Landscape and nursery
§ Right tree, right place
§ Scouting for weeds: corn speedwell
§ Tar spot on maple fungicide timing is now
§ Lawn tips to save cash
Turfgrass
§ Lawn tips to save cash
Christmas trees and forestry
§ Herbicide-resistant
weeds in
§ Charcoal
of Fraser and
§ Christmas trees and forestry insect update for May 2
§ Gypsy moth spray window update May 2
Around the home
§ Ground nesting bees are scary but harmless
§ Warm weather brought the ticks out
§ Polyxenus millipedes
§ Red squirrel injury to arborvitae
§ Where did all those winter cutworms go?
Other news
§ Weather news
Next issue May 9
Bert Cregg, Horticulture and Forestry
We’ve all heard the mantra “Right tree, right place.” For many people, however, it’s one of those pieces of advice like “Eat right and get regular exercise” that seems to go in one ear and out the other. None of us can debate the importance of matching tree to site; just like no one can deny that proper diet and exercise are important for our own health. Yet time and time again we run into landscape problems where a few minutes spent on assessing the site and considering which trees are best suited to the conditions would have prevented the trouble before it started. A couple of recent situations I’ve observed set me to thinking about all this. In one case, the problem is fairly minor; the second should make your blood boil if you’re a taxpayer.
In the first situation, a homeowner planted a row of white spruces on the north side of their property as a windbreak. The trees are about 8-10 years old and most are doing fine. The problem is right in the middle of the windbreak is a low spot that holds standing water every spring (Photo 1). Most of the spruces are doing fine but as the soil gets wetter moving toward the low area, the trees get shorter and shorter. At the lowest point, the spruces have finally succumbed after struggling the past couple of years. The situation is difficult since there are few, if any, evergreen conifers that will grow in this situation. Black spruce are among the most flood tolerant evergreen conifers, but not widely planted in the landscape trade. Several deciduous conifers such as baldcypress could tolerate the site, but wouldn’t provide the year round screen that was desired. Constructing a raised berm probably would be the ultimate solution to allow a continuous evergreen screen in this situation.
The second example of “wrong tree-wrong place” is a classic.
About 30 eastern white pines were installed as a screen for the rest area along
I-96 east of
The key in both situations is taking time to assess the site before planting. Assessing the site means accounting for the below ground environment (soil pH, soil texture, drainage) as well as the above ground environment (aspect, wind exposure, proximity of utility lines and buildings). Taking a little time before planting to size up the site and then selecting the tree to match the conditions is always easier than dealing with the consequences afterwards.
One of the earliest flowering weeds that homeowners may find
infesting their lawns and landscapes this spring is corn speedwell. There are
actually several species of speedwell (Veronica)
in
Corn speedwell (Veronica arvensis L.)
Family: Scrophulariaceae (Figwort).
Life cycle: Prostrate, spreading winter annual.
Leaves: Lower and middle leaves are opposite, broadly egg-shaped, hairy, short-stalked with rounded teeth along the margins. Small, narrow, bractlike upper leaves are alternate and without petioles.
Stems: Prostrate and mat-forming, with many branches that spread from the base.
Flowers and fruit: Light blue to violet, inconspicuous flowers are formed in the axils of the upper bract-like leaves on elongated flowering stems. Fruit are hairy, roundly heart-shaped capsules that contain many tiny, yellowish seeds.
Reproduction: Seeds.
Control: Corn speedwell can form dense mats in thin, poor quality turf. As with any lawn weed, understanding and addressing the cultural conditions that promote certain weeds in the landscape will certainly provide more control than any herbicide treatment alone. Generally, improving these cultural conditions in combination with an herbicide treatment can be very effective.
Homeowners have several herbicide options for control of
corn speedwell in the lawn. While these herbicides can be very effective, their
timing is more important than their application. Corn speedwell can germinate
in the fall or very early spring, resume growth in early spring and then flower
and set seed in April to May in
Herbicides that have good activity on corn speedwell in the lawn include 2,4-D, dicamba, MCPP and MCPA or mixtures of these active ingredients, commonly referred to as “3-way” broadleaf herbicides for turf.
Editor’s note: The identification information is from the
new field guide An IPM Pocket Guide for
Weed Identification in Nurseries and Landscapes. For ordering information,
call 517-353-6740 or visit: http://www.ipm.msu.edu/weeds-nursery/contents.htm
Tom Dudek, MSUE educator and Jan Bryne, MSU Diagnostic Services
Nursery tree growers who experienced problems and MDA restrictions last season with tar spot (Rhytisma sp.) leaf infections on maple trees should be targeting fungicide sprays now if "tree appearance" is critical. Apply either triadimefon, mancozeb or Junction at budbreak and at 7-14 day intervals.
Tar spot gets it name from the shiny black, tar-looking
lesions it creates on the leaves of several maple species. Several species of Rhytisma cause tar spot. Susceptible
maples include
Tissue is infected in the late spring and early summer after the leaves are fully expanded. Initially, the infected tissue turns light green or yellowish green. At this stage, the disease cannot be easily diagnosed. The pathogen grows slowly in culture; meanwhile more diagnostic symptoms will develop on the host. The diagnostic symptoms include the development of black, shiny, tar-like tissue on the surface of the foliage.
Destroying or fully composting fallen leaves in the fall
will help reduce innoculum for the next season in the residential setting. It
must be an area-wide effort. A good summary for homeowners’ questions is
contained in the Cornell Fact sheet on Tar Spot: http://plantclinic.cornell.edu/FactSheets/tarspot/tarspots.htm
Little, if any research is occurring on this disease especially resistant
cultivar trials and the problem is showing up all across the eastern USA.
Kevin Frank, Crop and Soil Sciences and Dean Krauskopf, MSUE educator
If you’re like me and keep getting cut-off at the pump by the max credit card charge, you’ve probably also thought about ways to reduce mowing or save money in other ways without compromising lawn quality. Here are some quick tips for maintaining a healthy lawn and saving some cash at the same time.
1. Mow high and follow the 1/3 rule of cutting only 1/3 of the top-growth at any one mowing. If you set the height of cut at 3.5 inches and follow the 1/3 rule, you would not need to mow until the turf reaches 5 ¼-inch height. The growth between mowing is 1 ¾-inch. If you mow at 2 inches and follow the 1/3 rule, you’d only have 1-inch between mowing. Mowing higher is healthier for the turf and should result in fewer mowings, which translates to less gas and less cash out of your pocket.
2. Mower check-up. How often do you change the oil in your car? Do you know where the oil goes in your mower? Tuning up the mower will help improve engine and mower efficiency. Invest a little in a tune-up and you could save a lot in the long-run.
3. Sharpen mower blades frequently. Have you ever had your mower start to “bog down?” One way to improve mower efficiency and improve turfgrass appearance and health is to sharpen mower blades. I try to sharpen my blades at least three times a year to keep the mower humming and turf at its best. Sharper blades will give you better looking and performing turf. Once again you could save some gas and some cash.
4. Return clippings. Mulching blade mowers really do a nice job of chopping up the turfgrass clippings, but even if you don’t have a mulching blade don’t let that stop you from returning clippings. Turfgrass clippings typically contain about 4 percent nitrogen, 0.5 percent phosphorus, and 2 percent potassium. Several researchers have suggested that continually recycling turfgrass clippings to the lawn could reduce nitrogen requirements by up to 25 percent. Don’t believe the hype that clippings contribute to thatch, clippings are about 80 percent water. Unless you’re leaving clippings in piles on the lawn, they won’t build up thatch. Returning clippings is free fertilizer and free definitely saves some cash.
5. Select slow release fertilizers. Select a fertilizer with a high amount of water insoluble nitrogen (WIN on the label) to extend the length of feeding to the turf. Slow release fertilizers will provide steady turf growth as opposed to quick release sources, such as urea, that result in growth surges that cause you to increase mowing frequency.
6. Irrigate when the turf needs it. Anyone that has followed this column throughout the years can recite my irrigation rants, so I’ll spare the repeat. Here’s some thinking points for now. In the last couple weeks, it’s actually turned into a dry spring. You might have noticed the turf isn’t actually surging with growth as lack of soil moisture is probably holding it back. However, the turf is still looking green as cool temperatures are balancing out the lack of moisture and keeping the turf looking good. Take advantage of this strange mix of weather and enjoy the time off the mower. I’m sure rains will come soon enough.
In the meantime if you’re looking for something to do, spend some time checking the distribution and accuracy of the irrigation system. We’ve all seen it too many times when sprinklers are watering sidewalks or even the street.
Steven Gower, MSU Diagnostic Services
Bernard Zandstra, Horticulture
Since the 2004 growing season, several greenhouse experiments have been conducted to evaluate triazine, ALS, glyphosate and PPO resistance in 58 weed samples collected from Michigan Christmas tree plantations. The most popular seedheads submitted were that of common lambsquarters, common ragweed, hoary alyssum, horseweed, Powell amaranth and velvetleaf.
During this screening process, herbicide resistance has been detected in several weeds collected from Christmas tree plantations throughout the state.
6 common lambsquarters populations.
2 pigweed populations.
12 horseweed populations.
4 velvetleaf populations.
1 common ragweed population.
7 horseweed populations.
1 horseweed population.
1 horseweed population.
Glyphosate resistance in horseweed was the most recent
herbicide resistance confirmed. This population was collected in the spring of
2007 from a Christmas tree plantation in Mason County, Michigan.
Weed control options for Christmas trees are severely restricted if growers have one or more weeds that are resistant to the triazines (Princep, Aatrex, Karmex), ALS-inhibitors (Oust, Westar) and/or glyphosate. The repeated use of an herbicide without other control methods is the primary cause of development of herbicide resistant biotypes. Practices to reduce the risk of herbicide-resistant weeds in Christmas tree plantations include:
1) Rotate herbicides with different modes of action.
2) Use soil-applied, residual herbicides in early spring.
3) Apply herbicide mixtures.
4) Scout fields for changes in weed populations or for weeds that escape herbicides that should control them.
5) Use tillage in combination with herbicides.
6) Incorporate the use of mulches, ground covers and timely mowing.
7) Use the recommended rates of herbicides for the appropriate weed height.
If herbicide resistance is suspected in any weed species, samples may be submitted to MSU Diagnostic Services for a resistance screen. Mature, high quality seed or seedheads should be collected from suspicious plants in late summer or fall and submitted in a paper bag or envelope. Do not seal plants or seeds in plastic! Fees associated with herbicide-resistant weed testing are $50 per sample per herbicide site of action (i.e. ACCase inhibitors, ALS inhibitors, Photosynthesis inhibitors). Each additional site of action is $20 per sample. Please contact Steven Gower (517-432-9693, sgower@msu.edu) with any questions regarding resistance confirmation or sample collection.
Certain weeds, such as horseweed, ragweeds, pigweeds and lambsquarters are more likely to develop resistance than other weeds due to prolific seed production and genetic plasticity/variability.
Dennis Fulbright, Plant Pathology and Jill O’Donnell, Christmas tree ICM educator
A disease that looks very similar to Phytophthora root rot
is beginning to be seen more often in Fraser and
Charcoal root rot is not new to
If you think you have seen this disease on your farm or nursery, please call Dennis Fulbright at 517-353-4506 or Jill O’Donnell at 231-779-9480.
Jill O’Donnell
Christmas Tree ICM educator
Scouting blue spruce this
past week, it seems we are seeing an increase in the numbers of spruce
needleminers. Right now you will find the larvae webbed into nests of
hollowed-out needles. These immature larvae over-wintered in these nest and
will feed for a few weeks and then pupate. Adults begin to emerge in mid-June
and lay eggs on the needles. In about two weeks, larvae hatch and begin mining
needles. Even though the larvae are present now, they are pretty protected in
the webbed nests. Timing to control this insect will be to control the larvae
just after they emerge from the eggs, in late June to mid-July. (View color
photo online at: http://www.ipm.msu.edu/cat08land/l05-02-08.htm.
Growers should begin to
scout for egg hatch of European pine sawfly (between 100 and 195 GDD50). This insect
rarely builds to high enough levels to significantly damage the health of
trees, but we have seen some pockets in past years with large numbers of sawfly
larvae causing severe defoliation. Often growers don’t realize they have a
problem until they see the trees turn brown from the larval feeding. Make sure
to walk through your fields. Scouting through the windshield you can mistake
this browning for Lophodermium needlecast on Scotch pine. If you see small
numbers of these little green larvae on your pine tree, just clip out the
colony. Lots of predators and parasitoids like to attack sawfly larvae too.
In the northern half of
the
In the
If you need to control
white pine weevil, your one opportunity is early in the spring. Insecticide
should be applied to the terminal leader once it begins to warm up somewhere
around 25-65 GDD50. It's
better to be a bit early than to be late with this application. Use a
persistent product, because the adult weevils don't all warm up at the same
rate.
Zimmerman pine moth is
another early season pest of Scotch pine and it will often infest Austrian pine
as well. The tiny caterpillars are currently on the bark of the stem and
branches, well protected in a silk shelter. Once they get warmed up, they will
start to chew under the bark. After they get under the bark, they will be well
protected for the rest of their life cycle. Therefore, if you plan to use an
insecticide to control Zimmerman pine moth, it needs to be applied early,
around 25-50 GDD50. Again,
use a persistent product and make sure to increase your amount of water per
acre to get good coverage on the trunk of the tree.
Mike Bryan, MDA
Growers should note that the spray window open date have been set for Zones 1 and 2 - all compounds for Tuesday, May 6. The spray window open date for Zone 3 – Dimilin has been set for Tuesday, May 6. The spray window open date for Zone 4 – Dimilin has been set for Saturday, May 10. 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 accompanying 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 Alerts 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 9 (projected) |
June 15 (projected) |
|
2 |
May 1 |
May 6 |
June 15 (projected) |
June 20 (projected) |
|
3 |
May 6 |
May 15 (projected) |
June 21 (projected) |
June 27 (projected) |
|
4 |
May 10 |
May 21 (projected) |
June 28 (projected) |
July 4 (projected) |
|
5 |
May 20 (projected) |
May 27 (projected) |
July 3 (projected) |
July 11 (projected) |
* DD = Degree days at base 50ºF.
Note: Projections are based on 30-year historical degree day data.
Zone map : A list of counties comprising each zone and a statewide zone map
appeared in the April
18, 2008 edition of the Landscape
Alert.
Howard Russell, MSU Diagnostic Services
Many people have called the lab recently to complain about large congregations of ground nesting bees in their yards. There are many common species of solitary bees that nest in the ground. Most of these belong to families Colletidae, Andrenidae and Halictidae. Those that terrorize us early in the spring are most likely andrenid bees. Unlike a colony of yellowjackets that use a single nest entrance and work together to raise their brood, each of these female bees construct individual nest tubes, each with its own opening. Even though large numbers of solitary bees often nest together, they do not cooperate or help each other raise their young, they just seem to enjoy each others company. Solitary bees are not aggressive and rarely sting, and there is no mass attack as might be found with honeybees and yellowjackets. People can mow over their nests and garden in close proximity to them with little worry of being stung.
Beginning in April or early May, females dig out their nesting tubes during the evening hours. These may reach six or more inches in depth. Tubes are lined with a secretion that protects the nest from moisture. Small mounds of soil may appear around each nest opening. During the day, the active females collect pollen and nectar to provision their nests. They lay a single egg on the collected pollen. After hatching, the larva feeds on the pollen and develops within the tube until it reaches adulthood in the fall. The new adult remains in the borrow until the following spring. At this time, mating takes place and bee activity begins to pick up as the nesting cycle resumes. Though adult bees feed on nectar, none store honey. Their nesting behavior usually lasts for four to six weeks. Ground nesting bees play a vital role in ecological systems, especially in pollination of crops and wild plants, and they should be preserved whenever possible.
Ground nesting bees generally prefer to nest in areas with morning sun exposure and well- drained soils containing little organic matter. Tunnels are excavated in areas of bare ground or sparse vegetation and damp soils are avoided. Damage to lawns and turf is usually minimal and control is often sought because the bees are perceived as a danger or annoyance.
Controlling solitary bees in yards is best accomplished by cultural control methods. The best cultural control method is to establish dense turf in the area(s) that the bees favor. Heavy watering or irrigation with a lawn sprinkler during the nest-building period may also help to discourage nesting behavior. If the soil or location is not conducive to a healthy, dense lawn, then using ground covers or heavy mulches may be an alternative solution. Mulches may be used on bare patches caused by heavy traffic where grass will not grow. I do not recommend control with insecticides because the bees are at worse a minor and temporary annoyance.
Howard Russell, MSU Diagnostic Services
Our recent warm snap fired up the dog ticks. We had several
people send us American dog ticks last week during our first real warm weather
of the year. Many more called the lab to report tick activity in their area. American
dog ticks, Dermacentor variabilis,
can readily be distinguished from other tick species by their white markings on
their backs. These markings appear differently on females and males. The American
dog tick is the most commonly found tick in
The cases of Rocky Mountain spotted fever reported in
These ticks are most likely to be encountered in the spring and early summer along animal paths in grassy, shrubby areas adjacent to woodlots and forests. Family members and pets should be inspected daily where ticks are known to be abundant. Insect repellents may help keep wood ticks from biting. Permethrin tick repellents can be applied to clothing to discourage ticks from climbing aboard. Yard borders can be sprayed with permethrin or Sevin to help reduce the number of ticks in yards.
Howard Russell, MSU Diagnostic Services
Last week a lady brought in some strange little creatures she found crawling on her basement walls. It was quite obvious that she was very annoyed with these little intruders. With a quick look through the scope, I was able to tell her that her bugs were adorable little Polyxenus millipedes, also known as duff millipedes. She didn’t want to hear about adorable. She didn’t want to hear about them being a rare find. She didn’t want to hear about them being incidental and temporary. She didn’t want to hear about them drying up and dying on their own. She wanted them dead and she wanted them dead immediately. She wanted a name of an insecticide that would kill them. Yes, ma’am. Right away, ma’am.
Polyxenus
millipedes are strange little critters that look more like carpet beetle larvae
than they do millipedes, but if one looks closely, they are definitely
millipedes. They have two pairs of jointed legs on each body segment whereas
carpet beetle larvae have a single pair of legs on just the first three
segments behind the head. Their minute size (2-3mm), soft integument (skin),
and the presence of rows of serrated setae (hairs) on their backs and sides,
and long posterior tufts of setae characterize Polyxenus millipedes. It is reported that polyxenid millipedes may
occur in pine litter in great numbers. Like other millipedes in
When found indoors, Polyxenus should be assumed to be coming from outside the building as indoor humidity levels would seem to be too dry to support the development of any millipede. I told the lady that perimeter treatments around the outside of the building with any number of insecticides should reduce the numbers found inside her home. Then she left. She left in a huff.
There are more than 10,000 described species of millipedes worldwide. These species are organized into 1,700 genera, 115 families and 15 orders. Most millipedes are worm-like with over 20 body segments. Each body segment, except for the first several segments behind the head bears two pairs of legs. In many species, the body segments contain internal glands that secrete volatile chemicals that repel or discourage predators.
Howard Russell, MSU Diagnostic Services
Last week a gentleman brought in a small arborvitae that he thought had died over the winter. He brought in the whole shrub, roots and all. A quick examination of the shrub told us that it was not dead. The branches were not brittle and many of the lateral buds had broken and new growth was appearing all over the shrub. But something had stripped all the foliage off of this shrub. As well as three more that were still in the ground back home in the client’s yard. We immediately thought deer were responsible because deer really like to munch on arborvitae during the winter months. But when the client told us these arborvitae were in an area of his yard that was pretty much inaccessible to deer and that all of the stripped off foliage was piled up at the bottom of the shrubs, we had to nix the deer theory. Deer would not leave the foliage, they would have eaten it.
The only thing we could think of was red squirrels (see the April 18 issue Landscape Alert). I could not find any reference that mentioned red squirrels feeding on arborvitae, but the MO is so similar to that of spruce, this remains our best guess. If you have a better one, email me at bugman@msu.edu.
Howard Russell, MSU Diagnostic Services
In the first issue of the
2008 Landscape Alerts, Chris DiFonzo and I documented a widespread outbreak of
winter cutworms that occurred last fall in many northern counties of the
Jill O’Donnell may have come across a possible answer: they all climbed up a spruce tree and died. Jill found hundreds in various states of near death and decomposition up in spruce trees when she scouted a Christmas tree plantation this week. Maybe winter cutworms are like elephants and Jill discovered their secret burial grounds. The mystery continues.
Jeff
Andresen
Agricultural Meteorology
Geography
An area of low pressure over the central Great Plains on
Friday, May 2, is expected to move northeastward through the
Another area of low pressure will approach the region once again by Wednesday or Thursday of next week with the next chance for significant precipitation. High temperatures will range from the low-mid 40's north to upper 60's south Saturday, falling back to the 40's north to upper 50's south Sunday. Low temperatures will range from the upper 30's north to mid-50's south Saturday morning falling back to the low or mid-30's north to the upper 30's south by Monday. Some scattered light frost is possible across inland northern sections of the state through the middle of next week.
Further ahead, medium‑range forecast guidance suggests
a series of upper air troughs moving from the western