This is the 7th 2009 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/ ; 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 19th conference call: Pam Bennett (Clark); Barb Bloetscher (C. Wayne Ellett Plant and Pest Diagnostic Clinic (CWEPPDC)); Joe Boggs (Hamilton); Cindy Burskey (Clermont); Dave Dyke (Hamilton); Gary Gao (Delaware); Dennis Lewandowski (Plant Pathology); Tim Malinich (Lorain); Bridget Meiring (CWEPPDC); Dave Shetlar (Entomology); Amy Stone (Lucas); Nancy J. Taylor (CWEPPDC); and Curtis Young (Hancock).

In This Issue:

1. WEATHERWATCH. 
2. HORT SHORTS:  Growing Degree Days (GDD); Trees Needing Kick-Start?!?; Vegetable Gardening 101 (Blossom-End Rot); Planting Strawberries; Integrated Pest Management in Vegetable Gardens; and Plants of the Week: Annual (Snapdragon), Perennial (Iris), Woody (Weigela), and Weed (Poison Ivy). 
3. GREEN SHORTS:  Composting and Cincinnati Area Green Infrastructure Network (CAPGIN) Meeting Report. 
4. CLINIC CLIPS.
5. BUGBYTES:  Seeing Red Spots? (Red Mites); Holey Oak Leaves (Oak Shothole Leafminer); Woolly Boolly Beech (Woolly Beech Leaf Aphid and Beech Blight Aphid); Sawfly Leafminers Revisted (Birch Leafminer Sawfly and Hawthorn Leafminer Sawfly); Annual Maple Leaf-Drop Commences (Maple Petiole Borer); and Windshield Wipes (European Pine Sawfly, Boxwood Psyllids, Pearleaf Blister Mite, and Emerald Ash Borer).
6. DISEASE DIGEST:  Down with Mildew (Downy Mildew); It's Not Your Usual Needle Blight; and Possible Pansy Problem - TMV! 
7. TURF TIPS:  Grubs-B-Goin' Down.
8. INDUSTRY INSIGHTS:  Garden Center Sales a Mixed Bag and Biz Buzz (Content of Training). 
9. COMING ATTRACTIONS:  Celebrate Master Gardener Volunteers (MGV) in Your Community This Week, May 17-23, 2009! and A Reminder: Hamilton County Extension Reloaded Tour. 
10. BYGLOSOPHY.

1.  WEATHERWATCH.  The following weather information summarizes data collected at various Ohio Agricultural Research Development Center (OARDC) Weather Stations spanning the dates:  May 1-20, 2009, with the exception of the soil temperatures which are readings from Wednesday, May 20 at 6:00 p.m.

Several BYGLers across the state mentioned being on the receiving end of scattered frosts earlier this week.  It is important to remember that lower temperatures can cause damage to tender foliage which sometimes goes unnoticed until later in the season.  If you were in an area that experienced a recent frost, beware of potential damage that might become more apparent in future weeks. 

For a link to the OARDC Weather Stations, visit: [ http://www.oardc.ohio-state.edu/centernet/weather.htm ]

2.  HORT SHORTS.

A.  GROWING DEGREE DAYS (GDD)

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 GDDs of ten OARDC weather stations and are available on the web at the site [ http://www.oardc.ohio-state.edu/gdd/ ].

The range of GDD accumulations in Ohio from north to south is 313 to 620.  Following is a report of GDD for several locations around Ohio as of May 20, 2009: Painesville, 313; Cleveland, 328; Toledo, 391; Canfield, 327; Findlay, 329; Wooster, 401; Coshocton, 421; Columbus, 511; Springfield, 517; Dayton, 523; Cincinnati, 574; Ironton, 586; Portsmouth, 589; and Piketon, 620.

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.

Red horsechestnut, first bloom, 304; pine needle scale, egg hatch - 1st generation, 305; cooley spruce gall adelgid, egg hatch, 308; eastern spruce gall adelgid, egg hatch, 308; common lilac, full bloom, 315; pink princess weigela, first bloom, 316; blackhaw viburnum, full bloom, 322; redosier dogwood, first bloom, 323; dwarf fothergilla, full bloom, 325; winter king hawthorn, first bloom, 328; 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.  TREES NEEDING KICK-START?!?  It all starts with a phone call.  An OSU Extension office receives a horticulture question from a concerned citizen; another office gets a call, and then another, and then an email goes out to all OSU ENLT Team members.  "Help - what is going on with this plant?" is the battle cry.  This is how it started last week.  Someone called Amy Stone in Lucas County to inquire if "something was affecting the sweetgums."  Pam Bennett received a sample of a "problem" on sweetgums.  After several back and forth email blitzes, BYGLers determined that there was likely no problem, but they were just slow to leaf out this year.  On top of that, the particular sweetgums that Pam observed had extreme winged ridges, which the caller suspected was a disease.  Sweetgums have ridges on the stems, but in this case, they were really extreme; and combined with the slow leaf development, one might have suspected a problem.  Joe Boggs checked on sweetgums in his area and noted a wide variability in leafing out stages from tree to tree. 

Situations like this usually lead to great BYGL discussions.  As BYGLers talked, many threw out various ideas regarding why some trees leaf out slower than others in the same species.  Pam had an example of 4 ash trees, planted at the same time.  Three of the 4 were barely beginning to leaf out while one was fully leafed out.  In this particular case, the "naked" trees have exhibited very little growth in the last few years, indicating a potential root stress problem.  This root stress could be delaying the development.  Other factors that delay development also include site problems, weather, microclimates, past stresses and more.  Patience is a virtue in this case.  Wait it out and then take a look at the tree to determine what might be causing the stress and then determine if it can be remedied. 

Some BYGLers speculated that perhaps sweetgums always leafed out slowly and no one really noticed them before.  The bottom line is that horticulturists must be vigilant in their observation of plants.  Observation is a critical key to diagnosing plant problems and continual observation might also be required.

C.  VEGETABLE GARDENING 101 - MAY 21, 2001 - BLOSSOM-END ROT.  It is too early to see the visual signs of blossom-end rot of tomatoes, pepper and eggplants.  However, this is the time when gardeners can do something about it.  Blossom‑end rot can be a serious disorder of tomato, pepper and eggplant.  Gardeners often are distressed to notice that a dry sunken decay has developed on the blossom end (opposite the stem) of many fruits, especially the first fruit of the season.  This non-parasitic disorder can be very damaging with losses of 50% or more in some years.   

Blossom‑end rot is not caused by a parasitic organism, rather it is a physiological disorder associated with a low concentration of calcium in the fruit.  Calcium is required in relatively high concentrations for normal cell growth.  When a rapidly growing fruit is deprived of necessary calcium, the tissues break down, leaving the characteristic dry, sunken lesion at the blossom end.  Blossom‑end rot is induced when demand for calcium exceeds supply.  This may result from low calcium levels or high amounts of competitive cations in the soil, drought stress or excessive soil moisture fluctuations which reduce uptake and movement of calcium into the plant or rapid, vegetative growth due to excessive nitrogen fertilization. 

The management of blossom-end rot includes:

*Maintaining the soil pH around 6.5.  Liming will supply calcium and will increase the ratio of calcium ions to other competitive ions in the soil.  It is a good idea to do a soil test to determine if and how much lime is needed.

*Use nitrate nitrogen as the fertilizer nitrogen source.  Ammoniacal nitrogen may increase blossom‑end rot as excess ammonium ions reduce calcium uptake.  Avoid over‑fertilization as side dressings during early fruiting, especially with ammoniacal forms of nitrogen.

*Avoid drought stress and wide fluctuations in soil moisture by using mulches and/or irrigation.  Plants generally need about one inch of moisture per week from rain or irrigation for proper growth and development.

Foliar applications of calcium, which are often advocated, are of little value because of poor absorption and movement to fruit where it is needed.  Early ripening tomato cultivars tend to get blossom end rot worse than the middle or late season cultivars.

D.  PLANTING STRAWBERRIES.  June-bearing and ever-bearing strawberry cultivars have bloomed and fruits are developing on them.  Before too long many of the berries will ripen.  Nothing beats juicy, sweet home grown strawberries!  Now is the perfect time to plant strawberries.  Gardeners should plant both June-bearing and ever-bearing cultivars.  Twenty-four to 30 plants are a good starting point for a strawberry patch.  At least two thirds of them should be the June-bearing type.  Some of the common cultivars of June-bearing strawberries are 'Earliglow', 'Surecrop' and 'Lateglow'.  If one has poorly drained soils, strawberry plants should be grown in a raised bed.  Select strawberry cultivars that are resistant to diseases, especially red stele.  For more information on growing strawberries and other fruit crops in the home garden, refer to the new OSU Extension Bulletin #940, "Midwest Home Fruit Production Guide."  This bulletin is available online at: [ http://ohioline.osu.edu/b940/index.html ] and can also be purchased from OSU Extension offices throughout the state.

E. INTEGRATED PEST MANAGEMENT IN VEGETABLE GARDENS.  Cindy Burskey received a sample of STRIPPED CUCUMBER BEETLE in the Clermont County Extension office.  The gardener indicated that she did not want to spray her plants with insecticides.  This approach may not work in the case of cucumber beetle since it is the vector of BACTERIAL WILT.  Each spring, cucumber beetles emerge from the ground in spring and feed on young plants, introducing bacteria into the leaves or stems.  The bacteria reproduce in the water‑conducting vessels, producing "gums" that interfere with water transport.  The beetles and bacteria are so intimately connected that controlling the beetles will control infection by the bacteria.  Once infection has occurred however, no control is possible, and wilting plants should be removed, if practical.  The disease is not seed‑borne. 

The only practical management measure is to use an insecticide when seedlings first emerge to control the black and yellow cucumber beetles.  Early infections are most severe, but total control depends on applications continuing at frequent intervals during the growing season.  In some cases, if insect pressure is heavy, it may be necessary to apply an insecticide when plants are just cracking the soil, but have not yet emerged.  Management of this disease is completely linked with preventing feeding of cucumber beetles on susceptible hosts.

For controlling insects in vegetable crops, it is important to practice integrated pest management.  The approach includes scouting the garden, cultural control, mechanical control, biological control, and sanitation.  For example, several types of barriers may be used to protect a crop.  Row covers, which allow for the penetration of sunlight and the movement of air and moisture (but not insects), can be used to protect a crop from migrating insects.  If crop rotation is not used, however, this type of cover can trap insects emerging from the soil in with the crop, creating a false sense of security.  Collars made of paper plates, aluminum pans and tin cans can also be placed around the bases of individual plants to protect the upper plant parts from crawling insects such as cutworms that live in the soil or to protect the stem base from egg‑laying by the cabbage maggot fly.  For more information, log on to Dr. Celeste Welty's website at: [ http://bugs.osu.edu/welty/ ].

F.  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 OF THE WEEK - SNAPDRAGON (Antirrhinum spp.).  Snapdragons are another of the cold-tolerant annuals that can be planted early in the spring season.  They perform best in full sun and will tolerate light shade.  People like to pinch the flowers to make the "dragon mouth" open.  The flowers are faintly fragrant and make excellent cut flowers.  Use the taller varieties for cut flower bouquets and the shorter varieties for bedding or border plants.  Deadhead on a regular basis to keep them fresh and blooming all season.

*PERENNIAL OF THE WEEK - IRIS (Iris spp).  The iris genus has between 200-300 species.  The name comes from the Greek word for "rainbow," referring to the numerous colors that are found.  The iris flower shape is unmistakable; it has 6 distinct parts.  There are many species grown in Ohio landscapes and most do well in full sun.  Some species grow well in dry soils while others prefer damp, moist soil.  The leaves are narrow and upright and provide a nice textural affect in the garden when the blooms are gone.  Some of the newer varieties are considered re-bloomers; they bloom in the spring and then provide a second flush of flowers in the later summer.

*WOODY ORNAMENTAL OF THE WEEK - WEIGELA (Weigela florida).  In bloom now in central Ohio, weigela is an excellent choice for tough urban landscape sites.  The upright arching branches are covered in red, pink, or white blooms, depending upon the cultivar.  It tolerates full sun and looks best in the shrub border where it can grow to its maximum height or 6-9' without being sheared or pruned.  'Wine and Roses' is a compact plant that grows 4-5' and has burgundy-purple foliage and pink flowers.  'Minuet' is a very small cultivar, growing to 30" and has red-purple flowers.  The leaves also have a reddish tinge.  The pink-flowering and red-flowering cultivars, 'Pink Princess' and 'Red Prince' respectively, grow to around 6' tall.

*WEED OF THE WEEK - POISON IVY (Rhus  radicans).  Poison ivy is a woody perennial weed that forms vines.  Poison ivy is adaptable and may look differently depending on its location.  Some plants may carpet the ground while others climb tree trunks, stone walls, fences and posts.  The edges of the leaflets may be lobed, smooth or toothed.  Poison ivy grows in the open, in deep shade or along path and road edges.  Poison ivy plants have a compound leaf arrangement made up of three leaflets on a leafstalk.  Two leaflets grow on opposing sides and the third stands by itself at the end of the stalk.  Poison ivy leaflets sometimes have hairy undersides.  Its stems are woody.

Each season, poison ivy has a slightly different color and appearance.  New springtime growth is often reddish and especially shiny.  After the leaves emerge, the plants may develop a cluster of greenish flowers.  Poison ivy fruit has a white, waxy appearance, a smooth surface and looks like mistletoe.  Summertime foliage is either dull or glossy green.  Fall foliage can be yellow, red or orange.

Poison ivy leaves, stems, fruit, flowers, and roots contain a toxic substance called urushiol.  It is released onto the plant surfaces when poison ivy is bruised or damaged.  If a sensitive person's skin touches such a plant, an allergic reaction can result.  In addition, poison ivy can contaminate people indirectly when they touch clothing, garden tools or pets, which came in contact with the poison ivy or inhale the smoke from a burning plant.  The oil remains potent for a couple of weeks, longer in very dry conditions.

Unfortunately, there is no magic cure for poison ivy, and the rash usually runs its course in two weeks or so.  Contact your family physician or pharmacist for more recommendations.

There are several methods to manage poison ivy.  Some of these include hand pulling or grubbing; severing the vine and then treating the regrowth with an herbicide; or applying an herbicide to individual leaflets.  Herbicides such as triclopyr or glyphosate are good choices for chemical treatment.  Always be sure to follow the directions on the product label.

3. GREEN SHORTS.

A.  COMPOSTING.  Yard trimmings and kitchen scraps use up valuable space in landfills.  Instead of sending these things to the curb, why not compost.  These materials make up 20 to 30 percent of all household wastes.  The use of compost can be a great addition to enhance your soil by returning organic matter in a useable form.

Wondering what you can compost?  How about how big, or small, a compost pile should be? Check out OSU Extension Home Yard and Garden FactSheet, #1189, "Composting at Home."

B.  CINCINNATI AREA GREEN INFRASTRUCTURE NETWORK (CAPGIN) MEETING REPORT.   The CAPGIN continues to gather momentum.  At its April 29th meeting a new domain name for CAPGIN was announced, [ http://capgin.osu.edu ], where information for the team will be posted in the future, the Resource Committee reported it had begun collecting resources and websites, and the Education/Training Committee announced a mission statement.

OSU Extension, Hamilton County reported on its collaboration with Project Evergreen and "Horticulture Magazine" to install a contour infiltration planting at Delhi Township Park.  Each step will be documented and photographed as well as collecting installation cost data.  "Horticulture Magazine" will be writing a feature article for the fall about this project.  Tim Young, Landscape Designer with Delhi Flower and Garden Centers has designed the planting.

Karen Ball with the Metropolitan Sewer District stressed the need for collection of data pre- and post installation of Green Infrastructures Demonstration Sites.  The MSD has a demonstration fund of 3 million dollars for 3 years under contract with the US Geological Survey.  Go to MSDGC website for details: [ http://MSDGC.org ].

An educational program was presented by Kaniz Saddiqui, Low Impact Development (LID) Program Manager with the Metropolitan Sewer District, "The MSD's Green Infrastructure Program" - this PowerPoint Presentation will be put on the CAGIN website.

The next CAPGIN meeting is scheduled for May 27, 2009 at the Cincinnati Zoo & Botanical Garden from 3:00-5:00 p.m. in the Treetops Building (just to the left of the Botanical Center at the old entrance).  An educational program on green roofs is to be presented by David Hart, Tremco; who has extensive experience designing and installing green roofs.  All horticultural and green infrastructure professionals are invited.

4.  CLINIC CLIPS.  Honey bee swarm calls continue to fly into the CWEPPDC.  It appears that this is a medium to good year for honey bee swarms.  This suggests that the honey bee colonies that survived the winter are doing well or at least that the colonies are crowded due to large number of eggs surviving and the larvae are developing to adults.  It is not an indication, however, that the bees will produce a good honey crop this summer.  Two nymphal stage American dog ticks were submitted as well, both had been attached to a human but neither had fed long enough to become engorged.

5.  BUGBYTES.

A.  SEEING RED SPOTS?  RED MITES have been reported crawling over sidewalks, decks, roofs and walls.  Although one "mite" assume they are European red mites, the clue to their identification is mainly that they are not on plants.  Instead, these soft, bright red mites are running around on hard surfaces, and thus are either BALUSTIUM SPECIES (Family Erythraeida) or RED VELVET MITES (Family Trombidiidae).

Balustium mites are oval and reddish gray with short, stiff hairs covering the body.  The front legs point forward, and a gap is obvious between the second and third set of legs.  Balustium mites suck plant juices from certain crops but usually are not considered to be pests.

Velvet mites have a soft, velvety, muscular appearance with broad "shoulders" and a narrow "waist", and are considered to be predators on small insects and insect eggs.  They often cluster in flowers where they eat pollen grains.  Their specialized mouth parts (chelicerae) enable them to grab a grain of pollen, pierce it, and suck out the nutrients.  When they breed in early spring, the population rises significantly.  On sunny days they are often seen crawling onto warm surfaces.  They commonly creep inside buildings through cracks and crevices of windows, doors and siding, causing displeasure to the building inhabitants.

Although insecticides inserted in cracks and crevices will reduce the number of these active mites, they are mostly beneficial and not requiring control.  To exclude them from inside, caulk and seal openings, and make sure screens are in good condition.  Ants help keep the numbers of both species of mites down by eating them.

B.  HOLEY OAK LEAVES.  Joe Boggs reported that the holey handiwork of the OAK SHOTHOLE LEAFMINER (Agromyza viridula) is becoming evident on oak leaves in southwest Ohio.  This tiny fly produces distinct holes in leaves through the feeding behavior of the adult females and the leaf mining activity of the larvae (maggots).  Females wing their way to oak leaves just as the leaves emerge from the bud.  They use their sharp, flexible ovipositors to penetrate the nascent leaves to release sap and their sponging mouthparts to lap up the nutrient rich fluid.  The resulting feeding wounds produce tiny holes in the juvenile leaves.

Occasionally, the females also use their ovipositors to insert eggs, one egg per wound.  The resulting maggots feed as a leafminers that produce tiny, circular, leaf mines.  The maggots rapidly complete their development and usually drop from the mines to pupate before the leaves are fully expanded.  The circular area of necrotic tissue caused by the leafmining activity eventually dries and falls away from the leaves, producing holes.

The small holes produced by the larval leafmining and adult feeding activity enlarge as the leaves expand.  A large number of holes may impart a "Swiss cheese" appearance to the leaves, or the holes may coalesce giving a tattered appearance.  Such symptoms mimic those produced by general defoliating caterpillars like gypsy moth, or symptoms produced by a phenomenon known as "oak tatters."  Fortunately, the damage caused by the oak shothole leafminer is seldom severe enough to cause serious harm to the health of the tree, so controls for the leafminer are generally not required.

C.  WOOLLY BOOLLY BEECH.  Dave Shetlar and Joe Boggs reported that the leaves on some European beech (Fagus sylvatica) trees in central and southwest Ohio, respectively, are becoming festooned with the white, waxy, flocculent material exuded by the nymphs of the woolly aphid, Phyllaphis fagi.  The aphid has no approved common name, but entomologists generally refer to it as the WOOLLY BEECH LEAF APHID.  The aphid is a European native that retains its preference for European beech in the U.S.

The woolly aphid appears to avoid American beech (F. grandifolia); however, it is sometimes mistaken for the similar looking BEECH BLIGHT APHID (Grylloprociphilus imbricator) that prefers American beech.  Nymphs of the blight aphid also exude white, waxy filaments, and the aphid forms large colonies that first appear on twigs and branches, then on leaves.  The blight aphids wiggle their abdomens in unison when disturbed, giving rise to the unapproved common name "boogie-woogie aphid."  Woolly beech leaf aphid colonies appear on leaves and occasionally creep onto surrounding twigs.  The nymphs also wiggle when disturbed, but their "dance" is very subdued and less organized.

Reports from Europe indicate the woolly beech leaf aphid can cause significant injury to its beech host; however, such reports are rare in the U.S.  The primary impact on European beech in the U.S. is the reduced aesthetics caused by the high contrast between the brilliant white aphid colonies and the lustrous dark green or dark purple beech leaves.  The aphids also exude copious quantities of honeydew and droplets of this sugary, sticky substance creates a gummy mess on underlying beech leaves, sidewalks, building decking, slow-moving gardeners, etc.  The deposited honeydew may become colonized with black sooty molds adding to the unsightly appearance of the goo.  Honeydew deposits can be washed away with a coarse stream of water, and most insecticides labeled for use on European beech will reduce aphid populations if control is considered necessary.

D.  SAWFLY LEAFMINERS REVISTED.  In BYGL 2009-03 (04/23/09), we reported that BIRCH LEAFMINER SAWFLY (Fenusa pusilla) and HAWTHORN LEAFMINER SAWFLY (Profenusa canadensis) adults were mating and laying eggs on their namesake hosts in southwest Ohio.  This week, Dave Shetlar reported that the resulting larvae of these sawflies have already pupated in the central part of the state and that he was amazed at how fast their egg-to-pupa development occurred.  Larvae of these sawflies 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 leafmining sawfly has only one generation per year, which means all of the damage produced by this sawfly has already occurred for this season.  However, the birch leafminer has three generations.

For most insect pests, the occurrence of multiple generations usually means upwardly spiraling populations and ever increasing damage as the season progresses.  However, for birch leafminer, the opposite is true.  Larvae can only mine new leaves.  So, most damage occurs in early spring when the first generation larvae mine the new, expanding leaves.  After they finish feeding for the season, around 80% of the first generation larvae drop to the ground and remain as pre‑pupae until the next spring.

None the less, Dave stressed that the second and third generations should not be ignored, because both can produce significant foliar damage on trees that are re-foliating after leaves were stripped by gypsy moth caterpillars, forest tent caterpillars, or dusky birch sawfly larvae.  Dave noted that a soil drench application of imidacloprid (e.g. Merit) made now will prevent further damage and plant stress caused by second and third generation birch leafmining sawflies on re-foliating trees.

E.  ANNUAL MAPLE LEAF-DROP COMMENCES.  Joe Boggs and Dave Shetlar reported that the annual leaf drop caused by MAPLE PETIOLE BORER (Caulocampus acericaulis) on sugar maples is beginning to occur in southwest and southern Ohio, respectively.  Although sugar maples are generally preferred, this sawfly will also occasionally infest other maples.  Fortunately, while the number of fallen leaves beneath an infested tree may look dramatic, defoliation seldom exceeds levels that are considered detrimental to the overall health of the tree.

This non-native sawfly was introduced into the United States from Europe.  It spends the winter in the pupal stage buried 2-3" in the soil beneath the affected tree.  Adults emerge in the spring.  After mating, the females use their saw-like ovipositors to insert a single egg into the petiole near the leaf blade.  The resulting grub-like larva feeds by boring down the center of the petiole.  Larvae drop to the ground once they complete their development.  They crawl into the soil to pupate and remain buried until the following spring.  There is one generation per year.

The initial symptoms of a maple petiole borer infestation are highly variable.  Some leaves may become wilted and discolored while still attached to the tree, with the petioles collapsing and turning brown just prior to leaf drop.  Other infested leaves show no outward symptoms and appear perfectly healthy when they drop from the tree.  However, all of the fallen leaves will retain only a very small portion of the hollow-out petiole.  Most of the petiole, along with the larva, remains attached to the tree.  Thus, raking and destroying fallen leaves will not reduce the sawfly population.  Fortunately, the sawfly has a minimal impact on tree health, so controls are not necessary.

F.  WINDSHIELD WIPES.  BYGLers also ran into several other insect and mite pests this week including:

* Dave Shetlar reported that a high percentage of EUROPEAN PINE SAWFLY (Neodiprion sertifer) larvae in central Ohio have pupated and the remainder is predominantly in the final instar stage.  This means almost all of the damage produced by this sawfly has now occurred for this season.  Most of the defoliation produced by this sawfly occurs on last year's needles since the sawfly completes its development before new needles fully elongate.  Consequently, heavily defoliated trees have been described as looking like "poodle trees" once the new growth fully expands.  Hosts include Scotch, mugo, red, jack, Table mountain and Swiss mountain pines.  White and Austrian pines are occasional hosts.

* Dave also reported that BOXWOOD PSYLLIDS (Psylla buxi) have completed their development and adults are on the wing in the central part of the state.  The adults are light green and about 1/8" long.  Dave noted that the adults will occasionally "bite" unsuspecting gardeners using their piercing mouthparts.  Fortunately, the bites cause little harm other than a slight stinging sensation.  The new adults will mate and lay small, orange, spindle-shaped eggs between bud scales of the host plant during the next few weeks.  There is only one generation per year; therefore the eggs being laid now will not hatch until spring of 2010.  The feeding activity by the resulting nymphs will cause new leaves to cup and sometimes, new twigs to twist.  The cupped foliage remains evident throughout the season.

* Joe Boggs noted that the blister-like leaf symptoms produced by the PEARLEAF BLISTER MITE (Phytoptus pyri) is becoming evident on ornamental pears in southwest Ohio.  This microscopic eriophyid mite lives between the upper and lower leaf surfaces.  Their feeding activity produces small, distinct blisters on the upper leaf surface and rough, irregular patches of necrotic tissue on the lower surface.  The blisters are currently light-green, but they will eventually turn pinkish-red, and finally brownish-black.  Although high populations of this mite produce dramatic symptoms, damage is seldom significant relative to tree health.  Control is generally not warranted since high populations on landscape trees seldom occur over successive years

*EAB TAKES FLIGHT.  Joe Boggs reported EMERALD ASH BORER (Agrilus planipennis) flying in Warren County in southwest Ohio.  First emergence of this exotic invader coincides with the flowering of black locust (Robinia pseudoacaia). 

6.  DISEASE DIGEST.

A.  DOWN WITH MILDEW.  DOWNY MILDEW (Peronospora or Plasmospora) is a group of fungi causing an emerging disease problem for the ornamental, greenhouse and garden center industry.  They are Oomycetes in the same group as more the more familiar Pythium and Phytophthora.  They are, however, different from the organisms that cause the powdery mildews.

Plants infected with downy mildew exhibit a wide range of symptoms, including leaf distortion, yellowing and stunting of plants as well as angular purplish-red to brown lesions.  Patches of fuzzy gray, purple, brown or white sporangia can be found on the underside of the leaves.  This helps to differentiate it from the powdery mildews, which produce gray or white fuzzy patches on the upper side of the leaves.  Downy mildew lesions might also be found on stems or twigs.

The disease is spread by spores and can be carried between crops on infected plants or plant debris and can be harbored in weed hosts of the disease.  Infected plant material should be removed from the growing area immediately.  Infection is favored by cool (50-75F), wet conditions and high humidity.  A film of water is needed for spores to germinate and infect the leaves.  As such, cultural controls include avoiding overhead irrigation, especially late in the day.  Use of drip irrigation, wider spacing of plant material and improved air circulation will all help to keep leaf wetness to a minimum.  High humidity in garden centers and greenhouses can be reduced through close attention to ventilation.

Care should be taken when using fungicides to control this and other emerging diseases.  Incorrect rotation of products, or total lack of rotation, can rapidly lead to fungicide resistance.  When choosing a rotation, pick products with different FRAC (Fungicide Resistance Action Committee) group numbers.  Fungicides are grouped by how they affect their targets, so rotating with different group numbers will help avoid resistance to any one product.  For example, rotations between group 33 (aluminum phosphanate, phosphanate), group 11 (fenamidone, strobilurins) and group 14 (dimethomorph) should provide some level of control for downy mildew.

B.  IT'S NOT YOUR USUAL NEEDLE BLIGHT.  At this time of year people may be noticing that the inner needles of their Austrian pines are brown on the tips, green on the base.  Samples examined in the CWEPPDC in the past week have been infected with DOTHISTROMA NEEDLE BLIGHT (Dothistroma septospora).  This fungus can infect needles from May to October, with intensification of symptoms from midsummer onward.  Infections developed during last season (2008) will start to produce spores this spring.  These spores can produce additional infections (on needles developed during 2009) during periods of rainy, overcast, cool weather.

A fungicide containing mancozeb (e.g. Junction) can be used to suppress this disease.  Although the disease can be active from May to October, it is not practical to treat season-long.  Most recommendations suggest two to several applications from the time new growth begins in the spring until sometime in June when new growth has hardened off.  While additional infections can occur later in the summer, most occur during the early season.

C.  POSSIBLE PETUNIA PROBLEM - TMV!  Dennis Lewandowski reported that the CWEPPDC had received a sample of a petunia suspected of being infected with TOBACCO MOSAIC VIRUS (TMV).  While not often thought of as a problem on petunias, TMV can indeed infect them, calibrachoas and a wide range of many other common greenhouse crops such as begonia, impatiens, lobelia, nicotiana, osteospermum, torenia and verbena.  Symptoms of TMV vary depending on the host, but look for yellowing, mosaic patterns, necrotic leaf spots, overall stunting and leaf distortion.  TMV can be spread by contact and handling and via infected seed, but unlike other common greenhouse viruses is not transmitted by insects.  Remove and discard any infected plants.  Weeds might also be infected - keep production areas weed free!  Do not handle healthy plants after handling infected plants or contaminated equipment without disinfesting tools and hands after infected plants or contaminated material have been handled.

For further information on this disease refer to Northeast Floriculture IPM Notes, Vol. 17, No. 3, Rutgers and Cornell Cooperative Extension [ http://74.125.47.132/search?q=cache:GyJa0N8zooMJ:njaes.rutgers.edu/pubs/fipmnotes/2007/fipmnotes17-03.pdf+tmv+on+pansies&cd=4&hl=en&ct=clnk&gl=us ]

7.  TURF TIPS.

A.  GRUBS-B-GOIN' DOWN.  Dave Shetlar provided a white grub development report based on a recent "grub dig" in central Ohio.  He found that most NORTHERN MASKED CHAFER BEETLE (Cyclocephals borealis) grubs have now moved deep into the soil to pupate.  Likewise, some JAPANESE BEETLE (Popillia japonica) grubs have also pupated and the remainder of the population appears to be clearing their intestinal tracts in preparation for pupation. 

For those who have noticed grub damage to turf and want to treat for grubs yet this spring, peel back the turfgrass to look for grubs near the surface of the soil.  If the grubs are no longer present or appear sluggish, it is too late to treat the grubs with an insecticide.  The grubs are finished feeding or are close to finishing and will not eat enough of the thatch and roots of the turfgrass to imbibe a lethal dose of the poison.  If raccoons and skunks are tearing up the turfgrass to get to the grubs, spread Milorganite or another composted sewage product which will repel the varmints.  Round two for white grubs begins when new adults emerge later this season.

8.  INDUSTRY INSIGHTS.

A.  GARDEN CENTER SALES A MIXED BAG.  Dave Dyke reported that the smiles of garden center owners in southwest Ohio get bigger and bigger as they report on their latest sales.  Just about all owners have reported significant increases in sales.  One actually complained that it was almost becoming too much, and that she and her employees were on the verge of becoming totally overwhelmed!  Joe Boggs reported that a landscaper complained it was becoming difficult to find plant materials.  The owners have attributed the higher sales volumes - at least partially - to wonderful weather over the last month.  Many operators stressed that the current level of sales needs to continue for several more weeks to assure that they have more than just an average sales season.  On the other hand, Tim Malinich reported that sales in northeastern Ohio were a bit more relaxed; with sales on nice days good, while sales on bad weather days were worse than the good sales on the nice days.

B.  BIZ BUZZ.  CONTENT OF TRAINING.  Dr. Bernie Erven, Professor Emeritus at The Ohio State University, suggests training employees involves four kinds of learning: knowing, doing, combination of what is known or can be done, and combinations of knowing and doing. Learning infers:

*Knowing something intellectually or conceptually one never knew before (e.g., pruning diseased plants without sanitizing equipment between cuts can transfer a pathogen to another plant).

*Being able to do something one could not do before (e.g., train an employee to prune correctly).

*Combining two knowns into a new understanding of a skill, piece of knowledge, concept, or behavior (e.g., knowledge about air movement within and around a plant with proper pruning can improve plant health).

*Being able to use or apply a new combination of skills, knowledge, concepts or behaviors (e.g., knowledge about the causes of specific fungal diseases and proper pruning, combine to understand the importance of ventilation in plant disease management).

All four kinds of learning should be part of a training program as appropriate.  Training must be more than teaching employees how to do things.  Helping them understand the importance of the job, the principles behind the job, and how they can use what they already know are important.

9.  COMING ATTRACTIONS.

A.  CELEBRATE MASTER GARDENER VOLUNTEERS (MGV) IN YOUR COMMUNITY THIS WEEK, MAY 17-23, 2009!  Celebrate and say thank you to the MGVs in Ohio communities for all of the great work they do to support OSU Extension.  MGV Week began last year and honors the hard work and dedication of MG volunteers throughout Ohio and recognizes OSU Extension's efforts in promoting the MGV program. The program provides leadership and educational development to individuals interested in gardening and giving back to their communities.

"Master Gardeners Volunteers Teaching 'Green'" is this year's theme for MGV Program Week and activities and programs will be held throughout Ohio's counties emphasizing that theme.  Learn more about being green in the landscape and garden from the following factsheet: [ http://mastergardener.osu.edu/pdf/MGVwk_flyer.pdf ].

To find out if there is an MGV program in a county, go to the MGV State website and click on counties at the top, then click on the county: [ http://mastergardener.osu.edu ].

B.  A REMINDER: HAMILTON COUNTY EXTENSION RELOADED TOUR.  As reported a couple of weeks ago, this tour of 4 leading Cincinnati area greenhouses will be led and conducted by a spectrum of OSU Extension educators and specialists on June 3, 2009. The focus of the tour will be to observe and learn greenhouse Integrated Pest Management (IPM) and cultural strategies to enable growers to produce better plants at a lower cost while using less pesticides, labor and energy.

The tour will end at a meeting of the Cincinnati Flower Growers Association at 5 p.m. hosted by Linda and Roger Feist, West Hills Greenhouses, 701 Feist Dr., Cincinnati, OH 45238, (513) 922-2378 [ This e-mail address is being protected from spambots. You need JavaScript enabled to view it - This e-mail address is being protected from spambots. You need JavaScript enabled to view it ] at The Farm, 239 Anderson Ferry Rd, Cincinnati, OH 45238. The meeting will include the restaurant's wonderful dinner buffet ($20.00 charge), a tour summary by Extension Educators and Specialists entitled, "What was seen and learned during our greenhouse visits," and a 1 hour presentation by Joanne Kick-Raack on "Greenhouse Pesticide Regulatory Compliance."

All horticultural professionals are invited to participate in the tour and subsequent meeting. If you will be participating in the tour please RSVP to Kim Martini at (513) 946-8989 or [ This e-mail address is being protected from spambots. You need JavaScript enabled to view it This e-mail address is being protected from spambots. You need JavaScript enabled to view it ]. If you will be attending the meeting, please RSVP to West Hills Greenhouses by Monday June 1 at (513) 922-2378 or [ This e-mail address is being protected from spambots. You need JavaScript enabled to view it This e-mail address is being protected from spambots. You need JavaScript enabled to view it ]. Go to [ http://hamilton.osu.edu/Horticulture/professional-horticulture ] for a complete tour itinerary.

Pesticide recertification credits available: 1 hour of core (commercial) & 5.5 hrs, categories 6 and 6D (commercial).

10.  BYGLOSOPHY.  But a weed is simply a plant that wants to grow where people want something else.  In blaming nature, people mistake the culprit.  Weeds are people's idea, not nature's. - Author Unknown

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.