Pam Bennett, Barb Bloetscher, Joe Boggs, Jim Chatfield, Erik Draper, Dave Dyke, Gary Gao, David Goerig, Tim Malinich, Amy Stone, and Curtis Young.
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August 30, 2007
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This is the twenty-second 2007 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 August 28, 2007 conference included: Pam Bennett (Clark); Barb Bloetscher, C. Wayne Ellett Plant and Pest Diagnostic Clinic (CWEPPD Clinic); Joe Boggs (OSU Extension Center at Piketon/Hamilton); Erik Draper (Geauga); Dave Dyke (Hamilton); Gary Gao (Delaware); Dave Goerig (Mahoning); Dave Shetlar (Entomology); Amy Stone (Lucas); 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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A weather subheading could be "A Tale of Two Cities - or at least parts of the state." The differences between the north and the south are striking. While 6 northern counties have been declared federal disaster areas because of recent floods, the Cincinnati area is experiencing a drought. What a difference 100 miles can make.
As of August 21, Cincinnati was rated as being in a "Severe Drought" according to the USDA-NOAA "Drought Monitor" http://www.drought.unl.edu/dm/monitor.html. The monitor is updated on Thursdays, and it is probable that Cincinnati will be upgraded to the "Extreme" drought category. The next and highest drought category is "Exceptional" which is currently being experienced in parts of Alabama, Georgia, North Carolina, and Tennessee. As of August 29, Cincinnati has had 25 days above 90 and 5 days at or above 100, both new records. They are on track for breaking the record for the warmest average temperature for the month of August. Additionally, this area is 2.82" below normal for the month of August and approximately 11" below normal for the year when it comes to rainfall total.
As rivers to the north have crested, the clean-up continues. The Putnam County Extension office in Ottawa, Ohio had 4' of water inside their building and had to move to a temporary location. Many locations are looking to break records for the greatest total August rainfall.
The following weather information has been summarized from data collected from August 1 - 29, 2007. BYGLers have selected four locations to highlight different regions of the state to be included each week as seen in the table below. Additionally, there are weather station sites in Avon (Lorain County), Madison (Lake County), Perry (Lake County), Jackson (Jackson County), at the Muck Crops Research Station (Huron County), at the North Central Research Station (Sandusky County), and at the Western Research Station (Clark County). The weather data collected from all the sites can be seen at http://www.oardc.ohio-state.edu/newweather/ .
| Weather Station |
Region of Ohio |
Ave. High Temp F |
Ave. Low Temp F |
Total Precip " |
Normal Precip " |
| Ashtabula |
NE |
78.9F |
61.6F |
2.61" |
4.4" |
| Wooster |
NE |
83.2F |
63.4F |
4.76" |
3.4" |
| Hoytville |
NW |
83.9F |
63.4F |
10.03" |
2.7" |
| Delaware |
Central |
86.4F |
64.9F |
3.74" |
3.1" |
| Piketon |
South |
91.0F |
65.9F |
0.34" |
2.5" |
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HORT SHORTS
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PLANTS OF THE WEEK
*PERENNIAL OF THE WEEK. GOLDENROD (Solidago spp.) - The saying one gardener's weed is another gardener's wildflower applies to the perennial for this week! In fact, some folks find it hard to believe that you would actually pay for goldenrod. However, there are a few really great varieties of this plant that make an excellent accent to the fall garden, at time when most of the summer color is fading quickly. S. rugosa 'Fireworks' grows to around 3-4' tall and resembles streaks of golden-yellow fireworks. S. sphacelata ' 'GoldenFleece' forms a thick yellow ground cover around 18" tall. 'Golden Baby' grows around 20" tall and is compact as opposed to the lanky form of the goldenrod found in the open. It can also be used as a cut flower. So try some of these cultivars in the perennial border - just don't tell anyone that you had to pay for them!
*WOODY PLANT OF THE WEEK. SWEETBAY MAGNOLIA (Magnolia virginiana) - This lovely small specimen tree or multi-stemmed shrub has passed its bloom period but is still a nice addition to the landscape. The orange-red fruits are beginning plump open, exposing the beautiful crimson-red seeds. In addition, the foliage of the plant still looks great for this time of the year. The fragrant, creamy-white flowers appeared in July, when few other trees were in bloom.
*ANNUAL OF THE WEEK. PETUNIA (Petunia spp.) - While many other annuals are beginning to fade, these flower garden backbones are just gearing up for a great fall run. In addition, these are not your grandma's petunias! New varieties on the market have led to plants that don't need deadheading and just keep blooming all summer until a hard frost. The difficulty in selecting petunias, however, comes with the multitude of varieties that are on the market today. Some of the top performing cultivars in field trials in Ohio include (in no particular order): Surfinia, Supertunia, Wave, Madness, Supercascades, Morn, Ultra, Celebrity, Carpet, and many more. The best way to determine growth habits and potential use in the garden is to check out field trials in order to see plants growing side by side. OSU Agriculture Campus houses one of these sites in front of Howlett Hall. Check out the many types of petunias as well as other plants.
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WEEKLY WEED
Our weed of interest this week is dedicated to all of you sniffling, sneezing, and suffering folks in the field. The common RAGWEED, Ambrosia artemisiifolia is a persistent summer annual found throughout North America including Dave Goerig's vegetable garden. Almost all of the seeds that each plant produces are viable (capable of germinating), and can survive up to 80 years in the soil. Common ragweed is a troublesome plant that invades most cultivated land when soil temperatures are between 50-80F. The leaves on common ragweed can be described as generally twice compound and arranged alternately as the plant stem pushes upward. A. artemisiifolia is in the Asteraceae (Aster) family of plants. The flowers are monoecious. The male flowers are racemes at the top of the plant and the female flowers are green, inconspicuous, and located in the axils of the leaves. Both flowers are present from late summer into autumn.
Giant ragweed Ambrosia trifida is a close relative to common ragweed. It can grow nearly twice as high as common ragweed, sometimes towering beyond 10ft. The leaves of A. trifida are opposite and mostly palmately 3-lobed. Pollen from both common and giant ragweed is the primary cause of hay fever even though their distant cousin, Canada goldenrod Solidago Canadensis, which blooms at the same time, gets all the blame. These plants will not tolerate frequent mowing. Broadleaf chemical controls should be selected based on the plant crop you are trying to protect. Always read the label.
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SQUIRRELS GOING NUTS OVER ACORNS
Dave Shetlar reported that the squirrels in Columbus are beginning to litter sidewalks, driveways, and lawns with discarded, ripped-open acorns. If one looks at the discarded acorns, one will see that most, if not all, of the acorn meat is still in the shell of the acorn. The squirrels are not after the meat of the acorn. At this time of the year, the meat of the acorn is too bitter to be eaten even for a nut-lover like a squirrel. Tannin levels in the meat of the acorns are too high to be palatable. What the squirrels really want is the sweet, meaty morsels that have infested the acorns, ACORN WEEVILS (Curculio spp.). The larvae of these weevils are packed with protein and are apparently relished by the squirrels, which rip open hundreds of acorns to get to the prize inside. Once they clean the larvae out of the acorns, the squirrels discard the remainder, covering everything on the ground below the trees with shells, caps, and acorn meat.
If the squirrels don't get them, then when the acorn falls from the tree, the acorn weevil larva will bore out of the acorn and dig into the ground. Acorn weevils normally overwinter in the ground. However, one should be careful when collecting acorns for fun or decoration. The acorn weevil larvae can bore out of the acorn anywhere the acorn may be laying, including on the kitchen counter, on the dining room table, from acorns glued to a poster, in a child's pants pocket, etc.
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BUG BYTES
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ALL LEAF-FEEDING CATERPILLARS ARE NOT GYPSY MOTHS
Amy Stone reported that she received a phone call from a homeowner in Northwest Ohio concerned that "gypsy moth" caterpillars were causing significant defoliation of large oaks. Amy knew it couldn't be gypsy moths since the insect only has one generation per season, and the caterpillars have long since disappeared for the season from Ohio forests. Gypsy moths are currently in the overwintering egg stage. Upon visiting the site, she found the heavy defoliation was in fact being caused by second generation YELLOWNECKED CATERPILLARS (Datana ministra).
Unlike gypsy moth caterpillars that retain a similar appearance throughout their development, yellownecked caterpillars pass through different "color phases." First instar caterpillars are copper-colored with no distinct lines. Second instars 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 are hairy, the hairs are most evident during the last instar stage. Another notable characteristic is that the caterpillars will lift their anterior and posterior ends to make their bodies "U"-shape when disturbed.
Yellownecked caterpillars feed gregariously in colonies, and their feeding behavior changes as they develop. 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. Adding to the potential to produce heavy defoliation, yellownecked caterpillars also have at least two generations per season in northern Ohio, and a possible third generation in the central and southern parts of the state.
The caterpillars feed on a wide variety of trees and shrubs including: crabapples and other ornamental fruit trees, oak, maple, elm, beech, linden, honey locust, azalea, and boxwood. Early instar caterpillars are susceptible to the biological insecticide, Bacillus thuringiensis (Bt) (e.g., Dipel, Thuricide, or Caterpillar Attack). More traditional insecticides are needed to control later instars. A more direct (satisfying?) control method is to knock the caterpillar colonies to the ground and perform the "caterpillar dance." Thus far, no populations have developed resistance to this control method.
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GRASSHOPPERS A-BOUND
Curtis Young and Joe Boggs reported observing significant numbers of grasshoppers and feeding damage to ornamental grasses in western and southwestern Ohio, respectively. Joe noted that as he recently walked through a local nature preserve, his movements were preceded by hundreds of grasshoppers leaping ahead (a common affect that Joe has on insects, people, etc.).
The differential (Melanoplus differentialis) and redlegged (Melanoplus femurrubrum) grasshoppers are the two most common species found in Ohio landscapes. Populations for these and other species fluctuate in cycles. High or very high populations may be present for two to four years followed by low to moderate populations for several years. Even when overall populations are relatively low, grasshoppers in and around the garden can be a nuisance. However, in outbreak years, grasshoppers can destroy unprotected gardens and threaten small trees and shrubs.
The potential for grasshopper damage increases as summer progresses. Adults will be more likely to move into yards and gardens in July, August, and September. Severe problems may arise when adjacent agricultural crops or grasslands mature or are harvested and grasshoppers move to find new food sources. Defoliation is the primary injury to plants, but fruit and ripening kernels of grain will also serve as food. Indeed, grasshoppers will feed on just about anything as long as they do not detect a feeding deterrent. Reports are common of grasshoppers eating paper, paint, window screens, window caulking, fence posts, hoe handles, etc. during grasshopper outbreak periods.
Heavy infestations of grasshoppers may require chemical treatment to reduce or prevent serious damage to sensitive plants. For a list of effective materials and control timing consult OSU Extension Bulletin 504 titled, "Insect and Mite Control on Woody Ornamentals and Herbaceous Perennials" http://ohioline.osu.edu/b504/index.html .
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THE BUZZ ON GROUND-NESTING BEES
Dave Dyke reported receiving a specimen of a small, shiny-green bee that had been found cruising over holes in the soil beneath a shrub. Based on the bee's appearance and location where it was collected, BYGLers surmised it was a HALICTID BEE (Family = Halictidae). These ground nesting bees are also called "metallic bees" because of their shiny appearance, or "sweat bees" because of their habit of landing on sweaty gardeners.
The bees most commonly associated with nests in the soil belong to one of three Hymenopteran families: Halictidae, Anthophoridae (digger bees); and Adrenidae (mining bees). Generally, these bees are hairy and about the size of a honey bee or smaller; although the digger bees are slightly larger and more robust. Some are considered solitary, since the females dig individual burrows; however, large numbers may select the same area giving rise to a "community" of hundreds of burrows. The females of other species dig a common vertical hole that is used by several bees, and individual females dig their own lateral borrows in which to lay eggs.
The affected areas of soil are often the sites of past bee-bashes, since some species re-use and expand nesting sites year after year. Communities of ground-nesting bees may grow to cover an area 3-10' in diameter, and the buzzing flights of hundreds of bees can be disconcerting to homeowners. Although they may appear menacing, these bees are not aggressive and not likely to sting. Also, keep in mind that most of the strafing is being done by the males, and they lack stingers!
The same bees may also be observed visiting nearby flowers, since a large percentage feed their young balls of pollen moistened with nectar. Thus, the bees are considered beneficial pollinators, so direct control using insecticides is not recommended. However, since the bees prefer to nest in areas of open soil, cultural practices can be applied to dissuade the bees from nesting. Mulching or covering the area with vegetation will cause the bees to buzz off to other more amenable nesting locations.
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GIANTS AMONG THE LEAVES
Dave Shetlar reported recently finding several black, ribbed, 1/2" long barrel-shaped pellets on a Columbus sidewalk beneath a large tree. Although he couldn't spot the pellet-maker in the canopy, Dave knew that his find indicated a giant was lurking among the leaves overhead. The pellets were the excrement (frass) produced by a caterpillar of one of the GIANT SILKWORM MOTHS (Family = Saturniidae).
Notable moths in this family include: IMPERIAL (Eacles imperialis); CECROPIA (Hyalophora cecropia); LUNA (Actias luna); POLYPHEMUS (Antheraea polyphemus); PROMETHIA (Callosamia promethean); and the impressively named HICKORY HORNED DEVIL (Citheronia regalis). These are some of the largest and most beautiful moths to grace Ohio's landscapes and forests. However, for reasons not entirely known, populations of these moths have been tumbling over the past few decades. While a digital version of a luna moth graces a current sleep-aide commercial, the real thing now rarely graces Ohio evenings.
The caterpillars of these moths have several things in common. First, these are our "super-sized" caterpillars. They can be huge with some growing to over 3" long. Second, the intimidation produced by their size may be enhanced by impressive ornamentation. Some sport spiky knobs or prickly horns (e.g. horned devil). Finally, despite their size, they rarely cause even noticeable damage to plants because they are solitary feeders. Indeed, it is amazing how difficult it is to spot one of these giants among the leaves of a tree or shrub. Of course, Dave's observation provides a good tip for looking. Super-sized frass means a super-sized caterpillar!
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BAGWORM DEVELOPMENT UPDATE
The annual bagworm (Thyridopteryx ephemeraeformis) watch continues. Joe Boggs, Dave Shetlar, and Curtis Young all contributed to the list of observations made on bagworm development this week. Curtis reported that caterpillars of several sizes could be observed on infested plants. The wide range in sizes suggest a possible wide range of hatching dates, however Dave suggested that an alternative explanation for the range of sizes could be that in large populations there could be an interference factor. As large populations of bagworm feed on host plants, they bump into one another on a regular basis. Some individuals may give in more quickly than others (bullies vs. wimps) resulting in the wimps feeding less efficiently and developing more slowly. Sex of the caterpillar also influences size. Male caterpillars tend to be smaller than female caterpillars.
Curtis also reported that bagworm pupation had begun in NW Ohio. Pupae that were found were almost exclusively male. Dave asked about the presence of parasitoids and at least in the NW Ohio population that Curtis was looking at, there were no obvious parasitoids present. This is a bit of a concern for biological control of bagworm populations.
Management of bagworm with insecticides this season is rapidly becoming less of an option as fewer and fewer caterpillars are present to feed on the foliage of treated host plants. Hand removal of bags remains an option for small populations.
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ZIMMERMAN PINE MOTHS OUT
Dave Shetlar reported that the Zimmerman pine moths would be emerging soon, and headed to pine trees near you, to lay the next generation of eggs.
Although the Zimmerman pine moth, Dioryctria Zimmermani is often held responsible for the damage, entomologists suspect that a complex of lepidopteran is actually involved in the tunneling and destruction of Scotch, Japanese red, Eastern white, and Austrian pine trees. The moths lay eggs in terminal buds, flaps of bark, and cracks and crevices of the trunks where the branches meet. Upon hatching, the caterpillars may feed a little, then form a silken tent-like hibernaculum in which they overwinter. In early spring, around mid-April, the larvae leave the hibernaculum and resume feeding.
These small reddish-pink, hairless caterpillars feed in the phloem and cambium areas of the trunk at the branch whorls, causing enormous amounts of pitch to flow from a wound in the bark. Close inspection of the sap will reveal bits of frass, indicating the presence of the borer. By the end of July the caterpillars have finished feeding, spin a cocoon within a mass of resin, then emerge in late August.
To treat for these pests, entomologists recommend two treatment strategies. Nurseries and Christmas tree growers may want to spray now with dimethoate to catch the hatching larvae, however the window of opportunity is questionable, since debate exists on the extent to which they feed. A more crucial time is in March, when the larvae leave their winter slumber to commence tunneling. At this time, a long residual borer control such as Astro (permethrin) or Onyx (bifenthrin) should be sprayed on the trunks of the tree. A better strategy is to drench the tree with a systemic insecticide containing Cygon (dimethoate). Remove infested trees when possible to reduce the population of adults.
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OOOEY GOOEY!
The TOMATO AND TOBACCO HORNWORMS have been sighted defoliating leaves and stems of tomato plants the last few weeks. When hungry, these smooth, luminous green caterpillars have been known to bite hunks out of the tomato fruit as well!
Infamous for their finger-width size and the "horn" on the tip of the abdomen, they are more positively identified by the white diagonal lines along each side. The tobacco hornworm, Manduca sexta has a series of white diagonal stripes, while the tomato hornworm, Manduca quinquemaculata has more of a series of white "V"s. Cleverly camouflaged, these caterpillars have been munching away for several weeks, unnoticed by even many careful observers. Only the piles of rounded black frass below them may disclose the presence of the masked marauders.
Control may not be necessary for these green monsters if one does not wish to pick them up and squash them, because several insect predators control the caterpillars. Paper wasps, yellow jackets, and other wasps will grab them, chew them up, and take the remains to their nests to feed their larvae. Several tiny, parasitic wasps will insert their eggs into the caterpillar, which the wasp larvae will consume, until the hornworm begins to sag. The full grown wasp larvae then erupt through the upper epidermis of the hornworm and form oval, white, pupal cases. Intensely parasitized hornworms may have several rows of these white pupae. When these "nurseries of parasitoids" are found, leave them in the garden, so that the Braconid wasps will return the following year to control the next year's population of hornworms.
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FALL WEBWORM UPDATE
Dave Shetlar and Joe Boggs reported that second generation fall webworms (Hyphantria cunea) are still going strong despite the heavy rainfalls that occurred throughout the northern half of the state. Sizes of nests vary tremendously. In some cases, the nests had to be regenerated after the heavy down pours of rain. Again, despite the heavy moisture content in the air, the fall webworm caterpillars seem to be doing fine showing no disease.
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DISEASE DIGEST
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WALNUT ANTHRACNOSE DEFOLIATING
Joe Boggs reported that despite drought, record-setting high temperatures, and a generally poor showing for other anthracnose diseases, walnut anthracnose is doing its defoliating deed in southwest Ohio. Joe stressed that not all walnut defoliation is being caused by anthracnose. Some leaf drop is clearly associated with moisture stress.
Walnut anthracnose is the handiwork of the fungal pathogen Gnomonia leptostyla. This is the most common disease of black walnut and occurs wherever black walnut is grown. It will also infect butternut, Persian walnut, and the first generation hybrids of Persian X black walnut. Like most anthracnose diseases, wet spring weather is ideal for its development; however, symptoms may not become visible until July or August. Although spring in the southwest part of the state was not particularly "wet," there was obviously just enough moisture to support infection on some trees.
Symptoms appear as dark brown circular lesions that range in size from a pinprick to 1/2" diameter on fully expanded leaflets and are typically surrounded by a yellow margin. These lesions are apparent from both the upper and lower leaflet surfaces. Lesions may also occur on the rachis and petioles of the walnut's compound leaves. The severity of walnut anthracnose tends to increase as the summer progresses. This is due to the cyclic nature of this fungus, which continues to infect leaf tissue during the growing season, especially if rainfall is frequent. Infections may also appear as dark, sunken spots on the nut husks. Anthracnose may also affect the quality of the nut meat and cause the nuts to drop prematurely.
Tree leaflets that are heavily infected with walnut anthracnose begin to turn yellow and drop. Defoliation usually progresses from loss of individual leaflets to loss of entire leaves; however, some defoliated trees retain the rachis and petioles, producing an unsightly "stemmy" appearance. The tree may be completely defoliated by the end of August. While overall tree growth during a growing season may be reduced by leaf loss, trees are not usually harmed by walnut anthracnose. However, Joe noted he is also seeing leaf drop on walnuts from drought stress. The differences in symptoms are not subtle. Leaflets shed because of moisture stress lack the characteristic anthracnose lesions. Instead, the leaflets often show characteristic "leaf scorch" symptoms, with browning and necrosis spreading from the edges inward.
Whether black walnut is used as shade, ornamental, or nut-producing trees, one of the best ways to minimize the affect of this fungus is to eliminate any fungus overwintering on leaves. This can be done by raking up the leaves and either burning them or properly composting them. This will reduce the amount of ascospore inoculum, which causes primary infection in the spring. Overall, this will help keep those nuts where they belong...in the trees!
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TURF TIPS
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CHINCH BUG CASE STUDY
Joe Boggs reported paying a visit to a Cincinnati lawn that was being hammered by chinch bugs (Blissus leucopterus). He found large numbers of chinch bugs frolicking about in areas where grass remained green. The bug problem had apparently been brewing for a number of years, and had already cost one lawn care service the patronage of the homeowner. Indeed, Joe noted the situation provides an instructive case study and cautionary tale for making a proper chinch bug diagnosis, and applying proper treatment.
Background:
Diagnostic Wrong-Turns:
Recommendations:
In fairness to all involved, BYGL readers should remember that while Cincinnati was a chinch bug haven up until about the 1980's, for unknown reasons the bugs virtually disappeared from the region after that time. However, in recent years, chinch bugs have re-appeared and are being encountered by some lawn care professionals who have had little past experience with the bug. Thus, the importance of sharing this case study.
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GRUBS UNPREDICTABLE
Dave Shetlar stated that grub populations will vary across the state due to the weather patterns. Areas such as southwestern Ohio that suffered a severe drought and 90 days of 90+ degree temperatures may have "baked" the grubs, while central and northern Ohio had areas which received enough rainfall to keep the turfgrass green, may have a "good" supply of grubs this fall. Dave noticed that the grubs in irrigated turfgrass have reached their second instar and may damage turf that is not irrigated regularly. Northwestern Ohio may see a range of grub populations depending upon how long areas were under water. Typically, grubs will not survive flooded conditions over 24 hours.
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COMING ATTRACTIONS
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THE ISA NORTHERN SUMMER MEETING
This meeting will be held Friday, September 28 at the Ehrnfelt Recreation & Senior Center, 18100 Royalton Rd., Strongsville, OH. Pesticide and Arborist CEUs available. Call Chris at 614-771-7494 or Al at 216-854-0508 or go to the Ohio Chapter ISA website. The cost is $65.00 (Ohio ISA or AGI Associated organization rate) and $75.00 for non members.
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CALLING ANYONE INTERESTED IN BECOMING A CERTIFIED ARBORIST
OSUE Greene County Master Gardeners, the Ohio Division of Forestry, and the Ohio Chapter of the International Arboriculture are sponsoring a Certified Arborist Preparation Course on Mondays from October 1 though November 12, 6:00 - 9:00 p.m., in Xenia, Ohio. This class is for any individual interested in becoming and ISA Certified Arborist. Contact the Ohio Chapter of ISA at 614-771-7494 for application information.
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BYGLOSOPHY
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"The greatest gift of the garden is the restoration of the five senses." - Hanna Rion
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