Pam Bennett, Barb Bloetscher, Joe Boggs, Jim Chatfield, Erik Draper, Dave Dyke, Gary Gao, Dave Goerig, Dan Herms, Tim Malinich, Jane Martin, Pam Sherratt, Amy Stone, and Curtis Young.
|
|
June 24, 2004
|
|
This is the Twelfth 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 June 22, 2004 conference included: Pam Bennett (Clark); Barb Bloetscher (Entomology and C. Wayne Ellett Plant & Pest Diagnostic Clinic); Joe Boggs (Hamilton/South District); Jim Chatfield (North District/HCS); Dave Dyke (Hamilton); Gary Gao (Clermont); Jane Martin (Franklin); Dave Shetlar (Entomology); Amy Stone (Lucas); and Nancy Taylor (Plant Pathology and C. Wayne Ellett Plant & Pest Diagnostic Clinic).
Additional factsheet information on any of these articles may be found
through the OSU Factsheet Database (http://plantfacts.ohio-state.edu/)
|
WEATHER WATCH
|
June rainfall in the Toledo area has been recorded at 3.70", but officially the area is still 2.15" below average for the year. Jane Martin reported the following weather highlights: Columbus has officially received 5.23" in the month of June, which is + 2.57"; year-to-date precipitation total has topped out at 25.49", + 8.0"; and temperatures over the weekend averaged 10 degrees below normal, with a low on Sunday morning of 49 F. Pam Bennett reported that Springfield is +5.43 for the year. Actual year-to-date precipitation total is 25.5", compared to the average of 20.07". For the month of June this area is +.33". Pam mentioned that the rain around her county has been very spotty.
In the Akron/Canton area, monthly totals for June are 5.45"; and for the year, the total is 22.97", +5.02" above normal. And in Cincinnati, Joe Boggs reported the following highlights: the current month's precipitation total is 2.78", compared to the average of 3.17", - 0.31; the year to date precipitation total for this southern city is 22.90", +1.61".
|
|
HORT SHORTS
|
PLANT PHENOLOGY
Plants in full bloom in southern Ohio are 'Annabelle' hydrangea (Hydrangea arborescens 'Annabelle') and just beginning to bloom is summersweet clethra (Clethra alnifolia) and peegee hydrangea (Hydrangea paniculata 'Grandiflora').
Plants in bloom in central Ohio were goldenraintree (Koelreuteria paniculata), clematis hybrids (Clematis hyb.), 'Annabelle' hydrangea (Hydrangea arborescens 'Annabelle'), albizia (mimosa) (Albizia jublivrissin), and bottlebrush buckeye (Aesculus parviflora).
|
|
GROWING DEGREE DAYS
The range of Growing Degree Day (GDD) accumulations in Ohio from north to south is 904 to 1351. The following is the report of GDD for several locations around Ohio as of June 23, 2004.
As of Wednesday afternoon, GDD accumulations were: Painesville, 904; Cleveland, 943; Toledo, 1064; Youngstown, 1025; Lima, 1057; Wooster, 1066; Coshocton, 1050; Columbus, 1096; Springfield, 1232; Dayton, 1275; Cincinnati, 1353; Ironton, 1349; and Portsmouth, 1351.
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 O.A.R.D.C. weather stations and available on the website at the website below.
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.
The following is a list of plants and their phenological events that occur at or around the following average GDD's, and insects and their phenological activities that have average GDD's close to the listed plants: American elder, first bloom, 909; southern catalpa, first bloom, 913; panicled goldenraintree, first bloom, 924; azalea bark scale, egg hatch, 957; Japanese beetle, adult emergence, 970; greenspire littleleaf linden, full bloom, 1047; southern catalpa, full bloom, 1073; June bride littleleaf linden, full bloom, 1115; and bottlebrush buckeye first bloom, 1158, panicled goldenraintree, full bloom, 1251; rose-of-Sharon, first bloom, 1347; and pine needle scale egg hatch, 1349.
|
|
BLACK WALNUT TOXICITY
Every season, Extension offices receive questions about the adverse affects of black walnut on nearby plants in the landscape, this plant chemical warfare known as an "alleopathy." The roots of black walnut (Juglans nigra L.) and butternut (Juglans cinerea L.) produce a substance known as juglone (5-hydroxy- alphanapthaquinone), which occurs in the leaves, bark, and wood of walnut, but in lower concentrations than in the roots. Juglone is poorly soluble in water and does not move very far in the soil. Many plants such as tomato, potato, blackberry, blueberry, azalea, mountain laurel, rhododendron, red pine, and apple may be injured or killed within one or two months of growth within the root zone of these trees. The toxic zone from a mature walnut tree occurs on average in a 50' to 60' radius from the trunk, but can be up to 80'. Young trees 3' to 8' in height can have a root diameter twice the height of the trees canopy, with susceptible plants dead within the root zone and dying at the margins
Susceptible plants that have contact with walnut roots wilt shortly thereafter, even when there is ample soil moisture. Wilting may occur on only part of a plant, or the whole plant may be affected. If detected early, plants in the early stages may recover if additional water is applied. Later wilting becomes more severe, and browning of the leaves along with wilting usually results in the death of the plant.
Gardeners should carefully consider the planting site for black walnut, butternut, or Persian walnut seedlings grafted to black walnut rootstock, if other garden or landscape plants are to be grown within the root zone of these trees. Persian walnut seedlings or trees grafted onto Persian walnut rootstocks do not appear to have a toxic effect on other plants.
Though we have anecdotal information on plants that are affected, there is no sound scientific research on the subject. Ohio State University Extension (OSUE) has a list of plants that have been observed growing near black walnuts and whether they are affected or not. You can see this list at ohioline.osu.edu/hyg-fact/1000/1148.html
|
|
TEN THINGS YOU NEED TO KNOW ABOUT LICHENS, PART III: WHAT'S IN A NAME?
The Chinese philosopher Krishtalka said that, "the beginning of wisdom is calling things by their right name." One way to indicate the right name of an organism is to use the universal language for a species, namely the Latin binomial name, specified according to the International Code of Botanical Nomenclature. But what about lichens? As we pointed out in previous BYGLs, lichens are dual organisms, composed of two species living together in a mutually beneficial symbiosis. One species in the lichen symbiosis is a fungus which provides a substrate and helps with mineral and water management, and the other species is an alga or a cyanobacterium (the photobiont) which uses water and carbon dioxide and the energy of sunlight to photosynthesize and produce food for the dual organism.
So what could the Latin binomial of a lichen be? Are the Latin binomials for lichens given as both the fungal and photobiont binomials? No. As it turns out, by convention of the Botanical Code of Nomenclature, lichen names are simply given as the Latin binomial of the fungal component of the dual lichen organism. This seems somewhat inelegant, but since the recognizable form of the lichen is the fungal component, the Latin name of the lichen is simply given as the Latin name of the fungus in the symbiosis. So, when the Cladonia cristatella sac fungus gets together with the green alga Trebouxia erici to form a lichen, the official Latin name of the lichen is simply Cladonia cristatella. So, now you know. Having gotten that little detail out of the way, let's face it - the real fun with lichens comes with their common names. Though common names can cause confusion because of local variations, there are some wonderfully evocative lichen names. We mentioned a few three BYGLs ago. Here are a few more.
The can-of-worms lichens (Conotroma urceolatum) is the fungal and lichen Latin binomial, so named for the long segmented spores of the fungus. How about these: Powder-tipped antler lichen; Black-eye lichen; Bloody heart lichen; Cowpie lichen; Elf-ear lichen; Five-o-clock shadow lichen; Hairball lichen; Naked kidney lichen; Tattered rag lichen; and Blackened toadskin lichen. And after that motley crew, a number of lichens with foodie names, such as candy lichen, rock licorice lichen, and chocolate chip lichen. No mas. But these last examples raise a question. Do lichens serve as a source of food for animals and humans? Stay tuned to next week's BYG!
|
|
BUG BYTES
|
ASSASSINS ON THE LOOSE
Predatory insects often have very interesting names. Some have friendly sounding names like lady beetles, lacewings, or hover flies. Others have more descriptive names like minute pirate bug, antlion, and aphidlion. The fairy tale quote, "all the better to see you with," renders the true meaning behind the name bigeyed bug. However, praying mantids have little interest in the spirituality of their prey. These predators have one thing in common: the brandish gnashing mandibles or piercing mouthparts designed to cut-short the life of other insects. It is a jungle out there.
ASSASSIN BUGS have one of the most descriptive names ... they are insecticidal maniacs! These Hemipterans, or "true bugs," belong to the Family Reduviidae. This is a large group with more than 160 North American species. Adults are usually black to dark brown in color, and have elongated heads with the part behind the head appearing almost neck-like. Most have somewhat narrow bodies and some have abdomens that are widened in the middle with lateral margins extending beyond the edges of the wings. Nymphs, which are also predaceous, have a narrow head and thorax and a large, rounded, red abdomen which they hold in a slightly elevated position. Coupled with long, spindly black legs, the raised abdomen gives the nymphs a decidedly "spider-like" appearance.
Assassin bugs wield long, piercing-sucking mouthparts that they use like soda straws to extract the essence of insects. Their victims are usually caterpillars or sawfly larvae, although assassin bugs will attempt to feed on any available meat item, including fingers of curious gardeners. They are aggressive, as are most meat eaters. Joe Boggs reported observing high numbers of assassin bug nymphs on various plants in southwest Ohio, and he noted Ron Wilson, of Natorp's Inc. in Cincinnati, shared digital photos sent to him by a home gardener of an assassin lurking on a pine tree. The home gardener indicated the bug was very aggressive.
Predatory insects can dramatically reduce pest populations. They are very good at what they do. However, their effectiveness can be degraded or eliminated by applications of insecticides. Look closely before spraying. If good insects are plentiful, weigh heavily the need to spray. If an insecticide must be used, select a systemic insecticide that works within the plant, not on the plant surface where the predators live. Work with, rather than against, our bio-allies.
|
|
HICKORY TUSSOCK MOTH
Dave Shetlar and Joe Boggs noted that early instar hickory tussock moth (Lophocampa caryae) larvae are skeletonizing oak leaves in central and southwest Ohio. Early instar caterpillars are gregarious, feeding side-by-side in large groups across the leaf surface. Their handiwork produces one of the best examples of leaf skeletonizing, with even the smallest veins remaining intact. Later instars disperse, feed separately, and consume entire leaves. In past years, these caterpillars have been responsible for heavy defoliation of oaks in southern Ohio
Although larvae of all instar stages are covered with stiff white hairs, which may cause a rash when handled, there are different color forms. All color forms are variations of a black on white motif and range from thin black stripes across the back ("tiger striping") to a row of black spots down the back. Most color forms also have two prominent side-by-side tufts of long black hairs immediately behind the head which is typical for a tussock moth caterpillar.
|
|
YELLOW POPLAR WEEVIL
Joe Boggs noted that he received a report from Dave Leonard (Consulting Arborist, Inc., Lexington, KY) that areas in central Kentucky are experiencing an outbreak of yellow poplar weevil (Odontopus (= Prionomerus) calceatus) this season. This insect is also sometimes called the sassafras weevil, tuliptree weevil, or tuliptree leaf miner. It is a pest of tuliptree, sassafras, and all species of magnolia. During past seasons in Ohio, the weevil has caused extensive leaf damage to its hosts. There have been no reports thus far this season of high populations in the state.
|
|
THE ANNUAL BROWNING OF BLACK LOCUST BEGINS
In last week's BYGL, we noted that feeding damage on black locust caused by LOCUST LEAFMINER (Xenochalepus (= Odontota) dorsalis) adult beetles in southern Ohio was "very mild, requiring a close examination of affected trees". This week, Dave Dyke reported that no close examinations were needed this week to see heavy damage black locusts in the eastern part of the state
Damage by this insect should be familiar to travelers motoring on Ohio's interstate highways. Larval and especially adult feeding activity produces a captivating reddish-brown leaf coloration that highlights infested trees, allowing black locusts to be positively identified at highway speeds! Usually, flamed trees do not become apparent until later in the season.
Locust leafminer adults have elongated flat bodies. They have a black head, orangish-yellow wing covers, and a distinct black wedge-shaped pattern running down the back. Overwintered adults lay eggs on leaves in May. Larvae feed as leaf miners and form "glove-shape" blotch mines. In late-June to early-July, new adults emerge and begin skeletonizing leaves by feeding on the lower or upper leaf surfaces. The damaged areas turn reddish-brown, the striking coloration that is becoming evident.
Although these beetles are most commonly found on their namesake host, they will also feed on dogwood, elm, oak, beech, cherry, yellowwood, wisteria, hawthorn, and crabapple, as well as several herbaceous plants. The larval stage is most commonly found on black locust; however, yellowwood may also support sizable larval populations. In southern Ohio, two generations can occur, while northern Ohio contends with only one generation per year.
|
|
FLATIDAE-FLUFF FLEECES FLORA!
Several BYGLers reported observing fleecy PLANTHOPPER nymphs covering the lower stems of herbaceous perennials and low-growing woody ornamentals. Planthopper nymphs cloak themselves in a dense tangle of waxy, white "fluff." It is this profusion of flocculent material that usually draws attention to the insects. The nymphs are highly mobile and move rapidly away from probing fingers, typically dropping bits of fluff as they flee. The jumping adults (= planthoppers) are 1/4" to 3/8" long, purplish blue, lime green, or powdery white. They are most easily recognized by the broad wings covering the sides of the body and legs.
There are several species of planthoppers, in the family Flatidae, that have nymphs which surround themselves with whitish, cottony material. They are usually found near the ground and may occur on a wide variety of small trees, shrubs, and flowers. The nymphs produce copious quantities of honeydew which may coat the plant and become colonized by a black sooty mold fungus. The immature stage of this insect seldom lasts more than a few weeks, and once the nymphs molt, the flocculent material quickly degrades and disappears. Aside from providing great entertainment value, these sap-sucking insects usually have little impact on the landscape. They seldom become more than a nuisance pest. Although no control measures are generally recommended, a heavy spray of water will wash the nymphs and fluff from the plant.
|
|
ANTS HIT THE PAVEMENT
Pavement ants are now swarming and the winged ants have been reported both indoors and outdoors. Just as carpenter ants and other species of ants swarm to produce a new colony, the pavement ants are producing winged reproductives to mate and establish a new colony. The 3/16" workers are dark brown and can be identified with a 30x hand lens, by examining the head, thorax, and petioles. The head and thorax are covered with tiny wrinkles or grooves, as if they had been soaked in dishwater. Between the thorax and abdomen are nodes, or petioles, which act as vertebrae to attach the two body segments. Some ants, like carpenter ants have only one node, but pavement ants have two nodes.
These ants build colonies under or near slabs of masonry and broken crumbs of cement and soil on top of the concrete. Their nests can be found under stones, rocks, patio slabs, or wood, as well as around building foundations and concrete steps. Inside, they forage for proteins, greasy foods and sweets, such as dog food, potato chips, and cookie crumbs. They may form a colony under thresholds, air conditioners, toilets, or along baseboards. Although they normally swarm in the spring, they can swarm several times, especially in slab homes. Control can be frustrating, as sprays often cause the ants to split and move, yet their preference for baits is often subsequent to crumbs. For a definitive identification, contact the CWEPPDC.
|
|
WINDSHIELD WIPE
BYGLers also ran into a few other insects and mites this week including:
* Jane Martin reported that her vegetable trial gardens are experiencing a beetle blitz from SPOTTED CUCUMBER BEETLE (Diabrotica undecimpunctata howardii) and STRIPED CUCUMBER BEETLE (Acalymma vittata). The beetles belong to the "leaf beetle" family Chrysomelidae, and they are some of the most damaging pests of cucurbits, such as cucumber, squash, melon, and pumpkin. Larvae feed on the below-ground portion of host plants, sometimes causing severe root damage. Adults feed on the above-ground portion of plants, causing damage to leaves and stems.
Jane's chrysomelid crisis could further escalate since both beetles can spread bacterial wilt and cucumber mosaic diseases to their hosts. Foliar applications of properly labeled insecticides can reduce beetle numbers, but control measure must to be initiated now to reduce chances of disease infections.
* Dave Shetlar reported that his light-traps catches include huge numbers of third generation COMMON ARMYWORM MOTHS (Pseudaletia unipuncta). In 2002, we reported that linden trees (Tilia spp.) in western Ohio appeared to be pulsating with swarms of armyworm moths hovering around the trees at night to get a quick nectar meal (BYGL 2002-12, 6/27/2002). The moths spawned numerous calls to Extension offices from concerned homeowners. Of course, no harm was done to the trees. Dave noted that lindens in full bloom now could engender a repeat performance of the moth-mania
* Dave Shetlar also reported that he is receiving calls concerning rows of small holes "appearing" in cannas. The culprit is EUROPEAN CORN BORER (Ostrinia nubilalis). The moth caterpillars produced the rows of holes by chewing through leaves while they were furled. The damage is done for the season; however, if this is a recurring problem, an insecticide product containing disulfoton (e.g. Di-Syston) applied in May should prevent the damage
*Barb Bloetscher reported that the GIANT LEOPARD MOTH (Ecpantheria scribonia (Stoll)) has been reported in Columbus and Cincinnati. This large, white moth with a wingspan of 2 1/2" - 3 1/2" is distinctive as its pure white forewings have black spots and circles. The hairy caterpillars eat leaves of cherry, maple, and willow trees, in addition to sunflowers, violets, dandelions, and cabbage. The moths are usually seen in southeastern states and Texas from April through September, however they are occasionally seen in Ohio, Michigan, and Canada.
*Amy Stone reported some gypsy moth highlights of the week that included: Ohio Department of Agriculture (ODA) wrapped up their phermone flaking project on Monday; gypsy moth caterpillars have begun to pupate in Fremont, in northwest Ohio; and Entomophaga (the gypsy moth fungus) is doing a job on some Lucas County caterpillars.
|
|
DISEASE DIGEST
|
POWDERY MILDEW APPEARING
Not surprisingly, powdery mildew is already rearing its ugly head on common lilac, monarda, and a few other landscape plants. Though we usually think of powdery mildew as a late season problem, any time the three partners in the disease triangle converge, it can appear.
Many powdery mildews are favored by dry weather with warm days and cool nights, while free water and rain actually inhibit its development. Then why do we have powdery mildew with all the rain that has been falling in Ohio? Although rain inhibits conidia (spore) germination, high humidity does not! And in fact, in areas where fog and dew occur frequently, like the West Coast, powdery mildews are perennially severe.
Powdery mildew fungi are unique in that virtually all of their fungal filaments (mycelium) are restricted to the surface of the leaf, so this disease is easy to identify on sight. This group of fungi are strictly dependent upon living hosts for nutrients and only grow in association with a specific host or host group. There are no cosmopolitan powdery mildew species, so no one mildew pathogen can infect all types or species of plants.
Powdery mildew diseases are typically easy to manage. The best option is to use genetic plant resistance to minimize or avoid the problem. If genetic resistance is not available, then fungicides are the next best management option. Treat at the first sign of the disease with a labeled fungicide and retreat as needed during cool, damp weather. Use a good spreader-sticker with the fungicide and be sure and cover both the top and bottom leaf surfaces.
|
|
SHRUB WORKSHOP DIAGNOSTIC SAMPLES
This past Tuesday and Wednesday, the Secrest Deciduous Shrub School was held at the Ohio Agricultural Research and Development Center (OARDC) of Ohio State University in Wooster. Following are some of the diseases noted by attendees during the sample quizzes and diagnostic walkabout
*DOWNY MILDEW OF CRANBERRYBUSH VIBURNUM. This common disease of the cranberrybush viburnum and leatherleaf viburnum usually becomes noticeable in mid-summer, but with wet weather this spring the fungus is already sporulating profusely on the undersides of leaves and starting to cause angular leaf scorching on upper leaf surfaces.
*ROSE DISEASES. Rose black spot is thriving with all of the recent rains and the requisite hours of leaf wetness needed for infection. Many leaves are peppered with numerous black lesions. In addition, light-colored rose petals show spotting from infections of the Botrytis gray mold fungus which infects the senescing blossoms.
*PYRACANTHA SCAB. This fungus (which does not cross-infect apples and crabapples and is a different fungus than the apple scab fungus) is causing some smudgy leaf spots, but more importantly relative to ornamental damage, it is discoloring and shriveling pyracantha fruits. Where the disease is heavy, the "fire" (intense orange and red colors) part of "firethorn" is being sublimated.
*POWDERY MILDEWS. A number of different powdery mildew fungi were exhibiting the powdery growths on their hosts, including magnolia (coupled by reddish to grayish leaf dessication), privet, and deciduous azalea.
*BACTERIAL FIREBLIGHT. This disease, limited to different host plants in the rose family (Rosaceae) was found in the Arboretum on ornamental pears including Callery pears and the small-leaved Pyrus faurei, an oriental photinia, purple leaf sand cherry, and several crabapple cultivars.
|
|
TURF TIPS
|
WET WEATHER AND CRABGRASS GERMINATION
The question has arisen about whether another pre-emergent application for crabgrass is in order since we've had so much rain and wet weather. If you recall in 1995, summer crabgrass pressure was the highest we had seen in several years. Back in 1995, warm temperatures and abundant rainfall in early summer promoted additional crabgrass germination and also likely shortened the residual and performance of the pre-emergent herbicides that were applied. Though we speculated then that heavy rains leached the herbicide out of the top inch of soil, it was more likely that the shortened residual was due to an accelerated rate of breakdown by soil microorganisms because their activity also increased.
We contacted Pam Sherratt for some information about whether to make an additional application of a pre-emergent herbicide this season because of the abundant rainfall, and she also visited with John Street. Both said that there is a possibility of more crabgrass germination due to the wet weather and the dissipation of pre-emergent herbicides. In central and northern Ohio, an additional application can be made, but do so before July 1. If a turf area has crabgrass that is smaller than one tiller, one alternative is to use Dimension, which has some early post-emergence activity. Another alternative is to use traditional pre-emergence herbicides with Drive (quinclorac). In the transition zone and southern Ohio, crabgrass can germinate into August so an additional pre-emergent herbicide can be applied in the next two to three weeks alone, or in combination with a post-emergence. Crabgrass typically germinating after September 1 will frost-out with the first frost in the fall, therefore not requiring any herbicide after that date.
|
|
BROWN SPOTS IN LAWNS
When trying to determine the cause of lawn browning, don't automatically assume the problem is related to insects or disease; there are also other things to think about including weather conditions, improper culture, and recent events on the lawn. Here are a few things that can cause brown areas in lawns, most of which are within our power to correct.
1. Mowing injury - Scalping on slopes or on uneven ground, mowing too short, and filling the mower with fuel on the lawn can cause brown areas. It is important to follow proper mowing recommendations, especially the one-third rule. Be aware of slopes and depressions in the lawn and mow accordingly and change mowing direction about every other mowing to avoid scalping.
2. Fertilizer misapplication or spill - Misapplying fertilizer, filling the spreader on the lawn, and fertilizer spills can all cause brown areas. Fill spreaders on the driveway or other hard surface and clean up spills. Make sure the spreader is calibrated correctly and is being used properly by making header strips around the lawn's perimeter and shutting of the spreader on turns.
3. Herbicide injury - Follow label directions whenever applying herbicides. Non-selective herbicides can be misused and/or accidentally sprayed on lawns, causing brown areas. We sometimes make the mistake of stepping in the treated area, then onto the lawn, leaving behind a trail of footprints that later turn brown; this is known as "sloppy foot." Broadleaf weed killers labeled for use on lawns will not cause injury as long as they are used properly.
4. Poor and/or compacted soil - If the soil is so poor that grass roots can't penetrate and fail to establish, brown areas may appear while the neighbors' lawns look fine. Soil in areas frequently trafficked, such as footpaths or animal paths, can become compacted and lead to a decline in lawn quality.
5. Weather - Drought is a major reason why lawns turn brown during the summer months if they are not being irrigated to keep them green. With the lack of rainfall or irrigation and higher temperatures, Kentucky bluegrass and perennial ryegrass lawns go into a dormant state in order to survive. South-facing lawns and slopes may begin to turn brown from exposure before other parts of the lawn. These lawns can survive drought periods for a few weeks with intermittent rainfall. Be aware of recommended care for dormant lawns in exceptionally dry and hot summer seasons. Intermittent irrigation with a half-inch of water every two or three weeks will help ensure survival. This is not enough water to regreen a lawn, but is enough to keep the crowns and roots hydrated.
6. Buried construction debris - Gardeners in new developments are likely to find buried block, siding, plywood, etc., which can all cause dry areas where grass roots poorly and can't absorb sufficient moisture. If one can't determine a cause for browning, do some digging to investigate what is below the brown area.
7. Competition with trees and shrubs - Woody plants compete with lawns for water, nutrients, and light. Plants with shallow roots, such as maples, may out-compete the lawn in hot, dry seasons. Deep, supplemental irrigation in some areas may be needed to avoid lawn browning.
8. Dog injury - Dog urine can be high in salt content and cause injury to lawns, especially if the soil is dry and infertile. A dark green ring of grass can surround the spot, related to nitrogen contained in the urine. Heavy watering reduces the salts to a less toxic concentration.
9. Insects and diseases - The common lawn insects and diseases can cause various patterns of discoloration, and often we jump to the conclusion that lawn browning is caused by insects or disease, rather than think about all the other potential causes.
The common lawn insects in much of Ohio include the bluegrass billbug, chinch bug, white grub, and sod webworm. They each produce different symptoms and signs. Though there are many lawn diseases, they are active only under certain environmental and/or cultural conditions, and can be limited to only one or two species of grass. Become aware of the signs to look for and the time of year that these pests are active in order to diagnose them accurately.
|
|
INDUSTRY INSIGHT
|
PERIODICAL CICADAS = FLAGGING SALES?
Most are well aware that periodical cicadas can cause of extensive flagging on certain trees. Could they also be responsible for flagging of another sort ... sales? Some greenhouse and garden center operators in the Cincinnati area belive so. Several operators have reported that their Mother's Day sales were the best ever, and then the bottom fell out of the market as soon as the cicadas started singing. Thank goodness that virtually all of them in the area have finally met their periodical fate.
While it is very difficult, if not impossible to generalize, the report of one retail greenhouse owner appears to be fairly typical. His sales for Mother's Day were fantastic. On the 15th of May, his sales for the month were up 15% over the previous year's. By the month's end, his sales were down 5%. His sales remained flat until this past week. This grower had to dump a lot of overgrown materials, offer sales, and introduce fresh materials to stimulate the return of business. Since the middle of June, sales at this greenhouse have returned to just about what they were at the same time last year. Other retailers who have not conducted somewhat major sales, report that their sales remain fairly flat. Wholesalers report only a trickle of business coming back.
In short, growers in the area that were questioned, reported that they felt that the cicadas had a very significant negative impact on sales. The very large plant inventories in garden centers and greenhouses are very vivid evidence of that depressing conclusion.
|
|
THE ROCKY MOUNTAIN LOCUST
As Joe Boggs says, "as an entomologist, Jim Chatfield is a great plant pathologist", but even Jim knows a great book when he hears one. Last week, Jim and his wife Laura did a driving and hiking vacation to Yellowstone and the Grand Tetons. With so much time in the car, they decided to read aloud to each other. Their choice of literature? "Locust" a new book by Jeffrey A. Lockwood of the University of Wyoming. The full title of the book is "Locust: The Devastating Rise and Mysterious Disappearance of the Insect That Shaped the American Frontier". It delivers all that and more.
"Locust" is a good mystery story, a true exposition of how science is done, an exploration of how hypotheses are tested, and of how paradigms change with new perspectives. It explores key biological issues, with everything from the very definition of species to the history of biological controls of insects. It is a tremendous ecological tale, exploring the roles of weather, land features, soils, and effects of interacting organisms - from bison to grasshoppers to birds to humans. It incorporates historical and cultural analyses, biographies of key players, the messy politics, and economics of science. "Locust" is written in an engaging style, sometimes soaring with its prose, and always entertaining.
Chatfield goes out on a limb: "Easily one of the ten best books, on any topic, that I have ever read." It even has a killer ending. As plant lovers and people making our living in horticulture, science and the many cultures that we intersect are key parts of our vocabulary. Improve that vocabulary with this most outstanding new book, available from Basic Books of $25.
|
|
COMING ATTRACTIONS
|
2004 OHIO PLANT HEALTH CARE WORKSHOP: ABIOTIC DISORDERS OF LANDSCAPE PLANTS.
This workshop will be held July 14-15, 2004 in Wooster, Ohio. It is the seventh in a series of plant health care workshops co-sponsored by The Ohio State University/OARDC Secrest Arboretum, Ohio State University Extension, and the Extension Nursery, Landscape, and Turf Team (ENLTT). The two-day course on abiotic disorders affecting plants in the landscape will combine proven concepts and practical information to help green industry professionals manage ornamental landscapes and urban forests.
Registration is limited to 40 participants. Deadline for registration is July 9, 2004. Registration for the two days includes breakfast and lunch both days, dinner on Wednesday, all sessions, materials and handouts for $225. For registration or program information, contact Denise Ellsworth, OSU Extension, Summit County, at 330-928-4769 ext 21, e-mail: ellsworth.2@osu.edu, or Diane Dunphy 330-928-4769 ext 27, e-mail: dunphy.2@osu.edu.
|
|
HOLD THESE DATES!
We wanted to give you a "heads up" on upcoming dates for various field days just so you get them on your calendar. More details on each of the programs and registration information will follow. Hold August 4 for the 7th Annual Northwest Ohio Summer Field Day on the campus of Owens Community College, packed with concurrent educational sessions, exhibitors, plant walks and more. Hold August 7 for the Clark Co. Field Day in Springfield, which features annual flower trials and perennial gardens, a regional turf plot, and more. August 18 is the ever popular OSU Turf Field Day in Columbus. Mark your calendar now!
|
|
WOSU's GREEN SCENE
Join WOSU News 820 host Tom Wiebell this Friday night from 6:30 to 8:00 pm with guests Deb Knapke (the Garden Sage) and Jane Martin on Green Scene, WOSU's gardening and landscaping Q&A show. They will even take a call from the University of Georgia's horticulturist par excellence Michael Dirr who will chat about his new hydrangea book. Tune in or call Green Scene at 614-292-8513 each Friday night for all your horticultural queries and quandaries.
|
|
BYGLOSOPHY
|
Learning is a treasure that will follow its owner everywhere. - Chinese Proverb
|
|
