Pam Bennett, Barb Bloetscher, Joe Boggs, Jim Chatfield, Erik Draper, Dave Dyke, Dave Goerig, Dan Herms, Tim Malinich, Jane Martin, Joseph Rimelspach, Pam Sherratt, Amy Stone, and Curtis Young
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July 15, 2004
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This is the Fifthteenth 2004 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 July 13, 2004 conference included: Barb Bloetscher (Entomology and C. Wayne Ellett Plant & Pest Diagnostic Clinic); Joe Boggs (Hamilton/South District); Erik Draper (Geauga); Jim Chatfield (North District/ Horticulture and Crop Science Department-HCS); Dave Dyke (Hamilton); Dave Goerig (Mahoning); Joe Rimelspach (Dept. Plant Pathology); Dave Shetlar (Entomology); Pam Sherratt (HCS); Curtis Young (Allen); and Randy Zondag (Lake).
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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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Joe Boggs gathered data recorded this past week at the Cincinnati/Northern Kentucky International Airport. It revealed current months precipitation totals stand at 2.66".That is +1.18" above comparative average for the month thus far. Year to date totals for that area weigh in at 25.71", which show +1.69" above comparative average for the year. Dave Goerig disclosed the Mahoning Valley has received 23.00" of rain for the year, as compared to the recorded average of 19.93", or +3.07". Month to date totals for the Youngstown area are disclosing a drier trend with 0.86"occurring and recorded average at 1.82". In Columbus, precipitation is 0.84" this month which is 1.11" below average for July. Temperatures are slightly higher than normal. Overall weather discussions from the conference indicated many parts of the state are drying out at this time.
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HORT SHORTS
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RECOGNIZING TREE HAZARDS
Ohio has sustained its share of tree damage from the storms this spring and early summer. Mahoning county Extension educator, Dave Goerig asked just what advice a garden center employee, landscaper, or lawn care professional should offer to a client who is working through this type of a problem? The Extension Nursery, Landscape, Turf Team's response was unanimous; seek out certified tree care professionals from the International Society of Arboriculture (ISA).
Trees offer many benefits to the homeowner, however when large trees pose a threat to people and property, they are a liability. It is the owner's responsibility to manage the plants on his/her property to minimize hazards. Persons working in the green industry are advised to steer questions concerning tree hazards to ISA, which offers a website containing valuable information on trees, as well as a published list of professionals who have attained Certified Arborist status with ISA.
A homeowner can count on these professionals to evaluate the hazard objectively with the tree in mind. Their website can be found at http://www.isa-arbor.com/home.asp
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CHICORY CHICK....
Chicory (Cichorium intybus L.) and Queen Anne's Lace are now gracing Ohio's roadways, as sure sign of summer. Most people are familiar with chicory's value as a coffee-free substitute, roots are dried and ground and used to enhance the flavor of coffee. Also known as blue sailor, wild endive and succory, the milky juice in the stems and leaves were used as a sedative by Europeans and early settlers in the US. The wider basal leaves were mixed into salads centuries ago. A native of the Mediterranean regions of Asia and Europe, it was used by the ancient Egyptians, Greeks and Romans for medicinal purposes. Water from boiling the roots was administered to treat jaundice, liver enlargement, gout, and rheumatism. The entire plant was boiled and used as a laxative and diuretic. Bruised leaves were mixed into a tincture to help soothe inflamed eyes and swellings. Blue dye was extracted from the beautiful dandelion-like blue flower petals. A weed? Only if it is growing in an undesirable location.
 
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BUG BYTES
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AVOIDING MOSQUITO BITES
The little blood suckers are out there and in great abundance this year. With all the rain that many parts of Ohio have received this year, there are plenty of breeding sites available for mosquito reproduction. The challenge now is to avoid being bitten by the blood thirsty little B-I-T-E-R-S!
According to the "Fight The Bite, Ohio" campaign, a product of The Ohio Department of Health (ODH) and the Ohio West Nile Virus (WNV) Workgroup, there are several measures one can take to avoid being bitten by mosquitoes. These actions include the following:
1. Wear light-colored clothing that is apparently less attractive to mosquitoes. The clothing should include long sleeved shirts, long pants, socks and shoes. Basically cover as much skin as possible. Loose clothing is better than tight fitting clothing. It may not be the most comfortable dress for hot, steamy summer days, but it will make it harder for the mosquitoes to get to your skin.
2. When possible, stay indoors during the early morning (dawn) and late evening (dusk). These are the times when mosquitoes are most actively seeking a blood meal. Mosquitoes will also be active on cloudy overcast days. They usually avoid open bright sunny areas during the heat of the day.
3. Keep away from places where mosquito populations are high... at this point you may have to go to some other state to accomplish this! More specifically, mosquitoes will be abundant in wood lots and other areas with heavy vegetative growth. These are good resting areas for mosquitoes.
4. Cut high weeds around your home to reduce mosquito resting areas.
5. Keep windows and door screens in good repair and closed to keep mosquitoes out of your home.
6. When you cannot avoid being in places and out at times where and when mosquitoes are active, protect yourself with a repellent that contains the active ingredient DEET (N,N-diethyl-meta-toluamide). Numerous products with varying concentrations of DEET are available for use in Ohio. However, adults should use products with no more than 30% DEET and children should use products containing 10% or less. One should limit how long they are exposed to DEET and avoid spraying large areas of exposed skin. Infants and pregnant women should not wear DEET, nor should DEET be applied directly to a child's body. First apply it to your own hands or a cloth, then put it on the child. Always use DEET according to the manufacturer's instructions.
Beyond the annoyance of being bitten and the irritation it can produce at the site of attack, we continue to be concerned with the potential of the spread of mosquito borne diseases such as St. Louis Encephalitis, La Crosse Encephalitis and more recently, West Nile Virus (WNV).
Surprisingly, the incidence of WNV is relatively low thus far in 2004. The following is the official test results posted on the Ohio Department of Health's (ODH) web site for WNV. As of July 9, 2004, ODH's Vector borne Disease Program has tested 1,365 birds and has found 15 positives. There are 31 positive mosquito pools out of 2,540 pools (74,202 mosquitoes) tested. Currently no horses or humans have tested positive in Ohio. According to the Centers for Disease Control and Prevention's records for 2004, the most active area for WNV in the country is Arizona followed by California. Thus far in 2004, only 8 states have recorded human cases of WNV. Although numbers are down at the current time, we should still remain vigilant and continue to protect ourselves from mosquitoes. Additional information on WNV and other mosquito vectored disease can be found at the ODH web site: http://www.odh.state.oh.us/ODHPrograms/ZOODIS/VBDP/vbdp1.htm
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DANCING APHIDS
The BEECH BLIGHT APHID (Grylloprociphilus imbricator) has waltzed through the BYGL on a number of occasions in past years. BYGL reports have bounced between treating this insect as only an occasional oddity, to signaling it as widespread in Ohio, with localized populations surging toward significant peaks. While Joe Boggs cautioned that he was not leaping to conclusions, he reported seeing heavy populations last week in northeast Ohio. He also noted that Brad Bonham (The Garden Fairy, Cincinnati) provided a great sample for this week's BYGLive! in Cincinnati that was collected in the southwest part of the state.
This woolly aphid enshrouds itself in a profuse mass of white, wool-like filaments. The aphids gather together in prominent colonies on twigs, branches, or on the underside of leaves of American beech trees. When a colony is disturbed, they exhibit an unusual collective behavior by vibrating their posterior ends in unison. Erik Draper very accurately described the aphids in a past BYGL report as looking like "dancing dust balls shaking their rear ends to the boogie woogie."
On large trees, aphid colonies are usually relegated to a few branches. However, on small trees, the entire canopy may become infested. The aphids are also prolific producers of honeydew causing branches, sidewalks, parked cars, slow-moving gardeners, etc., beneath the colonies to become covered in sticky goo. The honeydew may become colonized by black sooty molds converting the gummy accretions into blackish heaps. Fortunately, the aphids are easily controlled with a focused stream of water, and the water pressure available to most homeowners is sufficient to convert the aphid's dance into a cascading water ballet.
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LIONIZING LACEWINGS
Joe Boggs reported that participants in the BYGLive! in Cincinnati were treated to an awe-inspiring number of lacewing larvae, thanks to the sharp eyes of Larry Hanks (Pampered Properties, Inc., Lexington, KY). Participants were truly impressed by the wide ranging shapes and forms exhibited by these predators. The number of lacewing larvae found also demonstrated the significance of these bio-allies in reducing insect and mite pest populations.
Lacewings belong to the insect order Neuroptera, which means "nerve wing." The name refers to the delicate nerve-like venation of the wings. This lacy feature is invoked by the common names of two families in the order. They are Chrysopidae (green lacewings), and Hemerobiidae (brown lacewings). The green and brown names refer to the color of the adults.
Green lacewings are common throughout Ohio and the adults are familiar visitors to porch lights at night. The slender adults are about 3/4" in length and they have long, hair-like antennae. Their bead-like eyes are often a metallic golden color. They have light green, soft bodies and this color may impart a light green tint to their otherwise clear, large, membranous wings. The wings are held in a tent-like fashion over the body. Adults of some species are predaceous while others are not. The eggs laid by the adults are very distinctive: each oval, pearly-white egg is attached to a slender, hair-like, upright stalk that elevates the egg about 3/8" in the air, presumably to avoid predation. The eggs are laid singly, in clusters, or in rows.
The eggs hatch into small, slender, gray to brownish-gray, quick moving larvae that are sometimes called aphidlions in recognition of their favorite meat item. The larvae of some species pile debris on their backs as camouflage which may include pieces of bark, lichens, or the bodies of their victims. However, the true nature of these neato incognito larvae is given away by their impressively large, sickle-shaped mandibles that project forward in front of the head. The hollow, or grooved, mandibles are used to extract juices, which is usually the "essence of aphid," from the bodies of their hapless victims. Aside from aphids, these lacewings also chow-down on lace bugs, caterpillars, larvae of some beetles, insect eggs, and mites.
Most lacewing larvae behave as hunters, and actively pursue their prey, however, ANTLIONS set a trap, and wait for their prey to come to them. Also known as "doodlebugs," these lacewing larvae construct conical-shaped pits in loose soil, then wait at the bottom for a misfortunate ant to stumble in. Once trapped, the ant is impaled by the antlion's sickle-shaped mandibles, and the victim's juices are drained away. Beyond providing great entertainment value, the antlion also serves as a good teaching tool for demonstrating the diversity in insect predatory techniques.
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OF ALL THE GALLS
BYGLers reported that concerned home gardeners are making plant galls a frequent topic of inquiry. Many of the galls caused by insects and mites are now maturing, and becoming very obvious. While some galls may damage their host plants, the vast majority cause no appreciable harm. Indeed, students of pest-host interactions view insect and mite galls with a certain sense of wonder.
Following are a few gall-points that may help non-gall-enthusiasts to fully appreciate these fascinating plant growths:
* Most insect and mite galls consist entirely of plant tissue grown in a very specific way under the direction of a gall-maker.
* The galls can only form on tissue that is in the process of differentiating. Thus, leaf galls grow as leaves expand. Galls cannot form from plant cells that have stopped dividing.
* Insect and mite galls are usually so specific that the gall-maker can be accurately identified to species based entirely upon the gall structure, without benefit of actually observing the gall-maker.
* The interplay between gall-makers and their hosts remains a mystery for most galls, although research has revealed that some gall-making insects produce plant growth hormones, or hormone analogs, that stimulate growth of these intricate plant structures. Exactly how they chemically switch plant genes off and on remains an enigma.
Some notable galls currently noticed in Ohio include oak galls, produced by tiny, gnat-like wasps in the family Cynipidae. On white oak are: the bristly, descriptively named HEDGEHOG GALLS, formed on the lower leaf surface by Acraspis erinacei; and the off-white, marshmallow-like, 1" to 2" diameter WOOL SOWER GALLS produced by C. seminator on the surface of twigs and stems.
Those found on red and pin oaks include: the aptly named OAK APPLE GALLS produced by Amphibolips confluenta that look like tiny apples growing off stem tissue; the knobby club-like HORNED OAK GALLS produced by Callirhytis cornigera that incorporate stem tissue; and the similar looking OAK GOUTY GALLS produced by C. quercuspunctata that also incorporate stem tissue, but lacks protruding horns. Of the over 700 galls found on oaks, only the horned oak gall and oak gouty gall cause significant damage to their hosts. Opening these woody galls will reveal the jumbled mass of disorganized stem tissue that is responsible for disrupting vascular flow beyond the gall.
A tiny midge fly (Thecodiplosis ananassii) directs the growth of CYPRESS TWIG GALLS on baldcypress. The galls are cone-like, white to bluish-green in color, and range in size from 1/8" to &frac;" in length. A portion of this season's growth usually extends beyond the gall, and the new growth may become withered, turn brown, and die, however, this only causes aesthetic injury.
The handiwork of several gall-making mites in the family Eriophyidae may also be appreciated. These include: the light-green to reddish-green, finger-like SPINDLE GALLS on the upper leaf surface of sugar maple, caused by the eriophyid Vasates aceriscrumena, and on the upper leaf surface of black cherry, caused by the "cherry-ophyid mite," Phytoptus cerasicrumena.
Some species of eriophyid mites produce unusual patch-like growths called erineum galls, or erineum patch-galls. These appear on leaf surfaces as areas of felt-like growths. Some examples include: BEECH ERINEUM GALLS on the upper leaf surface of American beech caused by the eriophyid mite Acalitus fagerinea, and similar looking erineum galls on the lower leaf surface of little leaf linden produced by Eriophyes tiliae. The eriophyid Eriophyes elongatus produces one of the most colorful erineum galls in the form of crimson patches on the upper leaf surface of sugar maple.
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THE INCREDIBLE SHRINKING SQUASH
BYGLers in several locations around the state reported that home gardeners and vegetable growers are experiencing the handiwork of the SQUASH VINE BORER (Melittia cucurbitae). Caterpillars of this moth bore into the stalks of squash, pumpkins, and gourds. Their feeding damages the inner tissues causing vines to weaken, and collapse. Heavy infestations can cause lush, full, healthy-looking plants to rapidly wilt, and die. Joe Boggs reported that a home gardener described the damage as "the squash plants looked like they're shrinking."
This moth belongs to the family Sesiidae - the clearwinged moths. There are over 120 species of sesiids in North America, and all share some common traits. The caterpillars are borers, feeding inside stalks and stems of plants. The adults are wasp mimics. Some, such as the ASH/LILAC BORER (Podosesia syringae), are very good wasp impersonators, displaying both the clear wings and body size, shape and color of their hymenopteran models. Squash vine borer moths only slightly resemble wasps. Their front wings are covered in dark metallic-green scales, and only their hind wings are clear. The moth's thorax is greenish-black, and their abdomen is reddish-orange with a dorsal row of black dots. Indeed, this is a very flamboyant looking moth.
There are 1 to 2 generations of this moth per season in Ohio. Adults fly during the day, and they may be observed from early-June through early-August. Management strategies to minimize the overall impact of this insect include: catch moths resting on leaves in the afternoon before they lay eggs; hand-pick the dull red eggs from main stems before they hatch; wrap stems in strips of old nylon to prevent egg laying; and/or excavate larvae from infested stems then bury stem nodes to produce new plants. Of course, standard insecticide applications can also be used, but multiple applications are required and insecticides applied near the flowers will kill bees and other pollinators.
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HONEY BEES ABUZZ WITH ACTIVITY
After last year's dreary months of cold temperatures and rain, the honey bees who survived the winter are enjoying a wealth of plants with nectar and pollen needed for food, larval development, and storage for later use. Periods of cooler temperatures and rain prevent the bees from flying, plus the flowers do not produce much quality stock. What pollen the flowers did manifest was quickly washed away. Honey bee colonies which were not able to store enough honey and pollen for the winter starved if not tended by a beekeeper. This year though, honey bees are making up for lost time and many strong colonies have good, healthy brood, and reportedly already filled several supers with capped honey!
THE BYGL WINDSHIELD WIPE. BYGLers also ran into a few other insects this week including:
*BYGLive! participants in Cincinnati observed heavy infestations of OAK LACE BUG (Corythuca arcuata) on oak. Heavy stippling made the leaves appear greenish-white. Overlapping generations were evident with adults, eggs, and early instar nymphs present signifying that damage will continue.
* In BYGL 2004-11 (6/17/04), we reported that JAPANESE BEETLE (Popillia japonica) adults had arrived on the scene in southwest Ohio. This week, BYGLers from the southwest and northeast part of the state reported observing high populations and noticeable leaf skeletonizing feeding damage. Affected trees included well known hosts such as roses, crabapples, cherries, and lindens, as well as some less known hosts such as dawn redwood. Damage to dawn redwood ranges from reddish-brown foliage to partially consumed or missing foliage.
Curtis Young reported that HOLLYHOCK SAWFLY (Neoptilia malvacearum) continues to devour the leaves of unprotected hollyhocks. A recent observation revealed mature last instar larvae on the skeletonized leaves and adults searching for new oviposition sites to start the next generation. These hollyhocks are not getting a break from the sawflies.
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DISEASE DIGEST
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POWDERY MILDEW DUSTING VEGETABLES
Erik Draper reported seeing the telltale white spots of POWDERY MILDEW show up on zucchini in the vegetable fields. Powdery mildew (PM) is a common disease of vegetable plants. There are many different species of PM fungi (e.g., Erysiphe spp., Sphaerotheca spp.) and each species will attack specific plants. Many vegetable crops are affected by PM, including artichoke, beans, beets, carrot, cucumber, eggplant, lettuce, melons, parsnips, peas, peppers, pumpkins, radicchio, radishes, squash, tomatillo, tomatoes, and turnips. Contrary to most fungi, powdery mildews generally do not require moist conditions to establish and grow; and in fact, copious amounts of rain actually inhibits PM development. These unique fungi develop quite well when warm, dry days are combined with humid nights. Therefore, these powdery mildews are more prevalent than many other leaf-infecting diseases under summer like environmental conditions.
PM first appears as white, talcum-like spots that may form on both leaf surfaces, shoots, and even sometimes on flowers and fruit. These spots gradually spread over a large area of the leaves and stems. Infected leaves may gradually turn completely yellow, die, and fall off, causing immature fruit to sunburn. On some plants, powdery mildew may cause the leaves to be stunted, twist, curl or otherwise distort. Powdery mildew fungal growth does not usually develop on vegetable fruits, although pea pods may get brownish spots. Severe infections of PM may reduce overall yields, fruit quality, size, taste, shorten plant and fruiting duration, and cause incomplete ripening.
All powdery mildew fungi require living plant tissue to grow, and so are called obligate parasites. Year-round availability of crop or weed hosts is important for the survival of some PM fungi. Most powdery mildew fungi grow as thin layers of mycelium (fungal tissue) on the surface of the affected plant part. Spores, which are the primary means of dispersal, are moved throughout the country by wind. These spores make up the bulk of the white, powdery growth visible on the plant's surface and are produced in chains that can be seen with a microscope.
Although humidity requirements for germination vary, all species of powdery mildew can germinate and infect in the absence of free water. Moderate temperatures (60 to 80F) and shady conditions generally are the most favorable for powdery mildew development. Spores and fungal growth are sensitive to extreme heat (above 90 degrees) and direct sunlight.
The best method of control PM is prevention by selecting PM resistant vegetable varieties when available. Avoid planting varieties of veggies that are very susceptible to PM. Always plant veggies in full sun, and follow good cultural practices to minimize these fungi. Susceptible vegetables, like the cucurbits (i.e. cucumber, melons, squash, and pumpkins) may require fungicide treatments to help delay infections from PM. For these susceptible crops, fungicides are typically applied when the first symptoms or colonies of the disease appear and must continue until harvest. Once the mycelial growth becomes too extensive, attempting control with any fungicide becomes very difficult and next to impossible. So be sure to scout those veggies early and often or the Great Pumpkin may not show up in your patch this year!
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MOIST CHAMBER
Following are some of the common phytopathological parasites that continue to plague the outdoor landscape.
* Predictably, ROSE BLACK SPOT is rampant - and multiple protective fungicide applications with ongoing sanitation is crucial. Remove those black-spotted leaves not only at the end of the season, but when possible during the season as well. Fungicides cannot do the job alone.
* There are many reports of GRAPE BLACK ROT discoloring fruits, so do not harbor the illusion that some wonderful early ripening is occurring. Removing mummified grapes and affected vines are important sanitation practices in the home arbor.
* CEDAR QUINCE RUST is hammering many hawthorns right now, often with virtually every haw adorned with swirls of orange spore masses curling outward. Controls are ineffective at this point and there are no more infections of hawthorn occurring now, so turn thoughts to planning preventive applications next spring when spores are arriving from the juniper alternate hosts of this fungus.
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TURF TIPS
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BROWN SPOTS
are appearing in lawns across the state for many reasons. Some problems are caused by fungal diseases, others are due to weather patterns, soil conditions, and maintenance procedures.
Diseases that may be active at this time include RED THREAD, which is still lingering in some lawns. Symptoms may include patches of brown grass that are 2-6" in diameter or larger. Look carefully at this infected grass for evidence of pinkish fungal strands on the leaf blade or near the end of the cut grass blades. This disease is a nuisance but does not kill the grass.
DOLLAR SPOT is rampant on many lawns, especially in areas where the grass is growing slowly due to dry summer conditions. Again, distinct patches of grass may have a tan or straw color. Check the leaves for tan bands with dark brown edges. More information and photos are available on fact sheet, Dollar Spot on Turfgrass, HYG-3075-96. In most cases this will not kill the grass. If the lawn is growing well, this is usually a minor problem.
Non-Disease Factors include DRY AND POOR QUALITY SOILS- compacted soils, buried rock and debris, poor subsoils, and dry soil conditions are causing many lawns to have brown spots and look badly. These conditions give a lawn the one-two punch. First, poor soil conditions inhibit the turfgrass from developing a deep, healthy root system. Without this asset, turfgrass is susceptible to every sudden change in temperature, soil moisture, and intrusion of insects and disease. Secondly, these soils either hold water in the thatch layer, or drain quickly, away from the turf roots which creates drought conditions. These factors lead to many strange patterns of brown grass including brown spots, irregular areas or lines of dead grass, etc.... The key diagnostic tool is a soil probe, or use of some other tool such as a pocket knife or shovel to check the soil condition and moisture level.
Other miscellaneous factors include fireworks damage, car exhaust, wear from traffic, or objects such as trash cans or swimming pools that sat on the grass for several days.
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HEAT AND DROUGHT STRESS
Summertime decline of cool season turfgrasses is one of the more challenging problems facing turf managers. The optimum temperature range for cool season turfgrass growth is extremely narrow because most of cool season shoot growth occurs between 60 -75°F. As temperatures exceed the optimum, plants undergo both physiological and morphological changes. Physiological changes include an initial increase in photosynthesis (up to 86°F), then a rapid decline. As photosynthesis declines, respiration increases, causing a reduction in carbohydrates. High temperatures cause a reduction in stand density, leaf size, and shoot and root growth. Direct high temperature injury to cool season turfgrasses has been reported between 106 - 109°F. Complete kill of Kentucky bluegrass, perennial ryegrass, and annual bluegrass under laboratory conditions has been reported at 117°F. In the field, direct temperature kill is rarely observed, unless combined with other stresses like drought.
Additionally, turfgrass root growth is governed to a large extent by soil temperatures. High soil temperatures play an especially sinister role because the symptoms are not easily detected visually. The optimum soil temperatures for cool season turfgrass root growth is 50 - 65°F. As temperatures increase, root growth slows and begins to decline. Once soil temperatures are greater than 75°F, root loss exceeds 50 percent. The soil temperature at the OSU Turfgrass Research Facility this week was 80°F.
High temperature-moisture stress on turf can be minimized through fundamentally good MANAGEMENT PRACTICES. Some of these practices include:
* Alleviate compacted soils. Frequent coring before the summer stress period will enhance root growth and oxygen exchange. An extensive root system provides the potential for greater transpiration power.
* Monitor irrigation practices. During the summer, if root systems are reduced or restricted, more frequent but lower amounts of water may be needed to provide the necessary moisture for transpiration. Otherwise, to encourage healthy roots, water thoroughly (1") but infrequently (every 7-10 days)
* Proper turfgrass selection. If supplemental irrigation is not possible, choose a turf that is well adapted to minimal maintenance. For example, tall fescue has excellent heat and drought tolerance compared to other cool season turfgrasses. Obviously, there are other considerations to factor in such as geographical location, potential pests, etc.
* Monitor soil temperatures. As summer approaches and the soil temperature increases - 75°F can be a key to the beginning of turfgrass stress. Management practices can be adjusted to account for increased plant stress.
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INDUSTRY INSIGHT
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POWDERY MILDEWS
Powdery mildew diseases are common on many landscape ornamentals currently, from herbaceous plants such as monarda and phlox to shrubs such as common lilac (though excellent resistance with Korean lilacs) and magnolia, and trees including serviceberry and English oak. Observers are often confused because on some plants, powdery mildews do not show up as obvious powdery white mildew colonies on the foliage, but rather as reddened and grayish discoloration symptoms on the foliage. Reddened, desiccated areas from powdery mildew infestations are especially common right now on magnolia and flowering dogwood. Fungicides used for powdery mildew control often include such active ingredients as thiophanate methyl (e.g. Cleary's 3336), triadimefon (e.g. Bayleton), and azoxystrobin (e.g. Heritage).
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DOWNY MILDEWS
These diseases are a major problem for plants under conditions of 100% relative humidity, so the spring and summer of 2004 has resulted in more than usual pressure from the downy mildew fungi. Few landscape ornamentals have significant downy mildew diseases, but as noted in earlier BYGLs, downy mildew on rose (Peronospora sparsa) and viburnum (Plasmopara viburni) have become problems this year. Symptoms on rose include leaf purpling, browning and defoliation, with little evidence of signs of the pathogen, though sometimes the fungus may be observed on leaf undersides.
With viburnums, especially cranberrybush viburnums, symptoms of downy mildew include leaf scorching (often in angular patches) and eventual overall leaf browning and unsightliness. These symptoms are already well underway this year, and signs of the pathogen are obvious on the undersides of leaves, especially during dewy conditions. As is the rule with infectious diseases, good control of downy mildew involves preventive applications, with labeled fungicides, containing for example, such active ingredients as azoxystrobin (e.g. Heritage) and dimethomorph (e.g. Stature).
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CRABLANDIA WEST
Last week Erik Draper and Jim Chatfield helped dedicate a new National Crabapple Evaluation Project plot in Lewiston, Idaho (one of 19 plots nationwide). Why evaluate crabapples in so many sites? Several observations they made in Idaho are relevant.
First, in a small planting of crabapples at the University of Idaho arboretum in Moscow, clear differences in susceptibility to powdery mildew were noticed, with powdery mildew causing significant aesthetic damage to 'Mary Potter' while closely planted 'Golden Raindrops' were completely clean. Of course, 'Golden Raindrops' has significant fireblight problems in Ohio and many Eastern states, but in Idaho conditions are not wet enough during bloom to create much fireblight pressure.
Scab is also not a big deal on any crabapples in Idaho, though it is a major aesthetic problem on crabapples in many other environments, including Ohio. Thus, 'Thunderchild' crabapple, which in Ohio has real liability in our Crablandia plot in Wooster, with scab often almost completely defoliating it by August, was almost completely clean of scab in Idaho. This allowed 'Thunderchild' to show a very different face, namely attractive foliage with good purple tinges to leaves and outstanding blueberry-colored fruits. So, for a nurseryman selling plants throughout the U.S., the NCEP plots provide a full spectrum of suitability to different environments.
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COMING ATTRACTIONS
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WOSU GREEN SCENE
Join WOSU 820 AM host Tom Wiebell this Friday night on Green Scene, from 6:30 to 8:00 p.m. with frequent guest Fred Hower, Ohio's Master Gardener, and Randy Zondag, Commercial Horticulture Extension Educator in Lake County. Tune in or call Green Scene at 614-292-8513 for informed answers and advice for all your horticultural queries and quandaries.
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BYGLOSOPHY
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"An early morning walk is a blessing for the whole day."
- Henry David Thoreau
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