Pam Bennett, Barb Bloetscher, Joe Boggs, Jim Chatfield, Erik Draper, Dave Dyke, Dave Goerig, Tim Malinich, Jane Martin, Amy Stone, and Curtis Young
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May 25, 2006
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This is the Eighth 2006 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 May 23, 2006 conference included: Pam Bennett (Clark); Barb Bloetscher (Entomology/C. Wayne Ellett Plant and Pest Diagnostic Clinic (CWEPPDC)); Joe Boggs (Hamilton/Piketon); Jim Chatfield (OSU Extension Center at Wooster/ Hort and Crop Science); Monte Clayton (Consultations); Erik Draper (Geauga); Dave Goerig (Mahoning); Dennis Lewandowski (Plant Pathology); Tim Malinich (Cuyahoga); 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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This week's weather summary includes May 1-May 23. Average temperatures at 3 of the 5 stations were lower this week, when compared to the average last week. Some of the BYGLers in the north mentioned frost. It is important to highlight this, as plant problems maybe popping up because of the cold weather. Here is the weather summary for 5 OARDC weather stations across the buckeye state.
| 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 |
64.2 |
46.1 |
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4.41" |
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| Hoytville |
NW |
66.0 |
46.1 |
55.7 |
58.6 |
4.26" |
2.36" |
| Columbus |
Central |
67.8 |
48.1 |
57.4 |
60.2 |
2.95" |
3.08" |
| Miami |
SW |
67.2 |
49.6 |
57.4 |
60.7 |
3.35" |
3.52" |
| Jackson |
South |
68.7 |
46.1 |
56.2 |
60.6 |
1.78" |
3.15" |
For a link to the OARDC Weather Stations, check out: http://www.oardc.ohio-state.edu/centernet/weather.htm
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HORT SHORTS
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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 is available on the web at the site below.
The range of GDD accumulations in Ohio from north to south is 345 to 631. Following is a report of GDD for several locations around Ohio as of May 24, 2006: Painesville, 345; Cleveland, 371; Toledo, 413; Youngstown, 396; Lima, 447; Wooster, 435; Coshocton, 489; Columbus, 544; Springfield, 484; Dayton, 509; Cincinnati, 560; Ironton, 604; Portsmouth, 607; and Piketon, 631.
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.
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; multiflora rose, full bloom, 643; and northern catalpa, first bloom, 675.
 
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PLANTS OF THE WEEK
*PERENNIAL OF THE WEEK. COREOPSIS or tickseed, has a wide variety of flowers and heights among this species. C. lanceolata has bright yellow flowers on 1-2' tall stems which bloom all summer. The very popular C. verticillata has delicate and profuse flowers on 8-12" mounds, and in recent years a red blooming variety has been introduced. This species is often called the thread leaf coreopsis, due to its extremely fine leaves. C. rosea has pink daisy-like flowers with yellow centers and finely textured leaves. Deadheading or just cutting back the entire plant, will cause Coreopsis to bloom throughout most of the summer. Coreopsis is a great addition to any garden due to their cheery, sunny-yellow blooms. They can be used as border plants or work well as cut flowers; regardless, Coreopsis seems to brighten any spot where they are planted.
*WOODY PLANT OF THE WEEK: WEIGELA (Weigela florida). Weigelas have made quite a comeback in recent years, and new cultivars have helped with their renaissance. They are coming into bloom throughout Ohio now. Weigelas are spreading shrubs (up to 6-9') with arching branches and attractive flowers in pinks, reds and whites. This Zone 4 plant is adaptable to many sites and has good urban pollution tolerance. Plant in full sun exposure, mass planting is best for impact and performs well in the shrub border. Among the many popular cultivars are 'Wine and Roses' a compact 4-5' form with burgundy-purple foliage and pink flowers, 'Minuet', another small compact cultivar with ruby-red and yellow flowers and purple-edged dark green foliage, as well as 'Pink Princess' and 'Red Princess'.
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EDEMA, (OEDEMA) EVENT
Dave Goerig was called out last week to a greenhouse in the Youngstown area to evaluate the condition of a grower's tomato plants. The plants were showing symptoms of vascular wilt and were oozing a whitish, fuzzy exudate under the leaf mid-vein and onto the stem. The growers were questioned about sanitation practices, spraying schedules, products used, watering schedules and plant varieties. As a precaution, the plants were relocated to a holding area and samples were sent to the CWEPPD clinic. Dave reported this week that the plants were evaluated by Nancy Taylor and Rajya Shukla who found no evidence of vascular wilt or bacterial streaming. Nancy stated the fuzz was made up of enlarged plant cells; a characteristic of a condition called Edema, (sometimes spelled Oedema).
Edema is a common, noninfectious disorder of soft tissue in plants. It is the extended swelling of plant tissue caused mainly by excessive accumulation of water within that tissue. Edema can occur on many types of herbaceous plants. Symptoms vary depending on the plant species but typically appear as whitish colored, water blisters which rupture, causing the damaged tissue and exposed surface to turn brown and appear wart-like with a corky texture. Edema tends to occur when plants take up more water through the roots than they can use or release through their leaves. This usually happens during the spring when environmental conditions warm the wet soil, while the atmosphere remains cool. Edema may also result from the use of oil-based sprays being applied to actively growing plants in high humidity conditions like greenhouses. Although edema symptoms do very little damage to plants, they give the impression the plant is unhealthy, and for retail sales, appearance is everything.
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BUG BYTES
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FOREST TENT CATERPILLAR GIANTS
Joe Boggs reported that forest tent caterpillars (Malacosoma disstria) in southwest Ohio are now in the 4th and 5th (final) instar stages. Joe noted that the well fed 5th instar caterpillars are huge (by caterpillar standards), approaching 2" long. Forest tent caterpillars have short grayish-white hairs, and distinct white markings running down their backs. These markings have been variously described as looking like "foot prints," or as being "keyhole shaped." The markings are flanked by cobalt blue lines running the length of the caterpillars' bodies. Last instar caterpillars acquire a mottled brown hue.
During the final instar stages, the caterpillars often collect in large masses on the trunks of their host trees. They leave these masses at night to feed. Localized defoliation in the southwest part of the state has been heavy with some trees suffering 100% leaf loss. The caterpillars are feeding on a wide variety of deciduous trees with heavy defoliation observed on oak, maple, sweetgum, honeylocust, and ash. Fortunately, the moth only has one generation per year and the caterpillar onslaught is almost over for the season. New leaves are already being produced on heavily defoliated trees.
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TWISTED ASH FLOWERS
Joe also reported receiving a phone call from an irate homeowner who had misdiagnosed the bizarre looking ash inflorescence (flower) galls as being caused by an herbicide applied by their lawn care service. The broccoli-like growths gracing their ash tree were in fact caused by the eriophyid mite Eriophyes fraxinivorus. The galls consist of a profusion of clubby, distorted flower parts. They are sometimes described as looking like small witches' brooms growing just beneath this season's leaves.
Currently, the galls are light green, but they will turn brown to black later in the season. Old, blackened galls remain attached to the twigs and evident for a number of years. Although the galls may reduce the aesthetic appeal of heavily infested trees, they cause no harm to the health of the tree since only the flower parts are affected. Consequently, no control recommendations are available for this gall-inducing mite.
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HAWTHORN LEAFMINER BLOTCH MINES
Curtis Young reported that HAWTHORN LEAFMINING SAWFLY (Profenusa Canadensis) damage is showing up on a couple of species of hawthorn (Crataegus spp.) especially COCKSPUR HAWTHORN (Crataegus crus-galli). Larvae of this sawfly mines the leaf parenchyma between the leaf surfaces, producing large, blister-like, reddish-brown "blotch" mines, which usually extend from the leaf margin toward the mid-vein. Mines of this sawfly are now reaching about 3/4 of their maximum size, so infested leaves are very noticeable. Back lighting the mined leaf by holding it up to the sun may reveal the one to several larvae and their frass inside of the mine.
The hawthorn leafminer overwinters as a pupa in the soil below the host tree. It emerges from the soil early in the spring about the time the young leaves are expanding. The adult females lay eggs on multiple leaves by inserting the eggs just under the leaf surface. The eggs hatch, the larvae mine the leaves and by mid June the larvae complete their feeding, bore out of the mine, drop to the ground and build an earthen cell in which to overwinter. The hawthorn leafminer has one generation per year.
Heavily infested trees will have a brownish cast from a distance. Fortunately, mines will frequently break off and/or heavily damaged leaves will fall off and be replaced. Since the leafmining activity is already well underway for the season, it is too late to apply control measures to limit the damage.
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WEBWORM ON EUONYMUS?
Jim Chatfield and Erik Draper reported observing a EUROPEAN SPINDLE TREE (Euonymus europaea) that was covered by numerous webbed clusters of leaves at Secrest Arboretum. They initially thought the caterpillars inside of the webbed bags of leaves were fall webworm, but they were eventually identified as EUONYMUS CATERPILLARS (Yponomeuta cagnagella). This unusual caterpillar is native to Europe and was first reported in North America in 1967. Since then it has spread into Michigan, New York and other New England states, Pennsylvania, and Ohio.
The euonymus caterpillar primarily attacks ornamental plantings of the European spindle tree. However, there is concern that it may spread to other euonymus species such as the common winged euonymus or burning bush (E. alatus). Scattered infestations have occurred on the common winged euonymus in Michigan, New York and Vermont. In addition, infestations have been found in E. kiautschovicus, a Chinese spreading shrub that is partially evergreen, and evergreen euonymus (E. japonicus).
If the caterpillars are spotted early in their development, they can be easily managed with several insecticides recommended to control general caterpillars. The trick is spotting them before they have done extensive damage. They overwinter as first instar larvae and begin feeding on newly expanding foliage the following spring. Thus, they get a very early start.
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WINDSHIELD WIPES
BYGLers also ran into several other insects and mites this week including:
* Joe Boggs reported observing early instar IMPORTED WILLOW LEAF BEETLE (Plagiodera versicolora) larvae munching leaves on a variety of ornamental landscape willows in southwest Ohio. The beetle spends the winter in the adult stage. The oblong, black to greenish blue adults emerge in the spring and feed by chewing holes or notches in the foliage. The glossy black larvae skeletonize leaves, causing more damage than the adults. Young larvae may feed side by side and move as a group across the underside of the leaf. Later instars feed singly on the upper leaf surface. Damage can become significant since two or three generations may occur in Ohio. Several standard insecticides labeled for willow are effective in managing this pest, as well as insecticidal soap and horticultural oil sprays.
* ASH PLANT BUGS (Tropidosteptes amoenus) and SYCAMORE PLANT BUGS (Plagiognathus albatus) are very active on their namesakes in southwest Ohio. Feeding damage by these sucking insects at first appears as tiny yellow spots (stippling) on the leaves. The stippled spots eventually blacken and damaged tissue drops from the leaves leaving behind small holes. Injury to developing leaves interferes with normal leaf expansion, causing leaves to become wrinkled in appearance. Sycamore plant bugs have one generation per year with development complete by mid-July. Ash plant bugs have two generations per year, so new stippling may be observed throughout much of the season.
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DISEASE DIGEST
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OAK WILT AND PRUNING
Oak wilt (Ceratocystic fagacearum) is a serious vascular wilt disease of oaks, especially the red oak group. It is often difficult to diagnose, even with laboratory tests, but symptoms on the red oak group include: leaf discoloration of dull green, tan and bronze starting with the tips, some leaf curling and wilt, and defoliation, often of green leaves, and eventually development of brownish vascular discoloration in the sapwood. Do not confuse these symptoms with the leaf curl and blackish-gray discoloration and distortion of lower canopy leaves due to the much less serious oak anthracnose disease occurring now. In the red oak group, this vascular dysfunction progresses to tree death often within the year. Pads of fungal mycelium develop on the trunk under the bark in the fall of the season. The following spring, the bark cracks exposing the pads to insects.
Insects, primarily sap feeders in the Nitidulidae family of beetles, then can vector Ceratocystis fagacearum to healthy oaks. This is where the issue of pruning comes into play. These sap-feeding insects thrive on and are attracted to wounds, including pruning wounds. That is why we recommend that pruning be limited on oaks, especially oaks in the red oak group, to late summer and the dormant season, when there is less possibility of the vectoring of the fungus from diseased to healthy oaks via the Nitidulid beetles. If you must prune in spring and early summer, this is one case where we do recommend painting the pruning cuts in order to stymie the beetles. Ordinarily we do not recommend pruning paint since it interferes with wound "healing" by the tree, but this is the exception that proves the rule.
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WHY FUNGICIDES FAIL, PART 1- FAULTY DIAGNOSIS OF DISEASE
This fungicide does not work! I want my money back! Who recommended it! I just want a simple solution to this dratted disease! These are common laments when it comes to fungicides and when it comes to infectious diseases. These laments reflect an understandable but unreasonable desire to make horticulture, plant pathology (the study of plant diseases), and fungicide use simple. The fact is that control of diseases and the use of fungicides is anything but simple. It's now over a hundred years since a plant pathologist quipped that "Plant pathology must be far more than mere squirt gun botany", but this observation still holds true. There is more to disease control than fungicides, and there is more to proper fungicide use than simply pointing and spraying. Let's look at some of the key reasons that use of fungicides fail. It all starts with proper diagnosis.
Faulty diagnosis of disease is one of the most common reason "failures". For example, over the years, many growers and landscape managers have complained that this or that fungicide is just not effective in controlling Phomopsis. blight on juniper in their plantings. This disease causes the dieback of shoots of juniper and can cause quite a bit of unsightliness and damage to the plant. As pointed out by research in Pennsylvania and Ohio, however, one of the most common reasons for "failure" is that the problem was initially misdiagnosed. Many factors cause dieback on junipers, from juniper tip midge insects and juniper tip dwarfmites to winter desiccation injury and vole damage to the stems. Naturally, if these are the causes of the dieback rather than the Phomopsis fungus, then fungicides will surely "fail" over and over again. The problem is simply not a fungal disease. Proper diagnosis is Step 1 relative to proper, and successful, use of fungicides.
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THE MOIST CHAMBER
Last week BYGL mentioned the many samples of ash anthracnose and sycamore anthracnose Extension offices are receiving.
*Add OAK ANTHRACNOSE (Apiognomonia quercina) to that list. Oak anthracnose is not quite as noticeable this year as last on most areas, but there is a good bit of it on white oaks around the state. Symptoms present now include blackish-gray leaf blotching, distortion and curling, especially on the lower canopy. Though it may make the tree look a bit gnarly right now, oak anthracnose is not a major health problem for the tree.
*Other diseases noted by BYGLers last week include FIREBLIGHT ON PYRACANTHA (Erwinia amylovora), resulting in the typical "shepherd's crook" symptoms of curled shoots, PEACH LEAF CURL (Taphrina deformans) with its angry orange and red blisters on peach leaves, and OAK LEAF BLISTER (Taphrina caerulescens) causing clear-colored and later yellowish, reddish and brown blisters of little plant health importance on the leaves.
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INDUSTRY INSIGHT
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WHAT'S WRONG WITH MY OAKS?
Several BYGLers reported complaints about oaks with malformed leaves. Some oak leaves were cupped downward with brown margins, while other oak trees had rounded edges and shallow lobes, to the extent that some of the leaves had only the mid-veins remaining! These symptoms usually take place in May in years when cold temperatures or high winds occur in late spring, after the leaves have started to develop. Any combination of the above symptoms may appear.
The narrowed leaves and shallow lobes are often blamed on an insect, as the leaves look as if something has chewed around the perimeter of the leaves. This phenomenon is known as tatters, which occurs when newly opening and expanding leaves are damaged from wind, hail and/or cold temperatures. The downward cupping and browning of the leaves is believed to be a symptom of frost injury.
Yes, sometimes, both cankerworms and the oak shothole leafminer can be at least somewhat culpable, as they embark on their vocation when the leaves are unfurling. The cankerworms may nibble on the edges of some leaves, while the oak shothole leafminer mines the tender new leaves. Once the mine is complete and the tissue it encompasses dies, the rounded "mine" drops out, leaving a round hole in the leaf. As the leaf continues to enlarge and open, the hole enlarges and elongates. Leaves which are heavily mined often look like Swiss cheese.
So what can be done about these funky looking leaves? Nothing, because most well established trees will compensate by producing a second set of leaves. Obviously this can stress oaks with a compromised root system, but if they are protected from other stresses (compaction, poor drainage, root damage, etc.) they should recover.
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COMING ATTRACTIONS
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DIAGNOSTIC WORKSHOP IN NORTHEAST OHIO
This hands-on workshop will be held on Tuesday June 6, 2005 at the Donald W. Meyer Center in the beautiful Big Creek Park of the Geauga Park District. Join OSU Extension's Jim Chatfield, and Erik Draper as they combine their own zany experiences and skills to help you meet the diagnostic plant challenges of the coming season.
Some of the topics at this year's workshop include: Emerald Ash Borer; Diseases and Insects du Jour; Dr. Dendro's Diagnostic Case Studies; Digital Diagnostics; Clinic Catharsis Sample Sharing; and a Diagnostic Walk. Registration for this daylong program will begin at 9:30 A.M. and the program starts at 10 AM. Additionally, certification credits will be provided for ONLA technicians and Master Gardeners.
The registration fee is $30.00, which covers the cost of lunch, refreshments and all program materials. Fee is payable by check or cash to OSU Extension, Geauga County, at PO.BOX 387, Burton , OH. 44021-0387. If there are questions or to RSVP a place in this unique learning experience, please call 440.834.4656. For directions to the park see http://www.geaugaparkdistrict.org/parks/bigcreek.shtml
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BYGLOSOPHY
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"The best way to garden is to put on a wide-brimmed straw hat and some old clothes. And with a hoe in one hand and a cold drink in the other, tell somebody else where to dig." -Texas Bix Bender
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