperi (view photos) Hosts: Juniper, arborvitae and chamaecyparis. An infestation of this armored scale causes off-color foliage, yellowing and dieback of juniper needles. Severely infested junipers may have little to no new growth. Female scales overwinter as adults with eggs; there is one generation per year. Look for crawler emergence beginning early to mid-June, around the time Washington hawthorn or Japanese tree lilac is in bloom. Management: Several parasitic wasps are among the natural enemies of juniper scale. The overwintering adult female is vulnerable; otherwise the crawler stage should be targeted for treatment with insecticides. Diane Brown-Rytlewski's articles are excerpts from "A Pocket IPM Scouting Guide for Woody Landscape Plants." |
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| Scouting for disease: Cytospora canker Cause: Cytospora kunzei (fungus) (view photos) Hosts: The primary host is Colorado (blue) spruce. Other spruces, Douglas-fir, balsam fir, red and white pines, hemlock and larch are infrequently attacked. Symptoms: Wood under the cankered areas of the bark is dark and resin-soaked, compared with light-colored, healthy tissue. How it’s spread: The fungus overwinters in twig and branch cankers. Spores released from fruiting bodies during the growing season infect other branches, particularly at wound sites. Trees 15 to 20 years old (or older) suffering from drought, compaction or poor site conditions are prime targets. Trees aren’t usually killed outright, but the loss of major branches destroys the ornamental value of the tree. Management: Improve tree vigor; a layer of mulch around the base retains moisture and helps protect lower branches from wounding by lawnmowers. Keep trees watered during drought periods. Prune out diseased branches when the foliage and wood is dry; clean tools with bleach or other disinfectant after cutting out diseased wood and before cutting healthy tissue. |
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| Last call for spring basal soil drenches and trunk injections for emerald ash borer Emerald ash borer adult beetles were observed in many locations this week. Most of the research tests using imidacloprid as a basal soil drench, basal soil injection or trunk injection were done with applications being made in April, May or early June. So that insecticide would be present in trees during the period of adult feeding in June and early July, as well as when the larvae are feeding under the bark from July to October. Although later treatments may also work, we don’t have as much information on efficacy of late June and July treatments. The same concept applies to dinotefuran, another nicotinoid insecticide used as a trunk spray, trunk injection or drench. Tempo, Sevin or Onyx foliar sprays can still be applied as two applications; one in early to mid June and a second one in late June. |
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| Cottony maple scale and Lecanium scale on silver maple, honeylocust, oak and some ornamental Prunus spp. Cottony maple scale females are all puffed-up with white cottony egg masses now. The crawlers should begin to emerge in the next two weeks. Lecanium scale females have also produced eggs, which will be hatching soon. These two soft scale insects rarely reach populations dense enough to damage trees. Outbreaks on street trees are usually associated with mosquito spray programs and other insecticide sprays. Even so, tree injury is rare. However, honeydew drippings from scales in the spring and late summer can sometimes be a problem, and occasionally trees will begin to weaken and the foliage will become noticeably thinner. We are in need of more tests on which products give the best control of cottony maple scale and Lecanium scale. At this time. I am still hesitant to suggest particular products. If you have had good success treating for one of these scales, I would like to hear about it. For woodlots and other areas where no sprays are made, the outbreak will only last a year or two, and then will subside without any injury to the trees. |
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| Honeylocust plant bug injury continues for another week The bad news is that this past week the injury from honeylocust plant bug to honeylocust trees continued to grow more severe, causing substantial defoliation of trees (see photos). The good news is that the injury should draw to a close over the next two weeks, and trees will begin to recover and push out new leaves. Spraying trees at this point may allow trees to recover more quickly, but I expect all the trees to recover quickly after mid-June even without spraying. So, by July 1, the honeylocust trees should be looking much better. |
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| Clover, medic, and fertilizing Recent scouting of the landscape has revealed some pesky weeds invading turf. I’ve noticed some really healthy patches of both white clover (Trifolium repens) and black medic (Medicago lupulina). Thinking of the recent TV show about being smarter than a fifth grader, hopefully everyone knows how to identify white clover as it is one of the most commonly observed weeds in turfgrass. However, black medic could be a little trickier and may be confused with oxalis (Oxalis stricta). Oxalis is commonly referred to as yellow woodsorrel. Oxalis is similar to white clover in that it has the three-leaf cluster, but the leaves are almost perfectly heart shaped and have smooth edges. Oxalis can also be easily distinguished from clover by its yellow flowers. The flower could be described as resembling a miniature yellow daisy with petals. Black medic also has the three-leaf cluster, but its center leaf is on a small stalk and it lacks the water stain mark that is on the clover leaves. Another distinguishing characteristic of black medic that is currently present is the small ball-like yellow flowers. The flowers are about the size of a pencil eraser and have no distinct petals. If you’re looking for further help in identifying the weeds go to http://www.msuturfweeds.net Weeds are typically indicator species. They may indicate compact soils, shady conditions or low fertility just to name a few. So what stories are white clover, black medic and oxalis trying to tell. White clover is a natural nitrogen fixer, and although it is certainly wide spread throughout may different turf situations, I recently drove by a commercial building with an under fertilized turf and was not surprised to see the turf dominated by large patches of flowering white clover. Simply providing adequate nutrition for the turf will help the turf compete with the white clover. Black medic is very similar to white clover in that it often invades turf that is under fertilized. Oxalis is a little different from white clover and black medic in that it is a late germinating summer annual, so if you applied any herbicides earlier this spring to take out clover, the oxalis would have escaped simply because it was not present. It seems to have developed a nice niche for avoiding the early season broadleaf herbicide applications and then germinating in the voids created by killing those weeds. Controlling oxalis with the traditional 2 and 3 way broadleaf herbicide formulations can be difficult. Products containing triclopyr should be effective for controlling oxalis, black medic and white clover. In many cases, spot treatment of trouble areas can be conducted in lieu of treating the entire turf area. Keep in mind that treating these weeds at this time of year can be difficult and if you can sign some sort of truce with the weeds to make it through the summer, your best time for treatment is in the fall. With our mild and wet weather we’ve been experiencing lately, the weeds are really enjoying life and any herbicide application may initially damage the leaves, but there is so much food stored up in their roots that they can recover quickly and fight on. The best time to treat is in the fall when the weeds are starting to store carbohydrates in their roots for next year and any herbicide application will be more readily transported to the roots and effectively kill the weed once and for all. Fertilizing and red thread The abundant rainfall and prime growing conditions throughout many areas of Michigan has resulted in the turf using up any spring fertilizer applications rather quickly. I’ve noticed red thread disease popping up on golf course roughs and in home lawns. Red thread is typically indicative of low fertility, just like the clover and medic we mentioned earlier, applying a fertilizer application will help the turf out-grow the damaged areas. At this time of year, I would either apply a fertilizer that has slow release nitrogen, or if you’re going to use a fast release nitrogen fertilizer, apply it at a rather modest application rate such as 0.5 lb. N/1000 ft.2. The weather is sure to heat up sooner or later, and you don’t want to create a flush of growth from a fertilizer application just as it gets really hot and humid. That’s a recipe that will make the turf susceptible to heat stress and disease infestation. |
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| Christmas tree update Bird damage Each year we will find new growth on terminal shoots dead and hanging on the leader. At first glance, it looks like some insect may have girdled the shoot. However, these broken treetops are caused by birds perching on newly developed shoots. (view photo) Breakage typically occurs this time of the year when the new tops are elongating, before they are stiff enough to support a bird perching. We seem to see this damage more on blue spruce but have seen it on Fraser fir, Norway spruce and other conifers. Taller trees seem to be more affected, as the birds look for higher vantage points. Consider scouting for pine tortoise scale If you have Scotch pine trees with moderate or high populations of pine tortoise scale, you need to start scouting your trees. Pine tortoise scale is the reddish-brown, roundish scale that feeds on the woody part of pine shoots and small branches. It excretes amazing amounts of sugary honeydew. Black sooty mold then grows on the honeydew that coats the needles and branches. Remember to slow down and use lots of water to get full coverage of the trees. |
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| Gypsy moth spray window dates Growers should note that the spray window for all other compounds Zone 1 will be closed June 11. We are now estimating that the spray window for Zone 2 will be that all other compounds will be closed on June 16; and, the spray window for Zone 3 - Dimilin will be closed on the same date. Growers should pay close attention to degree day accumulations and larval development in their area. The 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. Always monitor development around your farm as local conditions can affect gypsy moth development. Watch the Landscape CAT Alert next week for any new announcements of possible early closing dates for other zones.
** Projections - based on 30 year historical degree day data unless otherwise noted. |
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| Powderpost beetles – The other, other wood destroying insects I routinely get calls requesting information on powderpost beetles. These calls are usually from people interested in preserving old barns, people with Michigan basements or people who discover piles of powder under a recently purchased piece of furniture or artwork. Unlike termites, which leave very little external evidence of their activity, powderpost beetles provide tell-tale signs of theirs. As their common name suggests, powderpost beetles often leave a pile of very fine powder under the wood in which they are feeding. The powder sifts out of the wood through the emergence holes chewed by new adult beetles exiting the wood to find mates and lay a new generation of eggs. These small, (less than 1/8 of an inch) round holes are another sign of a powderpost beetle infestation. The term powderpost beetle can refer to several species of wood-destroying beetles that belong to three (now two) different families of beetles: Lyctidae (formerly), Bostrichidae and Anobiidae). Only lyctid powderpost beetles produce the fine white powder that gives this group of beetles their common name. Anobiids or deathwatch beetles do not produce piles of powdery frass. They pack their frass in their feeding galleries. Powderpost beetles are second only to termites in their ability to destroy wood in structures and furniture. They are capable of re-infesting dry, seasoned wood year after year. The interior of the wood that is repeatedly attacked is completely riddled with holes and galleries packed with the powdery frass. Powderpost beetles can infest any untreated or non-sealed wood article. Some species only attack hardwoods, while others feed only on softwoods, and some species will feed on both. Under normal conditions, powderpost beetles require about a year to complete their development. However, if the wood has a high moisture and starch content, development may be completed in six months. The moisture content of the wood is a very important factor in managing powderpost beetles. Wood should be maintained below 20 percent moisture content to reduce its suitability to powderpost beetles. Some experts believe if the wood is kept dry enough, then no insecticide application is necessary, but I’m not sure that I agree with this. Powderpost beetles can also be controlled by sealing the surface of the wood with shellac, paint or varnish which discourages female powderpost beetles from laying eggs on these surfaces. Chemical control of powderpost beetles includes three options. Fumigation with a penetrating gas (like methyl bromide) is the most effective means of chemical control, but it is also the most expensive, and in most cases, prohibitively so. Fumigants are the most dangerous type of insecticide and can only be applied by a professional applicator with special certification. Insecticide sprays applied to wood surfaces are also effective in controlling powderpost beetles. Tempo (cyfluthrin) and two borate products called Bora-Care and Tim-Bor are the only registered insecticide sprays that can be used in occupied structures. Borates can be applied at anytime, but two applications are required to provide effective control. Borates must penetrate the wood to be effective, therefore, it should not be used when the wood to be treated has been painted or sealed with polyurethane. Bora-Care can be purchased from an outfit in Maryland called PRG (short for Preservation Resource Group) at (301) 309-2222. If you interested in Bora-Care, call these folks and they will send you a brochure about their product line or see them on the web at http://www.prginc.com. Tempo (cyfluthrin) is also available under the brand name Bayer Advanced Garden Insect Control or Bayer Advanced Home Insect Control. It must be applied just before the adult beetles emerge in late spring to be effective. Tempo should be applied in mid-May and again around the first of August. Eye goggles are a must when treating for powderpost beetles when you will be spraying areas above your eyes. Provide good ventilation when applying any insecticide indoors. Be sure to read and follow all the instructions and safety precautions found on the pesticide label before using any pesticide. |
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| Confused Cooley spruce adelgids in Jackson County Jill O’Donnell sent in a rather odd sample of what we both believe is Cooley spruce adelgid (view photos). I should note here that odd samples from Jill O’Donnell are nothing new to the lab. This sample of Cooley adelgids is odd because at this time of year the adelgids that feed on blue spruce should be in their newly formed galls at the end of this year’s new growth. This adelgid also utilizes Douglas Fir as an alternate host with winged females migrating back and forth between hosts. The adelgid does not cause galls to form on Douglas fir. They simply stick their needle-like mouthparts into a needle and suck on the juices. This feeding can result in yellow spots on the Douglas fir needles. Jill reported that the blue spruce sample came from a Christmas tree plantation in Jackson County in which the blue spruce was planted right next to a block of Douglas fir. Hundreds of blue spruce planted next to hundreds of Douglas fir, should be considered beneficial to the well-being of Cooley spruce adelgid. My best guess is that a portion of the winged female adelgids that were supposed to lay their eggs on Douglas fir simply became confused by the close proximity of so many of their alternate hosts and laid their eggs on blue spruce. |
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| Weather news A cold front trailing southward from an area of low pressure in central Ontario will move eastward through Michigan by late Friday. Scattered showers and thunderstorms ahead of the front will quickly come to an end in far eastern sections of the state by early evening. High pressure behind the front will move in for the weekend, leading to mostly fair and seasonably warm conditions Saturday and Sunday and likely early next week as well. A second, weaker cool front will approach the Upper Peninsula by late Sunday, bringing the chance for a few widely scattered showers to northern sections of the state, otherwise dry conditions are expected to continue through the weekend. Temperatures will fall back to near or slightly below normal levels early in the weekend, warming to near normal levels by Monday of next week. Highs by Sunday will generally range from the low 70's north to the low 80's north with lows in the 50's to low 60's. Rainfall will be possible once again by Wednesday, possibly continuing through the latter half of the week. Further ahead, medium range forecast guidance is consistent in calling for the formation of an upper air troughing feature across western sections of the United States with a ridge across the east. This would leave Michigan under southwesterly flow aloft with an active storm track across the Midwest. The official NOAA 6-10 day and 8-14 day outlooks for June 12-16 and June 14-20 call for above normal mean temperatures statewide. Precipitation during the 6-10 day period is forecast to range from near normal levels in Lower Michigan to above normal levels in the Upper Peninsula. During the 8-14 day period, precipitation to forecast to fall back to below normal levels over all of the state except for western Upper Michigan, where normal totals are expected. |
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