Pam Bennett, Barb Bloetscher, Joe Boggs, Jim Chatfield, Erik Draper, Dave Dyke, Dave Goerig, Tim Malinich, Jane Martin, Hannah Mathers, Pam Sherratt, Amy Stone, and Curtis Young
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July 28, 2005
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This is the Seventeenth 2005 edition of the Buckeye Yard and Garden Line (BYGL).
BYGL is developed from a Tuesday morning conference call of Extension
agents, specialists and other contributors in Ohio.
BYGL is also made available on the Internet from the Ohio State University
Horticulture and Crop Science (HCS) in Virtual Perspective website
(http://bygl.osu.edu). Additional fact sheet information on any of
these articles may be found through the OSU fact sheet database (http://plantfacts.osu.edu).
BYGL is a service of OSU Extension and is aided by major support
from the Ohio Nursery and Landscape Association (ONLA), with additional
funding from the Ohio Chapter of the International Society of Arboriculture
(ISA) to the OSU Extension Nursery Landscape, and Turf Team (ENLTT).
Participants in the July 26, 2005 conference included: Pam Bennett (Clark); Barb Bloetscher ©. Wayne Ellett Plant and Pest Diagnostic Clinic-CWEPPDC); Joe Boggs (Hamilton/Piketon); Erik Draper (Geauga); Dave Dyke (Hamilton); Amy Fulcher (University of Kentucky, Department of Horticulture), Dave Goerig (Mahoning); Dave Shetlar (Entomology); Amy Stone (Lucas); Nancy Taylor (CWEPPDC); Curtis Young (Allen); and Randy Zondag (Lake)..
Additional factsheet information on any of these articles may be found
through the OSU Factsheet Database (http://plantfacts.ohio-state.edu/)
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WEATHER WATCH
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Are you watching the weather? Warmer than normal temperatures continue across much of Ohio. If you are watching the calendar, another month is coming to an end. Soon our hot summer temperatures will turn cold and we will be wishing for more sun. Enjoy the hot dog days of summer while they are here!
Here are the weather summaries from selected OARDC weather stations across the buckeye state. The information is a summary of data collected from July 1 July 27.
| Weather Station |
Region of Ohio |
Ave. High Temp F | Ave. Low Temp F | Ave. Temp F | Normal Ave. Temp F | Total Precip " | Normal Precip " | | Perry |
NE |
83.9 |
65.7 |
N/A | N/A |
5.93 |
N/A | | Hoytville |
NW |
87.9 |
63.6 |
75.0 |
72.9 |
6.65 |
3.38 |
| Columbus |
Central |
87.6 |
67.4 |
77.2 |
74.1 |
3.88 |
4.11 |
| Miami |
SW |
87.5 |
67.8 |
77.0 |
74.0 |
3.19 |
3.46 |
| Jackson |
South |
87.7 |
66.3 |
76.1 |
73.5 |
3.00 |
3.92 |
For additional information, or to see the locations of all of the OARDC weather stations in Ohio, check out the website at [ http://www.oardc.ohio-state.edu/centernet/weather.htm ].
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HORT SHORTS
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PLANTS OF THE WEEK
Read all about perennials and landscape trees and shrubs in the new publications "Perennial Plants for Ohio" and "Landscape Plants for Ohio" published by the Ohio Nursery & Landscape Association (ONLA). The descriptions and photographs of plants were provided for this new publication by the OSU ENLT Team along with other industry plant lovers. These full-color publications are available for $5.00 at the following web site: [ http://www.buckeyegardening.com/ ]. Click on "garden store" and then "onla plant guides." ONLA members can purchase these in quantities at a reduced price at onla.org
* PERENNIAL OF THE WEEK - Heliopsis helianthoides or False sunflower. These overlooked plants provide great color in mid-summer. The bright yellow, daisy-like flowers grow on tall stems and are excellent in full sun. The cultivar ‛Summer Sun' is one of the most popular and ‛Loraine Sunshine' has green and white leaves that add color to the garden after the flowers fade. Excellent for use in hot, dry areas to provide a splash of color.
* WOODY PLANT OF THE WEEK - Hydrangea spp. Join other gardeners in the confusion of hydrangeas - what is what? The "Landscape Plants for Ohio" guide is an excellent resource to help sort through the types of hydrangeas and their requirements. From the smooth (H. arborescens) to the bigleaf (H. macrophylla) to the oakleaf (H. quercifolia), and more, you can learn when they bloom as well as the size and shape of the bloom and plant.
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COMMUNITIES IN BLOOM UPDATE
Pam Bennett reported on some of her travels while judging the International Small category for this competition. Judges visit a community and evaluate them on the following categories: Tidiness, Environmental Conservation, Heritage and Natural Resource Conservation, Community Involvement, Landscapes, Floral Displays, Urban Forestry, and Turf. The winner of this category is announced at the awards ceremony in September in Saskatoon, Saskatchewan.
As a judge, Pam is able to see wonderful and unique horticultural aspects around the world. For instance, what a surprise for a mid-westerner to see tree-lined streets in Boissevain, Manitoba. No big deal, eh? They were all American elms. That was a first for Pam.
In Rancho Santa Fe, California, which is located within an active forest fire zone, they are concerned about planting tree and shrub species that easily catch fire. A challenging question for this community is what to do with their established urban forest canopy that consists primarily of eucalyptus trees, an extremely flammable plant. These were planted back in the early 1900's when the mayor was interested in planting a tree that would help the area economy thrive. He sent someone to Australia to find the fastest-growing and straightest eucalyptus tree. They planted hundreds of trees on the ranch and thought that this was going to be a great boost for the area as these trees would be sold to the newly developing railroad for ties. However, little did they know that creosote was about to be invented, causing the entire project to flame-out. It did however, leave Rancho Santa Fe with a beautiful canopy of trees. And now they have come full circle again to the agonizing question of whether or not to remove these trees because of fire hazards. Isn't horticulture grand?????
If you are interested in learning more about the America in Bloom or CIB programs or interested in becoming a judge, contact Pam at [ pjbennett@ag.osu.edu ].
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WATCH YOUR PINES!
Dan Herms noted that Ohio weather patterns this year are very similar to those experienced in 1999. During that year, prolonged drought and onerous heat caused many conifers growing in undesirable locations to suffer stress and become susceptible to bark beetles. Although the primary bark beetle species in Ohio (Ips spp. and Dendroctonus spp.) do not attack healthy trees, the burrowing of the larvae under the bark, loss of sap, and diminished nutrient uptake add the final drop of doom for conifers already stressed by poor environmental or cultural conditions.
To improve the chance of pines, spruces, and firs surviving these insufferable periods, plant them in well-drained, but deep, organic soil, or amend the soil with organic matter before planting. Do not plant where the root zones will be inhibited in a few years or plant in low, wet areas or in hot, dry clay soils. Plant at the correct level and remove burlap, when possible. When forced with maintaining a tree already sentenced to stress, place 1-2" of mulch under the drip line and soak the soil at least every 14 days. Avoid digging near the root zone and treat for disease and insect problems.
Bark beetles can detect chemicals emitted by stressed trees, and will release their own aggregation pheromone once they find a good tree to call more bark beetles to the tree. The resultant attack of beetles enmasse and extensive tunneling from the larvae often leads to the eventual death of the tree.
To prevent conifer bark beetle infestations from occurring on specimen landscape pines, it is recommended that landscapers consider spraying the trunks of stressed evergreens with tree borer formulations of bifenthrin (e.g. Astro), or permethrin (e.g. Onyx) around August 1, before the next large generation of adults emerges. However, if trees are already infested with bark beetles, or are in such an acute state of decline that no cultural practices will revive their health, bark applications of insecticides will not prevent the eventual death of the tree.
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HOGWEED HIDEAWAY
The U.S. Department of Agriculture's (USDA) Animal and Plant Health Inspection Service (APHIS) regulates and monitors the whereabouts of noxious and invasive plant weeds as one of its many services. Dave Goerig reported that a sample of one particularly noxious weed, known as giant hogweed (Heracleum mantegazzianum), was recently brought into the OSU Extension Mahoning County office for identification.
Giant hogweed was introduced into this country from Eurasia. Currently, it is known to be growing in New York, Pennsylvania, and Washington, although reports of possible infestations have been received from Maine, Michigan, and Washington, D.C. Because this weed is listed as a federal noxious weed, it is illegal to bring this plant into the country or to move it across state lines.
Gardeners, landscapers, and nurserymen should exercise extreme caution around this plant: the plant's juices can cause phytophotodermatitis to the skin. If the plant's sap comes in contact with the skin in the presence of sunlight, a severe rash and/or blistering can occur. Indeed, the poor gardener who provided the sample to the Extension office was suffering from extensive skin blistering for which he was receiving medical attention. He had brought in the sample to learn the name of the weed responsible for his misfortune.
Giant hogweed is a herbaceous dicot plant and can be either a biennial or a perennial. It often colonizes close to the original site where it was introduced relying on its large, compound leaves to shade-out competing plant species. As a member of the Apiaceae (Umbelliferae) family, the inflorescence appear in the shape of umbrellas when in full bloom, and retain that shape as each of the little flowers are pollinated and begin to produce seed. The giant hogweed inflorescence is similar in appearance to other members of the Apiaceae family, such as wild carrot (Daucus carota) and cow parsnip (Heracleum lanatum).
When in full bloom, giant hogweed stands as much as 10 - 15' tall and produces flower heads up to 2 1/ 2' in diameter. The stems on this giant are hollow and generally measure 2 - 4" across. Cow parsnip and wild carrot may look similar to this weed, but their heights and inflorescence sizes rarely reach half the size of hogweed.
Extreme caution should be taken when eradicating this plant. If using hand cutting methods, remember to wear long sleeve clothing and face shields. Warn others standing at the site to keep a clear distances from power cutting tools and brush cutting mowers as the sap spray is toxic. Launder all work clothes separately from other clothing. Most herbicides labeled for the site of application will control this weed; however, multiple applications may be required. Always read and follow label directions.
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BUG BYTES
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BALDCYPRESS RUSTING
Joe Boggs reported that the handiwork of the BALDCYPRESS RUST MITE (Epitrimerus taxodii) is becoming evident on its namesake host in southwest Ohio. Damage observed thus far ranges from a subtle off-coloring of the foliage on trees with low populations to a very obvious reddening of the foliage on trees with heavy infestations. Baldcypress in nurseries as well as high-profile specimen landscape trees should be monitored closely since populations of this "warm-season" eriophyid mite can explode during periods of hot, dry weather. Their collective feeding activity can quickly turn green, healthy trees into rust-colored wrecks!
As with other eriophyid mites, the baldcypress rust mite is almost microscopic in size. Standard 10X and even 20X hand lenses render images of the mites that look like moving specks of dust. Under 40X magnification, the mites come into sharp focus and their unusual body arrangement can be seen. The mites cream-colored, semi-translucent bodies are carrot or spindle-shaped. They only have two pairs of legs which are clustered at the front end of the mite. No other mite has only two pairs of legs at any stage in their development.
The baldcypress rust mite is called a "free-living," or "leaf vagrant" eriophyid because it makes a living on the surface of the plant. Many mites in the Eriophyidae family are gall makers, and live inside plant structures. Baldcypress rust mites crawl over the surface of the needles, rasping through the epidermis and extracting the cell contents below. Under high magnification, the damage appears at first as distinct greenish-brown, sunken areas in the leaf tissue. Once these areas coalesce, they become apparent to the naked-eye as very fine greenish-brown spots, or stippling. The needles eventually become yellowish and then reddish brown or rusty in color. The tiny mites are susceptible to being washed from the outer foliage of the tree, so inner foliage generally affected first. Heavy populations eventually cause the entire tree to become orangish-red, and defoliate.
Unlike spider mites, eriophyids can be controlled with many standard insecticides including carbaryl (e.g. Sevin). Pyrethroid insecticides are also effective, as well as the miticide abamectin (e.g. Avid). Although horticultural oils are effective on free-living rust mites attacking other trees and shrubs, baldcypress is extremely sensitive to these oils; foliar damage from the oils far outpaces the potential destruction caused by the mites. For a list of effective materials consult OSU Extension Bulletin 504 titled, "Insect and Mite Control on Woody Ornamentals and Herbaceous Perennials" [ http://ohioline.osu.edu/b504/index.html ].
Borrowing from nature, baldcypress rust mite populations can be reduced on small trees using a concentrated stream of water from a garden hose to wash the mites from the trees. The water should be directed at the top of the tree first, then moved down the tree to wash the mites toward the ground. This control approach must be repeated at weekly intervals to prevent populations from building to damaging levels.
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SUMMER CATS MEOW
In BYGL 2005-13 (06/28/05), Dave Shetlar reported that landscapers should soon expect to see several species of general defoliating "summer caterpillars," such as WALNUT (Datana integerrima), and YELLOWNECKED CATERPILLARS (D. ministra). His prognostication came true, with Dave reporting this week that caterpillars of both of these species of moths are being found in central Ohio.
Caterpillars of both species feed gregariously in colonies. First instars feed as leaf skeletonizers, and later instars consume entire leaves. The colonies typically focus their attention on defoliating one branch before moving to another. Small trees with multiple colonies can be rapidly defoliated. The seasonal impact of these general defoliators is amplified by the occurrence of at least two generations, with yellownecked caterpillar moths occasionally producing a late season third generation in the southern part of the state. The apparent "disappearance" of the caterpillars between generations may lull landscapers into a false sense of security; it may only be the calm before the storm!
The yellownecked caterpillars feed on a wide variety of trees including: crabapples and other ornamental fruit trees, oak; maple, elm, beech, linden, honey locust, and boxwood. Walnut caterpillars possess an equally impressive cosmopolitan palate; however, they are most often found on oaks. Caterpillars of both species pass through different "color phases" during their development. The color motifs may cause individual caterpillars to stand-out. On the other hand, collectively the color patterns allow colonies to blend with the surrounding foliage of their hosts.
Early instar walnut caterpillars are yellow. Later instars are brick red with faint white stripes. Caterpillars in the final instar stage are grayish black with long, soft white hairs. The caterpillars practice an unusual molting behavior. They group together on the bark of their host tree and they all molt at the same time, leaving behind a mass of hairy exoskeletons that looks like a patch of fur.
The yellownecked caterpillars have black heads, and a bright orange "neck, or prothorax, that gives them their common name. First instar caterpillars are copper-colored with no distinct lines. Second instar caterpillars have distinct alternating longitudinal yellow and orangish-red lines. Caterpillars in the final instar stage have alternating longitudinal black and yellow lines. Although all instars have hairs, they are most evident during the last instar stage.
Early instars of both species are susceptible to the biological insecticide, Bacillus thuringiensis or Bt (e.g., Dipel, Thuricide, or Caterpillar Attack). More traditional insecticides are needed to control later instars. However, a much more direct (satisfying?) approach to controlling these general defoliators is to knock the caterpillar colonies to the ground and perform the "caterpillar dance." Thus far, there have been no reports of populations of these moths developing resistance to this control method.
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APHIDS WINGING THEIR WAY
Aphids might be moving from farms into your air space in the near future. Although this is a little out of our normal area of coverage, it may have impacts on non-agricultural folks just as much as farmers. The aphid that typically causes the most excitement is the ASIAN SOYBEAN APHID, Aphis glycines.
Since its recent introduction, this non-native aphid has become widespread throughout the Midwestern U.S. and Canada. This year the aphid populations are rapidly building in soybean producing areas of Ohio and other midwestern states. At times the aphid populations will produce massive numbers of winged individuals which will disperse to new locations, often being carried by wind currents into non-agricultural areas.
This Asian invader has gone as far as to interfere with Americas favorite sport, baseball. Infestations in eastern Michigan and southern Ontario were so severe in 2001 that a mass migration of the winged version of the aphid invaded the Toronto Blue Jays' retractable-roof baseball stadium and caused a game to be delayed. By closing the roof and reversing the stadium air system, the aphids were expelled and the game restarted. Others reported clouds of this aphid floating through urban centers throughout the Midwest, making walking outdoors a very unpleasant experience. People walking outdoors complained about the aphids landing all over their bodies, getting trapped in their hair, and being sucked up their noses as they tried to breath.
The soybean aphid is a small, yellow aphid with distinct black cornicles (tail pipes out of the back of the abdomen). The aphid has a complex life cycle with as many as 15 - 18 generations each year. Two very different types of host plants are required for the soybean aphid to complete its life cycle. The aphid spends the growing season feeding and reproducing on soybeans; then it overwinters as an egg on buckthorn (Rhamnus ssp.) plants.
High populations of the Asian soybean aphid have been linked during past seasons with high populations of another non-native nuisance pest: the multicolored Asian lady beetle, Harmonia axyridis. Thus, this is a forewarning to be prepared!
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ZIMMERMAN PINE MOTH
The larvae of this moth are nearing their completion of the larval stages and will soon be pupating. The caterpillars are about an inch in length at the current time and are feeding heavily on host pines, resulting in heavy pitch flows from the wounds produced by the larvae. Typical pitch masses produced by the Zimmerman pine moth, Dioryctria zimmermani, are creamy yellow to white in color, and peppered with the reddish-colored sawdust-like frass of the caterpillar.
Curtis Young and Joe Boggs taught at the Ohio Christmas Tree Associations (OCTA) Summer Meeting held this past weekend in Whitehouse, Ohio, where they pointed out the effects of the Zimmerman pine moth on a Scotch pine. Curtis pulled off the pitch mass to discover one of the large caterpillars in one of the tunnels that exist within the mass, suggesting that it was preparing to pupate. At this point, the action of scraping off the glob of pitch and stabbing the pinkish larvae that may be found underneath may be the only method of successfully reducing an infestation. Of course, this is only practical on relatively small trees.
The Zimmerman pine moth typically attacks Austrian, red and Scotch pines, but can also be found on a number of other pine species, including Eastern white pine. The moth preferentially infest host trees at branch crotches and margins of wounds found on the trunk and branches. Infested branches may break easily during wind and ice storms. Dead and dying branches, most often in the upper half of the tree, commonly indicate infestations.
The time of year that Zimmerman pine moth is most vulnerable to controls is when larvae are active and exposed on the bark in spring and, to a much lesser extent, in late summer. Drenching trunk sprays, especially around branch collars, that can penetrate the bark scales produces a protective layer to prevent the young larvae from establishing successfully. Apply the trunk drenches around mid-April or in August to kill active, exposed larvae before they enter tree trunks. See OSU Extension Bulletin 504, "Insect and Mite Control on Woody Ornamentals and Herbaceous Perennials" [ http://ohioline.osu.edu/b504/index.html ] for recommend insecticides to control the Zimmerman pine moth.
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PURPLE SPOTTED BLACK-EYED SUSAN
A black-eyed Susan, Rudbeckia hirta var. pulcherrima was submitted to the CWEPPDC with purple spots on the leaves. Microscopic examination revealed tiny psyllid nymphs in the green, raised "pockets" of these purple spots that were sucking nutrients from the leaves. As these RUDBECKIA PSYLLIDS ingest the sweet sap, they insert saliva into the leaves, causing the purple spots.
Although relatively harmless to the plants, populations can be reduced by removing and destroying infested leaves, or by squashing nymphs within the leaves as soon as the purpling symptom appears. Insecticide treatments are seldom warranted. Nymphs in the Clinic sample had already finished development and departed from their feeding sites. Thus, it is too late to apply control tactics this season.
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OUTDOOR FUN KILLED BY CICADA KILLERS
While Curtis Young and Joe Boggs were at the OCTA Summer Meeting, they noticed that the volleyball court was conspicuously empty. A closer inspection quickly revealed why: the court was literally buzzing with cicada killer wasps, Sphecius speciosus. Females of this wasp prefer to dig their brood burrows in sandy, bare, well drained soil exposed to full sunlight; this perfectly describes the volleyball court!
There were around 30-40 cicada killer wasps hovering and zooming around the court inches above the ground and there were a multitude of excavations into the court, indicating where the brood chambers were being dug. The wasps have a black body marked with yellow to white patches on the first three abdominal (rear part) segments. The head, thorax and legs are rusty red and the wings russet yellow (brownish).
Although quite impressive because of their size (1 1/8 - 1 5/8" long), the wasps flying around the court were harmless because they were all males; all buzz but no sting. Male Hymenopterans are incapable of stinging, only females can sting because the stinger is an ovipositor (an egg laying structure).
These wasps are solitary wasps, but they can be found in large numbers around preferred nesting sites. Other sites where these solitary wasps may become a nuisance include home lawns, flower beds, gardens, and golf course sand traps. Adult cicada killers are active for about 60-70 days from early-July through mid-September. There is only one generation per year.
Most of the time the cicada killer does not need to be controlled. In home lawns, cultural practices can prevent or eliminate the establishment of cicada killer groups. Cultural practices that promote a thick growth of turf usually eliminate a cicada killer infestation in one or two seasons. In cases of severe infestation, chemical control may be necessary to prevent danger from these stinging wasps.
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DISEASE DIGEST
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GREEN GRAPES GONE BAD
Erik Draper reported that calls have started to pour into his county office regarding unhappy backyard grape growers. Just as the connoisseurs were beginning to count their future bottles of homemade wine, little brown spots began to appear on the green grapes. The brown spots enlarge turning the whole grape brown, then black, and finally causing the entire grape to shrivel-up just like a raisin. These symptoms are a classic description of the fungal disease called BLACK ROT OF GRAPES. The pathogen, Guignardia bidwellii, overwinters in lesions on canes, tendrils and fruit mummies.
This fungal disease is favored by warm, humid weather, which has been around most of this summer; at least it seems that way. The first symptoms of black rot appear as small yellowish spots on leaves. As the spots or lesions enlarge, a dark border forms around the margins and the centers of the lesions become reddish brown. In about two weeks, the lesions reach 1/8-1/4" in diameter and small black dots begin to appear inside the lesion. These are fungal fruiting bodies called pycnidia and they contain thousands of spores called conidia. Pycnidia are often arranged in a ring pattern, just inside the margin of the lesions.
Lesions from infections may also appear on young shoots, cluster stems, and tendrils. These lesions are purple to black, oval in outline and sunken. Fruit symptoms often do not appear until the berries are about half grown. Small, round, light-brownish spots form on the fruit. The rotted tissue in the spot softens, and becomes sunken. The spot enlarges quickly, rotting the entire berry in a few days. The diseased fruit shrivels, becoming small, hard, black and wrinkled and are called mummies. Tiny black pycnidia also form on the fruit mummies. The mummies usually remain attached to the cluster.
Getting control of this grape disease involves good sanitation techniques, like proper pruning of grapevines and removal of the leaves and mummies in the fall. Only certain fungicides, like ferbam, mancozeb and azoxystrobins, are effective in controlling this grape plague. The timing of sprays is also very important to achieve control. This fungus will only infect green, unripened grapes; therefore fungicide applications should begin at shuck (petal) fall and continue until verasion, when grapes begin to show color.
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MESSING WITH MAPLES
Nancy Taylor reported that the CWEPPDC received three maple samples on which she identified Steganosporium ovatum, or TWIG BLIGHT OF MAPLES. Steganosporium is usually associated with maple decline and affects mainly sugar maple (Acer saccharum), Norway maple (A. platanoides) and red maple (A. rubrum) in the northeast U.S.. Though not a primary pathogen, Steganosporium favors attacking weakened or stressed trees as a secondary pathogen and may ultimately finish off the tree. These maple tree stresses include successive years of defoliation by insects, drought, de-icing salts, and/or road and sidewalk construction.
In a forest setting, decline of maples often occurs after several successive years of defoliation by insects. Large numbers of defoliating insects can strip a tree of the first set of leaves and the tree will then have to utilize valuable food reserves to produce a second set. During and after the push to re-foliate the tree, chemical changes occur in the tree that increase its susceptibility to secondary pathogens, like Steganosporium, or Armillaria mellea (root rot), and/or Nectria cinnabarina (branch canker).
In sugarbushes, predisposing stresses include drought, heavy grazing, over-tapping, and/or heavy traffic by farm machinery. Seriously affected trees are often over-mature and have been heavily tapped for many years. Tapping holes, animal-damaged roots, and machine-damaged roots are all routes for entry of wood decay organisms. Tree decline and death often results from stresses adding up, or being compounded by one another.
The best defense against secondary disease-causing pathogens is to keep maples clean, green, and growing. There is much to be said for "put the right plant in the right place" philosophy. Trees that are actively growing create their own defenses against these opportunistic pathogens and rarely are they overwhelmed by them. Maintain healthy trees by making certain they receive adequate moisture during dry periods. Other cultural practices, like proper fertilizing and pruning, are also of great benefit in helping to keep those trees active and growing.
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TURF TIPS
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THE BROWNING OF OHIO
Calls about turfgrass turning brown have been common since the intense heat punctuated Ohio. Although the browning turfgrass can be due to many abiotic factors, as well as insect and disease, the latest samples received by the CWEPPDC from high-cut grass areas have consistently contained a reoccurring problem: ROUGHSTALK BLUEGRASS, Poa trivialis.
This perennial grass is related to Kentucky bluegrass but its stemmy, prostrate growth habit makes it difficult to mow and maintain. Preferring cool, wet weather, this grass grows quickly in the spring and grows over the top of other grasses, inhibiting their growth. However, once temperatures climb and remain hot, roughstalk bluegrass turns brown and recedes. At this point, large patches of the grass suddenly appear dead.
To control this perennial weed, spray the roughstalk bluegrass with a systemic non-residual grass-killing herbicide (e.g. glyphosphate or glufosinate) when it is actively growing. Reapply as regrowth occurs, then rake and sod or seed with a desirable turfgrass species.
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INDUSTRY INSIGHT
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FORBID THE OBERON CONFUSION
Several BYGLers reported receiving calls concerning the new miticide products Oberon, Forbid, and Judo. They indicated that they had little information on the active ingredients and target sites for these products. To help clarify these products, Dave Shetlar provided a brief overview.
The three products all contain the same active ingredient: spiromesifen. The trade names differ based on the target sites. Spiromesifen has been shown to be highly effective on spider mites, especially mites in the nymphal stages. The chemical also controls whitefly nymphs and pupae, as well as some other insects. Spriomesifen has translaminar activity meaning that it penetrates leaf tissue and can circulate within the leaves. This allows applications made to the upper leaf surface to provide control for mites feeding on the lower leaf surface.
Spiromesifen is a lipid biosynthesis inhibitor (LBI). Lipids are fats that play a vital role in animal cell functions, particularly in the formation and maintenance of the cell membrane. Mites that are exposed to this chemical during their development produce plump, limp, fleshy legs, a condition called "flabby leg syndrome." Spriomesifen is the only miticide to use the LBI mode of action, which this should reduce the risk of resistance. Although it has about the same residual longevity as Kelthane, the product appears to have a low risk of toxicity to other species.
Oberon contains 23.1 % spiromesifen and is labeled for use on field crops, vegetables, and strawberries. The label directs the pesticide operator to apply Oberon at the first sign of an infestation, or at least before damage is severe. Oberon is also labeled to control broad mites and the potato/tomato psyllid on fruiting vegetables. It has a 7 day pre-harvest interval. Forbid is labeled for the lawn care industry, and has residual activity for 4-6 weeks. Judo is labeled for nurseries and greenhouses.
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WHITE PINE WEEVILS REAR UGLY SNOUTS
Curtis Young and Joe Boggs reported that white pine weevil (Pissodes strobi) was a major topic of conversation at OCTA Summer Meeting. While this stem-feeding borer has long been familiar to Christmas tree growers in northeast Ohio, the weevil has made appearances in recent years in the western, central, and occasionally in the southwest parts of the state. White pine weevil encounters also appear to be on the rise in nurseries and landscapes.
Despite its common name, the weevil also infests a wide range of conifers including: Scotch, jack, red, and pitch pines; Norway, white, and Colorado blue spruces; and Douglas-fir. Indeed, owing to its wide host range, the weevil is sometimes referred to as the "Sitka spruce weevil," or the "Englemann spruce weevil."
The white pine weevil has one generation per year. In early spring, overwintered females feed briefly on the terminals of conifer hosts, then they lay eggs into this feeding material. The resulting white, legless, slightly curved, grub-like larvae tunnel downward just beneath the bark until pupation. Larval development is typically completed by mid-to late-summer. The tops of infested trees become wilted, turn brown, and die. Main leaders are often curved into a shepherds crook.
The symptom development of wilting and browning terminals is seldom synchronous throughout a Christmas tree plantation or nursery. Depending upon the level of infestation, tree species, and the size of the tree, some terminals may wilt and turn brown earlier than others. This may cause observers to conclude that terminals are being re-infested; however, this is not the case. Egg laying by the adults only occurs in the spring. The removal and destruction of infested terminals remains a highly effective method to reduce localized populations of this insect, as long as care is taken to cut below the downward progress of the larvae. The practice must be repeated as symptoms develop on new terminals.
Currently, some weevil larvae have reached maturity and have constructed pupation chambers, called "chip cocoons," beneath the bark. The cocoons are created by the larvae positioning their bodies in grooves excavated in the xylem, and then surrounding themselves with small, white wood chips. The next generation of adults will soon emerge, so the opportunity to control the weevil by removing infested terminals is rapidly drawing to a close for this season; it may be too late in some parts of the state.
The emergence of new adults in the late-summer or fall may tempt growers and landscape managers to consider controlling the weevil by making late-season applications of insecticides. This is not recommended. The new adults are widely dispersed and seldom concentrated in large enough numbers on targeted trees to support the efficacy of late-season insecticide application. Effective insecticide applications should target where and when a high concentration of adults is known to occur; spray the main leaders of host trees in the early spring.
The use of imidacloprid (e.g. Merit) to control this weevil in landscapes and nurseries may appear to be an exception to this rule. Soil drench applications of imidacloprid made in October or November have proven to be highly effective in controlling this weevil. However, these applications are actually targeting the spring-feeding adults and early instar larvae through the systemic action and long residual activity of this insecticide.
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COMING ATTRACTIONS
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BYGLIVE! IN CINCINNATI
The fifth 2005 Cincinnati BYGLive! Diagnostic Walk-About will held from 12:00 - 3:00 p.m., Monday, August 1st, at the Boone County Arboretum at Central Park. This special Cincinnati BYGLive! is hosted by Dr. Mike Klahr, County Extension Agent for Horticulture, UK Cooperative Extension Service, Boone County, and Kris Stone, Director, Boone County Arboretum.
Mike founded the Arboretum in 1999. This truly impressive, ever-growing work in progress now encompasses 121 acres and includes over 800 trees and 1500 shrubs. All plants are labeled and their position noted using the Global Positioning System to better monitor and manage the Arboretum. For more information on the Walk-About, call Joe Boggs at 513-946-8993. For directions to the Arboretum, call the UK Boone County Cooperative Extension Office at: 859-586-6101, or visit the Arboretum website at: [ http://www.bcarboretum.org/].
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EIGHTH ANNUAL NORTHWEST OHIO GREEN INDUSTRY SUMMER SESSION
Wednesday, August 3rd, is the Eighth Annual Northwest Ohio Green Industry Summer Session, held at Owens Community College in Toledo. The half-day educational event is open for managers and all members of local garden centers, turf managers, landscapers, arborists, and Master Gardeners.
Attendees are provided the latest researched-based industry information, and may also have the opportunity to receive re-certification credits locally for Certified Arborist, ODA and ONLA. Additionally, we have added a management track featuring noted labor management consultant, OSU Emeritus, Dr. Bernie Erven.
If you are interested in more information on the 2005 Summer Session, please contact the OSU Extension, ABE Center office at (419) 354-6916 or download the registration at: [ www.abe.osu.edu/GISS ].
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BYGLOSOPHY
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Flowers leave some of their fragrance in the hand that bestows them. Chinese proverb
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