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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May 06, 2004
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This is the Fifth 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 April 04, 2004 conference included: Pam Bennett (Clark); Joe Boggs (Hamilton/South District); Jim Chatfield (North District/ Horticulture and Crop Science Department-HCS); Erik Draper (Geauga); Dave Dyke (Hamilton); Tim Malinich (Cuyahoga); Jane Martin (Franklin); Pam Sherratt (Agronomy); Joe Rimelspach (Plant Pathology); Dave Shetlar (Entomology); Amy Stone (Lucas); Nancy Taylor (Plant Pathology and C. Wayne Ellett Plant & Pest Diagnostic Clinic); and Curtis Young (Allen County).
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Additional factsheet information on any of these articles may be found
through the OSU Factsheet Database (http://plantfacts.ohio-state.edu/)
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WEATHER WATCH
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Pay attention now, we need to remember that it is still just barely May! The eager gardeners who planted tender plants were in a bind when temperatures dipped down across much of the state. Record lows were recorded early this week in Toledo when the thermostat bottomed out at 27F. Geauga County encountered 25F temperatures and a heavy frost. The Cincinnati area experienced frost pockets on both May 2 and May 3. Depending upon location and the plants stage of development, BYGLers reported seeing some frost injury on plants across the board.
Weather data from the Piketon Weather Station included the following highlights Mays official recorded precipitation has been 0.72" thus far; and the year-to-date precipitation total has been 12.06", compared to the average precipitation of 17.27". Joe Boggs mentioned the following weather information in his BYGL report from Cincinnati/Northern Kentucky International Airport. The month of May has brought 1.05" of rain, compared to the average of 0.42". That is + 0.63" for the month thus far. This area has received 14.32" of precipitation for the year, compared to 13.95". Joe Boggs also mentioned that some areas in the greater Cincinnati did receive heavy rains over the past weekend, with some locations recording 2 3".
Jane Martin reported that the Columbus area has also been under some frost warnings and some foliage has been nipped by Mother Nature. Aprils precipitation for the central portion of the state was 3.96" total for month, which is +.71". Mays rainfall amount has been 1.25", which is +.89". And looking at the areas year-to-date total, Columbus is +4.39", with total precipitation in 2004 thus far is 15.58".
Toledo is still lagging behind in the weather race. Year-to-date precipitation total is nearly 4.5" below average. Rainfall amounts in May have totaled 0.79".
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HORT SHORTS
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PLANT PHENOLOGY
Dave Dyke reported the following development in the southern part of Ohio: 'Winter King' green hawthorn (Crataegus viridis 'Winter King'), European cranberrybush viburnum (Viburnum opulus), royal paulownia (Paulownia tomentosa), and a few azaleas (Rhododendron spp.) were in full bloom. Black locusts (Robinia pseudoacacia) and amur honeysuckles (Lonicera maackii ) were just beginning to show color and dogwoods (Cornus florida) were at petal fall.
In the central part of the state in full bloom are wisteria (Wisteria floribunda), sweetshrub (Calycanthus floridus), red buckeye (Aesculus pavia), Vanhoutte spirea (Spiraea vanhouttei), fothergilla (Fothergilla gardenii), common lilac (Syringa vulgaris), fiveleaf akebia (Akebia quinata), and various oak (Quercus spp.) species. Dogwoods and redbuds (Cercis canadensis) are at petal fall and doublefile viburnums (Viburnum plicatum var. tomentosum) are just beginning to show color.
Amy Stone reported that Japanese kerria (Kerria japonica), dogwood, and crabapples (Malus spp.) are in full bloom in the Toledo area and common lilacs are just beginning to show color.
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GROWING DEGREE DAYS
The range of Growing Degree Day (GDD) accumulations in Ohio from north to south is 197 to 384. The following is the report of GDD for several locations around Ohio as of May 5, 2004.
As of Wednesday morning, GDD accumulations were: Painesville, 197; Cleveland, 209; Toledo, 248; Youngstown, 234; Lima, 245; Wooster, 246; Coshocton, 242; Columbus, 268; Springfield, 296; Dayton, 322; Cincinnati, 372; Ironton, 384; and Portsmouth, 384.
GDD is a measure of the daily maximum and minimum temperature and directly relates to growth and development of plants and insects. The GDD of any zip code location in Ohio is estimated using the GDD of ten OARDC weather stations and available on the web at: http://www.oardc.ohio-state.edu/gdd/
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: eastern redbud, first bloom, 191; gypsy moth, egg hatch, 192; Koreanspice viburnum, full bloom, 205; azalea lace bug, egg hatch, 206; spring snow crabapple, full bloom, 209; common flowering quince, full bloom, 214; birch leafminer, adult emergence, 215; coral burst crabapple, first bloom, 217; elm leafminer, adult emergence, 219; common chokecherry, full bloom, 221; alder leafminer, adult emergence, 224; honeylocust plant bug, egg hatch, 230; common lilac, first bloom, 234; Ohio buckeye, first bloom, 245; common horse chestnut, first bloom, 251; hawthorn lace bug, adult emergence, 253; hawthorn leafminer, adult emergence, 260; flowering dogwood, first bloom, 263; red buckeye, first bloom, 265; blackhaw viburnum, first bloom, 269; imported willow leaf beetle, adult emergence, 274; sargent crabapple, full bloom, 298; red horsechestnut, first bloom, 304; pine needle scale, egg hatch - 1st generation, 305; cooley spruce gall adelgid, egg hatch, 308; eastern spruce gall adelgid, egg hatch, 308; common lilac, full bloom, 315; winter king hawthorn, first bloom, 328; lilac borer, adult emergence, 330; Ohio buckeye, full bloom, 374; holly leafminer, adult emergence, 375; Vanhoutte spirea, full bloom, 406; and euonymus scale (first generation), egg hatch, 406.
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BLOOM OR BUST
One problem BYGLers pondered this week was the case of the barren tree. The question: What was the reason a particular tree or shrub may fail to bloom? The answer is often complex and the true reason usually requires a bit more investigative work. However, a short list of possibilities to investigate would include:
*Juvenility-In some cases the tree or shrub might just be too young to produce flowers. Some plants must reach a state of maturity to produce flowers and fruit. Some areas of a tree or shrub can retain these juvenile characteristics leaving the original, juvenile portion of the plant without flowers while newer, physiologically older tissues, produce blooms.
*Alternate Bearing-Production of flowers and fruit is an expensive investment for a plant. Without the availability of charge cards or a home equity line of credit, the plant relies on its own savings account to accumulate the physiological currency needed to enter a reproductive cycle. Most plants will be able to save enough on a yearly basis. However, some will need two years to build their account up to the point of being able to flower. Poor growing conditions lengthen the time. Also, some plants will spend so many resources in one year they may take a year off to replenish their savings account.
*Insects and diseases can inhibit flowering by causing decline in the entire tree or portion thereof. Check down the trunk, looking for signs of borer or canker that can be limiting the health of the plant and thus its ability to reproduce.
*Improper pruning can lead to loss of flowers. Some plants produce buds on old wood, while others flower on the current seasons growth (see BYGL 2004-3 Pruning Hydrangeas). You need to know the blooming cycle of the tree or shrub to determine the proper time for pruning or you might be cutting the buds right off the plant.
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CICADAS AND QUACKERS
A new insect recipe? Not exactly - more like a recipe for a mystery. While on our usual casual and informative BYGLive! stroll through Spring Grove Cemetery and Arboretum in Cincinnati this past Monday, an unusual and mysterious phenomenon was observed. Hundreds of round or oval-shaped holes about 1" to 1.5" in diameter and 3" deep adorned a very wet area (2" - 3" of rain had fallen within the last 2 days) under some trees. The size of the holes and lack of soil mounded around them indicated that they were not PERIODICAL CICADA emergence holes, although there were many of those in the area. The holes were far too neat and small to be the work of racoons digging for tasty periodical cicada nymphs or other subterranean snacks. A mystery indeed!
That is, until a trio of MALLARD DUCKS waddled by ... and we do mean waddled! Observation of those waddling wanderers - they were far from a pond or other water - revealed them drilling their bills into the soil with a twisting motion until their eyeballs were barely visible above the soil line. They obviously were enjoying the once in a lifetime (for a duck) opportunity to fatten up on cicada nymphs - and leaving the tell-tale holes as evidence of their good fortune. Perhaps cicadas and quackers actually is an excellent recipe ... for getting rid of pesky insects, fattening up a duck for dinner, or aerating your lawn!
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BUG BYTES
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CINCINNATI BYGLIVE!- BUG BITS
Participants at this weeks BYGLive! Diagnostic Walk-About at Spring Grove Cemetery and Arboretum in Cincinnati on Monday, May 3, observed the following insects:
* In the first BYGL this season (4/8/2004), we reported that participants at the April 5th Cincinnati BYGLive! observed numerous small EASTERN TENT CATERPILLAR (Malacosoma americanum) nests. Participants at this months BYGLive! took a look at some of the same nests and found that larval development is almost complete, with late instar caterpillars leaving large nests in search of food after plundering their hosts.
This wanderlust behavior may present some caterpillar identification challenges since observers may not connect the crawling caterpillars with their abandoned tents found in the branch forks of trees. Also, the caterpillars may be found on plants that are not listed among its preferred hosts. When populations are high, marauding hordes may "suddenly appear" on surrounding vegetation and cause damage to unusual hosts. But more often than not, they fail to find usable plant material, and simply wander until pupation. Only one generation is known to occur per year.
* Colonies of middle-to-late instar EUROPEAN PINE SAWFLY (Neodiprion sertifer) larvae were observed on mugo pine, with damage becoming very evident. Entire needles from last years growth were being consumed. The grayish-green larvae are caterpillar-like in appearance, and have bulbous, shiny-black head capsules. Although the larvae now sport faint grayish-white longitudinal stripes, they remain difficult to detect. Most insecticides labeled for use on pines will control this sawfly. However, several BYGLive! participants applied the alternative (and more entertaining) control option of knocking the colonies onto the ground...and doing the "sawfly two-step dance."
* Impressive numbers of BOXWOOD LEAFMINER (Monarthropalpus flavus) adults were observed cavorting amongst the leaves of their namesake. With the air temperature hovering in the mid-50's, very few of these midge flies were seen flying. To get a closer look at these tiny flies, several enterprising BYGLive! participants employed the "beating tray" plant pest disclosure method, normally reserved for spruce spider mites, to dislodge the torpid flies. Boxwood leafminer adults superficially resemble miniature mosquitoes; however, they have bright orange abdomens.
Larval control options were discussed since participants noted that localized leafminer populations in southwest Ohio appear to be high this year, and damage is becoming very evident. Control options include an application of imidacloprid (e.g. Merit) made as a soil drench in late fall, which will kill overwintering larvae. This strategy has proven to be very effective, and will also control BOXWOOD PSYLLIDS (Psylla buxi). A more traditional approach involves applying acephate (e.g. Orthene) as a foliar systemic spray once egg laying is completed in the spring. Timing of the application is critical, and requires close monitoring of leafminer activity.
* The tannish-white horns of the appropriately named HORNED OAK GALL were found protruding through the surface of these woody grayish-green twig galls. The horns made some galls look like Liliputian spiked maces. The galls were induced by a tiny wasp (Callirhytis cornigera) that belongs to the family, Cynipidae. The twig galls require almost 3 years to mature. Their maturation is signaled by the emergence of the horns, which had housed the immature wasps within the galls. Thanks to the sharp eyes of Larry Hanks (Pampered Properties, Inc., Lexington, KY), BYGLive! participants were also treated to the second stage in the complicated life cycle of this gall wasp: the blister galls which form on the main veins of the host's leaves. The wasps that are released from the horns crawl to newly expanding leaves and initiate leaf galls.
 
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TERMITES MUNCHING ON MULCH
Curtis Young received a bag full (1 gallon Ziploc) filled with composted hardwood mulch and about one hundred creamy white insects scurrying over and through the mulch . . . TERMITES!!! A landscaping company had been called by a customer about these little critters all through the mulch that had been recently spread on beds around their home. The landscaping company was not 100% certain as to the proper ID of the insects, but for good customer relations, they did scrap up all of the mulch and removed it from the site.
Most BYGLers were under the assumption that termites would not be a problem if they had been transported from another site and spread with the mulch. However, Dave Shetlar re-educated us with up to date information about termites and mulch. He too had believed the above assumption until our Structural Pest Extension Entomologist, Dr. Susan Jones helped change his mind. Susan's specialty is termites. She has informed us that under certain conditions and circumstances, some immature male and female termites mature sexually and become neotenic reproductives, termites that take over the role of the primary kings and queens. Thus, satellite feeding colonies that get separated from their main subterranean colonies can survive and continue to grow after being transported to new locations. The site from which the sample was collected could have termite problems. When asked about mulch, Susan's recommendation was not to use it around homes or at the very least, not to use it up against the foundation and limit its thickness.
Mulch can become infested under a number of conditions, some not as obvious as others. Storing bulk mulch on soil will increase the chances that it could become infested but mulch does not need to be in direct contact with soil to become infested. Even mulch stored on an asphalt surface can be infested if there are cracks in the hard top down to the soil. Bagged mulch has also been found to be infested with termites. Thus, transporting bagged mulch could also spread termites from one location to another.
One final note on the situation from Lima, Ohio, the sample brought to Curtis had many of these neotenic reproductives included. Because we don't know where the termites originated, it is highly recommended that the homeowner have their structure professionally inspected. This will help determine if the termites were already on the site and had been drawn to the surface by the new food resource.
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DISEASE DIGEST
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SYCAMORE ANTHRACNOSE
Sycamore anthracnose (Apiognomonia veneta) was observed at the Cincinnati BYGLive! at Spring Grove this past Monday. Blighting of young leaves and tell-tale discoloration along major leaf veins was noted. Not surprising, because of the moist, cool conditions during sycamore leaf expansion in that area over the past few weeks. Sycamore anthracnose is a common disease of American sycamore and to a lesser extent London planetree, with susceptibility of London planetree varying considerably with seed source. The fungus overwinters on twig tissue on the tree with spores splashing to new buds, shoots and leaves in the spring, and as noted disease is enhanced by cool, wet conditions during shoot and leaf development. Considerable defoliation, sometimes with complete leaf loss, occurs on many trees by late spring in some years. Trees typically re-leaf by early to mid-summer and are less susceptible to continued infections because of warmer, drier conditions.
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VOLUTELLA LEAF BLIGHT AND STEM CANKER OF PACHYSANDRA
This common disease is showing its two faces again this spring, with samples coming in to the PPDC and with numerous sightings by our first responders for BYGL in the phenologically advanced southern Ohio area. Symptoms include a zonate spotting on the foliage and blackened blighting of the stems. If you want to check to see if observed stem discoloration and wilting on pachysandra are caused by this fungus (Volutella pachysandricola), put some samples in a plastic bag and wait for a few days. Orangish-pick spore masses of the fungus develop in the cankered areas. Fungicide applications can help if you make multiple applications during periods of active growth of the pachysandra (much of the growing season, unfortunately). But mowing the planting down to an inch or two and removing all diseased and mowed plant tissue and avoiding overhead irrigation is often the more practical solution. This is especially true in dense, older pachysandra plantings for which mowing is sometimes a useful renovation technique where this disease is rampant.
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CONIFER DISEASE UPDATE
As a clarification to last weeks BYGL, Nancy Taylor, director of the Ohio State University C. Wayne Ellett Plant and Pest Diagnostic Clinic, reminds sample senders that when you send pine and spruce samples to the clinic to check for needle diseases, please keep a couple of sampling pointers in mind. You should include not only branches with the discolored needles attached, but also a bag of fallen needles collected from branch crotches (rather than from the ground). This is because many needle diseases involve fungal infections of last seasons needles. Examples include Rhizosphaera on spruce, Dothistroma on Austrian pine, and Lophodermium and Cycloneusma on Scots pine. Needles just starting to show symptoms are often quite difficult or impossible to properly diagnose. Why does all this matter - isn't a needle disease by any other name just a needle disease? No- control recommendations may differ significantly. For example, on Scots pine, protectant fungicides for Cycloneusma needlecast should be applied to prevent infections in spring, but for Lophodermium needlecast, fungicides should be applied to prevent infections in late summer. So, the correct diagnosis of which disease is on your pines is critical and to do this properly, collect older, fallen needles that have not yet dropped to the ground.
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MOIST CHAMBER
Additional diseases noted this past week included WITCHES BROOMS ON HACKBERRY, with clusters of short shoots of varying ages noted on hackberries at Spring Grove in Cincinnati. This malady is said to be due to the interaction of an eriophyid mite (Eriophyes celtis) and a powdery mildew fungus (Sphaerotheca phytoptophila). Both organisms are typically present in the witches brooms, but they may simply be torturing hackberry independently, with the mites attacking buds and causing the initial brooming and the powdery mildew fungus invading the newly altered habitat. Other diseases noted this week include FROGEYE LEAFSPOT OF CRABAPPLE (Botryosphaeria obtusa), and from the PPDC, BLACK ROOT ROT OF PANSY (Thielaviopsis basicola) occurring on pansies from greenhouse samples, and Phomopsis tip blight of juniper (Phomopsis juniperovora).
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TURF TIPS
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SPORTS FIELD RENOVATION- NOW IS THE TIME!
We receive dozens of calls in the weeks leading up to the fall football & soccer season from schools or sports clubs that have poor playing surfaces and want to remedy them before the season gets underway. In many instances, there is not ample time to do the work.
The aim is to enter the playing season with 100% desirable grass species. Fields with 100% grass cover will provide compaction resistance, player traction & friction, and a shock absorbency value. The best time of the year to establish a healthy stand of grass that will be mature enough to withstand play is NOW. The mild temperatures and amount of rainfall offer ideal growing conditions for establishing seed or sod before the hot, stressful summer months.
Once the soil has thawed, low or bare areas on the field need to be filled with a good quality topsoil, lightly tamped or rolled to reduce settling, and leveled. Once those bare areas are filled, fields need to be core aerified, fertilized, and seeded. This whole process does not have to cost a lot of money if there are students or volunteers willing to do the work.
For example, here is a summary of how much it can cost to renovate a soccer field:
2 cubic yards (approx. 3 tons) good quality topsoil for 2 goal mouths and bare spots on the field = $50.00
1 50lb bag perennial ryegrass seed = $60.00 (perennial ryegrass seed costs approx. $1.15/lb, Kentucky bluegrass seed costs approx. $2.50/lb., tall fescue costs approx. $0.75/lb.)
Starter Fertilizer applied at 1lb Nitrogen/1000 sq.ft would require 9 bags of 18-24-6 across a full sized soccer field (including edges & surrounds). At $15.00/bag = $135.00. Starter fertilizer ideally needs to be applied every 10-14 days to the newly seeded areas only, until the seed has established.
Aeration can cost anywhere between $300 to $600 per field, depending upon the contractor & equipment. Many contractors will lower the price if there are several fields that need aerating.
TOTAL COST = $545-845 per field
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WHEN GRASS NEEDS TO BE MOWED - MOW IT!!
A number of people think that if grass is wet, it should not be mowed. It is correct that mowing will be easier and more effectively done when grass is dry. However, mowing should not be delayed for long periods of time just because the grass is wet. Grass should be mowed frequently enough so that no more than 1/3 of the leaf blade length is removed during any one mowing. This can be a great challenge in the spring when grass is growing very rapidly and regular rains reduce the number of opportunities one has to get out and mow. Thus, there will be times when grass needs to be mowed wet.
Mowing wet grass will present problems. These problems include the following:
1) Wet grass is more difficult to cut. The grass may be matted down and it might not stand back up well enough to be cut by the blade.
2) Wet grass has a tendency to clog under rotary mowers causing one to stop frequently to clear clogs. These first two problems may require one to make a second pass in a different direction to complete the cutting and reduce clumps of clippings. Ultimately, the excess clippings may require manual removal.
3) If the grass is wet, the soil under the grass may be wet as well. Rutting of the soil may result from mowing when it is too wet. Some of this problem is alleviated by tire type on the mower. Larger mowers are usually equipped with floater tires which do not sink into the soil. Mud stained wheel tracks may occur but these are usually temporary. Smaller mowers with skinny hard tires may cause more rutting than the bigger tractors. Rutting can be extreme in areas where the mowing pattern is not altered. A mower that sinks unevenly or suddenly can produce uneven cuts and scalping. One needs to use common sense in these situations. There are limits to when conditions are too extreme.
4) Last, but by far not least, are the safety issues. The greatest concern for mowing wet grass is that it is very slippery. This is an issue for all sizes of mowers. Losing one's footing even with a push mower could result in great personal injury. Larger tractors could lose traction on slopes resulting in uncontrolled descents down the slope and/or rollovers.
Another safety issue with mowing wet grass as mentioned before is its tendency to clump under and clog mower blades and discharge openings. When dealing with clogs, all mowers should be turned off completely before reaching into reels or under mower decks. Extreme caution should be exercised even when mowers are shut down.
In summary, safety should always be our first concern and proper mowing should be second.
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RED THREAD RUNNING THROUGH TURF
Joe Rimmelspach reported that red thread has been observed in turf for the first time this season - from central to southern Ohio. This disease is rather easy to diagnose because of the pink to light reddish color on top of the grass. If you look closely, you will find reddish thread-like structures on the tips of infected blades. These are strands of mycelium that arises from infected leaf blades and sheaths.
The red thread fungus, Corticium fuciforme, survives over the winter in diseased leaf tissues or debris as mycelium and as stroma. It becomes active during extended periods of cool, wet weather and in temperatures between 60 to 75 degrees. It is severe in slow growing turf due to low fertility and/or nutrient deficiency, or from drought stress. In affected areas, turf looks blighted and discolored and appears to have a roughly circular pattern. Some live shoots can emerge from infected areas. Wind, foot traffic, mower, and other equipment used in the lawn can move the fungus from one infection site to another. The disease usually ceases when temperatures rise and conditions favorable to good turf growth resumes. However, lawns should be mowed at least once a week to remove infected leaf blades. Infrequent but deep watering will help, specially during daytime, to prevent drought stress as well as decrease leaf wetness. For further information on this disease refer to Rutgers Cooperative Extension Factsheet, "Plant Disease Control, An Integrated Approach to Red Thread and Pink Patch Disease Control in Landscape Turf" (http://www.rce.rutgers.edu/pubs/pdfs/fs798.pdf).
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INDUSTRY INSIGHT
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FUNGICIDE "FAILURES"- PART II
In last week's BYGL, we discussed that one of the reasons that people sometimes inaccurately rail against fungicide "failure" is that they treat with a fungicide when the problem was really caused by insects or mites. Lets continue this week by looking at how treatment failures can occur even if the problem is accurately diagnosed as a disease.
Faulty Diagnosis of the Type of Disease. Even when a problem is correctly diagnosed as an infectious disease, fungicides may not be even part of the answer. Remember that there are different types of plant pathogens, from fungi to bacteria, from viruses to nematodes. For example, a common term used for many diseases is "blight". Phomopsis blight of juniper, Sphaeropsis tip blight of pine, Volutella leaf blight of pachysandra - all are fungal diseases and fungicides may play a role in control of these diseases. However, fireblight of pyracantha, crabapple and Callery pear, and bacterial blight of lilac, are caused by bacteria and so different types of pesticides must be used for control, rather than simply using a fungicide, though certain copper products are helpful in control of some bacterial and fungal diseases. Simply thinking that if it is a blight, then a fungicide should help control it, is not good enough.
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BLACK ROOT ROT ON PANSIES
Nancy Taylor reported receiving pansies from a greenhouse that were subsequently diagnosed as being infected with black root rot. She also stated that a check of the soil revealed a pH of 6.0.
Black root rot is caused by the fungus, Thielaviopsis basicola. This fungus is very common and widespread. It has a wide host range and affects many other hosts besides greenhouse floral crops. Almost any factor that stresses the host plant can lead to parasitic development of this disease. Crops grown under conditions that are too cool or too warm are often subject to it. Nutritional imbalances are also frequently associated with disease development. Excess of ammonia nitrogen appears to be particularly troublesome for pansy growers dealing with black root rot. Growing media with a pH above 5.5-6.0 are also conducive to black root rot development. The good news is that correcting plant stress can allow infested plants to "outgrow" the disease and eventually recover.
Growers in areas with high alkalinity levels, such southwestern and northeastern Ohio, often have difficulty maintaining a pH low enough to discourage black root rot development. When using soiless media, especially (because it has very little buffering capacity), it is imperative that the pH is checked frequently with a quality pH meter. Steps must be taken through acid injection or a fertilizer regime to maintain a pH below 6.0 (ideally at 5.5 or lower) to assist in the prevention of black root rot on pansies. Refer to OSU Factsheet, HYG-3066-96, "Black Root Rot of Greenhouse Floral Crops" for further information on this disease.
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COMING ATTRACTIONS
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DIAGNOSTIC WALKABOUTS
Will again be offered in the greater Cleveland area this summer. Charles Behnke and Tim Malinich, horticulture agents with Ohio State University Extension will take a critical look at landscape and turf problems during the early morning walkabouts. The walks will be offered three times during the season, June 3, July 1, and August 5. Recertification credit available for 8 and 6A. Call 216-397-6023 to request a registration flyer with more information.
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WOSU's GREEN SCENE
Green Scene steps up to the mound this week, once again dodging its weekly line drive from the OSU baseball team vying for air time. WOSU Am 820's Green Scene host Tom Wiebell will be joined by Joe Boggs and an intrepid co-hort TBA this Friday night from 6:30 to 8:00 pm. So, call in your garden and landscaping questions at 614-292-8513, or simply listen in Friday night.
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