Pam Bennett, Barb Bloetscher, Joe Boggs, Jim Chatfield, Erik Draper, Dave Dyke, Dave Goerig, Tim Malinich, Jane Martin, Hannah Mathers, Pam Sherratt, Amy Stone, and Curtis Young
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July 14, 2005
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This is the Fifthteenth 2005 edition of the Buckeye Yard and Garden Line (BYGL).
BYGL is developed from a Tuesday morning conference call of Extension
agents, specialists and other contributors in Ohio.
BYGL is also made available on the Internet from the Ohio State University
Horticulture and Crop Science (HCS) in Virtual Perspective website
(http://bygl.osu.edu). Additional fact sheet information on any of
these articles may be found through the OSU fact sheet database (http://plantfacts.osu.edu).
BYGL is a service of OSU Extension and is aided by major support
from the Ohio Nursery and Landscape Association (ONLA), with additional
funding from the Ohio Chapter of the International Society of Arboriculture
(ISA) to the OSU Extension Nursery Landscape, and Turf Team (ENLTT).
Participants in the July 12, 2005 conference included: : Barb Bloetscher (C. Wayne Ellett Plant and Pest Diagnostic Clinic); Joe Boggs (Hamilton/Piketon); Jim Chatfield (Center at Wooster/HCS); Erik Draper (Geauga); Amy Fulcher (University of Kentucky, Department of Horticulture); Dave Goerig (Mahoning); Tim Malinich (Cuyahoga); Dave Shetlar (Entomology); Amy Stone (Lucas); Nancy Taylor (CWEPPDC); Curtis Young (Allen); and Randy Zondag (Lake)..
Additional factsheet information on any of these articles may be found
through the OSU Factsheet Database (http://plantfacts.ohio-state.edu/)
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WEATHER WATCH
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The dog-days of summer continue on. Temperatures remain high and rain is very spotty. Turf across much of the state is brown if it has not been irrigated or not located in one of the lucky places that has received some of the wet stuff in recent weeks.
Here is the weather summaries from selected OARDC weather stations across the buckeye state. The information is a summary of data collected from July 1 July 13.
| Weather Station |
Region of Ohio |
Ave. High Temp F | Ave. Low Temp F | Ave. Temp F | Normal Ave. Temp F | Total Precip " | Normal Precip " | | Perry |
NE |
81.6 |
61.5 |
N/A | N/A |
1.08 |
N/A | | Hoytville |
NW |
86.7 |
58.7 |
72.6 |
72.6 |
1.83 |
1.52 |
| Columbus |
Central |
86.0 |
63.8 |
75.0 |
73.7 |
2.17 |
2.03 |
| Miami |
SW |
85.6 |
63.7 |
74.9 |
73.7 |
0.30 |
1.77 |
| Jackson |
South |
87.1 |
62.8 |
74.6 |
72.8 |
0.51 |
2.08 |
For additional information, or to see the locations of all of the OARDC weather stations in Ohio, check out the website at http://www.oardc.ohio-state.edu/centernet/weather.htm
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HORT SHORTS
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GDD (GROWING DEGREE DAYS)
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/
The range of GDD accumulations in Ohio from north to south is 1,263 to 1,702. Following is a report of GDD for several locations around Ohio as of July 13, 2005: Painesville, 1,263; Cleveland, 1,271; Toledo, 1,420; Youngstown, 1,323; Lima, 1,447; Wooster, 1,415; Coshocton, 1,444; Columbus, 1,493; Springfield, 1,532; Dayton, 1,607; Cincinnati, 1,702; Ironton, 1,635; and Portsmouth, 1,637.
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.
Panicled goldenraintree, full bloom, 1251; rose-of-Sharon, first bloom, 1347; pine needle scale egg hatch, 1349; euonymus scale, egg hatch - 2nd generation, 1,923; magnolia scale, egg hatch, 1938; and banded ash clearwing borer, adult emergence, 2195.
This will be the last reporting of GDD for this year. Most locations for which GDD was being reported have accumulated enough GDDs to have exceeded most of the pests and flowering plants that are included in the phenology table. Reporting of GDD will be return in next years BYGL. Thanks for following along!
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BUG BYTES
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THE ANNUAL GALLING OF OAKS
Cincinnati BYGLive! participants were treated to a wide variety of plant galls, no doubt due to Joe Boggs' intemperate (unhealthy?) fascination with them! The growth of the galls are induced and directed by a "gall-maker" which may be an insect, mite, nematode, or a number of other organisms. Remember that true plant galls are plant structures that are unique to the host plant, and in most cases the structures are specific to the gall-maker. Indeed, the galls are so specific that the gall-maker may be identified to species just by the gall, without benefit of actually observing the gall-maker. In the vast majority of cases, galls are not damaging to the overall health of the host plant.
Oaks are known to host almost 800 different types of galls. Only two stand out as being consistently destructive to their host; namely the HORNED OAK GALL and OAK GOUTY GALL. Both of these stem galls arise from twigs and branches, and are caused by tiny wasps that belong to the family Cynipidae. These galls harm oaks by incorporating vascular tissue within their structure. The tissue may become so disorganized that vascular flow of water and nutrients are disrupted causing branches and twigs beyond the gall to die.
BYGLive! participants were treated to observing saucer-shaped OAK SPANGLE GALLS that were produced by a tiny midge fly (Cecidomyia poculum) on the underside of leaves of a swamp white oak. As their name implies, the flattened oak spangle galls resemble the spangles sown onto costumes. They form on the underside of the leaves and are attached in the center by a tiny, post-like structure. The overall affect makes the leaves look like they are sprouting octopus suction cups! Immature galls are white to whitish-green. Mature galls are approximately 3/16" in diameter and as they mature, the galls turn pinkish-white and eventually purplish-brown. Mature galls detach from the tree carrying the fly pupae to the ground where they overwinter.
Other oak galls that are being reported by Ohio Extension offices include OAK APPLE GALLS, caused by another Cynipid wasp (Amphibolips confluenta), as well as OAK POTATO GALLS, which are induced by midge flies. The aptly named oak apple galls are around 1/ 2" to 2" in diameter. They arise from the leaf midribs or petioles of red, black, and scarlet oaks. Earlier in the spring, the immature galls were light green in color, and filled with a spongy greenish-white material that is not unlike the flesh of an apple. The galls mature rapidly, becoming light brown in color, and their surfaces become thin, papery shells. Opening the mature galls will reveal a mass of tan fibers radiating from a central seed-like structure that contains a single maturing wasp.
The name "oak potato gall" is actually given to a number of leaf galls produced by midge flies. However, the most common midge gall-maker that induces these interesting galls is Macrodiplasis majalis. These galls arise from leaf veins on the upper leaf surface, and they resemble tiny rows of potatoes. Their surfaces are covered in a fine netting, and their color is at first green, then tannish-brown, and finally bright red. Again, these galls cause no harm to their hosts. Their occurrence represents a fascinating host-parasite relationship between the gall-maker and their oak-hosts.
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GALLS AD NAUSEAM!
The handiwork of several Eriophyid mite gall-makers were reported by BYGLers this week. Although often spectacular in appearance, none are considered harmful to their host plants. These include: the flat, patch-like, yellowish-gold BEECH ERINEUM GALLS on the upper leaf surface of American beech caused by the eriophyid mite Acalitus fagerinea, and the similar looking, but silvery colored erineum galls on the lower leaf surface of silver maple produced by Eriophyes modestus. The erineum patches on silver maple eventually turn a bright crimson red, and are very noticeable from the ground.
Some of the most dramatic galls currently being observed in Ohio involve reproductive structures of the host plant. The gnarly, green, witches broom-like flower galls produced by the eriophyid Eriophyes fraxinivorus are causing flowers of ash trees to resemble broccoli. Localized populations in Ohio appear to be high this year, with some ash trees being heavily galled. The similar looking catkin galls produced by Aculops tetanothrix are also arising on willow, although this gall is not very common.
Dave Shetlar reported that the handiwork of another Eriophyid mite that affects plant reproductive structures is now appearing on coneflowers. The mites live inside the opening flower buds and suck nutrients from the base of the flowers. As a result, both the disk flowers (the dark center) and the ray flowers (elongated purple petals) can become elongated, rising above the flowers, and covering the flower head with rosette-like stunted, misshapen flower parts. Little is known about this mite, including the scientific name this is a yet unidentified Eriophyid. Dave recommended cutting plants to the ground in the fall, and destroying the plant tissue (e.g. contributing the infested tissue to a landfill!). Plant debris should also be raked up and included in the landfill contribution.
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MIMOSA WEBWORM
Jim Chatfield reported that damage by mimosa webworm (Homadaula anisocentra) on honeylocust is becoming evident in central Ohio. When asked just how noticeable the damage was, Jim responded that he was making his observation, and reporting via cell-phone, while traveling down I-71! Caterpillars of this moth are capable of skeletonizing honeylocusts, although the full extent of their damage typically does not become apparent until later in the season.
Larvae of this moth feed gregariously within webs spun over the foliage. They feed as skeletonizers and their damage causes leaves to turn orangish-brown and appear fire-scorched. It is these clusters of "torched" leaves, rather than the actual webbing, that usually draws attention to an infestation.
There are two to three generations per season in Ohio, and they typically overlap so that larvae may be present anytime from June into September. Also, female moths often deposit their eggs on nests from which they developed, so nests continue to expand and become more dense with silk and spent leaves from one generation to the next. Consequently, damage by this moth becomes more extensive and apparent with each succeeding generation.
Once nests become large and tightly woven, control applications usually fail to penetrate the thick webbing. The best time to control the caterpillars is earlier in the season, when nests are small and consist of loosely woven silk. Although it may be getting too late to control this webworm this season, it is not too late to get ready for next season. Landscape managers should note which trees are heavily defoliated so they can monitor those trees next season, when something can be done. Effective early season materials include the naturally occurring bacterium, Bacillus thuringiensis (Bt), as well as other insecticides listed in OSU Extension Bulletin 504, "Insect and Mite Control on Woody Ornamentals and Herbaceous Perennials" available at the following web address: http://ohioline.osu.edu/b504/index.html
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PLANTHOPPER UPDATE
Last week (BYGL 2005-14, 07/07/05), we reported that BYGLers were observing fleecy PLANTHOPPER nymphs covering the lower stems of herbaceous perennials and low-growing woody ornamentals. This week, Joe Boggs reported that Cincinnati BYGLive! participants observed planthopper colonies several feet off the ground on the underside of European hornbeam and amur maple leaves. As indicated in last weeks BYGL, the nymphs of several planthopper species cloak themselves in a dense tangle of waxy, white "fluff."
The BYGLive! participants noted that the planthopper colonies strongly resembled woolly aphids, and without a close examination, the two types of insects could be easily mistaken. Adding to the diagnostic challenge, planthoppers and woolly aphids belong to the same insect order (Homoptera), and both are sucking insects. Both produce copious quantities of sticky honeydew, thus both may contribute to the occurrence of black sooty molds which colonize the sugary honeydew. Of course, planthoppers ... hop. Aphids just mosey around.
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SEEING SPOTS BEFORE YOUR EYES?
Two spotted spider mites have become prevalent, due to the warm, humid weather and lack of rainfall. The C. Wayne Ellett Plant and Pest Diagnostic Clinic received a muskmelon last week which was crawling with spider mites. Although leaves of trees and shrubs will pale and develop chlorotic specks as the spider mites suck nutrients from the veins, muskmelon leaves have a more severe reaction and will become pale yellow to white interveinally.
Fortunately, several products are available to control vegetables including Acromite, Avermectin, dimethoate, or Capture. A new product produced by Bayer which is available for fruits and vegetables is Oberon (spiromesifen) which kills all stages of spider mites, especially the larvae.
Burning bush (Euonymus elatus), as well as many other shrubs and trees have undergone serious infestations in landscapes and nurseries, to the point that the leaves are already showing fall coloration. In some cases, these outbreaks are due to insecticidal and miticidal sprays which have killed the predatory mites. Predatory mites take longer to recuperate from treatments than the pest species, which can "bounce back" and return to their host long before the predatory mites can recover to control the pest species. For this reason, entomologists suggest that horticultural oils and insecticidal soaps be alternated with the miticides to protect the predatory mite species.
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WATCH YOUR TAXUS!
Randy Zondag reminded nurserymen to scout their plants for scale and mealybugs. The combination of hot weather and scant rainfall has caused a great number of plants to become stressed at the same time that soft scales have reached peak populations.
The Taxus mealybug (Dysmicoccus wistariea) can be detected by inspecting Taxus species for sparse needles and dark, sticky honeydew caked on the needles. The white, fleecy female mealybugs bear live young in early summer, and normally have two generations a year. If populations of this pest are not controlled, taxus mealybugs as well as many scales on yews can cause needle drop and poor growth. Fortunately, with the new insecticides available, these sucking pests can be controlled systemically, as well as with the more conventional contact insecticides such as soaps, horticultural oils, permethrin (Astro), and pyrethroids. Systemic insecticides include imidacloprid (Marathon), clothianidin (Arena), or dinotefuran (Safari). The first step is to scout the fields and be aware of problem plants.
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DISEASE DIGEST
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OAK WILT PART II
Last week's BYGL (07-07-05) discussed the cause of the overland spread of oak wilt and the importance of not pruning oak trees, as the wounds are inviting to vectoring picnic beetles (Order Coleoptera Family Nitidulidae). This week's focus is on the underground spread of this vascular disease.
It is estimated that 90% of new infections of oak wilt occurs between neighboring trees through root grafts. In this situation, the fungus moves down the trunk, into the roots of diseased tree, and then into healthy trees via the root grafts formed among the neighboring trees. Once in the new tree, the pathogen moves throughout the vascular system and spreads to other trees via the intertwined root systems or the beetles, as described last week. When the pathogen spreads underground, it seems to radiate out and infects and kills red oaks in a grouping or pocket.
Trenching and chemical treatments are described in Home Yard and Garden FactSheet #3306, Oak Wilt. The FactSheet can be found on the web at http://ohioline.osu.edu/hyg-fact/3000/3306.html, or is available at your local OSU Extension office.
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TAPHRINA TOASTING TREES
Tim Malinich reported that OAK LEAF BLISTER, Taphrina caerulescens, has been showing up on office samples and at diagnostic walks in the Cuyahoga county area. This fungus causes quilting and cupping of oak foliage. These bumps and blisters can be generally distributed across the leaf and are distinct from the more angular lesions caused by OAK ANTHRACNOSE.
The infections occur earlier in the season, and, like many of the fungal pathogens, the result of the infection is only noticed well after the initial infestation. Extremely high temperatures and drought conditions have exacerbated the problem by accelerating the dessication of the blisters. The leaves are left toasted by scorching of the oak leaf blisters. The problem is generally cosmetic and no treatment is recommended.
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TURF TIPS
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CHINCH BUG CHALLENGE
Drought this season has many people looking upon their brown turf and wondering if irrigation is the answer. However, some of the blame for tan turf might be placed on CHINCH BUG activity in the lawn. Dave Shetlar, the BugDoc, is looking for populations of these turf pests for research purposes. If you know of, or have turf areas infested with chinch bug, contact Dave Shetlar at Shetlar.1@osu.edu.
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INDUSTRY INSIGHT
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PH PUZZLES
Randy Zondag reported that water is becoming a major issue for nurseries due to high temperatures and extended drought. This can lead to problems with the pH changing in container grown nursery stock. With the dry weather, water sources have decreased in volume leading to concentrated mineral levels in irrigation water. Frequent irrigation may also wash desired nutrients out into our water sources.
Root rots also become an increasing problem in containers due to over-watering or irregular watering; specifically, allowing plants to dry down too much then flooding the plants with water will result in damage to the roots. Also, if you allow containers to dry out the salts, will concentrate in the upper layers of the container leading to plant crown issues.
What can be done? First, monitor pH and soluble salt levels of your containerized plants and keep records of your measurements. This will help you monitor release of fertilizer along with any changes in pH. The pH change can come from the minerals in hard water or nutrients and minerals released as organic portions of the media break down. Many nurseries experiencing off-color plants incorrectly apply fertilizer. Be sure it is not a root problem or pH problem before applying fertilizer.
If you need to apply fertilizer to nursery stock, be sure to use a product that will finish its release before mid-September. This will mean you need to select a product that will have less than a three month release curve. Long release products may make plants more prone to winter injury.
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SCOUTING ESSENTIAL
Scouting for a pest requires time and training. Many growers discover problems only when it is too late to do any thing about them. First, make a list of pests you would expect to find on the plants. Then, spend time looking for both signs of the pest and the pest itself. This can be done by traps, or just walking through the production area. Train staff to look for pests as well. Controlling a pest before major damage is done will allow plants to grow to their proper size and shape. Finally, keep records of when the pests were present, the stage of growth of the plant, and area of the plant infested. Also note the type of damage done, and success of control measures. This information will help you better scout, target, and control pests.
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COMING ATTRACTIONS
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38TH ANNUAL SUMMER FIELD DAY
is scheduled to be held Tuesday, August 9 at Chalet DeBonne Vineyards 7743 Doty Rd. in Madison. Last year, this event attracted over 170 exhibitors and 650 participants and this year promises to be another quality event. For more detailed information on attending and/or exhibiting, call 440-241-7969, or visit the Nursery Growers of Lake County Ohio, Inc. website at: www.nglco.com
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BYGLOSOPHY
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"There can be no other occupation like gardening in which, if you were to creep up behind someone at their work, you would find them smiling." - Mirabel Osler
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