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
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June 17, 2004
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This is the Eleventh 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 15, 2004 conference included: Barb Bloetscher (Entomology and C. Wayne Ellett Plant & Pest Diagnostic Clinic); Joe Boggs (Hamilton/South District); Erik Draper (Geauga); Gary Gao (Clermont); Dave Goerig (Mahoning); Dan Herms (Entomology); Jane Martin (Franklin); Marianne Riofrio (HCS); Dave Shetlar (Entomology); Amy Stone (Lucas); Nancy Taylor (Plant Pathology and C. Wayne Ellett Plant & Pest Diagnostic Clinic); Curtis Young (Allen County); 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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Many BYGLers have been caught singing, "rain, rain, go away -- come back another day." Erik Draper reported that certain areas in Geauga County had received over 5" of the wet stuff in just over a week. Weather data highlights from the Cleveland Hopkins Airport include: 1.96" of rain has fallen in the month of June thus far; and 19.87" of precipitation has fallen between January - May 2004. Dave Goerig noted that Mahoning County had received 20.37" of precipitation thus far for the year, which is 4.42" above the average. For the month, his area has received 1.69", compared to the average of 1.75" (-0.06"). Most of Lucas County has received some rain, while certain areas were hard hit. High winds and heavy downpours moved through the area on Monday, with some locations counting rainfall amounts in inches. Flooding along the Maumee River was common, and trailers at a riverside campground had to be moved to higher ground.
The rain continued to fall in central Ohio. Soil is saturated. In the Martinscape, there was standing water where it has never been before. Many Franklin County Master Gardeners have commented to Jane Martin that perennial gardens seem larger (taller, lusher, and more robust), but annuals planted this spring are essentially "sitting still." The rain and cloudy weather has not provided the opportunity for the annuals to establish themselves and begin growing. Jane also mentioned that some gardeners are becoming depressed, unable to get out to work in and enjoy their gardens. Hopefully a sunny weekend will provide a cure!
Joe Boggs reported the following weather data has been collected at the Greater Cincinnati/Northern Kentucky International Airport: June rainfall so far has totaled 2.53", +0.41" when compared to the monthly average; the year-to-date total is 22.65", compared to the average of 20.24"; and temperatures have been very warm, ranging from the mid-to-high 80F. Some surrounding areas have even made it over the 90F mark.
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HORT SHORTS
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PLANT PHENOLOGY
Plants blooming in Geauga County include: catalapa (Catalapa speciosa); arrowwood viburnum (Viburnum dentatum); Bumald spirea (Spirea X bumaldi); Japanese tree lilac (Syringa reticulate); and inkberry(Ilex glabra). The oakleaf hydrangea (Hydranea quercifolia) is just beginning to bloom according to Erik Draper. Dave Goerig reported the American elder (Sambucus canadensis) and the hybrid teas, grandifloras, floribundas, and multiflora roses were blooming in Youngstown area. Astible, coral bells, daylilies, feverfew, and rue are this week's highlights in the perennial garden in northern Ohio. Larry Steward reported that linden (Tilia cordata) and (T. tomentosa); redosier dogwood (Cornus sericea); and inkberry (Ilex glabra) were blooming at ATI in Wooster.
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GROWING DEGREE DAYS
The range of Growing Degree Day (GDD) accumulations in Ohio from north to south is 810 to 1221. The following is the report of GDD for several locations around Ohio as of June 16, 2004.
As of Wednesday afternoon, GDD accumulations were: Painesville, 810; Cleveland, 847; Toledo, 954; Youngstown, 926; Lima, 996; Wooster, 963; Coshocton, 1013; Columbus, 1057; Springfield, 1109; Dayton, 1147; Cincinnati, 1221; Ironton, 1220; and Portsmouth, 1221.
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 site 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: rhododendron borer, adult emergence, 815; northern catalpa, full bloom, 816; dogwood borer, adult emergence, 830; oakleaf hydrangea first bloom, 835; cottony maple scale egg hatch, 851; fall and mimosa webworm egg hatch, 867 and 874 respectively; winged euonymous scale egg hatch, 892; spruce budscale egg hatch, 894; panicled goldenraintree, first bloom, 924; azalea bark scale, egg hatch, 957; Japanese beetle, adult emergence, 970; rosebay rhododendron, first bloom, 1010; greenspire littleleaf linden, full bloom, 1047; June bride littleleaf linden, full bloom, 1115; and bottlebrush buckeye first bloom, 1158.
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BEWARE OF SOUR MULCH
In Columbus, Jane Martin has talked with a few gardeners recently who had purchased "sour" mulch. Sour mulch is easy to detect; it will have a strong, acrid or sour odor, or smell like alcohol. Normally, mulch has a pleasant, humus-like odor similar to that of compost or freshly-cut wood. In all cases, plants in the beds where the mulch was applied were injured by this mulch. Within a couple of days of mulch application, annual flowers had turned yellow, were scorched, or were killed outright from fumes or by direct contact with the mulch. Perennial plants so affected usually exhibit leaf chlorosis and defoliation. In a couple of cases, grass on the edge of the beds where the mulch was applied also discolored and died back.
When organic mulches undergo anaerobic (without oxygen) decomposition, the microbes in the mulch produce organic alcohols and acids, which can be quite toxic to plants. The pH of such mulch can go as low as 1.9-2.5 and become very acidic. Anaerobic conditions can occur in wet mulch piles over six to eight feet in height. It can occur in bulk mulch piles or in bagged mulch, especially if water gets in the bags. Fortunately, this sour mulch can be salvaged for use. Spread it out in a thin layer on a driveway, tarp or patio to aerate until the odor dissipates, which may take several days.
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RIGHT PLANT FOR RIGHT LOCATION
Dave Shetlar reported that when he appeared as one of the guests on WOSU's Green Scene, he received quite a few calls about which landscape plants to select for various home sites. Selecting the "right plant for the right location" is the most important step in having a beautiful and thriving landscape. It can be a daunting task when you have to select a lot of plants for a home landscape, especially a brand-new home. It is quite important to do your homework.
There are many fact sheets, bulletins, and books that can help homeowners through this process. OSU Extension has many FactSheets on plant selection. These FactSheets are available at the following web address: http://ohioline.osu.edu/lines/trees.html#TSG_4 For example, you can refer to OSUE FactSheet HYG 1055, "Drought Resistance in the Home Landscape" [http://ohioline.osu.edu/hyg-fact/1000/1643.html] for a recommendation of drought-resistant plants. If you are trying to determine which perennials to plant, you could consult OSUE Fact Sheet HYG#1242, "Perennials for Specific Sites and Uses," [http://ohioline.osu.edu/hyg-fact/1000/1242.html], for suggestions.
Randy Zondag recommended a nice book that he carries with him every day. It is entitled "Pocket Guide to Choosing Woody Ornamentals: A Concise Manual for the Correct Use of Woody Landscape Plants" authored by Gerd Krussmann and translated by Michael Epp. You can also call your local county extension agents, Master Gardeners, or talk with employees at reputable garden centers and nurseries.
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BUG BYTES
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BROOD X PERIODICAL CICADA UPDATE
BYGLers reported that periodical cicada adult activity in Ohio is beginning to wind down ... or whine down, depending upon your perspective. The red-eye express is chugging to a stop, and Brood X is ready to head for the underground. Here are a few parting observations:
* BYGLers discussed possible reasons for the often dramatically uneven distribution of cicada populations within the historical boundaries of Brood X. High expectations of marauding hordes were often met with disappointing no-shows. Some reasons for the discontinuity of cicada populations are obvious. Brood X in Ohio primarily occurs in the western half of the state, an area with a long history of field crop production ... cicadas are not corn pests. Also, Ohio is one of the fastest urbanizing states in the U.S., and loss of mature trees as well as heavy soil disturbances translate into a loss of cicada nymphs. Other possible reasons were more speculative, such as the impact of unidentified pathogens
However, several BYGLers observed cicada behavior that may help stabilize cicada losses due to urbanization. Sizable numbers of cicadas were frequently observed moving from areas with high populations into areas where little emergence had occurred. These mass-migrations were from areas with a large number of mature trees into areas where soils have been heavily disturbed, and mature trees lost within the recent past. Heavy oviposition was observed on young trees planted in these "new-found" areas. While most of this movement occurred over relatively short distances, this behavior affirms that future generations of people will enjoy future generations of cicadas.
* BYGLers reported that oviposition damage is now becoming very evident. Currently, flagging is most visible on oak and beech, particularly European beech. As noted in last weeks BYGL, leaf drop on ash has been obvious, the result of oviposition into leaf petioles.
Erik Draper noted that oviposition damage remained evident for a number of years after Brood V emerged in eastern Ohio in 1999. A considerable amount of twig and branch dieback and breakage occurred for 2-3 years after the cicada event. Erik indicated that this sometimes presented an unexpected diagnostic challenge. Indeed, the flagging produced by cicada oviposition damage mimics a number of other plant problems.
* While periodical cicadas have been reported to lay eggs on over 270 plant species, Joe Boggs indicated that cicadas may be selective regarding suitable oviposition sites within the plants. He observed flowering crabapples with heavy oviposition slits on all branches and twigs except those that exhibited symptoms consistent with bacterial fireblight. Dave Shetlar noted that female cicadas often "sample" oviposition material with their piercing-sucking mouthparts before laying eggs. He speculated that the females may shun oviposition sites that fail to meet certain criteria. Thus, no oviposition was observed on wooden broom handles!
* Cicadas are now turning into little stinkers ... literally. Millions of dead bodies have dropped from trees and the odor of decay is becoming very evident. BYGLers reported that the more bullish cicada afficionados are reminding homeowners that the bodies are actually good fertilizer, being rich in nitrogen, phosphorus, and potassium. The cicada's goodwill may be spread about the landscape with a rake.
* During the cicada emergence, and subsequent adult activity, BYGLers noted that Ohioans living in Cicada-Land met the onslaught with a range of reactions, from genuine curiosity and amazement, to taciturn acceptance, to mild panic. Their sentiments are epitomized by a few selected farewells: "goodbye garish gadflies;" "adios transient troubadours;" and "don't let the door slam on your ovipositor on the way out."
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MIMOSA WEBWORMS ARE WEAVING TANGLED WEBS
Dan Herms reported that the nests of the first generation of mimosa webworm (Homadaula anisocentra) are appearing on honeylocusts in northeast Ohio. Nests at this time of the year may be difficult to detect without a close inspection of the tree. The nests are typically very small, about 1 to 2 inches long, and the loosely woven silk usually envelops only 2 or 3 newly expanding leaves at the tips of the branches. Larvae of this moth feed gregariously as leaf skeletonizers within webs spun over the foliage. Damaged leaves turn orangish-brown and appear fire-scorched. Unlike other web-makers, it is these clusters of "flamed" leaves, rather than the actual webbing, that usually draws attention to an infestation.
There are two to three generations per season, and they typically overlap so that larvae may be present from June until September. Female moths usually lay their eggs on the nest in which they developed, meaning that nests become larger with each generation. Once nests become large and tightly woven, control applications may fail to penetrate the thick webbing. Thus, the small nests currently being found represent an important window of opportunity for control. Effective control materials include Bacillus thuringiensis (Bt) as well as other insecticides listed in OSU Extension Bulletin 504, titled, "Insect and Mite Control on Woody Ornamentals and Herbaceous Perennials."
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HOME INVADERS
BYGLers located throughout Ohio reported problems with arthropods engaged in breaking and entering homes. Stampedes of millipedes have been observed migrating up the north sides of buildings en masse, due to the abundance of moisture, and usually an abundance of mulch. Other complaints of intruding pests included: pillbugs, spiders, earwigs, and carpenter ants.
Mulch piled higher than 2" accommodates a large number of insects and other arthropods. It provides the 3 ingredients necessary for them to survive: moisture (dew, irrigation, sweating pipes, and plugged downspouts) food (molds, dead leaves, and insects), and harborage.
An OSU entomology Ph.D. graduate studied the relationship between various ground covers and the incidence of insects found. He discovered that wood mulch, such as cypress and hardwood mulch, contained more insect species and more total insects than bark mulch. He also found that populations increased with thicker layers of mulch. Inorganic mulches, such as gravel, had some insects but fewer species and quantities. Therefore, to reduce the number of insects living near and/or creeping into buildings, keep organic matter at least 8" away from the outer perimeter of the structure, and maintain only 1-2" of mulch. Shrubs and vines, woodpiles, trash, and sheds should be kept away from the foundation as well.
Boxelder bugs were also reported to be showing-up in large numbers on sunny south or west-facing walls, causing alarm and red stains if squashed. These seed bugs suck sap from the seeds of boxelders and some species of maples; causing no real harm to the trees or people, but their tendency to gather on warm surfaces is distasteful to homeowners who don't like insects. To keep them away from structures, remove boxelder trees where possible, and seal homes so that they can't get inside. Painting the building a darker color or shading sunny walls may discourage heat seeking boxelder bugs from congregating.
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WINDSHIELD WIPE
BYGLers also ran into a few other insects and mites this week including:
* Gary Gao and Joe Boggs reported that JAPANESE BEETLE (Popillia japonica) adults are now appearing in southwest Ohio. Dave Shetlar noted that males typically emerge first, and may be found cavorting on grass blades waiting for love.
* Dave Shetlar reported that BAGWORM (Thyridopteryx ephemeraeformis) populations this season appear to be heavily slanted towards the southern part of Ohio. He indicated that I-70 provides a fairly accurate line of demarcation. Indeed, BYGLers in southwest Ohio noted that they are already seeing some significant damage being produced by early instar bagworms.
The early instar stages of these moth caterpillars are very susceptible to the biological insecticide, Bacillus thuringiensis or Bt (e.g., Dipel, Thuricide, or Caterpillar Attack), horticultural oil, or insecticidal soaps. Tree and shrub hosts should be closely inspected since the bagworms are well camouflaged by plant materials woven into their silk bags. Once the caterpillars grow to over 3/4" in length, even traditional insecticides may not penetrate the hydrophobic silken bag. Refer to OSU Extension Bulletin 504, "Insect and Mite Control on Woody Ornamentals and Herbaceous Perennials" for effective insecticides.
* Joe also noted that leaf damage caused by LOCUST LEAFMINER (Xenochalepus (= Odontota) dorsalis) may be found on black locust leaves in southern Ohio. Adults skeletonize leaves, and larvae produce glove-shaped blotch mines. Currently, damage is very mild, requiring a close examination of affected trees. Adults are small, elongated, flat beetles with a black head, brownish-orange wing covers and a distinct black wedge-shaped pattern running down the back.
* Erik Draper reported that damage caused by larvae of the WHITE PINE WEEVIL(Pissodes strobi) is becoming evident in northeast Ohio. As their common name implies, the weevil infests white pine, but it will also attack Scotch, jack, red, and pitch pine as well as Douglas-fir, Colorado blue and white spruce. The white, legless weevil larvae tunnel just beneath the bark downward from the terminals causing terminals to become wilted, turn brown, and die. Wilted terminals should be removed and examined for the larvae, and infested terminals destroyed to reduce weevil populations.
* Dan Herms reported that the ROSE MIDGE (Dasineura rhodophaga) is wreaking havoc on roses in northeast Ohio. The larvae tunnel below flower buds, causing the buds to shrivel and turn brown. They are also tunneling into new growth, causing new shoots to die and plants to be stunted. Although a few may be tolerated, high populations can seriously affect plant growth and flower production. Where applicable, a systemic insecticide such as "Bayer Advanced Garden 2-in-1 Systemic Rose & Flower Insecticide" provides extended protection for this pest and other labeled pests.
* In last week's BYGL (2004-10, 6/10/04), Joe Boggs reported observing ornamental pear trees in southwest Ohio with significant infestations of PEARLEAF BLISTER MITE (Phytoptus pyri). This week, BYGLers from throughout the state noted that they are also seeing substantial infestations of this eriophyid mite. To add to the challenge, bacterial fireblight is also being found on ornamental pears. Refer to last week's BYGL for a complete description of symptoms produced by the mite.
* BYGL readers are urged to remain on the lookout for SPRUCE SPIDER MITES (Oligonychus ununguis). Joe Boggs noted that adult mites persist in southwest Ohio, and their damage to the new growth of a number of conifers is evident. Temperatures have consistently remained above thresholds that usually cause spring populations of this mite to transition from the adult stage to the egg stage. However, Dave Shetlar noted that temperature is not the only factor important to this shift. High humidity can extend the early-summer activity of this cool-season mite. Conifers should be closely monitored.
* Dan Herms reported that crawlers of four soft scales are out and about in northeast Ohio. They include: COTTONY MAPLE SCALE (Pulvinaria innumerabilis), FLETCHER SCALE (Parthenolecanium fletcheri), EUROPEAN FRUIT LECANIUM (P. corni), and SPRUCE BUDSCALE (Physokermes hemicyphus). Also, crawlers of the WINGED EUONYMUS SCALE (Lepidosaphes yanagicola), a hard scale specific to its namesake, are beginning to hatch from eggs in that part of the state.
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DISEASE DIGEST
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VERT-ALERT ON SYRINGA
Nancy Taylor stunned BYGLers into silence, a very rare occurrence, when she reported finding and isolating the VERTICILLIUM WILT fungus on Japanese Tree Lilac (JTL) (Syringa reticulata). She further amazed all by indicating what really makes diagnosis of this disease on JTL difficult is that the fungus is asymptomatic for staining the xylem. There are no easy-to-see dark streaks in the cut branches, so to know if it is indeed verticillium, samples must be sent off to the C. Wayne Ellet Plant, Pest Diagnostic Clinic (CWEPPDC) where the fungus will be cultured and identified.
New discoveries are always fun for diagnosticians. On the other hand, the non-pathological types in the BYGL group offered-up a collective groan because of the implications of this discovery. JTL has long been recommended because of its nice summer bloom. It is a striking urban tree, and appeared very adaptable for Ohio conditions. However, we knew that JTL could not tolerate low, wet spots, that could produce stress. Lets review how this fungus operates.
Verticillium wilt is caused by one of two soil-borne fungi: Verticillium albo-atrum, and Verticillium dahliae. However, V. dahliae is the species that most commonly attacks woody ornamentals in the United States. Verticillium is found in many soils and can affect several hundred plant species, including both herbaceous and woody ornamentals. This fungus has definite host preferences, which include: redbud, some maples, Cotinus, barberry, Russian olive, rose, and tulip-poplar. Many times, infected hosts exhibit no symptoms. Since the fungus persists in the soil indefinitely, serious problems may arise when susceptible hosts are grown in infested soils.
This fungus directly invades the root system through wounds, both man-made and natural. Of course, digging up and planting a tree is a major man-made wounding process; however, wounds are also caused naturally by roots growing through soil, or being invaded by soil organisms. Once in plant tissues, the verticillium fungus produces toxins and invades the xylem, moving up the plant via spores. Anywhere these new spores lodge, while moving through the water conducting tissues, a new infection begins. Toxins produced by Verticillium may kill plant cells at some distance from those directly invaded. This is why the fungus often cannot be isolated from the tips of wilted branches or streaked wood, even though symptoms are apparent. A good sample for diagnosis is a section of branch about 1" thick and 6-8" long.
In response to the pathogens cellular invasion, the host produces substances called tyloses or gums to try and shut down the infected cells, thereby limiting the upward fungal movement in the plant. This shutting down of infected vascular tissues reduces the flow of water from the roots to the shoots. This combination of reduced water flow and cellular death from toxins often causes the typical external symptoms, which include: wilting, leaf scorch, and branch dieback.
Symptoms caused by Verticillium develop anytime during the growing season, but typically show up in July and August because of the increase in hot, dry conditions. Symptoms may appear off and on (chronically) or they may be acute and often lethal. Chronic symptoms include small, yellow foliage, leaf scorch (marginal browning), slow growth, and dieback of shoots and branches. Often, the foliage on one or more branches wilts suddenly. From year to year, recurrence of wilt is very unpredictable, as will be severity of infection. Acute symptoms include leaf curling, drying, an abnormal coloration of leaves or areas between leaf veins, partial defoliation, wilting and branch dieback. Usually one branch or one side or an entire section of the plant is affected. One important difference is that in the acute, lethal form, Verticillium wilt can cause a sudden and total collapse of the plant.
Verticillium wilt can be easily confused with other diseases or abiotic conditions. Herbicide damage, environmental extremes and mechanical damage at the plant's base may cause the same or similar symptoms. But if in doubt as to what is wrong, send off a generous sample to the CWEPPDC for confirmation.
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CONFUSING ASH SYMPTOMS?
As Emerald Ash Borer (EAB) findings continue to flare up in various areas of Ohio and other states, a generalized fear is wreaking havoc with people. People fear that any ash tree with dead branches and falling leaves is infested with EAB. For example, Jane Martin and Dave Dyke reported receiving numerous calls concerning leaf loss on ash trees. This is a good and bad thing! It's good that people are aware of EAB, and its potential for damaging ash. It's bad in that any ash tree problem can produce heart stopping panic.
Jane's callers were panicked about deformed ash leaves with dead areas which were falling from the tree right now. The problem was ASH ANTHRACNOSE. Dave reported receiving similar calls in Cincinnati, where the problem was both ash anthracnose and periodical cicada oviposition injury to the ash petioles.
Heightened awareness is a beautiful thing, but too much excitement can ultimately become annoying. So how can one keep on the cutting edge of awareness about EAB events? There is a great website for EAB that will help sort real concerns from excited events. The website can be found at ashalert.osu.edu/. Use this user-friendly and informative site as a reference point for clients to begin to sort out the possibilities when an ash tree is suspected of being infested. After going through this site, a client should be able to tell if the ash problem really is the EAB, or something else. This should lower the anxiety level and help keep everyone smiling. After all, no one likes to lose their ash!
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A PEEK IN THE MOIST CHAMBER
Here's a look at some of the other diseases noted and discussed by BYGL'ers and the CWEPPDC crew during the conference call:
*DUTCH ELM DISEASE: With the heat and first stresses of hot weather, many BYGL'ers mentioned seeing the telltale flagging and collapsing of branch terminals on American elm. Symptoms, such as leaf wilt, may appear on one main branch or scattered branches here and there throughout the tree. Leaves on infected branches turn yellow, then brown, and then drop off. Eventually the entire tree dies.
*APPLE SCAB: From Cincinnati to Cleveland, it appears to be a banner year for apple scab on crabapples. Joe Boggs thought it was a little early for defoliation to start from this fungus, but in a year with perfect weather conditions for fungal infection, leaf drop can indeed occur at this time of the year. However, it usually signifies infections of epidemic proportions. Erik Draper observed the beginning of early leaf drop on several extremely susceptible taxa in the Wooster crabapple plots. Jim Chatfield was overjoyed to see all of the apple scab and expressed his delight with "what more could anyone want than a real test to challenge the trees!"
* FIREBLIGHT: Randy Zondag reported seeing more strikes on ornamental pears this year than in past years. In crabapples at Wooster, the new strikes were just beginning to wilt and dry up this past week.
* DOTHISTROMA NEEDLECAST: Nancy Taylor reported receiving a sample of Dothistroma on Austrian pine. This fungal disease can be a fooler because the needle tips gradually die and turn brown but the base remains green. Infection is most common on older needles, but current season needles may also show symptoms. Typically, the disease is most severe in the lower portion of the tree. It can be confused with salt damage, or a number of other maladies on conifers.
* BACTERIAL LEAF SPOT: Erik reported observing symptoms of this disease on bell peppers. This disease is devastating problem in vegetable growing areas. It can be spread right down the row just by brushing wet leaves after touching an infected plant. It can also be spread over to tomatoes the same way, if hands are not washed, after working among infected pepper plants.
* ALTERNARIA LEAF SPOT: Erik also reported seeing this disease on watermelon transplants that were to be planted out to the field. The grower had them outside the greenhouse waiting for the ground to dry out so he could plant them. They were also under a slight nutrient deficiency stress due to the repeated rains falling this past week. The classic bulls-eye type of lesions were present, mainly on the older foliage.
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TURF TIPS
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BROWN PATCH REARS UGLY HEAD
Joe Boggs reported that recent high temperatures coupled with frequent thunderstorms have caused RHIZOCTONIA BROWN PATCH to appear on turf-type tall fescue in some lawns in southwest Ohio. All cool-season turfgrass species are susceptible to this disease; however, fescues, ryegrasses, and bentgrasses are particularly vulnerable. Brown patch can occasionally cause severe damage on close-cut turfgrass, requiring fungicidal applications to aid in recovery. On high-cut turfgrasses in home lawns, the disease may produce noticeable symptoms, but infected plants usually recover with time and improving environmental conditions.
This foliar fungal disease has been linked to two pathogens: Rhizoctonia solani and R. zeae. The two fungi sometimes work as a turf-tag-team with R. solani causing infections early in the season, when temperatures hover around 75 - 85F, and R. zeae taking its place later in the season when temperatures consistently rise above 90F. Both require abundant moisture.
Rhizoctonia brown patch can cause rounded, brown, or smoke-colored patches in close-cut turfgrass that may extend 1 - 2' in diameter. Occasionally, a purplish-gray border may appear around the affected patch of turfgrass, a symptom that is referred to as a "smoke ring." On high-cut turfgrass, such as in home lawns, the disease typically appears as small (6 - 10"), irregular-shaped patches of light-brown turfgrass. A close examination may reveal the following signs and symptoms: grayish-colored cobweb-like mycelia; green blades with irregular dark brown lesions along the leaf margins; blades that are purplish or grayish-green, and appear water soaked; and light-brown, to grayish-brown blades that appear dry and withered.
Here are a few tips for managing this disease in home lawns:
* Avoid excessive moisture. Do not make daily applications of water. Only water turfgrass as needed, and water thoroughly to allow deep penetration of the soil. Water during the early morning hours to permit turfgrass to dry throughout the day.
* Keep up with mowing, since frequent cuttings enhance drying conditions.
* Avoid excessive nitrogen. While nitrogen supports the recovery of affected turfgrass through the re-growth of blades, high nitrogen levels make turf plants more susceptible to this disease. Products used for early-summer fertilizer applications should be balanced formulations, and their nitrogen component should be at least a 50% slow-release form
* Core aerate during the spring and /or fall. Hollow-tined core aeration enhances water drainage, promotes root growth, and improves the overall health of the turf plants
* Over-seed with less susceptible cultivars during fall turfgrass rejuvenation.
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INDUSTRY INSIGHT
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FLEA BEETLE WARNING REINFORCED - BEWARE!
We reported in the May 27 issue of BYGL that Dave Dyke had responded to the somewhat anguished phone call from a greenhouse grower in the Cincinnati area. The grower was concerned about a few species of perennials in outdoor beds being virtually destroyed "overnight" by hordes of green beetles about 1/8 inch long. As reported, the culprit turned to be flea beetles. It was also reported that those beetles had definite preferences for certain plants ... OENOTHERA and LYTHRUM (plus some assorted weeds nearby). The plants were far apart from each other in the growing area. The leaves on the Oenothera were so badly chewed up that the 18 inch tall plants had to be cut back to a couple of inches.
Dave thereafter issued a warning via his "Cincinnati Floriculture" newsletter about the clear and present danger presented by the voracious little beetles. Guess what? Just a couple of days ago, while making his greenhouse rounds many miles from the site of his May 27 report, he again came across a grower who reported the virtual "overnight" destruction of 3 species of perennials. That grower made reference to reading the article about watching out for that possibility. Guess which perennials were attacked and virtually destroyed! Again, Oenothera and Lythrum, plus GUARA. Checking back with the greenhouse that originally reported the problem, Dave found that guara had also been attacked there. PERENNIAL FUSCHIA (Fuschia mangellonica) and CRAPE MYRTLE (Laegerstromia) also were attacked, but received relatively minor damage.
A couple of notes of interest:
*Oenothera, fuschia, and guara (along with EPILOBIUM) are all in the EVENING PRIMROSE family (Onagraceae).
*These beetles arrived seemingly out of nowhere by the thousands and really did destroy entire crops of certain species "overnight". Beware! Keep a very close eye on these plants!
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COMING ATTRACTIONS
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2004 OHIO PLANT HEALTH CARE WORKSHOP: ABIOTIC DISORDERS OF LANDSCAPE PLANTS
This must-not-miss 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.
Topics include diagnostics, salt injury, herbicide damage, winter injury, micronutrient deficiencies, mycorrhizae, and transplanting practices. Lectures by national experts will be integrated with hands-on laboratory sessions, and diagnostic walks. ISA continuing education credits (CEU) are offered for this program.
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.
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WOSU's GREEN SCENE
Join WOSU's News 820 AM host Tom Wiebell and his brilliant guest stars this Friday night from 6:30 to 8:00 pm on Green Scene, the weekly gardening and landscaping Q&A Show for Central Ohio. OSU Extension Entomologist, Dr. David Shetlar, and Horticulturalist/author, Deb Knapke, will demonstrate their informative wisdom and provide sage advice.
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BYGLOSOPHY
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"And tis my faith, that every flower enjoys the air it breathes." -- William Wordsworth
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