Pam Bennett, Barb Bloetscher, Joe Boggs, Jim Chatfield, Erik Draper, Dave Dyke, Dave Goerig, Tim Malinich, Jane Martin, Hannah Mathers, Pam Sherratt, Amy Stone, and Curtis Young
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June 02, 2005
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This is the ninth 2005 edition of the Buckeye Yard and Garden Line (BYGL).
BYGL is developed from a Tuesday morning conference call of Extension
agents, specialists and other contributors in Ohio.
BYGL is also made available on the Internet from the Ohio State University
Horticulture and Crop Science (HCS) in Virtual Perspective website
(http://bygl.osu.edu). Additional fact sheet information on any of
these articles may be found through the OSU fact sheet database (http://plantfacts.osu.edu).
BYGL is a service of OSU Extension and is aided by major support
from the Ohio Nursery and Landscape Association (ONLA), with additional
funding from the Ohio Chapter of the International Society of Arboriculture
(ISA) to the OSU Extension Nursery Landscape, and Turf Team (ENLTT).
Participants in the May 31, 2005 conference included: Pam Bennett (Clark); Barb Bloetscher (Entomology, C. Wayne Ellett Plant and Pest Diagnostic Clinic(CWEPPDC)); Joe Boggs (Hamilton/Piketon); Jim Chatfield (Center at Wooster/HCS); Erik Draper (Geauga); Dave Dyke (Hamilton); Amy Fulcher (University of Kentucky, Department of Horticulture); Pam Sherratt (HCS); Dave Goerig (Mahoning); Tim Malinich (Cuyahoga); Joe Rimelspach (Plant Pathology); Dave Shetlar (Entomology); Amy Stone (Lucas); Nancy Taylor (Pathology, 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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The month of May has come and gone. Monthly weather summaries indicate below normal temperatures and precipitation totals across much of the buckeye state. A rain gauge and recording tool are a must to stay on top of local conditions.
Here is the weather summaries from selected OARDC weather stations across the buckeye state. The information is a summary of data collected from May 1 - May 31.
| 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 |
64.6 |
44.7 |
N/A | N/A |
2.62" |
N/A | | Hoytville |
NW |
68.8 |
42.7 |
56.3 |
59.8 |
2.14" |
3.44" |
| Columbus |
Central |
70.8 |
46.4 |
59.0 |
61.4 |
4.1" |
4.38" |
| Miami |
SW |
71.6 |
47.5 |
59.8 |
61.6 |
2.93" |
4.68" |
| Jackson |
South |
72.3 |
42.6 |
57.8 |
61.7 |
1.63" |
4.16" |
For additional information, or to see the locations of all of the OARDC weather stations in Ohio, check out the website at: http://www.oardc.ohio-state.edu/centernet/weather.htm
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HORT SHORTS
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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: http://www.oardc.ohio-state.edu/gdd/
The range of GDD accumulations in Ohio from north to south is 326 to 661. Following is a report of GDD for several locations around Ohio as of June 1, 2005: Painesville, 326; Cleveland, 334; Toledo, 433; Youngstown, 383; Lima, 475; Wooster, 464; Coshocton, 491; Columbus, 521; Springfield, 540; Dayton, 591; Cincinnati, 661; Ironton, 640; and Portsmouth, 641.
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.
Common lilac, full bloom, 315; 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; doublefile viburnum, first bloom, 353; red Java weigela, first bloom, 365; black cherry, first bloom, 368; 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; multiflora rose, full bloom, 643; and northern catalpa, first bloom, 675.
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PERENNIAL OF THE WEEK
Dianthus spp. Many of these species and cultivars are in full bloom in central Ohio at this time. Dianthus or pinks as many know them, grow close to the ground with mounded green or blue-green foliage that can at times, be evergreen. Flower petals are fringed and range in the pinks, reds, and whites color spectrum. 'Tiny Rubies' is a dwarf cultivar with double rose-pink flowers that are somewhat fragrant. The low-growing foliage makes a nice tufted mat at the edge of the perennial border.
For more information on Dianthus and other fantastic perennials, check out the newest release from the ONLA: "Perennial Plants for Ohio." This updated bulletin has wonderful color pictures and is available from ONLA at onla.org.
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WOODY ORNAMENTAL OF THE WEEK - WHITE FIR
At the marvelous Cleveland Botanic Garden Show this past weekend there were thousands and thousands of plant lovers visiting the display gardens and vendors, the conservatory and the various CBG gardens. In the winding paths in the permanent gardens a plant familiar to some but not to many (to hear the many exclamations) was a concolor or white fir (Abies concolor). Especially viewed from below the fans of uplifted branch tips were quite charming. This fir will grow to 30'-50' or more and has an attractive pyramidal shape. The needle color is a showy blue to blue-green. White fir is tolerant of a wide range of dry, cold and heat conditions, but thrives best in moist, well-drained soils. It is the most adaptable fir for Midwest landscapes. In addition to the species, try out the 'Candicans' cultivar with its intensely silver-blue needles.
Read all about white fir and other landscape trees and shrubs in the new publication "Landscape Plants for Ohio" published by the Ohio Nursery & Landscape Association. The descriptions and photographs of plants were provided for this new publication by the OSU Extension Nursery Landscape and Turf Team with great help from friends such as Bill Hendricks and Fred Hower and in partnership with ONLA.
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MAPLE SEED MANIA CAUSES CONCERN
A few BYGLers reported receiving calls from concerned citizens regarding an apparent lack of development of maple tree canopies. The sparse, dinky foliage is due to all of the seeds, whirligigs or helicopters developing on maple trees this spring. Normal leaf development is slowed and reduced because the maple seeds are using most of the stored resources of the tree to ripen the gazillion seeds. The seeds mature, turn brown and then fall off to cover every square inch of the earth, easily filling and plugging all rain gutters. However, the anxiety is most intense after the seeds fall because there is no apparent reason for the lack of leaves and the "thinning canopy". Most callers are worried about the overall health of their trees while others erroneously associate heavy seed production with the last hurrah of dying trees.
Maple seed production is dependent upon various environmental factors and the growing conditions of the previous summer and fall, as well as the current spring. We all love that Indian summer weather before winter comes and all those warm, sunny days favor flower bud formation in many trees, including maples. Then this spring, when maples were in bloom, the dang weather also cooperated by remaining relatively mild and dry, resulting in good pollination and seed set. And doggone it, every single one all of those gazillion seeds began to fill out and ripen. Without some type of freeze or frost to kill or injure these developing seeds, the die is cast for maple seed mania.
Maple trees are capable of producing many seeds each year, but the limiting factor tends to be the weather, specifically those quick freezes and frosts after seed set. This year just happened to one that favored maple seed development. Remember that heavy seed production is not necessarily a good indicator of tree health nor should it be used as an indicator of impending tree death. It just means that we need some well timed freezes to reduce the seed numbers or hope for a really strong wind to blow them all to the neighbors yard!
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BUG BYTES
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BAGWORM EGGS HATCH
Overwintered bagworm (Thyridopteryx ephemeraeformis) eggs have hatched in the Cincinnati area, and first instar larvae were observed on Friday (May 27). The eggs spent the winter inside the dead, mummified bodies of last seasons females, with the dead females reposing in their bags.
When the eggs hatch, the small, blackish first instar larvae exit the bottom of the bag and spin down on a strand of silk. They may immediately begin feeding, and constructing their bag, or the silk thread my catch the wind and blow the larvae to new destinations. This wafting about on the wind is called "ballooning," and it is the primary means of dispersal for the insect since female bagworm moths never fly. In fact, the female larvae never pupate. They mate in the last instar larval stage, a form of reproduction called paedogenesis (reproduction by larvae). Only the males pupate and emerge as flying moths.
Localized bagworm populations can rapidly expand on preferred hosts, especially arborvitae, cedar, and juniper. If crowded, they may eat buds on these plants, causing branch dieback, and open, dead areas. If defoliation is excessive, plants may die the following season. Bagworms also attack numerous deciduous plants, although injury is generally not nearly as severe as on evergreens.
Keep an eye out for this pest, especially on plants infested last season. If there are just a few bagworms on a plant, they can be handpicked and destroyed. Bacillus thuringiensis, or Bt (e.g. Dipel, Thuricide, or Caterpillar Attack), is effective against bagworm caterpillars when bags are less than 3/8" in length. However, since eggs hatch over a 1-2 week period, this application should be delayed for 2-3 weeks after egg hatch first begins to suppress all caterpillars. Other properly labeled insecticides will have to be used if the caterpillars are allowed to get larger.
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FIREWOOD BLITZ SEIZES ILLEGAL FIREWOOD
Going camping? Pack your marshmallows, suntan lotion, and beach towels, but dont pack your firewood! Remember, state quarantines make it illegal to move ash-tree materials and firewood out of Michigan into Ohio and out of designated areas in northwest Ohio, including parts of Defiance, Fulton, Hancock, Henry, Lucas, and Wood Counties. Just last week, state and federal Department of Agriculture officials were enforcing the ban on firewood movement by checking vehicles at several northwest Ohio locations. Ohio law authorizes such inspections to prevent the spread of invasive pests. Officials seized 1,100 pieces of firewood over the two day period.
Moving firewood illegally can be costly. Quarantine violators can face fines up to $4,000. In addition to non-coniferous (non-evergreen) firewood, ash trees, logs, branches, limbs, woodchips larger than an inch, and other ash-tree materials are prohibited from leaving quarantined areas.
For more information or to view maps of Ohios quarantined areas, go to www.ohioagriculture.gov/eab and look for "Facts About Ohios Emerald Ash Borer Quarantine," or call the department toll-free at 1-888-OHIO-EAB.
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LOOK BEFORE YOU SHOOT
As Dave Shetlar (The Bug Doc) noted in his P.E.S.T. Newsletter this week (31 May 2005, Vol. 14, No. 6), the 2005 season is shaping-up to be "The Year of the Aphid." Prolonged periods of cool temperatures coupled with recurring rainfall have conspired to produce a bumper crop of aphids on a wide variety of landscape plants. The resulting leaf curl and accumulation of sticky honeydew blackened by sooty molds on leaves, stems, cars, and slow-moving gardeners may cause landscape managers to want to "do something!" The response often takes the form of an insecticide application.
However, managers are advised to look before they shoot. Aphids are an important meat item for a wide range of beneficial insects. Aphid antagonists include neuropteran lacewing predators such as aphidlions, with their impressive sickle-shaped mandibles; sneaky dipteran predators such as hover fly (family, Syrphidae) maggots that glide among unsuspecting herds of aphids, picking them off one by one; and of course coleopteran predators such as lady beetle adults and larvae. Additionally, the depredations of hymenopteran parasitoids should not be overlooked. Mummified aphids are the handiwork of important wasp parasitoids.
Collectively, these beneficial insects can have a significant impact on aphid populations. Indeed, they can cause damaging populations to virtually disappear. However, as with most meat eating animals, their populations take time to develop. Several BYGLers noted that the impact of beneficial insects is becoming apparent in their parts of the state. Although aphid damage is evident, there is nothing left of the aphids among the twisted leaves, except for a few cast skins. Probing fingers revealed hungry aphid predators, just waiting for the occasional hapless aphid ... meat's on the table!
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TIMBER NOT SO BORING
A landscaper in Columbus called the CWEPPDC with concerns about a borer which had chewed needle-diameter sized tunnels 11/2-2" straight into the trunk of several mature sycamores. Reddish, gooey sap and frass was emerging from 10 -15 holes per tree. Naturally, she was worried that these stately street- lined trees would succumb to these unknown borers. Fortunately, Dr. Shetlar recognized the description as that of the Columbian timber beetle, Corthylus columbianus.
Typical of most ambrosia beetles, the .2" long, black-reddish brown adult Columbian timber beetle females bore the tunnels into the heartwood then lay eggs, verses other boring beetles in which the larvae do the tunneling. The tiny white, legless, C shaped larvae develop in chambers in the heartwood, then emerge as adults that summer. Two to three generations may occur each year. Although normally a pest of oaks in the East, they may also bore into other hardwood trees. Damage may be seen in log ends where the staining is evident.
Fortunately, Columbian timber beetles are not known to kill trees, but may stress them. No control is necessary, however the trees should be protected from further stress. Interestingly, Dr. Shetlar and other BYGLers have noticed these and other ambrosia beetles this year, partly because of the foliar diseases occurring on sycamore. Because the trees are dropping leaves from sycamore anthracnose and other problems, more attention has been drawn to other diseases and insects attacking these trees.
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HAWTHORN HORRORS
BYGLers in southern, western, and central Ohio reported that the HAWTHORN LEAFMINER SAWFLY (Profenusa collaris) is completing its larval feeding period and beginning to abandon its leafmines. Populations appear to be heavy this season, although highly localized.
Eggs were laid by this sawfly as leaves were expanding in the spring. The resulting larvae fed between the upper and lower leaf surfaces producing large, blister-like, reddish-brown "blotch" mines that are now very evident. The mines often extend from the leaf margin to the midvein. The mature larvae are now dropping to the ground to form earthen cells where they will pupate and spend the winter. Although only a single generation occurs per year, heavily infested trees appear to have been singed by fire.
Joe Boggs reported that hawthorn cockscomb galls are becoming very evident on trees in his part of the state, adding to the leafmining woes. The galls are produced by a tiny midge fly and form along the midvein on the underside of leaves. Their raised, bumpy appearance and red color make them look like a cockscomb. The galls restrict normal leaf expansion, and cause leaves to become twisted or curled. Once formed, no controls are effective other than physical removal of the gall.
Landscapers who are dealing with trees that were heavily infested by hawthorn leafminer may consider applying imidacloprid (e.g. Merit; Bayer Advanced Tree & Shrub Insect Killer Concentrate) as a soil drench over the root zone in October or November. This application may also provide some relief from the hawthorn cockscomb midge fly.
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HOLLYHOCKS HARASSED
The HOLLYHOCK WEEVILS (Apion longirostre) and HOLLYHOCK SAWFLIES (Neoptilia malvacearum), are back at it, attacking their named host. Hollyhock sawfly larvae are light green with dark spots and a red head capsule. Although they begin chewing from the bottom of the leaves, causing "windowpanes", as they mature, they separate and skeletonize voraciously, often removing many of the leaves. If the first generation is left unchecked, the second generation may remove the rest of the leaves, leaving an unsightly tall plant.
The grayish, pubescent hollyhock weevils feed on flower buds, seeds and leaves, leaving puncture holes and tattered flowers. In June, the females mate and chew deep holes into the flower buds to lay eggs. The legless larvae feeds on the developing seed within the flower, then pupates within the seed. Most adults emerge in August-September then overwinter in plant debris near the hollyhock, however some remain in the spent flower and emerge the following spring.
To manage both of these pests, dead head flowers during the season and remove plant debris in the fall. A fall application of imidacloprid may eliminate these pests, however simple applications of insecticidal soap will control the sawflies easily.
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OAK GALLS AND CLEARWING MOTHS
Horned oak galls are gnarled, woody stem growths that may appear on twigs and branches of pin oak. The galls are produced by a tiny wasp (Callirhytis cornigera) that belongs the family Cynipidae. The name of the gall comes from horn-like structures that rise out of the galls when the immature wasps complete their development.
Research conducted by Eileen Eliason (now Buss, Entomology, University of Florida) while she was at the University of Kentucky revealed that horned oak galls serve as a home and feeding ground for a wide range of insects beyond the wasp responsible for directing the galls formation. Among the gall moochers are more than 20 other wasps, as well as two clearwing moths: DOGWOOD BORER (Synanthedon scitula) and OAK GALL BORER (S. decipiens). Indeed, Eileen found that around 15% of the 2-3 year old galls she used in her research were infested with dogwood borer.
Clearwing moths are so-named because the wings of many species lack scales they are clear. The clear wings and body shape allows the moths to mimic bees and wasps. Both the dogwood and oak gall borers are slim moths with steely-blue or black bodies and one or two thin yellow abdominal stripes. Both have very obvious flattened anal tufts of bristles on the tip of the abdomen. Dogwood borers have a rounded tuft. Oak gall borer has a pointed, almost arrow-shaped anal tuft.
Joe Boggs reported that he observed clearwing moth pupal skins hanging out of horned oak galls in southwest Ohio last Tuesday, and concluded they represented an early flight of dogwood borer. However, the true owners of the skins became clear when Joe opened his car's trunk on Friday to find a beautiful oak gall borer moth darting among galls he had collected for a diagnostic workshop! The oak gall borer confines its activity to woody galls on oaks and is not known to utilize other hosts.
This is not true for the dogwood borer. Along with infesting its namesake and horned oak galls, this borer has a wide host range including apple, plum, bayberry, beech, birch, black cherry, blueberry, chestnut, hazel nut, hickory, mountain ash, oak, pecan, and willow. Indeed, some consider this clearwing moth to be the most common sesiid in North America. Adults are present throughout much of the summer, although there are two discernable peaks in seasonal adult emergence activity. The moths extensive host range coupled with its prolonged period of adult activity presents serious pest management challenges.
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LOCUST LEAFMINER ADULTS ACTIVE
Curtis Young reported observing multitudes of locust leafminer adults (Odontota dorsalis) actively feeding on tree leaves in Akron, Ohio. This beetle is known for its feeding habits on black locust trees that results in the fired appearance of locust trees in mid to late summer. However, locust leafminer adults are not limited to skeletonizing the leaves of locust trees. In the spring, these small beetles, less than 1/4" long, feed on the leaves of several different species of trees including dogwood, elm, oak, beech, cherry, wisteria, hawthorn, and crabapple, as well as several herbaceous plants such as soybeans. Curtis observed the beetles feeding on recently expanded oak leaves. The adult is orange-red with a median black line down the center of the back. They are fairly flat beetles and frequently feed in clusters.
Eventually, the beetles will move to black locust trees where they lay clusters of three to five eggs in late May or early June on the undersides of the locust leaves. The larvae hatching from these eggs work their way into the leaf through one entrance hole and live in a common blotch mine that may involve half the leaf. Later, they go to other leaves and make separate mines. Larvae feed for about three weeks, pupation takes place in the mine, and beetles emerge a week or 10 days later and overwinter. In southern Ohio, two generations can occur, while northern Ohio contends with only one generation per year.
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BALSAM TWIG APHID
Populations of balsam twig aphids (Mindarus abitinus) were observed feeding in expanding needles of fir trees in the landscape of Ohio Northern University in northwest Ohio. Many of the expanding new candles were heavily infested with the aphids. Their feeding will cause the needles to twist and curl. In most cases this is cosmetic and not particularly damaging. The major exception is that curled needles can reduce the marketability and value of Christmas trees.
Balsam twig aphids also produce copious quantities of honeydew. Honeydew gives the needles a shiny appearance. At times the honeydew can be the growth medium for sooty molds, that turn the needles and twigs black. For Christmas tree growers this can also reduce marketability of the trees. Thus management of balsam twig aphids with chemical sprays is a must for Christmas tree growers producing fir trees.
According to the Michigan State University IPM program, the ideal time to spray for balsam twig aphid to limit its affects on needles is at 100 to 140 GDD after the stem mothers have hatched, but before the second generation aphids are present. Typically at this point, buds are swelling but have not yet broken. This GDD accumulation has been surpassed throughout Ohio, thus if fir trees have not yet been treated for balsam twig aphids, they should be treated as soon as possible. Especially those trees that are destined to be sold in the next year or two.
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DISEASE DIGEST
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FROGEYE LEAF SPOT
Certain cultivars of crabapple, such as 'Red Splendor', 'Professor Sprenger', and 'Adams' are now exhibiting considerable FROGEYE LEAF SPOT disease. This disease is caused by the fungus Botryosphaeria obtusa. Apple growers may recognize B. obtusa as the fungus that causes black rot cankers on apple tree twigs and branches and also causes a fruit rot. It is indeed the same fungus, that causes all these diseases on different apple tree plant parts, and is the same fungus that occurs on crabapples (simply Malus taxa that have fruits that are less than two inches in diameter at maturity), and on many other plants, including redbud, oak, viburnum, rhododendron, and scores of other hosts. B. obtusa is often called a "non-specialized opportunistic" pathogen for its wide host range and tendency to attack plant tissue often stressed by other factors.
The symptoms of frogeye leaf spot typically start with circular brownish spots with indefinite, purple margins. In some cases, as the season progresses, these spots enlarge into lobed brownish lesions with the lobes surrounding the original lesion. This lesion within a lesion (the original spot often turns grayish with age), develop a somewhat concentric ring configuration. This spot within a spot is what gives the name "frogeye" to this leaf spot. In some cases, crabapples with severe frogeye leaf spot exhibit considerable leaf yellowing and drop. In general the cool wet, weather this spring resulted in good conditions for development of frogeye leaf spot. But...
Why do certain crabapple types have more frogeye leaf spot than others right now? Of course, there are genetic differences in crabapple taxa relative to the various ways that crabapples resist B. obtusa infections, biochemical reactions and all that. But other factors come into play as well, relative to the full range of plant parts affected by this pathogen. For example, those crabapples that tend to retain fruit mummies from previous seasons have an additional source of fungal inoculum come spring. Adams for example retains mummies longer than most crabapples, and these little charcoal-like blobs are often infected with fruit rot from B. obtusa and with their retention on the tree into the next season, provide an extra source of overwintering inoculum to give this disease a head start each season.
Also, since B. obtusa colonizes declining and freshly dead plant tissue very well, pruning stubs and dead branches from other causes (winter injury, last years fireblight strikes etc.), are also sources of inoculum. Thus, each season you will see clusters of leaves with frogeye leaf spot adjacent to dead branches. As for frogeye leaf spot control, while extensive fungicide spray programs for scab control and other diseases help prevent frogeye leaf spot in apple orchards and in intensive nursery situations, in the landscape incidence is typically not severe enough to warrant special fungicide applications. However, good pruning practices, especially the removal of newly killed branches caused by other factors, is an excellent sanitation idea that can help keep these Botryosphaeria black rot cankers and frogeye leaf spot lesions down to a dull roar.
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MOIST CHAMBER
* Anthracnose diseases of ash and sycamore continue to be widely reported throughout Ohio, though often severity is spotty in a given area. As mentioned in last weeks BYGL, ASH ANTHRACNOSE, though it looks like a big problem when 10% or 15% of the leaves are on the ground, is generally not a serious health problem. In some cases, when observers see these ash leaves on the ground they start worrying that perhaps their ash has more severe problems, such as emerald ash borer. Not so! Leaf drop is NOT a symptom of emerald ash borer damage. As for ash anthracnose symptoms, look for the water-soaked grayish blotches delimited by the midvein of the ash leaflets.
* Other diseases reported commonly by BYGLers included rose black spot and fireblight on ornamental crabapples.
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TURF TIPS
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TURF TINTS, SHADES, AND HUES
BYGL'ers extended the conference call this week a bit longer to discuss some possible reasons for the color variations in turf plantings. Inquires from commercial firms and homeowners alike have come to educators and specialists wanting some sort of determination and solution to this off-color malarkey. Turfgrass can exhibit color variation for a number of reasons. Some of the possible reasons we squabbled through included; Nutrient availability, excessive moisture, mechanical manipulation and injury, fairy rings, and variety selection.
Over the last few years, heavy rainfall has challenged lawn care professionals. Fertilization and weed control programs were difficult to implement in such weather. Turf that is under stress from heavy, clay, saturated soils can appear to have different tints of green. This washed-out appearance could be a result of lack of nutrients from leaching or a lack of a way for the plant to absorb the nutrients due to root damage from flooding. One more reason for turf discoloration in wet weather may be the mower height. In cool, wet weather turf grows rapidly. Commercial lawn care firms, "making their way" through their customer list, may not always adhere to the one third rule. Cutting more than one-third of the turf off at any one mowing can result in scalping and a very pale green color. Another common off-color situation can occur in a lawn with fertilizer applications. Applicators are reminded it is good practice to apply half the recommended rate in a north/south direction and the other half in an east/west direction. This technique improves the uniformity of the application and avoids the light green, dark green streaks look. If these factors apply to your situation, this may be the cause of your color problems.
Another mechanical way to change the color of a lawn would be to Grain it. Grain is a term the golf industry uses to describe when turfgrass plants lay horizontally in one or more directions. Lawn professionals sometime refer to this as "striping a lawn". Turfgrass can appear several hues of green lighter from one mower direction path to another. All the more reason to be sure to keep your stripes straight.
Fairy Rings have been referred to as Club Fungi, or Basidiocarps. There are specific environmental conditions that cause these organisms to appear in a lawn. When they do appear, they look like rings, and half circles of turf that turn a darker shade of green. Controlling fairy rings are difficult and in most instances are left alone.
Finally, turfgrass color variations may be attributed to variety selection. Lawns that were established ten or more year ago have turfgrass varieties that may not be available today. If you asked your client to show you the label from the bag of seed used to establish the lawn, many would answer with a blank stare. Earnest attempts over the years to patch thin or damaged areas in the lawn were accomplished with newer varieties that were selected for disease resistance and of course, better color. These new patches sprout, grow and tend to appear greener than the rest of the yard.
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INDUSTRY INSIGHT
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MAPLE PETIOLE BORER IN NURSERIES
In BYGL 2005-07 (05/19/05), we reported that damage caused by the non-native maple petiole borer (Caulocampus acericaulis) was becoming evident on sugar maples in southwest Ohio. The tiny larvae of this sawfly tunnel out the inner tissues of the petiole causing the petioles to break a short distance from the leaf blade. This produces the symptom of green leaves with shortened, hollowed-out petioles dropping from the tree. Larvae remain inside the longer portion of the petiole that remains attached to the twig, so raking and destroying fallen leaves will not reduce the population.
As with past BYGL reports regarding this sawfly, we noted that damage to landscape trees is mostly aesthetic. Since there is only one generation per year, we have contended the leaf drop is seldom severe enough to cause serious harm to trees. Apparently, this is not the case in nurseries. Amy Fulcher reported that she has observed 100% defoliation caused by maple petiole borer in several Kentucky nurseries. This is serious damage!
Dave Shetlar indicated that while he does not have efficacy data, he suspects an application of imidacloprid (e.g. Merit; Bayer Advanced Tree & Shrub Concentrate) made as a soil drench over the root zone in October should suppress the activity of this insect the following season. Imidacloprid has proven effective against leafmining sawfly larvae, so it should move into the new leaves the following spring and protect them from the maple petiole borer.
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WHAT IS THE PH AND NUTRIENT STATUS OF YOUR POTTING MEDIA?
That is a question often asked by Amy Fulcher, Randy Zondag, Dave Dyke, and the other BYGLers when visiting nurseries or greenhouses ... or when teaching nursery or floriculture production practices.
It seems like a pretty simple question. However, it is one that a surprising number of growers are unable to answer even though maintaining the proper pH and nutrient levels is essential for professional plant production.
Every nursery needs to have someone who routinely checks Electrical Conductivity (EC) also called soluble salts, and the pH of container crops, potting inventories, and irrigation water. Checking the EC and pH should be considered part of the quality control and scouting program in the nursery. Results from testing 3 to 5 containers in a irrigation zone each week can be used to schedule irrigation the following week. Comparing leachate solution collected from containers to water collected from irrigation nozzles provides a good insight into nutrient levels in the containers. Checking EC and pH of nursery crops grown in containers doesn't have to be time consuming, complicated, or difficult.
Fortunately, checking the pH and nutrient status of container substrates and then maintaining them at the appropriate level is a simple task when using the Pour Thru extraction procedure. This procedure does not disturb plant roots as is necessary with other extraction procedures such as the Saturated Medium Extract procedure used at many commercial testing labs or the 1 to 2 procedure previously used by growers. In brief, 30 minutes to 2 hours after irrigation, pour approximately 1/2 cup (120 milliliters; 4.0 fl.oz.) of water over the surface of a 1 gallon container or 1.5 cups (360 milliliters; 12 fl.oz.) over a 3 gallon container for pine bark : sand potting mixes. More water may be required if the container mix contains sphagnum peat moss or other organic substrate amendments. Distilled water is recommended for determining existing leachate concentrations, however using water from irrigation risers for most production conditions is acceptable since the irrigation water contributes to the pH, EC and nutrient levels in the container. Reading the EC of the irrigation water and subtracting it's EC value from the container leachate EC indicates soluble salt concentrations in the container derived from fertilizer.
Leachate solution can also be obtained by picking up containers and tipping the container to drain leachate from drainage holes. Tipping the container 30 to 60 minutes after irrigation of containers provides a true reading of EC and pH levels in the container solution available to plant. It is important to remember that the PourThru extraction procedure provides an average of EC and pH concentrations in the container. If fertilizer is placed in one spot on one side of the plant in the container, the Pour Thru will not provide an accurate reading for the concentrated zone around the fertilizer; it will provide an average reading for the container.
For further information on the Pour Thru procedure, including desirable nutrient levels, please see, "Using the Pour Thru Procedure for Checking EC and pH for Nursery Crops", NCSUCES, HIL-401 (http://www.ces.ncsu.edu/depts/hort/hil/hil-401.html) or go to the Pour Thru Sampling section of the NCSU Commercial Floriculture site (http://www.ces.ncsu.edu/depts/hort/floriculture/crop/crop_PTS.htm).
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COMING ATTRACTIONS
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PLANT HEALTH CARE WORKSHOP
You wont want to miss Identification and Management of Weeds in Landscapes and Nurseries! Come join the fun at this years Plant Health Care Workshop in Wooster on July 12 -13. There will also be a pre-conference weed identification workshop on July 11.
The Plant Health Care Workshop combines proven concepts and practical information to help green industry professionals manage ornamental landscapes and urban forests. Topics for this years seminar include weed ecology, invasive weeds, weed identification, integrated strategies to manage weeds, and proper selection and use of herbicides.
Registration is limited to 40 participants. The program costs are as follows: Weed ID workshop only, $65; Plant Health Care Workshop, $225; or all three days, $260. For registration and program information, contact Denise Ellsworth or Diane Dunphy at 330-928-4769.
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OHIO PLANT DIAGNOSTIC WORKSHOP - SOUTHWEST OHIO
The southwest version of this traveling workshop will be held from 9:00 am. to 4:00 pm., on Monday, June 6, 2005, at the Cincinnati Zoo and Botanical Garden, Safari Lodge, in Cincinnati, Ohio. The action-packed diagnostic agenda includes: updates on emerald ash borer and sudden oak death; a general overview of "what's happening in Ohio;" and the ever-popular walk-til-you-drop (or get eaten) Diagnostic Walk-About. Instructors include Steve Foltz (Cincinnati Zoo), Jim Chatfield, Erik Draper, Dave Dyke, Joe Boggs, and various other animals.
Available Ohio Pesticide Applicator Re-Certification credits include: Core: 0.5 hr.; Category 6A (Ornamental Pest Control) 1.0 hr; Category 6C (Ornamental Weeds) 1.0 hr. ISA Certified Arborist CEUs are also available. The registration fee is $30.00 and covers the cost of a truly marvelous lunch, as well as training materials. The registration deadline is Friday, June 3, 12:00 pm. To register, contact Bob Warnock, OSU Extension, Hamilton County, at: Phone: 513-946-8992; Fax: 513-772-6126; or E-Mail: [ warnock.1@osu.edu ]. Come roar at the Ohio Plant Diagnostic Workshop - Southwest Ohio, at the Cincinnati Zoo and Botanical Garden!
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BYGLOSOPHY
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"Gardening is a kind of disease. It infects you, you cannot escape it. When you go visiting, your eyes rove about the garden; you interrupt the serious cocktail drinking because of an irresistible impulse to get up and pull a weed." - Lewis Gannit
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