Pam Bennett, Barb Bloetscher, Joe Boggs, Jim Chatfield, Erik Draper, Dave Dyke, Gary Gao, David Goerig, Tim Malinich, Amy Stone, and Curtis Young.
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July 19, 2007
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This is the Sixteenth 2007 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 17, 2007 conference included: Barb Bloetscher (Entomology/C. Wayne Ellett Plant and Pest Diagnostic Clinic (PPDC)); Joe Boggs (OSU Extension Center at Piketon/Hamilton-Clermont); Erik Draper (Geauga); Dave Dyke (Hamilton County) Becky McCann (ABE Center); 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 following weather information has been summarized from data collected from July 1-17, 2007. BYGLers have selected five locations to highlight different regions of the state to be included each week as seen in the table below. Additionally, there are weather station sites in Avon (Lorain County), Madison (Lake County), Perry (Lake County), at the Muck Crops Research Station (Huron County), at the North Central Research Station (Sandusky County), and at the Western Research Station (Clark County). The weather data collected from all the sites can be seen at http://www.oardc.ohio-state.edu/newweather/.
| Weather Station |
Region of Ohio |
Ave. High Temp F |
Ave. Low Temp F |
Total Precip " |
Normal Precip " |
| Ashtabula |
NE |
79.5F |
55F |
NA |
2.9" |
| Wooster |
NE |
82.7F |
56.2F |
1.27" |
4.1" |
| Hoytville |
NW |
84.6F |
56.8F |
0.68" |
3.8" |
| Delaware |
Central |
96.2F |
49F |
0.62" |
4.1" |
| Piketon |
South |
85.2 |
59.8 |
1.46" |
4.0" |
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HORT SHORTS
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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. COLEUS (Coleus x hybridus) (Solenostemon). Coleus have long been prized for their colorful foliage which may combine shades of green, yellow, pink, red and maroon. New introductions of this annual have been selected for increased sun and heat tolerance, turning coleus into a "plant for all locations" in the annual garden.
Today's coleus include cultivars that carry amazing sun tolerance along with a broad range of leaf colors, sizes, shapes and textures. Also, the newer cultivars are not long- day (summer blooming) plants and are vegetatively propagated. Their leaves remain the primary focal point throughout the summer with no unsightly flowers to remove. Coleus are multidimensional in their role in the garden bed or border. They make ideal companion plants for larger species and help to "fill in" vacant space under taller plants such as dahlia. Or, they can be used for creating effective color schemes by themselves or planted with other species of annuals.
A well-drained soil is a must if coleus is to thrive in the garden. Poorly drained soils and/or excessive watering will result in stunted plants with "muddied" colors and discolored leaf margins. Pinching growing terminals of young plants will encourage dense, compact growth. A midsummer boost of fertilizer in the form of liquid fertilizer at half- strength can be helpful.
When grown in properly prepared soil or in containers filled with a soilless medium, coleus is fairly resistant to serious disease or insect problems. The many coleus varieties that have done very well in the Cincinnati Zoo and Botanical Gardens Annual Plant Trials include: 'Freckles', 'Cranmore', 'Relgious Radish', 'Dipt in Wine', 'Life Lime', 'Saturn', 'Sedona', 'Sky Fire', 'Dark Star', 'Chocolate Drop', 'JoDonna', and 'Juliet Quartermain'.
* PERENNIAL PLANT OF THE WEEK. CROCOSMIA 'LUCIFER'. A montbretia cultivar, Crocosmia x crocosmiiflora (x Curtonus) 'Lucifer', is an Alan Bloom hybrid. This exotic looking perennial is bold and beautiful with tubular, nodding, scarlet red, flowers borne along stiffly arching, flower scapes rising up to 3 - 4' tall. This clump-forming plant has narrow, sword-shaped foliage similar to gladiolus, giving it the look of a tropical plant. Crocosmia 'Lucifer' is a good fresh cut flower and provides color and contrast to the perennial border. Hardy from zones 5 to 9, 'Lucifer' blooms from late June - August in full sun to part shade. It prefers moist soils in full sun and is tolerant of summer heat and humidity. Plant corms in spring 2 - 3" deep and 6 - 8" apart in clumps of 12 or more.
* WOODY PLANT OF THE WEEK. SEVEN-SON FLOWER, (Heptacodium miconioides). This little known member of the Caprifoliaceous family can be grown as a large shrub or small tree with year-round interest. Seven-son flower blooms in the late summer to early autumn with creamy white, fragrant flower whorls containing 7 tiny flowers (hence the common name of Seven-son flower). The flowers then fade and are replaced by stunning cherry red capsules and flower-like sepals until mid-November. Finally, its tan bark exfoliates to reveal attractive brown inner bark, which provides good winter interest.
Hardy from zone 5 to 9, Heptacodium is easy to grow and has few insect or disease problems. It is adaptable to most any soil type, from dry and sandy, to wet clays, and will grow in full sun or partial shade. It grows into a large, fountain-shaped, multi-stemmed, deciduous shrub reaching 15 - 20' at maturity with a 10' spread. Seven-son flower can be used as a small specimen tree, or in massed plantings. This woody plant is a nice addition to the landscape, particularly in the late summer and fall when practically nothing else is flowering. It is also a good source of nectar for butterflies in the fall.
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THE WEEKLY WEED
QUEEN ANNE'S LACE (Daucus carota) is currently gracing the fields and roadsides of Ohio with its white, lacey caps of tiny flowers. This plant hails from Europe, but is now common throughout Northern United States. The individual ray flowers make a tatted, round umbel, like a small, round piece of lace.
This biennial forms a rosette of pinnately compounded leaves the first year, then produces several flowers on tall stems (3 - 4') the second year. It will flower from late June through September when conditions favor its growth.
Queen Anne's lace is closely related to the carrot, in fact some people eat the young taproot, although it is not as sweet and tender as a carrot. It boasts of several herbal qualities, as the seeds have been used as an antiseptic diuretic, and for the prevention and flushing of urinary stones. The seeds are high in volatile oil and supposedly soothe the digestive system when flatulence arises. The root is used as an antacid for heartburn and gastritis. A poultice of the root has been found useful to treat itchy skin. As with any wildflower though, care should be taken to identify the plant correctly, as it has several toxic relatives, such as poison hemlock.
Queen Anne's lace is often seeded into wildflower and butterfly gardens, as many butterflies, wasps, and bees visit the flowers. The black swallowtail caterpillar favors Queen Anne's lace and other members of the Umbelliferae Family as its food source. Thus, although it may be considered to be a weed by some, it is a welcomed guest in other gardens.
 
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BUG BYTES
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POTATO LEAFHOPPER POPULATIONS BOOMING
The potato leafhopper (PLH) (Empoasca fabae) has been in Ohio since the beginning of June and has been continuously building in populations on field crops. Apparently the hot and dry weather conditions have favored their population explosions. Curtis Young reported observing dozens of the little, apple-green menaces at his porch lights in town for several days. Several BYGLers reported observing damage to nursery crops and speculated that PLH may now be relying upon their ornamental plant hosts for sustenance since a number of field crop host plants, such as alfalfa, have been cut, or may not be growing well.
PLH will feed on a wide range of trees and shrubs and can present a real challenge for plants grown in nursery production. Hedge, 'Red Sunset', and 'October Glory' maples can be severely impacted in their growth form and development, which may influence their salability. Leaves on these trees can be cupped and new growth stunted. Several other tree species that are very susceptible to injury include amur, Norway and sugar maples, birches, apple, chestnut, and Persian walnut. These trees can be injured both in the landscapes and nurseries areas.
Insecticide sprays will need to be applied in production areas to prevent reduced plant growth and vigor and to avoid distorted tree shape due to dieback and stunting. Trees and shrubs exhibiting distorted and/or discolored foliage should be examined closely for PLH activity. Some insecticides that appear to have fairly good activity against the PLH include foliar sprays of imidacloprid, cyfluthrin, or a combination product such as Discus. Read insecticide labels carefully for application restrictions and potential chemical injury to host plants. Refer to OSU Extension Bulletin 504, "Insect and Mite Control on Woody Ornamentals and Herbaceous Perennials" for further details.
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STINK BUG ON FLOWERS
Participants at a diagnostic walk-about held last Thursday at Cox Arboretum & Gardens Metropark (Dayton) observed the stink bug, Cosmopepla lintneriana, feeding on buds and flowers of mullein and mint. Stink bugs are Hemipterans ("True Bugs") that belong to the family Pentatomidae. As with all Hemipterans, they have sucking mouthparts.
While this stink bug has no approved common name, it is generally referred to as the TWICE-STABBED STINK BUG. The triangular-shaped 1/4" long shiny black bugs have a deep red line across the pronotum (the segment behind the head) that it is crossed by a shorter red mark that is in-line with the head. The "stabbing" in its name relates to two side-by-side red marks prominently displayed in the middle of the front wings. The highly reflective membranous portion of the front wings appears silvery against the black body of the bug.
The bug feeds on a wide range of plants beyond mullein and mint including: milk thistle, cone flowers, asparagus, oats, and goldenrod. It appears to be most strongly associated with sucking juices from seeds; however, as with many seed-feeding insects, the bug may occasionally feed on other plant parts, including buds and stems. Indeed, it was speculated that the heavy bug population, coupled with damage to flower buds, may account for the stunting of mint blooms and a general lack of blooming by the mullein this season and in past seasons.
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GROUND-NESTING BEES ARE BUZZING
Curtis Young reported that his office is buzzing with calls concerning ground-nesting bees. Tis the season. There are a number of species of small bees that may be found at this time of the year cruising a few inches above areas of open soil perforated by their nesting holes. The affected areas are often the site of past bee-bashes, since some species re-use and expand nesting sites year after year. The same bees may also be observed visiting nearby flowers, since a large percentage feed their young balls of pollen moistened with nectar. Thus, the bees are considered beneficial pollinators.
The bees most commonly associated with nests in the soil belong to one of three Hymenopteran families: Anthophoridae (digger bees); Halictidae (sweat bees); and Adrenidae (mining bees). Generally, these bees are hairy and about the size of a honey bee or smaller; although the digger bees are slightly larger and more robust. Some are considered solitary, since the females dig individual burrows; however, large numbers may select the same area giving rise to a "community" of hundreds of burrows. The females of other species dig a common vertical hole that is used by several bees, and individual females dig their own lateral borrows in which to lay eggs.
Regardless of their social behavior, communities of ground-nesting bees may cover an area 3 - 10' in diameter. The buzzing flights of hundreds bees can be disconcerting to homeowners. Although they may appear menacing, these bees are not aggressive and not likely to sting. Also, keep in mind that most of the strafing is being done by the males, and they lack stingers!
The bees are considered beneficial pollinators, so direct control using insecticides is not recommended. However, since the bees prefer to nest in areas of open soil, cultural practices can be applied to dissuade the bees from nesting. Mulching or covering the area with vegetation will cause the bees to move their communities to other locations. Of course, such bee-blocking activity should be done either early in the season or later in the season when the bee-buzzing and nesting activity is not occurring.
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ROBBERS ON THE WING
Joe Boggs reported observing ROBBER FLIES snatching insects out of the air in southwest Ohio. Robber flies belong to the Dipteran family Asilidae. With over a thousand species representing this family in North America, there is a wide range of forms and sizes. Adults of all species are predators and will attack a variety of insects including bees, wasps, grasshoppers, dragonflies, damselflies, and other insects. They often seize prey that is much larger than their own body size. Their larvae are also predaceous and live in the soil, or in decaying wood and other organic matter, where they feed on insect larvae.
The adult flies have a stout thorax that appears slightly humped when viewed in profile. Each long, strong leg is tipped with two formidable tarsal claws that look and function like grappling hooks. The robber fly slams into its airborne quarry which stuns the victim. The high-speed collision produces a snapping sound that may be heard several feet away. This smashing display of aerial acrobatics illustrates why some entomologists consider these flies the "fighter planes" of the insect world.
The fly then grasps its dazed prey with its claws, and uses its piercing-sucking mouthparts to inject saliva containing neurotoxic and proteolytic enzymes. The enzymes paralyze the victim and digest the internal tissues. The fly then lands, and has an insect Slurpee. If you listen closely, and use a little imagination, you can hear these predators sipping away the life of their victims. It's a bug's life.
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MONARCH SIGHTING
Several BYGLers reported seeing the lovely monarch butterfly gliding over coneflowers and milkweed plants. This favorite landmark of Ohio butterflies has endured good and bad years, but continues to command attention from butterfly enthusiasts and casual observers. At this time in Ohio and northern states, the monarch females are laying eggs for the next generation to begin the migration toward Mexico. Monarchs will be seen in the Northeastern states and Canada from now until mid-late September.
Although the adults will nectar on many flowers, the larvae feed primarily on milkweed species, especially common milkweed (Asclepias syriaca1), swamp milkweed (A. incarnate), and the showy butterfly plant (A. tuberose). The caterpillars will eat the new leaves which contain poisonous alkaloids in the form cardiac glycosides, which are toxic to birds and mammals. Both the caterpillar and adult incorporate into their flesh a higher concentration of the alkaloids than are found in the plant; hence, any unknowing creature that tries to feast on monarchs will get the royal treatment!
For those who wish to invite monarchs into their yard, plant a milkweed for the larvae and attractive nectar plants for the adults. Even a small yard can have a corner with a variety of yellow, purple or blue flowers. Favorite flowers include: aster, black-eyed Susan, coneflower, coreopsis, ironweed and Joe-Pye weed.
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IT'S A BIRD, IT'S A PLANE, NO, IT'S A HUMMINGBIRD MOTH!
Buzzing and hovering just like a hummingbird, one of the most fascinating winged creatures that appear around flowers this time of the year is hummingbird moths. Several species of day-flying moths in the family Sphingidae (Sphinx moths) are commonly called hummingbird moths. The moths share with their avian namesake a fondness for deep throated, pink and red flowers. However, the moths lap nectar using a long, coiled tongue (proboscis) rather than a long, pointed beak.
The largest of these fast-flying moths is the hummingbird clearwing, Hemaris thysbe. This moth has a greenish body and a dark reddish-brown band near the back of the body. Its wing-span is nearly 2", and the wings are almost devoid of scales, thus the common name. A less common species is the slender clearwing moth, Hemaris gracilus, which is slightly smaller than the hummingbird clearwing. This moth also has a more yellow body and a gold ring between the yellow portion and the dark band near the abdomen.
Another Sphinx moth that looks like something that it's not is the snowberry clearwing, Hemaris diffinis. The moth has the size and coloring of a bumble bee, and a wing-span of 1 1/4". Although they don't land on a flower like bees, most people are not willing to get close enough to notice the difference! None of these moths are considered to be pests, and in fact the caterpillars eat honeysuckle, Virginia Creeper, and weeds! Truly spectacular moths!
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BEAUTIFUL BEETLE
BYGL reports are usually focused on plant nasties. However, this week Joe Boggs reported observing one of the most beautiful beetles found in Ohio. The beetle lacks a common name, but is generally referred to as the "DOGBANE BEETLE" because it primarily feeds on...dogbane. The beetle's scientific name, Chrysochus auratus, loosely translates to mean "made of gold."
Indeed, these beautiful iridescent beetles may look like shimmering spots of gold on the leaves of dogbane, or they may blaze with an array of other colors depending on the viewer's angle to the beetle. A slight change in viewing angle will cause the beetles to glisten with multiple shades of green, copper, blue, and red.
The secret to this kaleidoscope of colors can be found just beneath the surface of the exoskeleton. Beneath an outer translucent layer rests stacks of tiny slanting plates that cover color pigments. Light rays that strike the surface of the plates are reflected as a shimmering sheen, while light rays that bounce off the pigments produce an array of colors. The result is a mix of changing lustrous colors that are almost unmatched in the insect world.
The beetles are found during the day feeding and resting on dogbane leaves. Other insects practicing this behavior would be easy pickings for predators. However, dogbane beetles have a nasty chemical defense. Dogbane has milky sap that contains poisonous alkaloids (cardiac glycosides), as with the closely related "milkweeds". The beetle ingests the cardiac glycosides, stores them in glands, and then secretes them when threatened by predators. It is believed that the bright colors of the beetles advertise their ability to practice chemical warfare. Pay close attention to areas with dogbane to see these iridescent spots of gold.
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WINDSHIELD WIPES
BYGLers also ran into a few other insects this week including:
* Several BYGLers reported observing first generation FALL WEBWORM (Hyphantria cunea) nests. Caterpillars of this moth feed gregariously as skeletonizers on leaves within webs spun over the foliage. Damaged leaves appear to fade away. Female moths from the current generation will lay eggs on the current nests causing nests to expand during the next generation. Thus, control of the current first generation caterpillars will reduce the size and impact of the second generation nests appearing later this season. The webworms may graze on more than 120 species of deciduous trees.
* Randy Zondag reported that second generation MIMOSA WEBWORM (Homadaula anisocentra) nests are now becoming very apparent on honeylocusts in northeast Ohio. Caterpillars of this moth feed gregariously as leaf skeletonizers within webs spun over honeylocust foliage. Their damage causes leaves to turn orangish brown and appear fire scorched. Female moths often deposit their eggs on nests from which they developed, so nests continue to expand and become denser from one generation to the next. Once nests become large and tightly woven, control applications usually fail to penetrate the thick webbing. There are two to three generations per year in Ohio.
* Joe Boggs reported that participants in the diagnostic walk-about at the Cox Arboretum & Gardens Metropark observed a bur oak with lower leaf surfaces festooned with a dense, white, flocculent material. Parting the waxy filaments revealed nymphs and adults of a WOOLLY OAK APHID frolicking about beneath the tangled strands. There are several species of woolly aphids in the genus Stegophylla that may be found on oaks, including S. querci and S. quercicola, so Joe was uncertain of the exact identity of the aphids. Although very apparent against the dark green foliage, the population appeared to be light and the aphids seemed to be causing little damage. They had also been discovered by a number of predators including hover fly and lacewing larvae as well as lady beetles.
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DISEASE DIGEST
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IS HOSTA VIRUS X IN YOUR GARDEN - AND ARE YOU SPREADING IT?
BYGLers discussed the challenge with hosta virus X (HVX) in Ohio gardens. This virus produces symptoms of mosaic (chlorophyll-clear areas) and can lead to leaf desiccation and death in some hosta cultivars. Hosta cultivars can respond to HVX in three different ways: 1) Susceptible to infection, with symptoms of varying degrees of severity; 2) Susceptible but showing no visual symptoms (tolerant); and 3) Immune to infection with no symptoms. Because plants can be tolerant, or asymptomatic when purchased, but develop symptoms weeks, months or years later, HVX is often undiagnosed and infected plants may be sold. Diagnosis is further complicated because of the range of symptoms exhibited by different varieties.
Unfortunately, the virus is the most commonly occurring virus of hostas (Hosta spp.) in the United States, and its occurrence seems to be increasing. This due to several factors, including: 1) While, this disease is only mechanically transmitted by sap-to-sap contact between infected and healthy plants, some individuals who use tools to propagate this plant by division, or to deadhead, may not be sterilizing their tools. 2) As noted above, some varieties are tolerant and show no visible symptoms, or they can be susceptible but not show symptoms for an extended period of time but serve as a source of infection to susceptible varieties. 3) Many home growers freely share their plants with friends and neighbors after division. That is, obviously, not a good thing. Also remember that no plants can be sold without a license and inspection by the ODA.
For further information on this disease, including a chart of susceptible, tolerant, and immune hosta varieties, refer to, "About hosta virus X", Michigan State University "Landscape Alert", Vol. 20, No. 16, August 26, 2005, at http://www.ipm.msu.edu/CAT05_land/L08-26-05txt.htm and University of Mn "Yard and Garden Line News", Vol. 7 No. 8, June 1, 2005, at http://www.extension.umn.edu/yardandgarden/YGLNews/YGLN-June0105.html#x. Excellent photos of HVX are available at http://hostalibrary.org/ .
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MELTING PACHYSANDRA
Curtis Young reported visiting a landscape to examine patches of dying pachysandra (Pachysandra terminalis). Large sections of the pachysandra planting were withered, brown and leafless. Sections that remained green had numerous plants with brown leaf and stem lesions. Adding insult to injury, infestations of OYSTERSHELL SCALE (Lepidosaphes ulmi) on the pachysandra stems were sprinkled throughout the planting. Curtis sent a sample of the pachysandra to the C. Wayne Ellett Plant and Pest Diagnostic Clinic in Columbus for positive identification of the suspected disease causing organism.
The pachysandra was determined to be infected with a fungal disease known as Volutella canker and leaf blight, caused by Volutella pachysandricola. According to Diseases of Trees and Shrubs, by Sinclair, Lyon and Johnson "Most reports of outbreaks of Volutella blight mention the association of previous winter damage, infestation by scale insects, recent transplanting or shearing, or exposure to bright sun. Thus V. pachysandricola is considered to be an opportunistic parasite that causes little or no damage to vigorous plants but aggressively colonizes those previously injured or stressed."
In Ohio this disease usually first appears in the spring; winter injury and/or winter drying are often suspected. However, these plants were also infested with oystershell scale and symptoms of the disease had appeared the fall before. Lesions on diseased plants produce spores prolifically and can spread the disease rapidly once established.
Management of the disease includes roguing and destroying as much of the dead and dying plant material as possible as soon as it appears. Irrigate judiciously. The less the leaves stay wet, the less likely disease is to develop. This problem could also arise in nursery production areas and if not managed promptly, it could spread and quickly destroy entire plant stocks. For more information and suggestions for alleviating this problem, please refer to OSU Home Yard and Garden Factsheet HYG-3064, "Diseases of Ground Cover Plants," which is on the web at: http://ohioline.osu.edu/hyg-fact/3000/3064.html.
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CUKE GROWERS IN A REAL PICKLE
Erik Draper reported vegetable growers in Geauga County (NE Ohio) have begun to report DOWNY MILDEW appearing on cucumbers. This important foliar fungus Pseudoperonospora cubensis only infects members of the Curucbitaceae family like cucumbers, melons, squash, and pumpkins. This disease is particularly harmful due to the rapid rates of infection followed by leaf death. The rapid loss of leaves exposes the fruit to excessive sun, which rapidly overheats any immature fruit, resulting in sunscald and reducing the quality of any remaining fruit.
Downy mildew is easily identified on cucumbers by the odd appearance of a checkerboard of yellow and green on older leaves. The leaf infections cause a rapid chlorosis of areas seemingly restricted by leaf veins, resulting in angular lesions that are sharply defined. At first, just the leaf blade dies and turns brown, while the remaining leaf petiole and the vine remain untouched and green. Eventually, the entire plant collapses due to the rapid leaf loss. In moist, humid conditions, a layer of fungal mycelia that is white to purplish to almost black in color may appear on the underside of yellowed, infected leaves.
Fortunately, with the dryer weather this season coupled with the proper use of fungicides, it is possible to hold off the plant's demise long enough to get the crop picked. The strobilurin and phenylamide fungicides appear to most effective during periods of infection. Chloronitriles and dithiocarbamates are useful protectant fungicides. When downy mildew symptoms become apparent on plants, fungicides must be used immediately and throughout the life of the plant. As with most diseases, the best ways to manage downy mildew is to select cultivars with genetic resistance to diseases.
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SPOTTY SPINACH
It is hard to beat a crisp summer salad of fresh spinach (Spinacia oleracea) and other home grown treats. Because it is high in vitamins and minerals, growing and consuming spinach has become more popular, but who wants to eat spotty spinach?
Spinach thrives during the cool, moist seasons of the year. During periods of warm temperatures and high humidity or leaf wetness, tan necrotic spots, 1/8 - 3/16" in diameter, may begin to appear on leaves. This leaf spotting is known as CERCOSPORA LEAF SPOT because it is caused by the fungus Cercospora beticola.
This fungus produces numerous small circular to angular, grayish-brown spots with reddish-brown margins. These lesions appear first on older spinach leaves and are the result of infections from spores that are carried by the wind, splashed onto the leaves by water, or introduced from infected seed. Crop residue is also a major source of disease inoculum. Black dots about the size of pepper grains form during humid weather and are easily seen with a hand lens. When the weather is warm and wet, silver or steel-gray colored spores arise, giving the spots a fuzzy appearance. Leaf spots eventually coalesce and large areas of leaf tissue are killed, lowering the overall leaf quality. Severe infections can make the spinach unmarketable.
Methods for prevention and control include the following cultural practices: crop rotation; using disease-free seeds or resistant cultivars; using proper plant spacing; applying proper field sanitation; removal and proper disposal of infected plants; burning infected plant tissues when possible; cleaning contaminated equipment; and avoiding working with wet plants.
Complete reliance on fungicides to control this disease will not overcome poor cultural practices. However, fungicides may be helpful when used in conjunction with the aforementioned cultural practices and applied when conditions favor infection. These conditions include warm temperatures, high humidity, extended periods of leaf wetness, and a history of Cercospora problems. Fresh market fields are usually not sprayed due to visible evidence of copper on leaves. If needed Amistar/Quadris, Cabrio and copper are labeled for control. No more than two sequential applications of either Amistar/Quadris or Cabrio should be made to avoid resistance in the fungus. One final caution is to stay away from the copper when the risk of phytotoxicity is high.
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TURF TIPS
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TO FERTILIZE OR NOT?
Several BYGLers reported receiving telephone calls from homeowners inquiring whether or not they should fertilize their turfgrass now, considering the drought and periods of high temperatures. The rhetorical answer is, "it depends!" It depends on answering a number of other questions that have a direct impact on the decision to fertilize the turfgrass. These questions include: what is the overall condition of the turfgrass; is the turfgrass alive, dormant, or still partly green; does the area have water restrictions; what level of quality does the turfgrass owner desire; is the turfgrass prone to rust disease or other leaf diseases; what species of turfgrass is predominant; and finally, when was the lawn last fertilized?
If the lawn is dormant, check the crowns to make sure the plants are still alive. A healthy crown is white and somewhat soft. Dead crowns will be brown when scratched with a key or knife, and may fall apart, or the are extremely hard. If the crowns are dead, the lawn manager should ascertain the areas that will require renovation this fall. Fertilization may not be necessary if large portions of the lawn are dead. Dry, dormant turfgrass will not be able to use the fertilizer before the granules vaporize, break down, or wash away in a hard downpour.
If the turfgrass has been watered weekly or enough to keep it slightly green, applying a granular fertilizer containing 30 - 50% slow release nitrogen will help the turfgrass replenish lost nutrients and commence root growth, once soil temperatures subside and moisture is more plentiful. Rust and other leaf diseases occur when drought stressed turfgrass cannot grow quickly enough to outgrow fungal infections, therefore a light application of fertilizer will strengthen the resistance to diseases.
The key to a successful fertilizer application is to use a granular form containing slow release nitrogen to feed the roots and prevent rapid, succulent leaf growth. Use natural fertilizers with "slowly available" or "water-insoluble" nitrogen, or synthetic fertilizers containing a slow-release form of nitrogen, such as urea formaldehyde, or sulfur-coated urea. The nitrogen in these types of fertilizer does not wash away quickly, and it supports green turf color without causing excessive leaf growth.
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INDUSTRY INSIGHT
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NO MONEY FOR ASH REMOVAL
Several BYGLers noted that Extension offices continue to receive phone calls from Ohio landowners inquiring about money to underwrite removal of their ash trees. Unfortunately, the answer is very short...there is none. In Ohio, the payment for removal of ash trees infested with or killed by EMERALD ASH BORER is the responsibility of the owner. This is true for ash located both inside and outside the quarantined counties.
The misconception concerning ash removal money is a remnant of the discontinued EAB Eradication Program. Under the Eradication Program, when an ash tree was found to be infested with EAB, the infested tree and with all ash trees within a 1/2 mile radius of the infested tree were cut down and destroyed, using funding supplied by the USDA and applied by the Ohio Department of Agriculture. Although cutting of ash trees generated very negative reactions from some landowners, at the landowners did not have to pay for the tree removal.
Once the program was discontinued, two things changed. First, there was no longer a requirement to cut down and destroy infested ash trees, or other ash trees in close proximity to an infested tree. Second, the cost for tree removal became the responsibility of the tree's owner. Owners of dead or dying ash trees are urged to seek 2 - 3 removal estimates from International Society of Arboriculture, Certified Arborists. Names of local ISA Certified Arborists can be found on the ISA website at: http://www.isa-arbor.com/ .
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SUPPORT EAB RESEARCH!
The need continues for dollars to support EAB research aimed at slowing the spread of this highly destructive, non-native pest. Make a contribution to the American Nursery and Landscape Association, Horticultural Research Institute's special EAB Project fund. Contributions are tax deductible. Send your contribution to:
The EAB Project c/o
Horticultural Research Institute
1000 Vermont Ave, NW, Suite 300
Washington, D.C. 20005
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RAINFALL BREAKS DRY SPELL - NOT DROUGHT!
With scattered rain falling around the state, many are beginning to believe the drought has finally ended, but it's just not so! The recent rainfall may have broken the dry spell, but it hasn't ended the drought. Due to the extreme lack of soil moisture, it will take many, many inches of rain to restore the soil moisture. How fast soil moisture levels are returned to normal will depend on a number of factors including: infiltration rates as influenced by soil type; amounts of rainfall; and how fast or slow the precipitation comes down.
How fast the water percolates down through the soil profile depends on the soil type. For example, most irrigation recommendations are based on inches of water. If 1" of water is applied to a clay soil, it will only move 1- 2" down through the soil. If more than 1" of water is applied at one application, it will most likely just run off because clay soils can't absorb water that quickly. If 1" of water is applied to a silt soil, it can move 2 - 4" down through the soil. However, if 1" of water is applied to a sandy type soil, it can move 8 - 12" down through the soil.
In order for rainfall to move maximally down through the soil profile, it is important to note how quickly or slowly the precipitation came down. The slower the rain falls, like 1" every 2 - 3 hours, the more likely the water will be fully absorbed into the soil. For example, a precipitation rate of around 1" every 2 - 3 hrs. is considered a good "soaking ran" relative to improving soil moisture. Conversely, if the rain falls at a rate of 1" in 10 - 15 minutes, most of that moisture will run off laterally instead of moving down into the soil.
One of the odd problems that may occur during a drought is overwatering! Watering every day can lead to constantly saturated soils, which in turn leads to root rots. This problem of root rot is difficult to detect because the symptoms of overwatering mimic those of the plants being too dry. There is no apparent difference between plants burning up from a lack of water and a plant burning up because the roots are non-functional. The correct approach to irrigation is to allow the soil to dry out between irrigations and to water less often and deep, rather than frequently, using small amounts.
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COMING ATTRACTIONS
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10th ANNUAL GREEN INDUSTRY SUMMER SESSION SET FOR AUGUST 1
This August 1, 2007, all Northwestern Ohio industry professionals are invited to attend the 10th annual educational event, held at Owens Community College in Toledo, OH. Credits for ONCT, ASLA, ISA, Pesticide Applicators, and/or Master Gardeners will be available. Registration information can be found at http://abe.osu.edu/upcoming-events. If there are questions contact OSU Extension, Green Industry Center (419-354-6916).
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40TH ANNUAL NURSERY GROWERS OF LAKE COUNTY OHIO (NGLCO) FIELD DAY
40TH ANNUAL NURSERY GROWERS OF LAKE COUNTY OHIO (NGLCO) FIELD DAY is August 14, 2007. The NGLCO Field Day will be held at Holden Arboretum in Kirtland Ohio. The program this year will feature garden tours of the 3500 acre Holden Arboretum, which is has a new feature- a garden railroad. Time and location information will be on the following website http://www.nglco.com/fieldday.htm . Master Gardeners and students will receive a special price. For further information call 440-241-7969.
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BYGLOSOPHY
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"You've got to go out on a limb sometimes because that's where the fruit is." -- Will Rogers
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