Vol. 20, No. 14, August 12, 2005

Other news
Weather news

Next issue: August 26

Dave Smitley, Entomology

Just about everywhere you go in southern Michigan this week you will see lots of webbing covering the branch tips of Walnut, hickory, ash, crabapples and many other types of trees. The small yellowish-gray webworm caterpillars hide in the webs during the day. Some trees have actually been defoliated from having a tent on nearly every branch. But in most cases, each tree has three or four tents. They look bad, but cause little harm to the trees. Tree health is not affected until more than 50 percent of the foliage is consumed, and even then, the trees usually come back just fine the following spring.

Pruning-out infested branches is the best strategy if you can reach them. Spraying the foliage around tents with B.t., Sevin, Orthene, or a pyrethroid insecticide will prevent further feeding injury, but the old tent will remain visible. We have many natural parasites and pathogens of fall webworm that will bring these infestations under control. Places with lots of fall webworm this year may not have much next year. Outbreaks usually last two or three years.

Mike Bryan,
Michigan Department of Agriculture

MDA inspectors recently found and ordered destroyed a shipment of honey locust (Gleditsia) infected with knots or galls. The disease has been dubbed honey locust knot. The infected plants came from a large supplier in Minnesota and resemble similarly infected plants found in 2002 at another Michigan nursery and also at a site in Ohio. The detection in 2002 was one of the first known occurrences of this disease on honey locust.

The disease is thought to be caused by a bacterium, Pseudomonas syringae pv. Savastano. This bacterial disease is relatively common on olive and oleander plants in the tropical/semi-tropical areas of the world. It is known that there are different strains of this bacterium. The bacteria enter and infect plants through leaf and blossom scars, wounds caused by pruning, mechanical damage, hailstorms or strong winds. Rain, sprinkler water and pruning tools can spread bacteria from diseased to healthy plants. Common names included tuberculosis of olive-tree, olive knot and oleander gall. This pathogen is noted having different strains that occur worldwide. The known hosts include olive, oleander and ash trees.

Descriptions of this disease indicate that the galls occur on twigs, branches, leaves, flowers and seedpods. Initially galls appear as small protuberances that subsequently develop into wart-like growths with roughened, fissured surfaces. Galls vary in size but average about a half to one inch in diameter with larger galls made up of several small galls that have grown together.

Growers and homeowners are encouraged to report instances of this disease to the Michigan Department of Agriculture. A list of offices and contact numbers can be found at: www.michigan.gov/mda, key word Regions.

Tuberculosis of Olive-Tree, HYPP Pathology = http://www.inra.fr/Internet/Produits/HYP3/pathogene/6pssysa.htm

Bert Cregg,
Horticulture and Forestry

Dateline Atlanta. This week I attended the 50^th Annual Southern Nursery Association (SNA) Research Conference in Atlanta. Because of the size of the nursery industry and the number of researchers working on nursery crops in the South, this meeting offers a good opportunity to pick up on some of the latest research and emerging issues in the industry. Researchers presented over 170 papers on nursery production, crop improvement, pest management and economics and marketing. Here are a few highlights that may be of interest to Michigan growers.

Charles Hall discussed a recent survey of national nursery marketing practices. A few tidbits: 61% of nurseries nation-wide sell natives plants, Minnesota was the highest with 81% of nurseries selling natives. Natives make up 13.2% of sales. Well water is the main source (53%) of water for nurseries followed by surface water (24%), city water (12%) and recaptured water (10%). Home Depot is piloting Landscape Superstores in Georgia. Richard Parish (LSU) examined the economics of various systems to prevent blow-over of above-ground containers including wire basket systems, above ground pot-in-pot systems and the Tree-Mate-O system. All the systems reduced blow-over more than the grower standard (metal rod down through the pot) but even figuring in the cost of standing trees back up, the grower system was the most cost-effective.

Past SNA Research Conference proceedings are available on-line and this year’s proceedings will be added soon. A link is available on my department page (http://www.hrt.msu.edu/faculty/cregg.htm)

Dave Smitley,
Entomology

Japanese beetle and European chafer are by far the most important grub pests of turfgrass in Michigan: Japanese beetle in irrigated turf and European chafer in low-maintenance turf. Japanese beetle has now spread north along Lake Michigan to the Traverse City area and inland as far north as a line through Bay City, Midland, Big Rapids and Ludington. European chafer has now been picked-up in the Traverse City area and at several other locations in the northern Lower Peninsula, but has not built-up enough in the northern Lower Peninsula to cause extensive turf damage like it has in the southern half of Michigan.

Several species of native June beetle grubs occasionally cause turf damage (especially when skunks or raccoons dig-up turf to eat them) throughout the state. Oriental beetle has been found near Monroe Michigan and just west of Grand Rapids. Sampling is now underway to determine how widespread it is in Michigan. The grubs of Oriental beetle could become just as serious of a turf pest as Japanese beetle grubs, but the adults do not cause nearly as much feeding damage to trees, flowers and shrubs as the Japanese beetle adults do. An active population of green June beetle was discovered in southwest Michigan near Sturgis. I don't expect the green June beetle to become much of a problem in Michigan.

Ataenius and Aphodius are about the same as they were 10 years ago: a sporadic problem on golf courses throughout the state.

1. Allectus: imidacloprid + bifenthrin (like Merit + Talstar). Bayer and FMC have joined forces to offer a product that combines grub control with surface insect control. Imidacloprid has been a turf standard for grub control for many years, and bifenthrin has good activity on cutworms, ants, ataenius adults and annual bluegrass weevil (not found in Michigan, yet). The only downside is that at the high rate you are only applying 0.25 lbs ai/Acre of imidacloprid, somewhat less than the 0.4 lbs ai/Acre on the Merit label.

2. Arena: clothianidin. Arena is a new turf insecticide in the same chemical class as Merit. In the first two years of testing, it has worked at least as well as Merit for grub control. Like Merit, it works great for grubs when applied in June or July for late summer and fall grubs. We are in the process of testing May and September applications to see if they work as well as the July application.

Kevin Frank,
Crop & Soil Sciences

The summer of 2005 was the perfect example of why we recommend that the best time to establish turfgrass is in the later summer or early autumn. I have heard numerous stories of seeding failures from homeowners, lawn care operators and whoever else has tried to establish turf this summer. The high temperatures, sporadic rainfall and high humidity have resulted in very stressful conditions, plenty of disease and numerous seeding failures. Often, the common thread in many of the failure stories is from the inability of the person caring for the turf to avoid fertilizing or watering the turf out of the poor condition. By adding more fertilizer and water, the turf manager just increased the odds of disease wiping out the complete turf stand. OK, we’re past all of that now – the weather should be better – and turf seeded in late August to early September should bring sanity back to the landscape.

Some of you may be trying to rescue a less than stellar summer establishment; others may be starting from scratch. If you’re looking to rescue an earlier establishment, make sure to make a sober assessment of the amount of turf surviving. If the turf was simply thinned from the tough summer or there are small patches of dead grass, a fertilizer application and a return to cooler temperatures should help the existing turfgrass stand to recover and fill in those bare spots. If the damaged areas are large, for example I have seen sites where 15 x 30 ft. areas essentially have only sporadic green turf plants, and plenty of crabgrass, areas this large are going to require reseeding.

For the mid-Michigan area, the recommended latest seeding date for ensuring success is about September 15. As you travel north, the latest seeding date is going to creep up until you get to the Upper Peninsula where you probably want to get that seed in the ground by September 1. As you head to the Ohio/Indiana border you can probably get away with seeding as late as the third week of September.

To be safe, avoid applying all herbicides this autumn, i.e. no fertilizer + broadleaf weed control products. Young seedlings don’t tolerate herbicides very well and the guideline is usually to wait three "real" mowings before applying any herbicides or in some cases at least 60 days. By "real" mowings, I mean you’re actually cutting significant grass, not just running over the area to trim down any weeds. Finally, don’t be afraid to get out there and mow the area. Mowing turf helps it spread laterally and fill the area, so start those engines as soon as you start to see the grass creep up to about three inches.

Ron Calhoun,
Crop & Soil Sciences

Poison ivy is an aggressive perennial vine that takes some dedication and persistence to eliminate. Physical removal can be tricky because of the inherit perils of breaking out in a rash. Poison ivy is most susceptible to chemical controls when sprayed in the late summer and early fall. At this time the poison ivy will be transporting energy reserves to the root system to ensure next year's growth. Products containing triclopyr and 2,4-D or triclopyr and glyphosate (e.g. Roundup Poison Ivy Killer) are the most effective.

In addition to following the label directions, be mindful that either of these products will kill any broadleaf plants to which they are applied. If you use the product that contains glyphosate it will kill any green plants that come into contact with the spray solution. I would recommend making your first application in the next few weeks (before Labor Day) and then again one month later. It is OK if you don't see a lot of injury on the poison ivy after you make the applications. Actually, the healthier the top remains the better the product is being moved into the root system. You should notice a big difference next spring. I would keep a small amount of spray solution handy for follow-up, and spot treat the ivy at first signs of growth next year.

Mike Kaufman,
Entomology

It’s been a relatively subdued year thus far for mosquito activity and related disease threats. West Nile virus (WNV) in Michigan and elsewhere in the United States seems to have slipped beneath the radar of public interest, and indeed human cases are down this year nationwide. Although we don’t yet know the reasons, the amplification cycle in birds (which necessarily precedes any human infection) doesn’t seem to have started as early as we’ve seen in previous years. It may be that the public and community health departments have been less vigilant in reporting and turning in dead corvids for testing. Nonetheless, the disease is still present in Michigan; birds have tested positive in some areas and the percentage positive is rising, and we’ve recently detected the virus in mosquitoes collected from the Detroit and Saginaw areas. It’s important to note that there’s still a lot of time left for risks to increase – particularly if our trend of higher than normal temperatures continues into September. Additionally, WNV isn’t the only mosquito-borne disease one can contract in Michigan. St. Louis, La Crosse, and Eastern Equine viral encephalitis diseases are always present at low levels in the state in some areas. August is a prime month for mosquito-borne disease activity because it follows periods of adult mosquito population increases and amplification cycles in animals. It’s not yet time to let your guard down.

This is not to leave you with the idea that every mosquito you might come across presents a grave danger. However, it’s still prudent to take precautions against being bitten. Disease transmission isn’t necessarily related to overall mosquito numbers – it’s more a function of the particular mosquito vectors present and the percentage of their population carrying the virus. Aside from disease risks, however, mosquitoes are simply annoying and protection from being bitten is most often a question of comfort. It’s important to remember that we have about 60 species of mosquitoes in the state and each has different “favorite” habitat, host range and seasonal activity schedule. The mosquitoes trying to bite you in the spring are not the same ones looking for blood in late summer. It’s one of the reasons that nuisance mosquito problems tend to be sporadic from year-to-year and within a season. Even if rainfall isn’t particularly heavy, there are plenty of aquatic habitats capable of serving as breeding sites and some species use these exclusively. Most particularly “bad” mosquito years or periods do involve an increase in temporarily flooded areas – e.g., river flood plains, roadside drainage ditches. In our region, summer rains heavy enough to keep low areas in fields submerged for over a week are usually a sign that we’ll be inundated with what are known as “summer flood water” species. If this group emerges along with either the spring species or late summer species that inhabit permanent water bodies, then nuisance becomes a term of understatement. Fortunately, we haven’t seen those conditions this year – rainfall hasn’t been excessive and the ground has rarely been saturated.

There are relatively few new approaches to minimizing your chances of mosquito bites. The basic common sense approaches still apply. Repair screens, minimize outdoor activity between dusk and dawn, eliminate mosquito breeding sites where possible or practical, and use an effective repellant. In past articles on mosquito avoidance, I’ve recommended using repellants with 10 to 30 percent DEET. I still recommend these, but am happy to report that there a few newly available alternatives that approach or equal the effectiveness of DEET. The CDC now lists repellant formulations with picaridin (also known as KBR 3023. Sold under Cutter brand) and lemon eucalyptus oil (active ingredient PMD = p-menthane-3,8-diol. Sold under Repel brand). Both of these tend to be less irritating than DEET-based products and give protection duration comparable to 15 percent DEET products. All three products work to mask attractive odors and confuse host-seeking female mosquitoes. Picaridin has been widely used in Europe and Australia and has been recommended by the World Health Organization. PMD has been used for years in China. Picaridin is also derived from natural plant compounds, but for those of you who think all botanicals are safer than synthetic compounds, note that picaridin is derived from the active substances in poison hemlock (piperidine). None of the repellants should be ingested or applied near the eyes, and only lower concentration versions should be considered for use on young children.

An additional protective measure that has recently emerged on the market is the use of permethrin-impregnated clothing and fabric. Permethrin, of course, is a plant-derived insecticide with an excellent safety record and widespread use. It’s approved for use in animal flea collars and for control of head lice in humans, so it has low toxicity risk even with prolonged and direct applications. Permethrin-impregnated bednets have been used for years as an effective means of malarial control in Africa and Asia. It can also be applied to existing fabrics or clothing can be purchased with the substance already incorporated. If properly applied, it can withstand repeated washings. Permethrin on fabrics has insecticidal properties, but usually acts as a contact repellant for questing mosquitoes. That is, the mosquito lands, experiences irritation and then flies away. Although permethrin-impregnated fabrics repel mosquitoes, it’s important to note that exposed skin is not protected. Some manufacturers claim that by simply wearing a few articles of the clothing the individual is protected by an “invisible shield.” Unfortunately, this is not true. I have personally placed my arm in a cage of hungry mosquitoes while wearing a long-sleeve permethrin-impregnated shirt. The mosquitoes had no trouble finding the exposed skin on the top of my hand and feed within a few centimeters of the cloth.

Jackie Smith and Howard Russell, MSU Diagnostic Services

Tim Moore, MSU Department of Police and Public Safety

Editor’s note: This week’s article is accompanied by several pictures. To view the first slide of pictures, click here and then follow the “next” buttons to view following images.

Wild (or feral) honeybees have been struggling to hang on ever since the Varroa Mite and Tracheal mite were introduced into Michigan back in the eighties. During the 90s, I went through entire summers without seeing a single honeybee in my yard. Recently there have been signs of honeybee comeback of sorts. I see them more and as I reported last spring, I received more calls on honeybee swarms this year than in the previous 10 years combined. It is unfortunate that occasionally these swarms select interior compartments of homes for their new home. Such was the case for our own Jackie Smith. Fortunately for Jackie (and unfortunately for the bees), she is friends with Tim Moore who works as pest control person for MSU’s Department of Police and Public Safety. Tim is licensed in the State of Michigan as a structural pest control professional. He knows his stuff, and he’s got good juice. Everybody should know a pest control person like Tim.

Honeybees are much more serious than wasps and yellow jackets when they decide to nest in our homes. With yellow jackets, one can simply kill the colony and leave the clean up to the carpet beetles. Not so with honeybees. Honeybees store many, many gallons of honey in their colony to get them through the winter, and it’s the honey that makes them far more complicated than yellow jackets. If one decides to kill off a hive of honeybees that has taken up residence in one’s home, then the honey, comb and dead bees have to be removed. Honeybees store their honey in wax combs. If the bees are not present to ventilate and cool the honeycomb with the beating of their wings, the wax melts and the honey is free to flow wherever gravity takes it. Besides the honey, there is the matter of the thousands of dead, rotting bees (very smelly) to contend with too.

Last spring, scout bees from a nearby honeybee swarm investigated two holes in the wooden siding on the second floor of Jackie’s Lansing home. They found the interior stud cavity to their liking, and the swarm moved in and began constructing comb, raising brood and making honey. Jackie did not notice her new tenants until last week. She had little choice but to call Tim and have the colony destroyed.

Tim started the process by treating the outside entrances to the colony with a pyrethrin-based dust material and then waited a few days for the dust to work. The real dirty work then moved inside.

Since it is a lot less work to repair interior walls, it’s best to cut a hole on the inside wall where the colony is located to remove the comb. To insure the colony residents were no longer a threat, Tim determined the extent of the colony with a stethoscope and drilled several holes in order to douse the colony with a synthetic pyrethroid insecticide spray. Once that was completed, Tim cut a hole in the lath boards and plaster and removed the comb and dead bees. Fortunately, it was a small colony and there wasn’t a lot of comb to remove. Now all there is left to do is to repair the gaping hole in Jackie’s wall.

Too bad for the bees. Hopefully their comeback will continue, and they choose somewhere other than Jackie’s house to set up shop.

Jennie Stanger,
Consumer Horticulture Educator

Home vegetable gardeners can tap into a web resource specific to current vegetable growing problems in southeast Michigan at www.msue.msu.edu/monroe by clicking in the upper right corner on “Local vegetable report.”

Retired veteran vegetable crop agent Paul Marks is scouting commercial vegetable crops part-time this growing season and posts weekly updates that often include photos of current problems. The whole list of reports and photos are available with the most current report at the top. His photos and comments may help home growers diagnose such summer vegetable problems as virus or powdery mildew on pumpkins; corn and squash vine borers; blossom end rot and poor pollination, etc.

Home gardeners may wish to contact their county MSUE office for specific management recommendations, since the commercial ones may not fit their situation.

Rebecca Finneran,
Horticulture Educator

I’ll bet you have heard the term many times; MSU Extension Master Gardener. Have you ever pondered what the heck it is? The black belt of gardening? The king of compost? The Jack of the beanstalk? The answer just may surprise you.

The MSU Extension Master Gardener program began in 1978 in Wayne County with just a handful of people, according to Jerry Draheim, MSU Extension Emeritus District Horticulture Agent and one of the state’s program founders. “The program was an off shoot of one that had started in Washington State in 1972. Its initial intent was to recruit volunteers to carry on the mission of MSUE and bring knowledge to people,” he said. By incorporating a popular gardening program with involving volunteers into the community, it has gone well beyond anyone’s expectations. As a matter of fact, today you can take the Master Gardener Program in almost every state of the United States and if you move, just transfer into a program here.

The training program consists of twelve basic topics including plant science, soils and managing plant health. Specific classes like flower gardening, fruits and vegetables are taught by MSU Extension specialists and industry professionals. “I really never thought I would be interested in lawns,” said Stacey VanderEide a 2004 Student. “The teacher made the subject come to life for me and I am much more aware of my own lawn at home,” she said. Another benefit to VanderEide and many others is that they become more ecologically conscious as gardeners. “For instance, I learned that I could reduce water usage in the lawn if I raised the mowing height – now that’s smart,” she said.

Drahiem sited volunteer activities that have gone well beyond the program founder’s expectations in the 70s. “We never envisioned all the types of work that MSU Master Gardeners would do, nor the skill level individuals bring to the program,” he said. People have used the MG program to launch a career in Horticulture and obtain a degree. “We also never envisioned that it would generate gardening businesses like it has,” said Drahiem. “New gardening businesses pop up every year, owned by an entrepreneurial MSU Extension Master Gardener.”

Jeff Andresen
Agricultural Meteorology,
Geography

After several weeks of a persistent ridging pattern across the central United States, the jet stream has shifted southward to the United States/Canada border during the past few days, resulting in cooler and wetter weather for much of the Great Lakes region. The cool front that moved across Michigan Wednesday (August 10) will linger across the region through early next week, bringing a chance for showers and thunderstorms to southern sections of the state on an almost daily basis through Sunday. Fair and dry weather is likely across the north during the upcoming weekend and statewide for the Monday through Wednesday time frame.

Temperatures during the next few days will remain near or slightly below normal levels with highs ranging from the low and mid-70s north to mid-80s south and lows from the upper 40s north to low 60s south.

In the medium-range time frame, computer model guidance is suggesting that the formation of an upper air troughing pattern in the western United States with a broad ridge across the east. This pattern is similar to the upper air pattern that persisted for much of June and July. The NOAA CPC 6-10 and 8-14 day outlooks, covering August 17-21 and 19-25 both call for a return of above normal temperature statewide across Michigan. Precipitation totals during both time frames are expected to range from below normal levels across much of Lower and extreme eastern Upper Michigan to near normal across the central and western Upper Peninsula.