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.
|
|
August 12, 2004
|
|
This is the nineteenth 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 August 10, 2004 conference included: Pam Bennett (Clark); Barb Bloetscher (C. Wayne Ellett Plant and Pest Diagnostic Clinic); Joe Boggs (Hamilton/South East Region); Jim Chatfield (HCS/North Central Region), Erik Draper (Geauga); Gary Gao (Clermont); Tim Malinich (Cuyahoga); Dave Shetlar (Entomology); Pam Sherratt (HCS); Amy Stone (Lucas); Nancy Taylor (CWEPPD Clinic); and Curtis Young (Allen).
.
Additional factsheet information on any of these articles may be found
through the OSU Factsheet Database (http://plantfacts.ohio-state.edu/)
|
WEATHER WATCH
|
It doesn't feel much like August. Cooler than average temperatures are dominant across the state and rainfall amounts continue to be scattered. Shawn Wright reported that recent rainfall totals in the Piketon area ranged from 1/4" to a little more than 1".
Joe Boggs reported that the Cincinnati area has officially received 1.43" of rainfall in August, +0.18" when compared to the average. This area has received 30.62" of precipitation this year, +3.08" when compared to the average year-to-date.
Although recent rains have been recorded, the Toledo area's year-to-date precipitation total lags behind 3.0" when compared to the average. Officially, 0.29" of rain fell at the Toledo Express Airport in August thus far, although some showers were much more substantial in pockets across the county according to Amy Stone.
|
|
HORT SHORTS
|
CRABAPPLES IN BLOOM: IS IT REALLY AUGUST?
Pam Bennett was beginning to wonder if she and Toto really were in Kansas. The spring-like temperatures coupled with the sighting of a crabapple bloom really had her questioning her sanity. No, it's not spring and Pam's not crazy...well, that's debatable.
This interesting phenomena of plants blooming out of season is not completely unusual. In July 2001, there was a moderate flush of saucer magnolia blooms. A few years ago, Jim Chatfield got a great picture in the fall of a forsythia in full fall color while at the same time showing off its bright yellow blooms. Species of viburnums have also been observed blooming out of season in the past.
There is no clear reason why plants bloom out of season. Some speculate that it's because the plants "think" that they have gone through a slight dormancy (cooler temperatures) and therefore, when environmental conditions are right again, they bloom. Another possible reason is that stress induced the plants to bloom again. In the case of the saucer magnolia, Micheal Dirr mentions the following in the "Manual of Woody Landscape Plants:" "..the plant has a curious habit of flowering sporadically on new growth of the season but the flowers are never as brightly pigmented because of the heat and are often slightly twisted and misshapen.."
This occurrence is a mere curiosity more than anything and besides, what can be done to stop it?
|
|
DEADLEAFING DAYLILIES
Now is a good time to deadleaf daylilies since many of the leaves are loaded with brown streaks. These streaks are characteristic of daylily streak, a common fungal disease of daylily. Deadleafing is similar to deadheading. Removal of leaves heavily infected with diseases or damaged by insects greatly improves the appearance of these plants, especially daylilies. Before too long, daylilies produce new leaves and look very nice again.
|
|
CSI - WHITE PINE, EPISODE III, "THE POWER OF PROVENANCE"
In recent BYGLs, we looked at a number of hort-crime suspects commonly (and sometimes incorrectly) fingered by witnesses as being responsible for the death of a white pine tree in Ohio. In this episode, we will take another look at the most important participant in any crime scene investigation: the victim. After all, "death by natural causes" is a valid CSI conclusion, although it does little for television program ratings!
Where did our victim come from? Eastern white pine is found across southern Canada from Newfoundland west to central and western Ontario and extreme southeastern Manitoba. In the United States, its natural range extends from Maine south along the Appalachian Mountains to northern Georgia and northwestern South Carolina. Eastern white pine ranges west across the New England states, through New York, Pennsylvania, and across much of Michigan, Wisconsin, and into eastern Minnesota. Prongs of this tree's natural range extend into Illinois, eastern West Virginia, parts of eastern Tennessee, and eastern Kentucky. Finally, eastern white pine's natural range also stretches into northeast Ohio.
Given this wide natural range, it is legitimate to conclude that there is an associated range in the genetic diversity within the species. The term "provenance" is used by forestry researchers to help define naturally occurring genetic diversity within a tree species, based on geographic locations within the natural range of the species. A provenance test compares trees grown from seeds or cuttings collected from many parts of a species range. In 1963, researchers with the USDA Forest Service, Southern Forest Experiment Station, conducted a white pine provenance study at three Southern Appalachian sites. They found significant differences in both height and survival among the provenances in just 3 years, at all three sites.
Currently, a high percentage of white pine trees grown in landscapes in Ohio, and elsewhere, are from parent trees of unknown provenance. In other words, a row of ten white pine trees may represent the genetic diversity of different parent trees located hundreds of miles apart. Some provenances may do well, while others poorly on the same site. The cause of death of a single tree, or two or three trees, in a row of thriving trees is often a difficult investigation to wrap-up. Investigators may speculate on planting technique, management issues, soil conditions and other environmental challenges, without being able to pin the blame on a single culprit. In fact, the end result may have been genetically preordained - the provenance was poorly suited for the site ... it is indeed "death by natural causes." The power of provenance is an important piece of the CSI investigative pie.
|
|
BUG BYTES
|
KILLER SIZED WASPS. CICADA KILLER WASPS
Sphecius speciosus, have been buzzing people on golf courses, playgrounds, and yards, mistaking them for mates or possible dinner entrees. Although menacing by their large size (1-1 1/8") and yellow jacket-like appearance, they tend not to be aggressive toward people and are not likely to sting unless trapped or excessively aggravated. The males buzz and strafe individuals to ward off straying male cicada killers but since they do not have stingers, they are quite harmless. The females tend to fly directly back and forth to their tunnel and are too busy to bother people.
Cicada killer wasps can be identified by their rusty red head and thorax, and topaz colored wings. The yellow legs show well against the black and yellow striped abdomen. They prefer to tunnel in loose soil, especially sand, gardens, and areas with bare soil. These angled tunnels may extend 12-18" and descend 6-10". Each tunnel has up to 16 cells each with a paralyzed cicada and an egg. Upon hatching, the developing wasp larvae consume the cicada. Control is usually not recommended as they are considered beneficial, and normally are only a nuisance for a short period of time. Areas which are sensitive to marauding and stinging insects should endeavor to cover soil with mulch, landscape fabric or dense plant cover.
|
|
BAGWORM SAGA CONTINUES
Several BYGLers reported receiving calls from distressed homeowners who have finally discovered bagworms, Thyridopteryx ephemeraeformis, devouring their favorite spruce, arborvitae, juniper or cedar. The owners of these trees are disturbed by the absence of needles on large portions of the above trees leaving only naked branches behind with funny looking cones dangling from the branches. For those of us who are continuously monitoring trees and shrubs for the development of pest populations, it always amazes us at how much damage must develop before others notice that something is wrong. Of course once the discovery is made, the questions that follows is, "How do we get rid of them?"
The problem at this time is that we are fast approaching the point in the bagworms development where they will complete their feeding, close their bags, settle down to pupate, and complete their metamorphosis to the adult stage. As stated in BYGL-2004-18, when the bagworm caterpillar is close to completion of its larval development, and if they were to be treated with an insecticide, they would avoid the toxic effects of the insecticide by halting feeding, tying off their bags and pupating early.
Joe Boggs continues to keep a close watch on the development of the bagworm in the Cincinnati area and thinks that the male caterpillars ought to be pupating in the very near future. Once the bags are tied off, the caterpillar inside is well protected from chemicals sprayed on the tree or shrub upon which the caterpillars had been feeding. This is a point of concern because several BYGLers reported they have recently heard from a number of sources that recommendations are being made to spray insecticides such as Cygon (dimethoate) on infested plants in September or October to control bagworm. This will not work, it is the wrong time to attempt to control bagworm with any insecticide. Once the caterpillars have tied off, about the only effective control measures are to hand pick bags off the infested plant and/or if the plant is infested badly enough, cut down the plant and dispose of it, bagworms and all. The only other option is to leave things alone and attack them next year after the overwintered eggs hatch in June.
|
|
IT IS A MATTER OF SCALE
Magnolia scale, Neolecanium cornuparvum, is the largest scale found in the landscape. It begins as an overwintered purple crawler in the spring before developing a gray waxy-coated scale which covers the purple body beneath. A common diagnostic sign of magnolia scale is the copious amount of honeydew produced by the feeding scales. The honeydew accumulates on surfaces beneath the infested tree. Growth of sooty mold follows heavy honeydew buildup.
Successful control of this scale centers around activity of the crawlers. Magnolia scale crawlers normally emerge in mid to late August. Also, crawlers do not emerge en masse, but will slowly emerge over a period of days. Therefore, monitoring the development of the crawlers is vital to the timing of sprays-pesticide applications should target emerged crawlers, not mature scales. Numerous spray options are listed in OSU Extension bulletin #504, "Insect and Mite Control on Woody Ornamentals and Herbaceous Perennials."
While looking for crawler activity, two diagnosticians reported finding eggs below the scale. Dave Shetlar was quick to point out that magnolia scale gives birth to live crawlers. However, eggs found may have been expressed from the female during sampling--to put it another way, the eggs popped out when the scale was squished. If eggs were indeed present then the scale may actually have been the tuliptree scale, Toumeyella liriodendri. This is also a large scale, just slightly smaller than magnolia scale. It lacks the waxy coating and sports a grayish-green to pink-orange mottled covering. Crawlers are also present in late August. Spray options are the same.
|
|
MUTANT MANTID-LACEWING?
Participants at last week's Cincinnati BYGLive! Diagnostic Walk-About were treated to a specimen of a fascinating and somewhat rare insect that looked like a strange cross between a lacewing and a mantid. The back-half looked like a lacewing. The wings were held tent-like over the abdomen, and they had the characteristic delicate nerve-like venation that gives lacewings their common name.
The front-half of the insect looked like a mantid. The prothorax, which is the part of the insect between the head and the wings, was narrow and very elongated, like a mantid. The front legs, which were held in a "prayerful pose," were powerful-looking raptorial legs, the kind of legs made for grasping ... like a mantid.
However, the insect was not a mutant mantid, or a freakish lacewing, or a product of a genetic experiment gone wrong. It was a MANTIDFLY. Lacewings and mantidflies share traits because they both belong to the insect order Neuroptera, which means "nerve wing." Lacewings belong to the family Chrysopidae, and mantidflies belong to the family Mantispidae. Mantidfly adults are predators, and they use their mantid-like front legs to capture and grasp prey ... causing prey to pray! While this is very interesting, it is the behavior of the larvae that is truly fascinating.
The larvae undergo "hypermetamorphosis," which means they pass through distinctly different stages. First instars resemble lacewing larvae. They have narrow, elongated bodies, and three pairs of functional thoracic legs. These first stage larvae are very active, and spend their time balanced on their abdomens (often in flowers) awaiting a passing spider, bee or wasp. When a suitable host comes near, they grab on and hitch a ride back to the host's nest. Once in the host's nest, the larvae molt into grub-like second stage larvae. These larvae are not very active. They simply lounge-about feeding on the immature stages of their host. This includes spider eggs, as well as the larvae of bees and wasps. Pretty sneaky!
Mantiflies are considered rare insects in Ohio. They are most frequently found in the southern U.S. So, it was indeed a rare treat for the Cincinnati BYGLive! participants to see this fascinating insect.
|
|
MIMOSA WEBWORMS TORCH HONEYLOCUSTS
Curtis Young reported that mimosa webworms (Homadaula anisocentra) are torching honeylocusts in western Ohio. Joe Boggs noted that there are pockets of high populations in the southern part of the state, and Dave Shetlar indicated he is seeing some heavy localized infestations just east of Columbus. The second generation is now appearing in Ohio, and caterpillar leaf feeding damage is becoming very apparent. 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. 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.
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." 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.
|
|
FALL WEBWORMS SACK TREES
Joe Boggs reported that fall webworm's (Hyphantria cunea) second act for this season is now appearing in southwest Ohio. Likewise, Curtis Young noted that he observed a second generation nest high in a crabapple tree in the western part of the state. Joe indicated that although most caterpillars remain in the first instar stage, a few nests contained second instar larvae. Most nests are currently small and sometimes difficult to spot.
Like the aforementioned mimosa webworms, fall webworms create nests by enveloping leaves at the tips of branches with silk webbing, and they only feed on leaves encompassed by the webbing. The caterpillars are cosmopolitan feeders and they may graze on more than 90 species of trees, including almost all species of shade, fruit, and ornamental trees found in Ohio, except conifers. They seem to be particularly fond of sweetgum, black walnut, elm, maples, and hickory, as well as ornamental fruit trees such as crabapple. Heavy infestations can cause complete defoliation of affected trees.
This moth has at least two generations in Ohio, and eggs hatch over an extended period of time in both generations. While each nest typically contains larvae of equal age, it is not unusual to find neighboring nests populated by a wide range of instars. Occasionally, a range of instars may be found within a single nest. Second generation nests are usually more numerous than first generation nests, unless first generation larvae were hammered by disease, parasitoids, or predators. Nests produced second generation moths may also become much larger because first generation females often lay their eggs on or near the nests in which they developed.
If nests are few in number and easily accessible, the best control approach is to physically remove and destroy the nests and caterpillars. Otherwise, there are several effective materials listed in the OSU Extension Bulletin 504, "Control of Insects and Mites of Woody Ornamentals and Herbaceous Perennials." However, insecticides may also limit the impact of bio-allies. There are over 50 species of parasitoids, and 36 species of predators known to make a living off of fall webworm. In past seasons, parasitoids have proven to be very effective in reducing year-to-year populations of this defoliator.
|
|
BYGL WINDSHIELD WIPE
BYGLers also ran into a few other insects and mites this week including:
*SPRUCE SPIDER MITE (Oligonychus ununguis) populations in some areas of Ohio are remaining active, and causing damage, despite environmental conditions that should have driven the mites into their summer egg stage. Dave Shetlar indicated that he is not certain why some populations of these "cool-season" mites have not subsided into the summer egg stage. Typically, this mite produces damaging populations in the spring and fall. He speculated the mites were spared because micro-environments shielded them from high temperatures, as well as recent heavy rains. Regardless, Dave cautioned that landscape and nursery managers should remain vigilant and monitor for this mite.
*Joe Boggs noted that OAK SPIDER MITES (Oligonychus bicolor) are combining forces with OAK LACE BUGS (Corythuca arcuata) in southwest Ohio to make some oaks look horrendous. The small, red, oak spider mites are "warm-season" mites, with populations reaching their peak during the hot days of summer. Oak lace bugs are found on the lower leaf surface, while the spider mites live on the upper leaf surface. It's a double-whammy since both produce small yellow spots, or stippling, that may coalesce into large yellow-to-brown areas on infested leaves.
The location of the spider mites make them susceptible to being washed off by heavy rains; however, the foliage on the upper branches can produce an "umbrella effect" and provide some protection from heavy rain wash. This is why higher populations are usually found on lower branches. The mites also tend to concentrate around the leaf mid-vein, thus the heaviest leaf stippling is generally found on the central part of the leaf. As the common name of this mite implies, the oak spider mite is particularly fond of oaks, but it can also injure birch, beech, elm, maple, and hickory.
|
|
DISEASE DIGEST
|
HIGHLIGHTS OF DISEASE SAMPLES AT THE URBAN FORESTRY WORKSHOP
It was the first Friday in August, and that means it must be Lola Lewis's urban forestry workshop at Mt. Union College in Alliance, OH. Lola is with the Division of Forestry, Ohio Department of Natural Resources. Lola wanted disease samples to diagnose, and as the saying goes, whatever Lola wants - Lola gets. Here are just a few of the seasonal pathological prizes that were enjoyed by all.
*WALNUT ANTHRACNOSE: Like many anthracnose diseases, initial infections of the causal fungus (in this case Gnomonia leptostyla) occur in cool spring conditions, but with walnut anthracnose, the symptoms of the disease typically do not become severe until later in the season. Multiple infections by the fungus continue through the warmer weather of the summer and eventually small lesions develop on the undersides of walnut leaflets, followed by associated leaf browning, yellow haloing around affected areas and defoliation. In some years, black walnuts and other Juglans species exhibit severe defoliation by late summer. The good news is that since most of the defoliation occurs late in the season, damage is not too severe relative to overall plant growth and health, though considerable decline in nut quality occurs due to shriveling when incidence and defoliation is severe.
*TAR SPOT OF MAPLE: Tar spot of maple is another example of a disease in which infections occur relatively early in the season, but the development of symptoms and signs progress from a light yellow area on the leaves to the tarry black spots on the leaves that we are now seeing. There are two common tar spot diseases of maples. One, caused by the Rhytisma acerina fungus, produces solid irregularly-shaped tarry spots up to 2/3" in diameter or more. The other tar spot, caused by Rhytisma punctatum, often called speckled tar spot, results in a circle of tiny one millimeter spots clustered together. Tar spots of maple are generally considered no big deal, especially because they are noticed and cause considerable leaf damage only late in the season, but can be more severe (though never killers) in areas of very poor air drainage.
*COCCOMYCES LEAF SPOT OF CHERRY: "Mild, wet summer weather promotes Coccomyces leaf spot." That should be enough to predict it would be more noticeable than usual this summer, and that is indeed the case. This leaf spot is a big deal if you are a sour cherry orchardist and spray programs are important in such cases, but for landscape and woodland cherries, this disease is more a matter of curiosity, though we tend to get Curiouser and curiouser in years like the cool, wet summer of 2004. Symptoms start with clusters of small purple spots on one area of the leaf blade, coalescing over time, turning a dark brown, and being associated eventually with leaf yellowing and leaf drop. Sometimes areas of the spots drop out, leaving a shothole appearance, but there are also several other cherry leaf diseases which also exhibit shothole symptoms.
Final note: Modern taxonomists identify this pathogen as Blumeriella jaapii, but the use of the old (incorrect) name of Coccomyces as the pathogen name is so entrenched that "Coccomyces leaf spot" is retained. More than you wanted to know!
*BOTRYOSPHAERIA DIEBACK OF VIBURNUM: It is that time of year when it is common to see what looks like early fall coloration on plants, from red maples to burning bushes. This early coloration often indicates that the plant is stressed and that it is a good idea to investigate what might be wrong and at least to make a note that there is a history of developing problems on the plant. If the early coloration is on a doublefile or cranberrybush viburnum, especially if it is only on individual branches, make sure to check for Botryosphaeria canker on the stems back from the area of leaf discoloration. This coloring is the first sign of trouble. To check for Botryosphaeria canker or bot rot, look for roughened, cracked, darkly discolored areas on the stem. Also, when you cut into the stem, there is internal discoloration in the cankered area. Best control: prune out the cankered branches at a good node a foot or so back of the canker.
*POWDERY MILDEWS - AGAIN: Powdery mildew diseases continue to be prevalent, and misdiagnoses continue as well. As mentioned in BYGLs throughout this summer, clear-cut powdery growth is often seen, such as on powdery mildew of lilac. In other cases, such as magnolia there is often considerable red and gray discoloration noted where the mildew fungal infections have resulted in some dessication of plant tissue. Distortion of new leaves is also common from powdery mildew diseases, for example with rose powdery mildew and on powdery mildew of planetrees.
Then there is this suspicious forensic tale, fresh from the Sunday, August 8 edition of the Akron Beacon Journal. From the Community Crime Watch section, sandwiched between a video game system burglary and paint being thrown on the walls and floors by a woman's angry teenage son, was this entry listed as "criminal damaging:" "Leaves are shriveling up on a McNaughton man's dogwood trees, it was reported July 24. It's believed that the white powdery substance found on the leaves has caused the leaves to shrivel."
It brings to mind a sample in a chain-of-custody evidence bag that Nancy Taylor received from a central Ohio police department a few years ago in the PPDC. In that case it was lilac powdery mildew, and in this case of the McNaughton Man again we suspect this to be a no more than a typical crime of nature - powdery mildew of dogwood.
|
|
MILDEW SQUASHING PUMPKINS
Erik Draper reported seeing DOWNY MILDEW (Pseudoperonospora cubensis) beginning to show up in fields of pumpkins in Geauga County. Nancy Taylor chimed in mentioning various downy mildew reports coming from other diagnostic centers up and down the east coast. Once this particularly virulent disease gets started, if left unchecked or ignored, it can run rampant through muskmelons, watermelons, winter squash and pumpkins.
Symptoms vary according to crop, but small slightly chlorotic to bright yellow areas on the upper leaf surface. These mosaic tile-like areas are distinctly bordered by secondary leaf veins. Lesions appear first on the older leaves, right around the crown of the plant. These lesions can be irregular but can also appear angular and bound by leaf veins. Symptoms rapidly progress from older to younger leaves. As the lesions expand, they may remain chlorotic or yellow or become brown and necrotic. In just a few days, the coalescing lesions may kill the leaf. As the leaves die they tend to curl upward, yet the petioles and vine remains intact and green. This disease mainly affects the foliage, but it becomes impossible for the plant to function without any leaves left on the vine.
When conditions favor spore production, the underside of these lesions produce sporangia with a downy texture ranging from white to grey in color. The sporangia appear on the underside of the leaf, which is a key diagnostic clue; "down under" the leaf...humm, downy mildew! The most amazing thing about this disease, speaking purely pathologically, is that under ideal conditions this fungus can go from infecting a leaf, to releasing spores for the next infection cycle in four days!! Specific environmental conditions, like above 90% relative humidity for 6-24 hours with temperatures ranging from 50-80F (61-72F being optimum), are key aspects that can result in leaf infections.
Fungicides can be effective, but only specific types. The azoxystrobins, fosetyl-Al or mefenoxam are toxic to this fungus, however, it is difficult to predict when this disease will occur. Unfortunately, when it does happen, it is usually detected too late and the fungus really does a number on the leaves, which in turn shuts down the plant. If detected soon enough, and if the proper fungicides are applied on a consistent schedule, the plant can survive on the younger foliage; however, the older previously infected foliage will die.
|
|
TURF TIPS
|
SPEED MOWING
Speed mowing is a phenomenon whereby the objective of the exercise is to mow grass in the shortest possible time period. It usually involves the mower operator putting the mower into full throttle and putting the foot to the floor (i.e. lead-foot syndrome).
Joking aside, the symptoms of speed mowing includes scalped and yellow unattractive grass where the mower has jumped over bumpy ground and come crashing down onto the grass, an uneven cut, and bent or damaged mower blades. This is a problem for lawn care companies hoping to please customers, or athletic field managers hoping to provide coaches and athletes with quality playing surfaces. We usually see this problem for three reasons:
*Budget cuts! There is too much grass and not enough mower operators, which is common at schools or parks and recreation areas.
*Wet conditions have prevented timely mowing. The "one-third rule" dictates that no more than one-third of the leaf tissue be removed in any one mowing, but consistent rainfall can prevent that from happening. On many occasions this summer there has been only a short period of dry weather to get grass cut.
*The operator has something more pressing to do. How fast should a mower go? As a rule of thumb, a walk-behind mower should be operated at 4-7 mph (brisk walking pace). For ride-on mowers, it depends upon the type of mower, but it is important for the operator to pay attention to signs of engine strain. Generally, the higher and thicker the grass, the longer it takes to cut. And the damper the grass, the more likely it is to clump. Therefore, as grass height, density and moisture content increase, mowing speed should decrease proportionately.
Wherever possible, mow to the one-third rule and mow at the correct mowing height for the species of grass in question. For example, Kentucky bluegrass should be mowed between 1.5-2.5". Plant growth regulators, such as Primo (trinexapac-ethyl), are products that reduce top growth for up to 6 weeks. Products such as these can reduce mowing frequency in areas that are not subjected to high traffic/wear. To keep grass that has grown too tall from going into shock, operators should raise the mowing height and gradually lower it back to the original height over a few weeks.
|
|
LEAF SPOT ON PERENNIAL RYEGRASS
In the past week samples of severely damaged perennial ryegrass from leaf spot have been received at the CWEPPD Clinic. The question was asked if the problem was GRAY LEAF SPOT caused by (Pyricularia grisea) or common leaf spots. In ALL of these cases, NO gray leaf spot was found! Several weeks ago Gray leaf spot was reported in eastern Pennsylvania, but the resent samples from western Pennsylvania and Ohio all had the traditional leaf spots caused by the Helminthosporium type leaf spot complex (Drechslera spp. etc). It appears that the affected sites have ryegrass quite genetically susceptible to certain leaf spots. It is not known if the wet spring conditions contributed to this problem.
In turf areas, the two diseases may be somewhat difficult to distinguish, since over-all symptoms may appear similar. However, in the lab identification is easy by examining the spores. The resent cool weather patterns in Ohio are not conducive to Gray leaf spot and it would be surprising to see active gray leaf spot at this time. If hot humid conditions develop and persist then the picture could change.
To manage these areas, follow sound management procedures to promote healthy turfgrass. This would include proper mowing, moderate fertilization, and avoid over watering. The fungicide chemical family Dicarboximides (iprodione and vinclozolin) are among the best for leaf spots of this kind. Due to new restrictions on fungicides for residential lawns, mancozeb, trifloxystrobin, or PCNB may be considered. Check OSU bulletin L-187, Management of Turfgrass Pests, for more information.
|
|
JAPANESE BEETLES FLUSHING AGAIN
A discussion regarding the appearance or absence of Japanese beetles and impending threat of grub damage revealed interesting differences. Southern Ohio had a patchy outbreak of JB adults in early to mid-July with high numbers in some areas and low numbers elsewhere, while the northern third of Ohio is experiencing a second flush of beetle feeding. Dr. Shetlar believes that due to the summer droughts since 2001, many JB females delayed egg laying until August or September when soil moisture had improved. These grubs overwintered as second instars, which in turn, emerged later the following year. This may explain why some northern Ohio counties noted Japanese beetles in July and again more recently. Also, counties with high populations of the European chafer tend to have lower numbers of JB.
So what about grub activity? Turfgrass which is well tended and irrigated regularly may have a good population of grubs if JB adults were present in the area. Plants such as linden, basswood and crabapple trees, grapevines and roses which attract JB have a greater likelihood of supporting a healthy grub population if the turfgrass is green and dense. On the other hand, if JB were not evident, grub numbers may be low enough not to cause noticeable damage. If grubs have caused damage in the past, turfgrass in northern Ohio may still be treated with imidacloprid, however time is quickly running out. Make sure to water well after application. Remember that grub damage can be masked by irrigation in some situations.
|
|
INDUSTRY INSIGHT
|
OSU-OLCA DIAGNOSTIC SEMINAR
The 10th annual Ohio Lawn Care Diagnostic Seminar is August 19 at the OSU Turfgrass Foundation Research and Education Facility in the Waterman Farm Complex. Group sessions start at 9:00 a.m. in which registrants rotate to different stops and learn about pesticide MOA, calibration and safety, lawn weeds, landscape plant problems, turfgrass insects and seeding establishment. For more information contact the OTF at 1-800-510-5296 or go to the following website to print a brochure. http://www.ohioturfgrass.org/mds_dev/04ColumbusBrochure.pdf
|
|
COMING ATTRACTIONS
|
WOSU GREEN SCENE
Join host Tom Wiebell this Friday night for AM 820 AM, WOSU's Green Scene gardening and landscape Q&A call-in show. Regular Deb Knapke, Columbus State's "Garden Sage," will be joined by the inimitable Joe Boggs. Be sure to stump them with your horticultural and entomological conundrums and puzzlers from 6:30 to 8:00 p.m., by calling 614-292-8513.
|
|
OSU 2004 TURFGRASS RESEARCH FIELD DAY
The annual Turfgrass Research Field Day is scheduled for Wednesday, August 18 at the OSU Turfgrass Foundation Research and Education Facility in the Waterman Farm Complex. Starting at 9:30 a.m., attendees will learn about fairway irrigation and water conservation, green speed, topdressing/greensmix, shade physiology, dollar spot fungicide timing, chinch bug research, corn gluten use for weed control, entomopathogenic nematodes, new insecticides, Bermudagrass, foliar feeding of bentgrass and more! After the perennial BBQ lunch, take time to look at new equipment and demonstrations. Register with Ohio Turfgrass Foundation (OTF) and plan for an invigorating, intriguing day! Call OTF at 1-800-510-5296 to register or go to the following website to print a brochure. http://www.ohioturfgrass.org/mds_dev/04OTFFieldDayBrochure.pdf
|
|
OSU-OLCA DIAGNOSTIC SEMINAR
The 10th annual Ohio Lawn Care Diagnostic Seminar is August 19 at the OSU Turfgrass Foundation Research and Education Facility in the Waterman Farm Complex. Group sessions start at 9:00 a.m. in which registrants rotate to different stops and learn about pesticide MOA, calibration and safety, lawn weeds, landscape plant problems, turfgrass insects and seeding establishment. For more information contact the OTF at 1-800-510-5296 or go to the following website to print a brochure. http://www.ohioturfgrass.org/mds_dev/04ColumbusBrochure.pdf
|
|
BYGLOSOPHY
|
The best fertilizer for a piece of land is the footprints of its owner.--Lyndon B. Johnson
|
|
