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Landscape Alert newsletter

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Vol. 23, No. 9, June 6, 2008

In this issue
Landscape and nursery

A big year for outbreaks of soft scales in Michigan

Irrigation critical for newly planted trees and shrubs

Selecting trees for deep rooting

Scouting for weeds: Mossy stonecrop

Weed-whackers gone mad
Turfgrass

What’s popping up in turf?

Landscape and Turf Diagnostic tour of the Applewood Estate
Christmas trees and forestry

Frosted oaks observed between Wexford and Manistee counties

Gypsy moth spray window update

Forestry field report from north central Michigan
Other news

Weather news

A big year for outbreaks of soft scales in Michigan
Dave Smitley
Entomology

Lecanium scale, calico scale and cottony maple scale are covering branches of silver maple, honeylocust and many other species of hardwood trees in southeast Michigan, the Saginaw Valley region, and a few other parts of the state. The biggest problem comes from the droplets of honeydew raining down from infested trees in May and early June. Eggs have formed under female lecanium scales in the Detroit area, and should be forming soon under calico and cottony maple scale females. Once the eggs form, the female stops feeding and the rain of honeydew subsides until later in the summer when the next generation begins to develop. Honeydew is the sugary liquid waste excreted by scale insects. A considerable amount of honeydew is excreted because scale insects need to suck lots of sap from trees in order to get the amount of protein they need for growth and development. This creates a large excess of sugars that are excreted in the honeydew. Honeydew rain is particularly annoying when branches of infested trees are over decks or parked cars. The scale infestations rarely damage trees, even when the trees are very heavily infested. In Saginaw and Bay counties where the mosquito spray programs suppress predators and increase the intensity of scale outbreaks, we sometimes see trees that become thin and experience branch dieback.
	Lecanium scale. Photo credit: Vermont Extension Service.

	Cottony maple scale. Photo credit: University of Georgia.

For some tips on insecticide management of lecanium scale and cottony maple scale, I talked to Dave Sutton, a Tri-City Tree Doctor, about his test trials with different insecticide treatments in Saginaw and Bay counties. Until a few years ago, he relied on using acephate (Orthene) or pyrethroid insecticide sprays at peak crawler emergence in mid-June to early July for scale control. More recently he has had better success with imidacloprid or imidacloprid/acephate trunk injections. Dave prefers to use the Arborjet trunk injection system, but several other trunk injection products are also available (Table 1). Spring trunk injections of imidacloprid have not given very good control of the large female scales in May or early June, but they give excellent control of the next generation of crawlers and young scales that settle on the leaves in July and August. That is why he injects both acephate and imidacloprid in May, because the acephate controls the females feeding in May and June, and the imidacloprid controls the young scales during the summer. In order to do this, the acephate is injected first because it is taken-up rapidly. After the acephate goes in, the lines are cleaned and then imidacloprid is injected through the same ports. More information is available at his website: www.tree-doc.com. When the rain of honeydew stops in the next two to three weeks, there will be little benefit to using acephate, and the imidacloprid can be used by itself.

Another treatment option that Dave Sutton likes to use is adding an imidacloprid basal drench (or basal soil injection) to the imidacloprid/acephate trunk injection. He feels confident in achieving long term soft scale control when the trunk injections/drenches are followed with basal drenches alone each year afterwards.

Table 1. Imidacloprid trunk injection products

Irrigation critical for newly planted trees and shrubs
Bert Cregg
Horticulture and Forestry

After a fairly cool start to our spring, it looks like we will jump right into summer with temperatures forecast in the 80s and even 90s in the next week. With such warm temperatures this early in the season, it is essential to keep newly planted trees and shrubs watered to insure survival and rapid establishment. New trees, whether container-grown or balled-in-burlap, need time for their roots to grow into surrounding soil in order to survive the transpiration water loss associated with afternoon temperatures in the 80s and 90s. When planting trees in the spring, remember to give them a good watering immediately after planting and then once a week for the first two months. For the rest of the summer, watering once every two weeks should be adequate unless we get into an especially hot and dry spell.

MSU campus arborist Paul Swartz is an advocate of using irrigation devices such as GatorBags to water newly planted trees. The bags are designed to trickle out 20 gallons of water over six to eight hours; this improves the efficiency of water use by reducing surface run-off and allowing the water to soak deeper into the soil, promoting greater rooting. “This year we’re having a major planting effort on campus and we’re using about 1,200 Gator Bags” Swartz notes. “They give us flexibility because we can zip two or three together for larger trees.” MSU Landscape Services crews fill the bags once a week during the establishment year.

Mulching is another key to improving survival and early growth on newly planted trees and shrubs. As we’ve noted before, mulching provides multiple benefits for plants; conserving soil moisture by reducing surface evaporation and reducing weeds are highest on the list. Our research on mulch at the MSU Horticulture Teaching and Research Center suggests that almost all organic mulches (wood chips, ground or shredded bark) can fulfill these functions. To paraphrase the old Nike ads, our motto is, “Mulch: Just Do It!”

GatorBags around trees on MSU’s campus.

Selecting trees for deep rooting
Bert Cregg
Horticulture and Forestry

I recently received a phone call from a person responsible for planting trees in a small local cemetery. The landscaper was interested in selecting deep-rooted trees to avoid development of extensive root systems that might interfere with gravesites. Unfortunately, there is relatively little information on selection of deep-rooting trees. Most of the information in this regard is based on avoidance of shallow-rooted trees that can damage sidewalks by growing underneath them.

The leading “problem children” for sidewalks are sweetgum, elms, ashes and maples. The common denominator for these trees is that they are adapted to bottomland or wet-site sites and tend to form extensive root systems. Conversely, trees from upland sites such as oaks, hickory, and beech tend to form tap-root or heart root systems and may be less likely to send roots into adjacent areas where they are unwanted. The caveat with recommending trees based on root habit is that soil conditions can trump the tree’s predisposition to form either spreading roots or a tap root. For example, studies have shown that eucalyptus trees grown on sandy sites will form a deep taproot while the same species grown on a poorly drained area will form an extensive root system. So the key, as always, is to know your site, know your trees and plant the right tree in the right place.

Scouting for weeds: Mossy stonecrop
Steven Gower
Diagnostic Services

Mossy stonecrop (sedum acre) is a small, fleshy plant that can become a very difficult-to-control weed once established in a lawn. Mossy stonecrop belongs to a family of succulent plants (crassulaceae) introduced as an ornamental for rock gardens because of its ability to grow in very coarse, sandy soils of poor fertility. Unfortunately, mossy stonecrop can infest lawns with similar characteristics, out-competing desirable lawn grasses to become a serious weed. Mossy stonecrop, the only weedy Sedum sp. commonly found in Michigan, can be found on shores and dunes, along roadsides, in waste areas and in lawns.

Mossy stonecrop infesting a lawn.

Mossy stonecrop: (Sedum acre)

Family: Crassulaceae (Orpine).

Life cycle: Low-growing, spreading perennial.

Leaves: Thick, succulent, pointed leaves are egg-shaped to round in cross-section. The small, waxy, alternate leaves are generally light green in color.

Stems: Matted stems contain densely overlapping leaves.

Flowers and fruit: Bright yellow, five-petalled flowers form in June and July. Seeds are produced in pointed seedpods.

Reproduction: Seeds, creeping horizontal stems and stem fragments.

Control: Mossy stonecrop can form dense mats in sandy soils low in fertility. As with any lawn weed, understanding and addressing the cultural conditions that promote certain weeds in the lawn will certainly provide more control than any herbicide treatment alone. Mossy stonecrop can be very difficult to control with broadleaf herbicides for turf. Therefore, improving soil health, fertility and organic matter in combination with an herbicide treatment can be very effective. When intermixed with desirable lawn grasses, herbicides that contain 2,4-D, dicamba, MCPP, MCPA, triclopyr or mixtures of these active ingredients can provide some control. Repeated applications will be necessary. Herbicides that contain glyphoste (Roundup, others) may be the best choice for control of large, established patches. Remember, glyphosate is non-selective and will also kill any desirable grasses present.

Note: Additional surfactants (spreader/sticker agents) will greatly improve control of these products due to the very waxy leaf surface of mossy stonecrop.

Note: Identification information for more weeds is available in the field guide An IPM Pocket Guide for Weed Identification in Nurseries and Landscapes. To order, call 517-353-6740.


Thick, succulent, densely overlapping leaves.

Weed-whackers gone mad Andrea Buchholz, assistant editor Our newest challenge idea comes from Duke Elsner, Grand Traverse County MSUE educator. He submitted a photo demonstrating some horrendous weed-whacker damage. Please submit your disastrous weed-whacker photos to catalert@msu.edu. Remember to include a short caption and credit to the photographer. Challenge ends June 27.
	Weed-whacker damage on tree. Photo credit: D. Elsner

What’s popping up in turf?
Kevin Frank
Crop and Soil Sciences

White clover and black medic
There are many weeds actively flowering in lawns right now. A couple that always catch my attention and are often found growing together are white clover and black medic. White clover is a unique weed in that some folks prefer to leave it in their lawns and has sometimes even been seeded in turfgrass mixtures for lawns. You might wonder why on earth anyone would want to seed white clover into their lawn when you may be thinking of how to get rid of it.

White clover is a nitrogen fixer, so the idea is that you could have clover and turfgrass co-exist in a lawn and the white clover would provide some nitrogen for the turfgrass. White clover’s ability to fix nitrogen makes this weed very competitive in lawns that are not fertilized or are growing on low fertility soils. One cultural recommendation to help turfgrass compete with both white clover and black medic is to fertilize. If you feel the need to kill either of these weeds before it takes over your entire lawn, products that contain the active ingredient triclopyr will be effective especially if you can hit them while they are flowering. If you can make it through the summer coexisting with these weeds in your lawn, your best time for treatment is in the fall when the weeds are storing carbohydrates in their roots for next year. Herbicide applications in the fall are more readily transported to the roots and effectively kill the weed once and for all.

Seedheads in lawns

Many lawns are really pumping out the seedheads right now. Some lawns had seedheads popping earlier in the spring, but many lawns have come on really strong with the seedheads in the last week. The cool temperatures and lack of moisture may have delayed the seedhead production in some lawns this spring. Seedhead production requires energy from the plant, so it is likely the turf will not only look stemmy due to the seed stalks, but the turfgrass may even thin out. Keep the blade sharp and provide some fertilization if you haven’t recently to help the turf recover. Also, the lawn is not going to be reseeded by seedhead production. Even if the seed was allowed to reach maturity, which would take about four months, allowed to dry and then harvested, you’d still need to make sure that seed would find a home in the soil in order to germinate. If you need to fill in some areas in your lawn, it’ll be easier to go buy some seed.

Crabgrass
Following the very light rainfall earlier this week, it didn’t take long to find some young crabgrass popping through the soil. There are certainly plenty of voids in the turf right now for crabgrass to invade, so keep your eyes open. If you’re going to try and control it, doing it when it’s young is going to be easier than once it matures.

Landscape and Turf Diagnostic tour of the Applewood Estate

Genesee is sponsoring a Landscape and Turf Diagnostic tour of the Applewood Estate in Flint, Thursday, July 10 from 6:00-8:00PM. Cost for attending the workdshop is $15 per person before July 3 and $20 after July 4. Registration will be open until the class is filled (35 people maximum).

This hands-on workshop is meant for commercial pesticide applicators, landscape and nursery professionals, and anyone interested in improving their ability to diagnose landscape issues. Two MDA credits for either commercial core, category 3A, category 3B or category 6 have been applied for.

The registration brochure has also been posted at
http://www.ipm.msu.edu/cat08land/pdf/6-06applewood.pdf

For more information, please call 810-244-8512.

Frosted oaks observed between Wexford and Manistee counties
Dennis Fulbright, Plant Pathology
Jill O'Donnell, Christmas Tree ICM educator

Oak trees that line the roads from western Wexford County all the way to Manistee were burned by the frost of Wednesday, May 28. These lifeless looking trees had been in the process of leafing out when the frost struck. Chances are good that they will re-bud and leaf out again this spring. At first, the problem may look like insect damage, such as gypsy moth, or anthracnose disease, but in our best judgment, the lack of leaves is from the frost.

Gypsy moth spray window update
Mike Bryan
MDA

Growers should note that for the Zone 5 Upper Peninsula counties, the open date for all other compounds has been set as Monday, June 9. The Dimilin spray window close date for Zone 1 and Zone 2 has been set as Sunday, June 15. Spruce, fir and Douglas-fir nursery stock being shipped to destinations outside the gypsy moth regulated area requires a new treatment once the spray window is open. The reason is that gypsy moth hatch is imminent and nursery stock is at risk for infestation by larvae ballooning on their silk. Those who ship nursery stock outside the regulated area should consult with MDA staff for obtaining certification to meet the USDA Gypsy Moth Quarantine.

The following chart shows actual and projected open/close dates for application of the two groups of pesticides used for regulatory treatment of gypsy moth in nursery stock and Christmas trees. We are listing the projected dates as guidelines to help you plan your pest management program. Since gypsy moth development will vary by location, you will need to monitor development around your farm. Weather conditions will affect caterpillar development and may effect end date of the spray windows. Growers should watch the Landscape Alert for additional announcements.

Zone	*Open – Dimilin (150 DD)**	Open – all other compounds (200 DD)	Close – Dimilin (700 DD)	Close – all other compounds (800 DD)
1	May 1	May 6	June 15	Delayed until after June 15
2	May 1	May 6	June 15	June 20 (projected)
3	May 6	May 17	June 21 (projected)	June 27 (projected)
4	May 10	May 21	June 28 (projected)	July 4 (projected)
5	May 16 - Lower Peninsula counties only in Zone 5	May 27 – L.P. counties only in Zone 5	July 3 (projected)	July 11 (projected)
5	June 5 - Upper Peninsula counties only in Zone 5	June 9 - U.P. counties only in Zone 5	July 3 (projected)	July 11 (projected)

Forestry field report from north central Michigan
Russell Kidd
Roscommon CED
District forestry educator, NLP

The freeze that hit northern Michigan on the morning of Wednesday, May 28, resulted in some freeze damage to plants in scattered locations. temperatures fell to as low as 25-26°F in some inland areas of the north. Freeze damage to red oaks, still in the tender “mouse-eared” stage of growth, was evident in parts of Roscommon, Crawford and possibly other areas. Some minor damage to low-growing plants, such as bracken fern and young forest trees, was also observed in some areas.

It’s been a banner year in many areas of north central Michigan for the Eastern tent caterpillar. Populations exploded this spring with many scrub cherries supporting several tents of Eastern tent caterpillar. Complete defoliation is now evident on some trees, and the larva are abandoning their tents in search of places to pupate.

Of significant interest are the scattered reports and observations that are starting to emerge from across the north about building populations of forest tent caterpillar. Northern lower Michigan has not experienced a significant outbreak of forest tent caterpillar since 1988-1990. At the height of the last outbreak, wide scale defoliation of northern hardwood stands was very evident across many areas of the lower peninsula. This insect is known to experience high populations that lead to major defoliating events about every 15 years or so.

Here in the Roscommon and Crawford County area, forest tent caterpillars have been observed spinning down on silken threads from red oaks as well as masses of caterpillars forming on the base of scattered trees. No real defoliation was observed, however, at this point. Some calls and reports also were received from Manistee and Otsego counties. So, a major outbreak of forest tent caterpillars may be in the making across the north!

Many of tree species that produce seed in the springtime are experiencing extremely large seed crops this year. In many areas of north central Michigan, the heavy seed crop is very evident on red maples. Looking ahead, once this seed drops to the ground, many of these trees are likely to look bare in spots as the seed crop appears to be displacing a lot of the foliage, therefore expect calls from clients as to “Why is my maple tree looking so bare and ragged?”.

Other species, such as aspen and oaks, also appear to be producing bumper crops of both male pollen and female flowers. Over the last week, oak male flower chains are falling everywhere in mass and there is a lot of cotton flying through the air from aspen and other poplar species. The long summer drought of 2008 is likely the cause of this excess seed production

Weather news
Jeff Andresen
Agricultural Meteorology
Geography

The gradual change of the upper air configuration across North America to a western trough, eastern ridge pattern mentioned in last week=s column took place earlier this week, resulting in strong southwesterly flow aloft currently across the Great Lakes region. On the ground surface, a frontal boundary marking the boundary between a relatively cool, dry air mass centered over the Canadian Maritimes and a hot, humid air mass across much of the southern United States stretched from an area of low pressure in the northern Great Plains eastward through Michigan to the Mid-Atlantic region. This frontal boundary is expected to oscillate north- and southward across the Great Lakes region during much of the next week, setting the stage for an extended period of unsettled weather conditions with a chance of showers and thunderstorms on an almost daily basis.

Saturday (June 7) and Sunday (June 8) the front will linger across southern sections of the state, setting off scattered showers and thunderstorms. Given strong winds aloft and low level heat and humidity in place, some thunderstorms both days could be severe, with high winds, hail and tornadoes possible. Scattered, more garden variety showers and thunderstorms are also possible each day Monday through Wednesday of next week. Rainfall totals during the next five days are expected to be variable, ranging from 0.50-inch in some locations to more than 1.00 inch in others. Some 1.00-2.00 inch totals are possible, especially across northern sections of the state. Temperatures during the next few days will remain at much above normal levels with highs Saturday and Sunday reaching the upper 70s north to low 90s south with lows from the upper to mid-50s to upper 60s. Humidity levels will also remain at high levels, with dew point temperatures through Sunday generally reaching the 60s to near 70°F in some spots, leading to uncomfortably muggy conditions, especially during afternoon and early evening hours. Temperatures are expected to drop back a few degrees by the middle of next week, with highs generally ranging from the mid- or upper 70s north to the mid-80s south and lows from the low or mid-50s far north to the mid-60s south.

The medium‑range forecast guidance calls for a gradual flattening out of the upper air pattern mentioned above by mid-June, which might ultimately result in cooler temperatures during the latter half of the month. The National Weather Service 6‑10 day and 8-14 day outlooks covering June 11 through June 15 and June 13 through June 19 both call for above normal precipitation totals. Mean temperatures during the 6-10 day period are forecast to range from below normal levels across northwestern sections of the state and for above normal levels across central and southern sections. Temperatures during the 8-14 day time frame are forecast to range from near below normal levels across extreme northern and central sections of the state to near normal across the south.

The MSU IPM Program maintains this site as an access point to pest management information at MSU. The IPM Program is administered within the Department of Entomology, fueled by research from the Michigan Agricultural Experiment Station, delivered to citizens through MSU Extension, and proud to be a part of Project GREEEN.
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06-06-08