| BYGL 05-29-08 Text |
 |
 |
|
BUCKEYE YARD AND GARDEN LINE 2008-09 5/29/08
From: Pam Bennett, Barb Bloetscher, Joe Boggs, Cindy Burskey, Jim Chatfield, Erik Draper, Dave Dyke, Gary Gao, David Goerig, Tim Malinich, Becky McCann, Amy Stone, and Curtis Young.
This is the 9th 2008 edition of the Buckeye Yard and Garden Line (BYGL). BYGL is developed from a Tuesday morning conference call of Extension Educators, Specialists, and other contributors in Ohio.
BYGL is available via email, contact Cheryl Fischnich [ This e-mail address is being protected from spambots. You need JavaScript enabled to view it ] to subscribe. Additional Factsheet 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 ONLA (Ohio Nursery and Landscape Association) [ http://onla.org/ ] and [ http://buckeyegardening.com/ ] to the OSU Extension Nursery, Landscape and Turf Team (ENLTT). Any materials in this newsletter may be reproduced for educational purposes providing the source is credited.
BYGL is available online at: [ http://bygl.osu.edu ], a web site sponsored by the Ohio State University Department of Horticulture and Crop Sciences (HCS) as part of the "Horticulture in Virtual Perspective." The online version of BYGL has images associated with the articles and links to additional information.
Following are the participants in the May 27th conference call: Pam Bennett (Clark); Joe Boggs (Hamilton/Piketon); Cindy Burskey (Clemont); Jim Chatfield (OSU Extension Center at Wooster/ Hort and Crop Science); Erik Draper (Geauga); Dave Dyke (Hamilton); Gary Gao (Delaware); Michael Loos (Cuyahoga); Tim Malinich (Lorain); Joe Rimelspach (Plant Pathology); Dave Shetlar (Entomology); Amy Stone (Lucas); Nancy Taylor (C. Wayne Ellett Plant and Pest Diagnostic Clinic (CWEPPDC)); Shawn Wright (OSU Piketon Centers); Curtis Young (Allen); and Randy Zondag (Lake).
In This Issue:
1. WEATHERWATCH. 2. HORT SHORTS: GDD (Growing Degree Days); Is the Growing Degree Day Calendar Failing?; Plants of the Week [Gerbera Daisy; Coral Bells; Maples; Poison Hemlock]; Dripping Tuliptrees: A Diagnostic Look-a-like; and Evergreens are Not Always Green. 3. BUGBYTES: Periodical Cicada Emergence Begins; A Swarm of Calls [Honey Bees]; Emerald Ash Borer Begin to Take Flight; Lace Bugs [Oak Lace Bug; Hawthorn Lace Bug]; Erineum Patch "Galls" [Erineum Mites]; and Windshield Wipes [Dusky Birch Sawfly; Hawthorn Leafminer; Bagworm]. 4. DISEASE DIGEST: Anthranose on Sycamore; and Moist Chamber [Sphaeropsis Tip Blight of Pine; Dothistroma Needle Blight of Pine; Volutella Leaf Blight and Stem Canker of Pachysandra; Peach Leaf Curl]. 5. TURF TIPS: Why is My Turf Red? [Red Thread]. 6. INDUSTRY INSIGHTS: Sampling 101-2; and Potato Leafhopper is Here. 7. COMING ATTRACTIONS: Landscape Diagnostic Workshop in Central Ohio; Total Plant Healthcare Workshop; Cincinnati BygLive! Diagnostic Walk-about; Plant Diagnostic Academy; and Schnormeier Garden Tour.
1. WEATHERWATCH. Night-time temperatures in the north dropped into the mid-thirties Tuesday and Wednesday evening in the northern counties, with some areas experiencing a little frost, while everywhere else is frost-free (thank goodness). This illustrates the wide weather variances experienced across the Buckeye state. Also important to mention, four of the five weather station sites are experiencing less than normal or average precipitation thus far in May.
The following weather information summarizes data collected at various OARDC Weather Stations spanning the dates: May 1-28, 2008, with the exception of the soil temperatures which are readings from Wednesday, May 28 at 12:30 p.m.
For a link to the OARDC Weather Stations, visit: [ http://www.oardc.ohio-state.edu/centernet/weather.htm ]
2. HORT SHORTS.
A. GDD (GROWING DEGREE DAYS). GDD is a measure of the daily maximum and minimum temperature and directly relates to growth and development of plants and insects. The GDD of any zip code location in Ohio is estimated using the GDD of ten OARDC weather stations and available on the web at the site below.
The range of GDD accumulations in Ohio from north to south is 376 to 636. Following is a report of GDD for several locations around Ohio as of May 27, 2008: Painesville, 376; Cleveland, 396; Toledo, 423; Canfield, 403; Lima, 432; Wooster, 419; Coshocton, 465; Columbus, 528; Springfield, 492; Dayton, 501; Cincinnati, 581; Ironton, 602; Portsmouth, 605; and Piketon, 636.
To put these GDD accumulations into perspective, the following is an abbreviated listing of plant and insect species with their respective phenological event and average GDD accumulations at which these events occur. Due to variations in weather, temperature, humidity, etc., these events may occur a few days earlier or later than predicted by the average GDD. By looking at a city, town, or village near you from the above list, or visiting the above web site, you can see what could be taking place in the landscape around you.
Lilac borer, adult emergence, 330; slender Deutsia, first bloom, 338; Japanese kerria, full bloom, 342; common horsechestnut, full bloom, 344; red chokeberry, full bloom, 351; doublefile viburnum, first bloom, 353; Pagoda dogwood, first bloom, 363; red Java weigela, first bloom, 365; black cherry, first bloom, 368; common sweetshrub, first bloom, 371; lesser peach tree borer, adult emergence, 372; Ohio buckeye, full bloom, 374; holly leafminer, adult emergence, 375; Vanhoutte spirea, full bloom, 406; euonymus scale (first generation), egg hatch, 406; black cherry, full bloom, 419; Miss Kim Manchurian lilac, first bloom, 422; locust leafminer, adult emergence, 437; doublefile viburnum, full bloom, 444; black locust, first bloom, 467; common ninebark, first bloom, 478; oystershell scale, egg hatch, 497; smokebush, first bloom, 501; arrowwood viburnum, first bloom, 534; American yellowwood, first bloom, 546; bronze birch borer, adult emergence, 547; black locust, full bloom, 548; American Holly, first bloom, 556; mountain laurel, first bloom, 565; potato leafhopper, adult arrival, 568; juniper scale, egg hatch, 571; common ninebark, full bloom, 596; American yellowwood, full bloom, 599; arrowwood viburnum, full bloom, 621; and multiflora rose, full bloom, 643.
B. IS THE GROWING DEGREE DAY CALENDAR FAILING? Dan Herms has responded to this question several times this year because everything seems to be occurring sooner than the growing degree-day models predict.
Dave Shetlar added the following note to the above discussion. Dave noticed that there can be a range of blooming of plants (e.g. black locust) in a particular area (e.g. central Ohio). This range of blooming can lead to some confusion as to exactly where plants may be in their phenological development. Microclimates can cause these variations, for example trees in open areas may reach full bloom days before a tree that is sheltered or shaded by neighboring trees. Additional error can be injected into the system from variation in interpretation by the eye of the evaluator. From a distance trees can appear to be in full bloom, but up close they may actually be anywhere from 1/3 to 2/3 to full bloom. Obviously, phenological calendars and growing degree-day models always have margins of error, both from the physiological responses, as well as from location in the landscape and observer biases in estimating condition of bloom.
C. PLANTS OF THE WEEK. Read all about perennials and landscape trees and shrubs in the ONLA publications "Perennial Plants for Ohio" and "Landscape Plants for Ohio." The descriptions and photographs of plants were provided for these publications by the OSU ENLT Team along with other industry plant lovers. These full-color publications are available at [ http://Buckeyegardening.com ] for $5.00. Click on "garden store" and then "ONLA plant guides." ONLA members can purchase these in quantities at a reduced price at [ http://onla.org ].
*ANNUAL PLANT OF THE WEEK. GERBERA DAISY - (Gerbera jamesonii). When in bloom, this plant elicits delight and wonder at the color and beauty of the flower. In the sunflower family, the gerbera daisy requires full sun and the daisy-like flowers bloom throughout the summer with colors in the red, pink, yellow, orange and scarlet ranges. Keep the flowers deadheaded in order to prolong blooming. Flowers can be used in fresh arrangements, however, provide a wire support for the stems. The foliage is compact and the blooms are held on stems anywhere from 8-10" tall therefore, it is best planted in the front of the border or in containers.
*PERENNIAL PLANT OF THE WEEK. CORAL BELLS (Heuchera spp.) The number of varieties in this genus has grown exponentially in the past several years due to extensive breeding, making it somewhat difficult for gardeners to choose from all of the fantastic options! The plant used to be valued for the flowers; today, however, the foliage makes a great impact in flower beds and gardens. Cultivars include foliage colors of bronze, purple, silver, green leaf variegations, as well as scalloped and ruffled leaf edges. Don't discount the flowers, however, as many of the cultivars have great flower potential as well as foliage. Many plants tolerate full sun to part shade; leaf colors tend to be stronger and bolder with just a few hours of sun and cooler temperatures. Some of the bronze foliage varieties fade away in the hot sun. Most plants grow to around 10-12" and form a mound about 12" across. Blooms appear in May and last for 2-3 weeks and can be used as cut flowers.
*WOODY PLANT OF THE WEEK. MAPLES (Acer spp.). Maples, of course, make up a large slice of the arboreal palette. They are an important part of urban forests, landscapes, and woodlands in Ohio, and a good knowledge of the different maples is important for plant selection decisions. Maples are in the genus Acer in the Aceraceae family, which includes only the genera Acer (with up to 200 species) and the rarely planted Chinese native Dipteronia (two species). All members of the Aceraceae are woody. Both genera are characterized by two-winged dry fruits known as samaras and leaves with opposite arrangement on the stem. All maples are native to the northern hemisphere except for one species in the mountains of Java. Most maples have simple leaves, with the exception of several trifoliate species and box elder (Acer negundo). Many, but not all, maples have palmate-like leaves, but some such as hornbeam maple (Acer carpinifolium) noticeably do not.
Maples are widely used both for their wood and other plant products and as ornamental plants. The wood has long been used by man, as suggested by Virgil's account in the Aeneid, in which maple is described as being one of the woods used in the Trojan Horse. Today it is used widely in floors and walls of buildings, in bowling alleys and gymnasium floors, and as D.M. Gelderen et. al. note in Maples of the World, the sycamore maple (Acer pseudoplatanus) "provides the most famous and distinguished use of maple wood - the back, sidewalls, and pegs of violins." We all know of the wondrous qualities of maple sap from sugar maple (Acer saccharum) as the source of maple syrup, and several maples are amongst the best-known sources of honey (hedge maple, Acer campestre, and sycamore maple).
As ornamental plants, maples provide much to landscapes, street tree plantings and other sites. They have the structural features to be outstanding shade trees, they are among the most spectacular of all trees for their fall foliage, and on some maples twig color, exfoliating bark, flowers and fruits are quite ornamental. Among the maples are a diverse group of plants tolerant of a wide range of soil moisture, soil pH and light tolerance. Sizes range from small shrub-like trees to towering giants, and shapes from pencil-like uprights to wide spreading shade trees. So, how to pick just one maple? Impossible, but here is one species and its variants that are particularly beautiful this spring with its chains of fruits, wonderful bark and very attractive leaves: striped maple (Acer pensylvanicum).
This small maple, sometimes known as moosewood, (15-25' and sometimes to 30-35') is common in the Laurel highlands of Pennsylvania, the Appalachians and in the woods of New England. It thrives in Ohio as an understory species and well-drained soils, protected from sunny and hot, urban exposures. The prime landscape feature is the elegant creamy white-striped bark on the reddish and greenish young stems (this striping eventually fades on the bark with maturity). Leaves are 5" or more and three-lobed. The hanging cluster of greenish-yellow flowers and tiny samaras are attractive though often overlooked. Fall color is yellow.
In landscapes, striped maples are often multistemmed. If you visit OSU's Secrest Arboretum in Wooster, A. pensylvanicum, the hybrid Acer x 'White Tigress' introduced by nurseryman Tim Brotzman of Lake County Ohio, and specimens of the Asian Manchustriped maple (A. tegmentosum) are all along the upper trail of the John Ford Azalea Allee. A. pensylvanicum is the only so-called "snakebark" maple native to North America; there are over a dozen snakebark species of Asiatic origin. The "misspelling" of the A. pensylvanicum specific epithet is enshrined forever by the International Code of Botanical Nomenclature courtesy of Linnaeus's original citation.
*THE WEEKLY WEED. Joe Boggs reported that POISON HEMLOCK (Conium maculatum) is now producing flower heads in southern Ohio. This non-native invasive biennial weed spends the first year as a basal rosette, and the second year as an erect, towering flowering plant that can measure 6-10' tall. Poison-hemlock is a member of the carrot family, so it shares many characteristics with other weeds found in Ohio including QUEEN ANNE'S LACE (Daucus carota), COW PARSNIP (Heracleum lanatum), and GIANT HOGWEED (H. mantegazzianum).
Since poison-hemlock is among the most toxic plants in North America, it is important to correctly identify this weed. Flowering plants have hairless, light-green to bluish-green stems that are covered with obvious purplish blotches. The bluish-green leaves are 3-4 times pinnately compound, and the deeply cut parsley-like leaflets have sharp points. Clusters of tiny white flowers are borne on structures called umbels that look like upside-down umbrellas. The plant contains highly toxic piperidine alkaloid compounds, including coniine and gamma-coniceine, which cause respiratory failure and death in mammals.
Poison Hemlock can be controlled by mowing, tilling, or by using selective or non-selective post-emergent herbicides including glyphosate (e.g. Roundup) or herbicide mixtures containing 2,4-D, 2,4-DP and MCPP or 2,4-D, dicamba and MCPP (e.g. Trimec). Applications of herbicides made now will control both the first season rosette stage and the second season flowering stage, before seeds are produced. All parts of the plant are toxic, though roots are more toxic than leaves or stems.
D. DRIPPING TULIPTREES: A DIAGNOSTIC LOOK-A-LIKE. Joe Boggs reported observing an unusual phenomenon on a tuliptree (Liriodendron tulipifera) in southwest Ohio over the weekend. The tree was in full bloom, displaying the delicate tulip-like flowers responsible for the common name. However, what really drew Joe's attention was a voluminous flow of nectar literally dripping from the flowers. The nectar was collecting in the base of the cup-shaped flowers and leaking out once the tepals (a floral part unique to members of the Magnoliaceae family) separated during maturation. The nectar flowed from the flowers to coat the tree's leaves and drip onto cars parked beneath the tree.
The heavy nectar flow was a dead-ringer for the watery, sticky-sugary substance known as honeydew that is produced by various sucking insects. Joe noted that he had observed this same nectar-dripping phenomenon on tuliptrees several years ago, and he had been convinced the trees were infested by a sucking insect. Several insects are capable of producing copious quantities of honeydew on tuliptrees including soft scales such as TULIPTREE SCALE (Toumeyella liriodendri), MAGNOLIA SCALE (Neolecanium cornuparvum), and CALICO SCALE (Eulecanium cerasorum), as well as the aptly named TULIPTREE APHID (Illinoia liriodendri).
Tuliptrees are a well-known bountiful source of nectar for honeybees and other pollinators. The occurrence of an occasional "overflow" of nectar may be common, but generally masked by rainfall. Joe indicated there had been no rainfall for several days prior to his observation. However, given the strong visual similarities between the plant nectar and insect honeydew, this natural phenomenon should be taken into account before making a diagnosis of an insect infestation on tuliptrees without actually seeing the insect.
E. EVERGREENS ARE NOT ALWAYS GREEN. The term evergreen can be a misnomer to the uninitiated. There is a season to everything and even evergreen leaves must eventually cease to be green. Leaves of hollies and needles of spruces, taxus and pines (to name a few) all need to be shed eventually. When this happens they will turn yellow prior to dropping. This can send a false signal to the casual observer that the plant is suffering from a strange leaf-yellowing malady. In fact, this is a normal cycle of leaf replacement.
Leaves of evergreens may persist 2 or more years, depending on the type of plant. After that point, the oldest (inner) leaves and needles will change color. Yellowing and drop of the current season's growth or premature drop of older needles can indicate a problem and should bear further investigation. Also, trees and shrubs may have good years of substantial growth and poor years with little growth. When they shed their needles from a good year the entire tree may look yellow, especially if only a poor year's growth remains.
3. BUGBYTES.
A. PERIODICAL CICADA EMERGENCE BEGINS. Joe Boggs reported that Brood XIV of the 17-year periodical cicada (Magicicada spp.) has started to emerge in southern Ohio. The emergence was originally predicted to commence around mid-May, but cool temperatures apparently delayed the onslaught. This Brood will only affect a small portion of the southern part of the state. However, the total geographical area experiencing this emergence is impressive and includes parts of Indiana, Kentucky, Tennessee, Georgia, North Carolina, Virginia, Maryland, Pennsylvania, New Jersey, New York, and Massachusetts.
The cicada offensive begins with cream-colored adult cicadas crawling from the soil onto any handy vertical structure (e.g. trees, shrubs, grass, fence posts, etc.). The adults are still wrapped in the skin of the last instar nymph, but their true identity is given-away by their red eyes. The adults emerge from the nymphal skin and a few hours are required for their wings to expand and their exoskeleton to harden to acquire the cicada's characteristic coloration. This phase of cicada activity usually lasts several days with the cicada numbers increasing by the hour.
Eventually, the cicadas will take flight and the males will begin to sing. Songs of individuals are augmented by a synchronic orchestra of tens of thousands. The sound can become deafening. Of course, the cacophony is music to the "ears" of a female cicada, and ultimately brings her to a mating meeting. Once mated, the female cicada will use her spade-like ovipositor to insert eggs through the bark of twigs into the white wood. The resulting damage splits the bark and white wood leaving deep furrows of ruptured tissue. The injury often causes the twig to die, the leaves to turn brown ("flag"), and the twig to detach and drop.
In most cases, management of the periodical cicada is not necessary, but fruit trees and newly transplanted trees may need to be protected. Small trees and shrubs can be covered with a fine mesh nylon netting as a physical barrier to prevent oviposition damage. Few chemicals that are available to homeowners will limit the damage. Nurseries and orchards have a greater arsenal available to them than landscapers and homeowners.
B. A SWARM OF CALLS about bees was the buzz for this BYGL. Tim Malinich indicated that an active swarm season is pleasant change from last year when many hives died out throughout fall, winter and spring. Callers to the office are reporting swarms of bees in an around homes--sometimes incorrectly. Wasps and hornets are often improperly labeled as bees. However, the nests these insects make die out in the fall whereas honeybees (Apis mellifera) maintain a hive throughout the year. The population of a honeybee colony is at its lowest just after winter. As spring progresses the population grows and the hive may run out of room for expansion. If this happens, the colony swarms.
A few eggs are laid which will become new queens. Just before the new queen emerges, the old queen leaves the hive with several thousand worker bees. This cluster of bees will find a temporary rest stop while scouts seek out building sites for a new colony. It is this temporary cluster of bees that incites panicked calls from homeowners or businesses that are not used to thousands of bees buzzing about their property. Once the colony identifies a new home, the cluster takes flight en masse and will be gone within minutes--very impressive in sight and sound. Clusters that do not find immediate lodgings may literally hang out for a day or more, but they almost always leave within the day. Field bees that were out when the cluster left will return to the temporary rest stop but will eventually reconnect with a nearby hive. This swarm season is most active in May and will trail off with only a rare swarm in summer.
Honeybees that take up residence in walls, attics or other voids can be a continuous source of stress for property owners. If the colony is well-established, it may have a substantial amount of wax comb and 50 or more pounds of honey. The bees constantly maintain, repair and defend the comb. If the bees are killed or removed, the comb may deteriorate leaving a sticky mess or other insects (wasps) or mammals (mice) may loot the comb. Complete removal of the colony would entail removal of the comb and honey as well as related repairs to the structure. The best time for removal would be late winter when populations and honey stores are low. Also, swarms can be captured and put into a beehive. Most extension offices have a list of local beekeepers willing to hive a swarm.
C. EMERALD ASH BORER BEGIN TO TAKE FLIGHT. Dave Shetlar reported that during a visit on Friday, May 23rd to Mingo City Park in Delaware (just north of Columbus), that he found emerald ash borer (EAB) adults chewing their way into the outside (of the tree) world. EAB adults were flying when Joe Boggs stopped by the Warren County infestation on Sunday, May 25th. While Amy Stone is still waiting for adult emergence in the Toledo area, she probably won't have to wait much longer.
Adult emergence typically occurs between May and August. As adults emerge, they leave 1/8" small, distinctly D-shaped exit holes in the trunk and main branches, which is a sure sign of infestation. Adults feed on foliage for one to two weeks prior to mating. Females produce about 50 to 100 eggs, which are laid individually on the bark surface or within bark cracks and crevices of ash trees. Observations indicate that higher branches and upper portions of the trunk are colonized initially, making it difficult to detect early infestations.
As larvae hatch, they tunnel into the tree, where they feed through the summer and early fall on the phloem and outer sapwood, excavating S-shaped, serpentine galleries just under the bark. Most complete their development prior to over-wintering in the outer bark or just under the inner bark within the outer inch of sapwood. Pupation occurs in mid- to late-spring the following year. Adults emerge soon thereafter to complete the typical one-year cycle.
D. LACE BUGS. Dave Shetlar reported that he observed overwintered HAWTHORN LACE BUG (Corythucha cydoniae) and OAK LACE BUG (C. arcuata) adults laying eggs on the leaves of their namesake hosts in central Ohio. Like most lace bugs, hawthorn lace bugs live on the underside of leaves. They have a cosmopolitan palate and may be found on several species in the Rosaceae family including cotoneaster and Amelanchier as well as hawthorn. Oak lace bugs focus their attention on their namesake host, but they are particularly fond of oaks in the white oak group. These lace bugs are unusual in that they live on the upper leaf surface.
Lace bugs use their piercing/sucking mouth parts to suck juices from their host plants. Their feeding produces tiny yellow or whitish leaf spots (stippling) that may coalesce to produce large, yellow-to-copper colored areas on leaves, and early leaf drop. Lace bugs also deposit unsightly hard, black, varnish-like tar-spots of excrement onto the leaf surface as they feed. The bugs have multiple generations per season, and their damage builds with each succeeding crop of bugs. It is important to closely monitor and control lace bugs early in the season to avoid the collective damage produced by successive generations.
E. ERINEUM PATCH "GALLS". Several BYGLers reported that they are getting questions regarding erineum patches occurring on a number of landscape trees including beech, birch, linden and maple. Although the felt-like erineum patches are frequently referred to as "galls," there is some debate as to whether these leaf structures are true galls. They appear to arise like scar tissue from leaf cell damage caused by mite feeding activity rather than by a gall-maker exuding chemicals to direct plant growth. Regardless, like most true gall-makers, the eriophyids that produce the erineum patches are very specific to their host plant species.
The eriophyid mite (Acalitus fagerinea) produces erineum patches on American beech. The patches are located on the upper leaf surface; however, they cause a dimpling of the lower leaf surface beneath the patch. The patches are currently light green in color, but they will eventually turn a brilliant golden-yellow, and then reddish brown. The mite A. brevitarsus generates pinkish-red erineum patches on the upper leaf surface of birch leaves. Currently, the patches are silvery-white with slight overtones of pink.
Two different eriophyid mites produce erineum patches on sugar maple. Eriophyes elongatus generates patches on the upper leaf surface that are currently greenish-white in color. The patches will eventually become crimson red. E. modestus produces silvery colored patches on the lower leaf surface of sugar maple leaves in the forks in the leaf veins. The eriophyid E. tiliae generates a very similar looking silvery erineum patch on the lower leaf surface of lindens.
Although erineum patches may become very evident when eriophyid mite populations are high, the damage is usually insignificant relative to the overall health of the tree. Additionally, no control recommendations are currently available.
F. WINDSHIELD WIPES. BYGLers also ran into a few other insects and mites this week, including:
*Dave Shetlar reported that first generation DUSKY BIRCH SAWFLY (Croesus latitarsus) larvae are appearing on river birch leaves in central Ohio. Early instar larvae are dark gray, middle-instars are greenish-gray, and late instars are yellowish-green. All instars have shiny black head capsules and distinct black spots on their bodies. Larvae feed in colonies, lined up head‑to‑tail along leaf margins. When disturbed, the larvae form their bodies into a distinct "S" shape (S for sawfly?). Early instar larvae consume all but the mid-veins and main lateral veins, while late instars consume entire leaves. There are two generations of this sawfly in Ohio.
*Jim Chatfield reported that the depredations of HAWTHORN LEAFMINER (Profenusa canadensis) are becoming very apparent on hawthorns in central Ohio. Larvae of this sawfly mine the leaf parenchyma producing large, blister‑like, reddish‑brown blotch mines. The mines usually extend from the leaf margin toward the midvein. The hawthorn leafminer has one generation per year, so much of the damage this season has already occurred. Imidacloprid (e.g. Merit) can prevent a recurrence of damage next season if applied as a soil drench in October or November.
*BAGWORMS (Thyridopteryx ephemeraeformis) eggs should be starting to hatch in the southern portion of Ohio as was reported in last week's BYGL (issue 2008-8). And, as stated in the same issue, now is the time to start monitoring bagworm infestations very closely for newly hatched caterpillars, but it is not the time to treat for the bagworm. The time to treat for bagworm is after the majority of the eggs have hatched which coincides with the full bloom of Japanese tree lilac. Typically, this phenological event does not occur until around mid-June. Thus, to review, bagworm egg hatch starts with the full bloom to fading of full bloom of black locust and most egg hatch is completed by the time Japanese tree lilac is in full bloom.
4. DISEASE DIGEST. A. ANTHRANOSE ON SYCAMORE is being noted more commonly throughout the state, and estimates that this may not be a big year for this disease may have been premature, at least in localized areas. Some observers may simply have assumed that sycamores were late leafing out. In actuality, twig cankers had formed during the dormant period resulting in early infections, bud death and shoot blight. This resulted in very sparse sycamore trees in some areas this spring. It should also be noted that early disease reports associated with whether or not there was cool, wet conditions favoring anthracnose during leaf emergence from the southern part of the state may not match up what occurs during leaf out in more northerly regions. B. MOIST CHAMBER. The OSU Plant and Pest Diagnostic Clinic continues to get samples of SPHAEROPSIS TIP BLIGHT OF PINE disease, resulting in tip dieback and needle stunting on Austrian pine and tip curling and browning and needle stunting on Scots pines from last year's infections. New infections have occurred this year, but symptoms from these infections are not yet evident. Other diseases on pine include DOTHISTROMA NEEDLE BLIGHT OF PINE, and samples noted in previous BYGL's this spring, including VOLUTELLA LEAF BLIGHT AND STEM CANKER OF PACHYSANDRA and PEACH LEAF CURL.
5. TURF TIPS.
A. WHY IS MY TURF RED? There have been many reports of the turf disease known as RED THREAD (Laetisaria fuciformis) around the state. Red thread takes its name from the red or pink fungal structures on the tips of infected leaf blades. From a distance, symptoms appear as patches of tan or pink turf. Other diseases, including dollar spot, pink snow mold, and pink patch, resemble red thread from far away. However, after careful inspection, red thread can be distinguished by the presence of the strands of pink or reddish fungus, otherwise known as sclerotia.
This fungus is very common on all cool season turfgrasses: perennial ryegrass; Kentucky bluegrass; fine fescue; creeping bentgrass; and tall fescue. This disease is most active when temperatures are cool and moderate, when the turfgrass foliage is wet and when the grass is growing slowly. Take note that turf will recover because red thread does not affect turf-grass crowns so ultimately will not kill the plants.
In almost all cases, practices that result in a well-nourished, actively growing lawn will also suppress red thread. When renovating a lawn or establishing new turf, one should select the best red thread and other disease-resistant turfgrass varieties available. In well established lawns do not skimp on fertilization but also do not overdo the fertilizer program as it could lead to other problems. A preventative application of fungicide can be used in rare cases to suppress the disease.
6. INDUSTRY INSIGHTS.
A. SAMPLING 101-2. Last week, BYGL highlighted plant diagnostic sample-sending tips such as sending as much of the plant as you can (including roots when possible), shipping early in the week and without adding water to the sample, and protecting samples with padded envelopes. We also noted:
"Stem and branch sections should include a short section of healthy tissue so that the transition area between healthy and diseased tissue is included. For example, if collecting a sample to check for Verticillium wilt disease, select 1" diameter stem sections about 6" long, ideally from the area where the stem transitions between healthy and diseased tissue, rather than collecting completely dead stems." We cannot overemphasize this point, so are repeating it here. "Dead, brown sticks" are the bane of plant diagnostic clinics, the equivalent of sending fingernails to your physician and then hoping for useful information on your shortness of breath. Send us the best sample possible, hopefully as early in the game as possible, rather than dead sticks and browned grass.
B. POTATO LEAFHOPPER IS HERE. The annual migration and distribution of the potato leafhopper (PLH) (Empoasca fabae) into Ohio has occurred in most areas. Curtis Young was the first to report seeing the little, apple-green menace in the Lima area. Although PLH will initially migrate toward field and forage crops such as alfalfa, it will also spread into many landscape plants. Of particular interest will be plants in nursery production areas. Plants such as hedge, 'Red Sunset' and 'October Glory' maples can be severely impacted in their growth form and development which may influence their salability. Leaves on these trees can be cupped and new growth stunted.
Growers of nursery stock and landscapers need to be on the look out for PLH especially on plants still expanding new growth that could be damaged by PLH feeding.
Several other tree species that are very susceptible to injury include amur, Norway and sugar maples, birches, apple, chestnut, and Persian walnut. These trees can be injured both in the landscapes and nurseries areas, especially if located near alfalfa production fields.
Insecticide sprays will need to be applied in production areas to prevent reduced plant growth and vigor and to avoid distorted tree shape due to dieback and stunting. Some insecticides that appear to have fairly good activity against the PLH include foliar sprays of imidacloprid, cyfluthrin or a product with a combination of the two (e.g. Discus). Read insecticide labels carefully for application restrictions and potential chemical injury to host plants. Refer to OSU Extension Bulletin 504, "Insect and Mite Control on Woody Ornamentals and Herbaceous Perennials" for further details.
7. COMING ATTRACTIONS.
A. LANDSCAPE DIAGNOSTIC WORKSHOP IN CENTRAL OHIO. OSU Extension in Delaware County is proud to present the 2008 Landscape Diagnostic Workshop in Delaware, Ohio on June 9, 2008. This will be an all-day program which features Jim Chatfield, Dr. Dave Shetlar, Dr. Gary Gao and Amy Stone. Topics include: Diagnosing Nutrient Disorders in the Landscape; The Most Damaging Insects of Herbaceous Perennials; 20 Infectious Diseases in the Landscape; Diagnosing Insects and Mites of Woody Plants in the Landscape; Emerald Ash Borer (EAB) Update; and EAB Hands‑on Training. The registration fee is $40.00 per person. The fee includes the program, handouts, breaks and lunch, and a certificate of completion.
The registration deadline is June 5, 2008. Space is limited to 80 attendees. Registration will be accepted on a first come, first served basis. Late or on‑site registration is subject to a $5.00 late fee. Please call OSU Extension at 740‑833‑2030 to confirm space availability before registering onsite. Follow this link [ http://delaware.osu.edu/horticulture/upcoming‑programs ] to download a program flyer or email Cindy Kaelber at: [ This e-mail address is being protected from spambots. You need JavaScript enabled to view it ] for a program flyer.
B. TOTAL PLANT HEALTHCARE WORKSHOP. Greene County Master Gardener volunteers present this workshop on Thursday, June 5 from 8:30 a.m. to 4:00 p.m. at the OSUE Greene County office in Xenia. Special guest speaker is Roger Funk, PhD, Vice President and Chief Technical Officer of the Davey Tree Expert Company in Kent, Ohio. He will discuss the plant health care concept, how plants grow and respond to the environment, preventing growth factors from becoming limiting factors, plant nutrition, and the science of organics. The cost for the day is $40.00 and includes a great lasagna lunch. MG volunteer advanced training hours are available for this program; the general public is also invited. For more information, refer to the following website: [ http://greene.osu.edu ] or email Barb Mills at: [ This e-mail address is being protected from spambots. You need JavaScript enabled to view it ] or call 937-372-9971.
C. CINCINNATI BYGLIVE! DIAGNOSTIC WALK-ABOUT. The 3rd monthly BYGLive! Diagnostic Walk-About for 2008 will be held Monday, June 9, from 12:00-3:00 p.m., at the Stanley M. Rowe Arboretum, 4600 Muchmore Rd., Indian Hill. This monthly hands-on training for green industry professionals focuses on diagnosing plant pest, disease and physiological problems. ISA Certified Arborist CEU's will be available. For more information, contact Joe Boggs at 513-946-8993.
D. PLANT DIAGNOSTIC ACADEMY: July 9-11, 2008. Check out this 3 day class consisting of a hands-on approach to learning or refining plant diagnostic skills. These skills include discovering the process to properly diagnose plant problems, identification of woody plant diseases and detecting insect and mite problems. Determine how plants respond to cultural and environmental problems as hundreds of samples will be used to help participants identify symptoms. Diagnostic walks, to learn to really see the entire plant site environment, will also be a feature of this class. This experiential program will be held at Secrest Arboretum in Wooster, Ohio. Registration deadline is July 1, 2008, and classroom space is limited. Registration fee is $250 which includes all meals, snacks and class materials. Instructors include OSU Extension faculty Dave Apsley, Joe Boggs, Jim Chatfield, Bruce Cubberley (ATI), Erik Draper and Kathy Smith. For more information contact Kathy Smith at 614-688-3421 or visit: [ http://woodlandstewards.osu.edu/calendar ].
E. SCHNORMEIER GARDEN TOUR. This past week, thanks to Ted Schnormeier and his contact with Dan Herms, BYGLers and ENLTTers had a rare chance to tour the wonderful Schnormeier Gardens near Mt. Vernon and Gambier in Knox County, Ohio. Put on your calendar the dates of June 14-15, 2008, because these weekend dates will be the once-a-year opportunity for public tours of the gardens.
Schnormeier Gardens, started in 1996, provide world-class vistas on the 50 acres that include the Waterfall Garden, Stream Garden, Chinese Garden, Meadow Garden, Serenity Garden and Woodland Garden. There is a beautiful and peaceful Japanese tea house, a Chinese pavilion, numerous sculptures, many rare plants and a beautiful Frank Lloyd Wright-inspired home built in 1994. Ten lakes, wide swaths of emerald turfgrass swards, boulders, stone walls, and what Ted Schnormeier termed the "stairway to heaven" - rows of ornamental crabapples and pagoda dogwoods. Check out their website for further information and directions: [ http://www.schnormeiergardens.org ].
8. BYGLOSOPHY. "An optimist is the human personification of spring." - Susan J. Bissonette
Where trade names are used, no discrimination is intended and no endorsement by Ohio State University Extension is implied. Although every attempt is made to produce information that is complete, timely, and accurate, the pesticide user bears responsibility of consulting the pesticide label and adhering to those directions.
OSU Extension embraces human diversity and is committed to ensuring that all educational programs conducted by Ohio State University Extension are available to clientele on a nondiscriminatory basis without regard to race, color, age, gender identity, or expression, disability, religion, sexual orientation, national origin or veteran's status. Keith L. Smith, Associate Vice President for Ag. Adm. and Director, OSU Extension, TDD No. 800-589-8292 (Ohio only) or 614-292-1868. |
||||||||||||||||||||||||||||||||||||||||||
| Last Updated ( Thursday, 29 May 2008 20:22 ) |
