In this issue
Landscape and nursery
Black locust trees turning brown from leafminer
Basswood leafminer turning basswood trees brown north of Lansing
Asiatic garden beetle beginning to show in a few hot spots
Japanese beetle biocontrol field day
Research highlights from Southern Nursery Association conference
Chestnut growing in Michigan
Turfgrass
White grubs begin feasting on turf roots
Turf tips as autumn appears
Around the home
Foreign grain beetle: A fall invading insect that prefers new homes
Dogwood sawfly larva: a wood destroying pest?
Boxelder bugs: Looks like another bumper crop this year
Will we have good fall color this year?
Other news
Weather news

Black locust trees turning brown from leafminer
Dave Smitley, Entomology

Driving between Kalamazoo and Battle Creek on I-94 last week, I was surprised to see hundreds of black locust trees had turned completely brown by the locust leafminer. This is a small (6 mm) burnt orange-colored beetle with broad black stripe down the center of its back. The larvae are maggot-like and tunnel inside the leaves, eventually turning them brown. This is a native insect with good parasites and predators that usually keep locust leafminer under control. However, like many of our native defoliators, populations tend to go in cycles. We seem to be at a peak in the cycle this year.

Hopefully, next year or the year after, predators and parasites will catch-up with the leafminer, and get it back under natural control. Meanwhile, many black locust trees in southern Michigan are heavily defoliated. Because this is a late-season defoliator, the trees will still leaf-out just fine next spring, although you may see some branch die-back symptoms. Heavy defoliation for two or three years in a row may result in some tree mortality.

Basswood leafminer turning basswood trees brown north of Lansing
Dave Smitley, Entomology

Interestingly enough, at the same time the locust leafminer is browning trees in southern Michigan, a closely related beetle, the basswood leafminer, is browning trees in central Michigan. The most noticeable damage seems be from just north of Lansing to Bay City, but there could be damage in other parts of Michigan that I have not yet heard about.

The basswood leafminer is about the same size as the locust leafminer (6 mm) but is a dark reddish-yellow color with wedge-shaped wing covers. The majority of the damage is also caused by the larvae tunneling mines in the leaves. The cycle of damage and natural control by parasites is the same as is described above for the locust leafminer. Basswood or lindens (all Tilia spp.) are the primary host trees, but these beetles may make mines in the leaves of apple, birch, cherry and maple, too.

Asiatic garden beetle beginning to show in a few hot spots
Dave Smitley, Entomology

Ken and Jan DeBruyn of DeBruyn Seed in Zeeland alerted me to this new problem last year. The potted geraniums and other flowers in the Zeeland Cemetery are being defoliated in July by a 1/2 inch-long reddish-brown beetle that looks somewhat like a small June beetle. I was just there last week following the West Michigan Nursery Field Day, and had no trouble finding 10 to 20 beetles under most pots of flowers, and lots of old defoliation damage.

Asiatic garden beetle appears to love geraniums, a plant that is toxic to most insects. The only way to prevent feeding damage is to spray the geraniums with Sevin or Tempo in early July and again every week or two until August. Another sample of Asiatic garden beetle came into Diagnostic Services last week from a different location in southwest Michigan. This is a new pest to start watching for in southern Michigan.

Japanese beetle biocontrol field day
Dave Smitley, Entomology

A Japanese beetle bicontrol field day will be held on Saturday, October 21, at the Binder Park Golf Course in Battle Creek. Anyone interested in digging-up infected grubs to take back to their part of the state to facilitate the spread of Japanese beetle pathogens throughout Michigan is invited to attend. The meeting will start at 10:00 AM at the Pro shop. We will walk about a quarter of a mile to an area between two fairways to collect infected grubs.

You should bring a flat shovel or sod-cutter, thin gloves, a plastic bucket for each person, and your sense of humor. (I mean, who is really going to believe what you are doing?)

Please let others know about this biocontrol field day. At this time, only the Battle Creek-Kalamazoo area has the most important pathogens. The rest of Michigan, and neighboring states, need to be seeded with infected grubs. Only seed infected grubs into areas with active Japanese beetle infestations (The pathogens can only be introduced where an active population will support them.). Also, Japanese beetles cannot be transported to the Upper Peninsula of Michigan, or to states or portions of states that are not yet infested. These are live grubs and could start a new infestation.

Research highlights from the 51st Southern Nursery Association Research conference
Bert Cregg
Horticulture and Forestry

Dateline: Atlanta
Nursery researchers from throughout the country met at the Georgia World Congress Center August 9 and 10 to present over 170 papers and posters on the latest developments in nursery production at the Southern Nursery Association (SNA) Research conference. The SNA is one of the largest gatherings in the country devoted exclusively to nursery research. Here are some of the highlights of this year’s conference.

Proceedings of past SNA research conferences are available on-line at: http://www.sna.org/research/

Effect of vermicompost on nutrient kinetics of pine bark substrate
Michelle McGinnis (NC State) followed the cumulative nutrient release of container media amended with either 10% or 40% vermicompost. Over the course of the study, the addition of vermicompost greatly increased nitrogen availability, but reduced P availability. McGinnis noted that the difference in the availability of the elements is due to the fact that nitrogen release is directly related to microbial activity, whereas phosphorus availability is a physical/chemical phenomenon with greater amounts of P adsorbed with increased organic matter.

Alternative container substrates
The potential of a shortage (or at least escalating prices) of pine bark has spurred interest in developing alterative container substrates. Research in the South is focusing on two primary alternatives.

Use of wood chips as container substrates
Southern nurseries continue to be concerned with availability of pine bark for container substrate. A growing body of evidence has shown the wood chip media can grow an acceptable nursery crop. Research at Virginia Tech examined effects of species and chip size on wood-chip media. Decreasing wood chip particle size from ¼ to 1/16” increased plant growth of container-grown plants. The benefit of reduced of particle size was attributed to increased water holding capacity and increased EC compared to the larger particle size.

Breanna Rau (Va Tech) examined growth of container-grown plants grown in wood chips from five different species. Growth varied depending on the species of trees used to produce the chips. The ranking of the species was (from most to least crop growth):
loblolly pine > sycamore > white pine > red maple > white oak

The effect of chip species was attributed to amount of extractable polyphenolics in the chips, which was negatively correlated to crop growth rates.

Calcined clay amendments
Jim Owens (Oregon State University) reported on the continuation of his Ph.D. research at NC State on the use of calcined clay as an amendment for pine bark-based media. Previously Dr. Owens had reported that calcined clay improved growth of cotoneaster by improving water and nutrient holding properties of the media. Additional research, however, has shown that the benefit of the clay amendment is species specific.

Cheryl Boyer (Auburn) reported on trials using clean-chip residuals as a substrate for bedding plants. Clean-chip residuals are the by-product of whole-tree chipping, which is an increasingly common practice in Southern forest management. In harvesting operations whole tree chippers are brought onto the logging site. As part of the whole-tree chipping process, trees are first passed through a chain-flail delimber/debarker before the stem is passed though the chipper. The residual limbs, needles and bark were previously left on the site, but Boyer and his co-workers found the material may be a suitable substrate for annual production. They found that growth and physiology of salvia was similar for plants grown in the clean-chip residual substrate versus plants grown in a standard pine-bark media.

Frank Henning (Univ. Of Georgia) monitored cold hardiness of azaleas following fall fertilization. Azaleas were fertilized at rates up to 125 mg/l as late as November. At the highest rate/latest fertilization combination cold hardiness was reduced by 5-8oC.

Mid-season pruning reduced cold hardiness in five out of six Abelia cultivars in a trial conducted by Matt Chappell (UGA). Chappell recommends dormant season pruning to reduce potential for winter injury.

Ursula Schuch (University of Arizona) reported that capillary irrigation mats reduced water use by 63 to 71% compared to hand watering in two trials conducted at retail garden centers. Schuch listed various benefits of the mats in retail centers including uniformity, no wet floor, no run-off, personnel sell plants instead of watering them, no evaporation from empty mats, no emitters to clog. The principle disadvantages of the system are initial setup cost, cleaning and maintenance, and the need for a level surface.

Cyclanilide as a branching agent of nursery crops
Cyclanilide, an auxin inhibitor, increased lateral branch density on Indian Hawthron at rates up to 50 ppm. Phytotoxicity was observed at 300 ppm.

Phosphorus – how low can you go?
The environmental impacts of nursery production – particularly the fate of phosphorus and nitrates – continue to be an active area of research. Container fertilizers commonly contain a Nitrogen Phosphorus ratio of 5:1. K.N. Walton (NC State) grew herbaceous perennials with varying ratios of N:P, maintaining N at 150 ppm and K at 50 ppm. Crop growth was unaffected even at the lowest P levels tested (N:P 32:1), suggesting significant reductions in P additions may be possible without adversely affecting crop growth.

Chestnut growing in Michigan
Dennis Fulbright
Plant Pathology

My laboratory at Michigan State University is involved in a long-term project to help growers establish chestnut orchards in the state. This program is dedicated to growing chestnut trees for the emerging chestnut industry in Michigan and other states.

If you are interested in bringing back the American chestnut tree, we have a research program on that, too. The center of activity for this research is at the Rogers Reserve, an MSU research farm working on chestnut research in Jackson. You can go to www.chestnutgrower.org for more information on growing chestnut trees in Michigan.

Basically, there are three groups involved in the nut industry in Michigan: The Michigan Nut Growers Association (MNGA), the Midwest Nut Producers Council (MNPC), and Chestnut Growers, Inc (CGI). The MNGA is the oldest and is a good group to start with. It holds its annual meeting the second Saturday in April each year. The meeting is held on campus in Farrall Hall, the ag engineering building on Shaw Lane. Anyone is welcome to attend and find out more about growing nut trees, including chestnuts in Michigan. The time of the meeting each year is 9:00 AM to 2:00 PM. The MNPC meeting follows this meeting from 2:30 PM to 5:00 PM and is currently dedicated to research on chestnuts. Mark your calendars if you are interested in growing nuts for fun or profit.

White grubs begin feasting on turf roots
Dave Smitley
Entomology

I have seen lots of small European chafer and Japanese beetle grubs feeding in lawns and on golf courses. The grubs will be getting larger and eating more in September. Watch for grub damage to appear in late September and October, especially during dry periods when the turf is stressed and wilting.

Also, with the bumper crop of Japanese beetle adults this year, expect more grubs and more skunk and raccoon damage than usual. Merit and Arena will give some control of grubs in September, but not nearly the level of control that you get when it is applied in July. The only other products labeled for control of grubs in the fall are Sevin and Dylox, which work fairly well when watered-in immediately after application with a 1/2 inch of irrigation. Use a granular formulation when treating areas that are not irrigated. Sevin and Dylox degrade quickly in soils with a high pH (> 7.5).

Turf tips as autumn appears
Kevin Frank
Crop & Soil Sciences

It happened this morning on my drive into campus. I knew it was coming, the invasion of 40,000 students back to campus obviously gave me the first warning; the promise of another college football season that would be different than the past Spartan struggles was another sign. However, this morning when I saw that maple tree on the corner starting to show its crimson red colors, I knew autumn was officially right around the corner.

In the August 25 Landscape Alert issue, I covered the basics for reseeding damaged turf areas and touched on fall fertilization applications. Here is a wrap-up on turf issues you may want to think about in the next month.

Rusty sneakers
One of the dangers of autumn is turning those new, white school sneakers to orange after walking through the lawn. After what was a sporadically sultry summer, the cool temperatures in autumn often result in rust showing up on lawns. Rust is very diverse; there is stem rust, crown rust, leaf rust and stripe rust. Don’t worry about what rust might be contaminating your lawn, as a general rule in almost all cases rust is considered a cosmetic turfgrass disease that although it may discolor the turf, it will not result in wide-spread death of the turfgrass. If you find yourself inundated with a bad case of rust, make sure to keep up on your mowing, and if you haven’t applied any fertilizer in a while, consider a fertilizer application to stimulate turf growth, which will help diminish the impact of the rust.

Broadleaf weed control
Just a reminder that all of those tough to control broadleaf weeds that you’ve struggled with all season long can be effectively controlled in the autumn with a well timed herbicide application in the latter part of September and first week of October.

Foreign grain beetle: A fall invading insect that prefers new homes
Howard Russell
Entomology

There is a strange little bug that shows up about this time every year called the foreign grain beetle, Ahasverus advena (Coleoptera: Cucujidae). This tiny beetle is considered a stored product pest in the literature, although it feeds primarily on molds and fungi growing on damp grain, grain products and other materials. It is found throughout the world and is very common around grain processing facilities where damp, moldy grain is allowed to accumulate.

Little is known about its habits in "nature," however, it is reasonable to assume this beetle can occur in any damp situation where fungi persist. One odd thing about this beetle is that most of the specimens sent to this lab are collected from new homes. Possibly because the wood, plaster, concrete and other building materials in new construction may not be completely dry and will support a thin, invisible layer of fungi which attracts the beetles. These beetles can fly and are very small, so it is possible for them find their way into the house through screens and around loosely fitting windows and doors. These insects will stop coming in from the outside as colder fall temperatures arrive.

Dogwood sawfly larva: a wood destroying pest?
Howard Russell
Entomology

Not only is the dogwood sawfly a pest of dogwood trees, it can also be a problem to homeowners by boring into landscape timbers and other wooden objects in ground contact in the fall of year. It doesn’t eat wood, but instead it chews out little chambers in which to spend the winter.

There are three species of Macrempytus (Hymenoptera: Tenthredinidae) sawflies in the eastern United States. All three species feed on the foliage of dogwood. Early larval stages are covered in a white powdery substance, which is thought to mimic bird droppings. This white covering is shed in the fall as the larvae prepare to pupate. The larvae construct pupal chambers by boring into dead wood on the ground.

Sprays containing Sevin, cyfluthrin or Malathion will control them on dogwood. Their damage to wood can be controlled by applying residual insecticide, such as cyfluthrin, to the areas where the larvae are boring.

Boxelder bugs: Looks like another bumper crop this year
Howard Russell
Entomology

Will we have good fall color this year?
Bert Cregg
Horticulture and Forestry

As an Extension specialist, this is one of the calls I dread. Newspaper reporters, school kids – everyone wants a prediction on fall color. Although it doesn’t stop us from trying, a reliable prediction on fall color in Michigan is virtually impossible. Environmental conditions going into the fall certainly influence fall color (With relatively mild conditions of late for much of the state we would expect pretty good fall color this year.). But conditions during fall also influence fall color, and likely to a greater degree.

While the intensity of fall color certainly varies from year-to-year, I contend that the duration of fall color and our perception of fall color vary more. Fall color is greatest when we have bright, clear days and cool nights. However, if conditions are too dry leading into the color season, leaves may begin to turn early and drop quickly. We may still have fairly intense color, but if the show doesn’t last long, we’re less likely to notice. This could be the case on the west side of the state, where the weather has been dry and some trees are already beginning to turn. Also, I believe weather during the fall influences how we perceive tree color. If you drive up north on a bright, clear day with a brilliant blue sky, we’ll perceive the color as more striking than if we saw the same trees on a drizzly, grey overcast day.

If you want to learn more about the development of fall color in trees and keep track of this year’s fall color, check out the USDA Forest Service Fall Color website at:
http://www.fs.fed.us/r2/recreation/fallcolors/chemistry

Weather news
Jeff Andresen
Agricultural Meteorology
Geography

An upper air troughing feature will build into the Great Lakes region by Saturday, September 9, bringing much cooler weather to Michigan for the upcoming weekend. A cool front will move from northwest to southeast across the state during the day Friday into Saturday, leading to scattered showers and thunderstorms. Precipitation totals through Sunday will generally range from a quarter to a half inch where rain falls with some areas remaining dry. Canadian high pressure will move into the state and region late Saturday and Sunday behind the frontal system, bringing noticeably cooler and drier weather. Mean temperatures during the next several days will fall back below the normals with highs into the upper 50s north to the low 70s south with lows reaching the upper 30s to the mid-50s. Some scattered frost and freezing temperatures are a possibility in low-lying, interior sections of Upper Michigan and northern Lower Michigan overnight Saturday. Early next week, forecast guidance is offering contrasting solutions with some guidance suggesting the formation and passage of an area of low pressure and widespread precipitation through at least southern sections of Michigan on Tuesday while other guidance keeps all of the state cool and dry under the influence of high pressure to our north. Highs during that time frame will range from the 60s north to the low 70s south with lows in the 40s to low 50s.

Medium range forecast guidance calls for the upper air troughing pattern mentioned above to gradually give way to a more west to east zonal pattern over the continental United States. The official NOAA Climate Prediction Center 6-10 and 8-14 day outlooks (covering September 13-17 and September 15-21) both call for near normal precipitation totals. For the 6-10 day period, mean temperatures are forecast to range from near normal over Lower Michigan to above normal over the Upper Peninsula. During the 8-14 day time frame, temperatures are expected to increase to above normal levels statewide. Unfortunately, given recent discontinuity and disparity among some of the forecast guidance tools, forecaster confidence in both of these outlooks is rated as much below normal.

Further ahead, the latest version of NOAA’s long lead outlook for the month of September calls for increased odds of above normal temperatures over northern sections of the state and for the equal chances/climatology scenario of near equal odds of above-, near-, and below-normal temperatures over southern sections of the state. The outlook also calls for the climatology scenario for precipitation statewide. Finally, the three-month seasonal outlook for the September-November period calls for increased chances of milder and drier than normal weather statewide.