Landscape and nursery
§ June
beetles flying in southern
§ Living with lichens
§ Scouting for weeds: Field horsetail
§ Scouting
for diseases: Downy mildew
§ Scouting
for diseases: Veronica rust
§ Christmas
peppers
Turfgrass
§ Meridian insecticide available now
§ Airing out the turf
Christmas trees and forestry
§ Christmas tree and forestry pest update
§ Important to
time insecticide applications for pine needle scale
§ Gypsy moth spray window dates
Around the home
§ There is a lot to be learned about invasive arthropods
Other news
§
Glyphosate-resistant horseweed confirmed in
§ Weather news
Dave Smitley
Entomology
June beetles were observed in several locations in southern
Noting the adult
flight is important for Christmas tree growers and nurseries because the
most effective insecticides – imidacloprid, clothianidin and thiamethoxam –
work best when applied at the time of egg-laying or within six weeks of that
time. To prevent damage from grubs that develop from eggs laid now, growers
should apply one of the above insecticides between now and July 1. Please note
that for Christmas tree growers in the northern
Homeowners and other owners of low maintenance turfgrass should also note if they have a large June beetle flight in their area, because we occasionally see turf damage from June beetle grubs in the two years following a large flight.
Bert Cregg
Horticulture and Forestry
Among our recent “Whatzat?” questions, is a grayish or
greenish growth that forms on the trunks and stems of trees. (Lichen photo 1).
These growths are lichens. Lichens are actually two organisms; a fungus and an algae
that form a symbiotic relationship and function very much like one organism. A
common question about lichens is “Do they harm trees?” The answer is no. The algae
part of the lichen is photosynthetic, and therefore they are able to produce
their own energy and do not take any resources away from the tree. In fact,
lichens often grow on non-living substrates such as wood, concrete, tombstones,
benches and so on (Lichen photo 2). If a homeowner observes a dead tree or dead
branch covered with lichens on it, this is a coincidence; the lichens did not
cause the branch or the tree to fail. The tree trunk or branch simply provides
a porous surface for the lichen to attach. Lichens are often fairly
inconspicuous, but in some moist areas, such as the
Lichens grow in some of the most inhospitable places on earth from deserts to tundras.
Lichens are commonly grayish-green, but may also be yellow or red, depending of the type of algae associated with the fungus.
Lichens are sensitive to air pollution, and researchers are investigating their use as a bio-indicator of air pollutants such as sulfur dioxide and ozone.
Lichens are fascinating organisms, if you are taking a liking to lichens try these websites:
http://www.nmnh.si.edu/botany/projects/lichens/
http://www.ucmp.berkeley.edu/fungi/lichens/lichens.html
Mike Marshall, Horticulture
Steven Gower, MSU Diagnostic Services
Field horsetail (Equisetum arvense L.) (view images)
Family. Equisetaceae (Horsetail)
Life cycle. Perennial, spore-producing plant.
Leaves. Not present.
Stems. Vegetative stems are green and branch in whorls. Stems may have a bottle-brush appearance and should not exceed 2 feet in height. Stems die back to the ground in winter.
Flowers and fruit. Erect, unbranched, white to brown fruiting stalks (stems) bear terminal spore-releasing cones. Flowers are not produced.
Reproduction. Spores and prolific rhizomes.
Control. Field horsetail has a deeply positioned rhizome system that is comprised of creeping rhizomes and storage tubers. Rhizomes can reach up to six feet in depth in the soil profile. Rhizome fragments, as small as one inch, can produce new plants. Control options for field horsetail are limited due to its extensive underground rhizome system. As with any perennial weed, several years of persistent control measures are needed to ensure success. Casoron is an excellent herbicide product for horsetail control; however, due to its residual activity, it will severely injure desirable plants placed in the treated soil for up to one year after treatment. Other herbicide options include MCPA and 2,4-D. Roundup is not considered a good, long-term option for field horsetail control. However, Roundup allows planting of desirable plants right after treatment. Always check manufactures label for specific details. Mechanical control options include pulling of the shoots or removal of the infested soil, but due to its rhizome system, soil would need to be removed to a depth of at least six feet. If that is not possible, placing a geotextile fabric in a shallowly excavated area before backfilling with new soil would prevent rhizomes from entering the bed. Fabric must be placed on the bottom, as well as the sides of the hole.
Editor’s note: This and more weed identification information is available in the new field guide An IPM Pocket Guide for Weed Identification in Nurseries and Landscapes. To order, call 517-353-6740.
Scouting for diseases: Downy
mildew
Jan Byrne
Diagnostic Services
Pathogen: Peronospora spp. and Plasmopara spp. (view images)
Hosts: Many fungi cause downy mildew. Each has a fairly limited host range. Common hosts include: Buddleia, Delphinium, Dianthus, Dicentra, Geum, Helianthus, Iberis, Lamium, Lathyrus, Oenothera, Papaver, Potentilla, Primula, Rudbeckia, Veronica and Viola.
Symptoms: Fuzzy, gray to black mold develops on the undersides of infected leaves. Chlorotic or necrotic lesions appear on the upper surfaces of infected leaves. Lesions may have angular edges; some lesions are bordered by veins. Infected foliage may be cupped, and new growth may become distorted. Severely affected plants are stunted. Some seedlings can be infected systemically, causing new growth to be stunted and severely distorted.
Spread: Spores are readily released and carried by air currents. Peak spore release often occurs when relative humidity rapidly decreases, which typically occurs in the morning. Some downy mildews are spread by contaminated seed; others are effectively spread on vegetative cuttings and seedlings.
Management: Scout susceptible incoming plant material carefully for signs of downy mildew paying careful attention to leaf undersides. Remove and destroy infected plants. Do not compost the plant debris. Warm days and cool nights with high humidity are favorable conditions for downy mildew spore production. Maintain good air circulation and increase night temperatures in greenhouses. Fungicides should be used preventively on especially susceptible crops. Downy mildews are capable of developing resistance to several effective systemic fungicides. Rotate use of systemic fungicides with protectants to slow resistance development.
Scouting for diseases: Veronica
rust
Jan Byrne
Diagnostic Services
Pathogen: Puccinia veronicae-longifoliae. (view images)
Hosts: Veronica longifolia and V. spicata.
Symptoms: Bronze, purplish overcast on the upper surface of infected foliage. Raised, reddish brown pustules on the underside of foliage. When disease is severe, significant foliar blighting occurs.
Spread: This
disease was unintentionally introduced to
Management: Carefully inspect incoming plant material for signs of rust; pay particular attention to material that originated offshore. Plants with rust pustules or other disease symptoms should be destroyed. Fungicide applications are needed for disease control in some situations. Resistance development is a concern – follow recommended fungicide resistance management strategies.
I’m not sure if I have ever tried to pick a peck of pickled peppers, but I’ll bet Peter Piper never even heard of an “ornamental” pepper. If he could pick some now, there would be more than a peck of cultivars to choose from!
In an effort dating back 25 years, plant breeders started
making strides towards producing peppers with fruits that are just as pleasing
for the eye as the palate. Breeding and testing a new cultivar that eventually
makes it to our home gardens can take as many as 15 years. In the past two or
three gardening seasons, the results have started to show up in garden centers
and botanic gardens around the country according to Robert Griesbach, research
geneticist of the Agricultural Research Service in
Ornamental peppers really made their claim to fame at the turn of the century, long before the poinsettia became popular as an indoor holiday plant, says Griesbach. Potted, brilliantly colored “Christmas peppers” were very popular because they could take the cool indoor home environment and yet last a long time.
From a gardener’s standpoint, ornamental peppers are one of the most fruitful annuals one could plant, no pun intended. With little or no dead-heading, the peppers not only last, but get better looking on the plant throughout the season. Many of the cultivars chosen for superior ornamental quality have an intensely colored bloom, which is followed by heavy fruit production. The fruits are often cone-shaped like the traditional chili pepper, but can also be round or even lumpy, like a miniature bell pepper.
The interesting thing is that as the fruit develops, it slowly ripens magically transforming as the color deepens. For instance, the Kent MSU Extension office had a display last summer of a dwarf pepper with variegated leaves known as ‘Shu.’ This tiny pepper plant produced one-inch fruits that began a pale yellow then transformed to purple and eventually brilliant red. Throughout the season, the plants were continually covered with peppers at all stages of ripening. With adequate fertility and a bit of supplemental water, these plants were both ornamental and somewhat entertaining. Once established in a container or the garden, pepper plants seem to take all kinds of abuse such as scorching hot sun.
At the Chicago Botanic Gardens this past summer, a display of a deep purple pepper ,known as ‘Masquerade,’ was complimented by the purple foliage of ornamental basil and the brilliant, and also heat tolerant blooms of Gazania. Another cultivar, ‘Chilly-Chili’ has uniform, brightly colored peppers similar in size and shape to a chili. It produces heavy loads of the showy fruits in the center of the plant and never gets too tall. This plant is excellent used as a border, (Did I mention color?) in combination with other bright colored annuals or in containers. By the end of the season, most of the subtle yellow peppers will have turned a brilliant scarlet. I love the idea of not needing dead-heading.
The 2006 All American Selection (AAS) winner ‘Black Pearl’
is the latest eye-catching cultivar to be developed and released by the ARS. (view
image) To receive the AAS award, a cultivar must show “superior garden
performance.” I can attest to the outstanding performance of ‘Black Pearl,’ which
became a pirate’s treasure in our
If the names ‘Tangerine Dream,’ ‘Holiday Flame’ or ‘Red Misssile’ sound intriguing, you can look forward to yet another peck of ornamental peppers landing in a garden center near you in the next few years. According to Griesbach, the future for development and release of new ornamental peppers looks bright. Plant breeding to him is kind of like assembling a Mr. Potato Head doll. He looks for outstanding fruit, to combine with cool foliage and interesting habit. This next season, Griesbach says we can look forward to a ground cover pepper with black foliage. If it is anything like the ‘Black Pearl,’ I could quickly become a pirate gardener!
Dave Smitley
Entomology
In February 2007, Syngenta announced EPA approval of Meridian Insecticide for Turf. The active ingredient is thiamethoxam, a neonicotinoid insecticide in the same chemical group as Merit.
“The insecticide is designed to provide lasting control of a broad spectrum of grubs and other insects, such as billbugs, white grubs, Japanese beetles, oriental beetles, European, Southern and Northern masked chafer, aphids, whiteflies, mealybugs and leafhoppers.”
The company says
Kevin Frank
Crop & Soil Sciences
The spring rollercoaster of wet and dry conditions continues
to persist across much of
It doesn’t take long once the soil is saturated for soil oxygen levels to decline and root hairs to begin to die. As the turf’s root system becomes impaired nutrient extraction and water uptake will be limited and the turf won’t look emerald green anymore. The solutions, of course, are rather simple assuming you can do some earth movement or cut in drain lines to help take the water away. However, in some situations neither of these options may seem realistic. One simple practice that can help the turf in these areas, but will probably not completely eliminate the problem, is core aeration. Of course, before you start thinking of a core aerifier going submersible in these soggy areas, you need to let them dry out. Core aeration will help get air and, most importantly, oxygen to the roots and it may also help water infiltrate quicker into the soil thereby preventing puddle formation.
Typically the “best” time of year to core aerate lawns is in the autumn because it is more likely the soil will not be too moist and it also gives the turf plenty of time to recover from this rather invasive procedure during the cooler temperatures of the autumn. However, for those trying to manage turf on soils that have a high clay content, I often recommend that they core aerate both in the spring and the fall and maybe even in the summer if the weather conditions are not too extreme in terms of heat and drought. Core aeration will increase oxygen in the soil, facilitate rooting, improve water infiltration, and can gradually over time reduce thatch.
Do you have an in-ground irrigation system? Be sure to know where the sprinkler heads are located. Also be aware of any other underground lines, e.g., invisible dog fence wire. Normally, these lines should be buried deep enough to avoid any trouble, but it never hurts to double check.
Jill O’Donnell
Christmas tree ICM educator
Gall rust
On Scotch pine, gall rust can be found on branches and on the main trunk. Infection begins when spores infect green, succulent stems during wet springs. Symptoms rarely appear the year of infection, but galls on the twigs near the point of infection appear in subsequent years. The conspicuous, perennial, round-stem galls can be one to four inches in size. The galls are now beginning to turn yellow-orange due to the release of spores. This rust rarely kills mature Christmas trees, but it disfigures and severely reduces their quality. Pruning out these galls before they produce spores may help to reduce the spread of this rust.
Cooley's adelgids
also feed on Douglas fir needles. They do not cause galls to form on Douglas
fir, but they do cause the needles to become distorted, and at high densities,
will reduce needle and shoot growth. You will usually find the adelgids on the
undersides of the needles. They look like tiny, white cotton balls on the
needles because the adelgids secrete white, waxy material as they feed. One
stage of adelgid eggs often hatch in the spring, soon after buds break. The new
nymphs will move onto the tender, succulent young needles. It often looks like
someone has sprinkled black pepper on the new needles. If you need to apply an
insecticide, this is a good time to do it. There is usually a second hatch of
eggs later in the summer too.
Christmas tree
growers enrolled in the compliance program need to collect and destroy all trap
logs or trap trees by May 20. Be sure you chip or burn trap logs and
trap trees, as well as any other pine brood material you might have generated
over the last several months.
Important to time
insecticide applications for pine needle scale
Jill O’Donnell
Christmas tree ICM educator
Applying insecticides at the proper time is a key element in controlling pine needle scale. Pine needle scale is most vulnerable to insecticides during the crawler stage. Although crawlers are tiny, they are readily visible on the needles, especially if you use a hand lens or magnifying glass. The ideal time to apply an insecticide spray is after nearly all the pine needle scale eggs have hatched and most crawlers have reached the hyaline stage. At this point, the young crawlers are exposed on the needles and have not yet started to produce the hard, white armor.
Spring generation eggs hatch in May or early June at roughly 300 GDD50. Usually, eggs hatch within about a week, and most crawlers should be in the hyaline stage by 400 to 500 GDD50. This is the ideal time to apply an insecticide. If the weather cools down, hatching may continue over two to three weeks. Good scouting will help you assess the size of the pine needle scale population in your field, determine whether control is necessary and the best timing for control.
Mike Bryan
Michigan Dept.Agriculture
Growers should note that spray window open dates have now been set for Zone 3 - all compounds and Zone 4 - Dimilin. The accompanying updated 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. 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 CAT Alerts for additional announcements.
Note: Please record which zone you are locate in as we will not be printing this list in subsequent issues of this newsletter this spring.
Zone 1 - Includes the counties of
Berrien, Cass and Monroe.
Zone 2 - Includes
the counties of Allegan, Barry, Branch, Calhoun,
Zone 3 - Includes the counties of Arenac, Bay, Benzie, Clare, Gladwin, Grand
Traverse, Huron, Isabella, Lake, Leelanau, Manistee, Mason, Mecosta,
Zone 4 - Includes
the counties of Alcona, Alpena, Antrim, Baraga,
Crawford, Delta,
Zone 5 - Includes the counties of Alger, Charlevoix, Cheboygan, Chippewa, Emmet, Keweenaw, Luce, Mackinac, Presque Isle and Schoolcraft.
Table 1. Gypsy moth spray window dates
|
Zone |
Open – Dimilin (150 DD*) |
Open – all other compounds (200 DD) |
Close – Dimilin (700 DD) |
Close – all other compounds (800 DD) |
|
1 |
April 23 |
May 4 |
June 9 (projected) ** |
June 15 (projected) |
|
2 |
April 30 |
May 7 |
June 15 (projected) |
June 20 (projected) |
|
3 |
May 3 |
May 15 |
June 21 (projected) |
June 27 (projected) |
|
4 |
May 15 |
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 50
degrees F.
** Projections are based on
30 year historical degree day data.
Correction: Last week, we incorrectly labeled this photo. The caption should have read: a boxwood leaf showing the blistering and discoloration caused by the boxwood leafminer. Our apologies to the author.
Howard Russell
MSU Diagnostic Services
During the earlier part of this week, I attended an Invasive
Arthropod Workshop at
It was at this workshop, that I learned that I had misidentified a very common home invading insect almost 20 years ago, when I first became the insect diagnostician in the MSU Department of Entomology. The bug that I incorrectly identified then, and for which I have provided the wrong information for nearly 20 years to the citizens of Michigan is the Western conifer-seed bug, Leptoglossus occidentalis (Hemiptera: Coreidae). I had erroneously called it the Leaf-footed pine seed bug, Leptoglossus corrculus (Hemiptera: Coreidae). Dang!
The Western conifer-seed bug was a topic of the invasive
species workshop, because it is a native species that has been rapidly
expanding over the past several decades and now threatens southern
If you are willing to forgive me and read further, I would like to share with you some other interesting things that I learned about invasive arthropods from the workshop. When my kids were in elementary school, many of the projects they were assigned included coming up with one or two fun facts about the topic they had been assigned to research and write up. Given there is nothing “fun” about invasive arthropods, I will call the following some “Not so fun facts” about exotic and invasive arthropods. These were presented by Joe Cavey, National Identification Services, Plant Safeguarding & Pest Identification, USDA/APHIS/PPQ.
§
Two percent of accidentally introduced species
of arthropods become established in the
§
65 percent of 212 insect major pests
accidentally introduced into the
§ Seven percent of the animal and plant accidental introductions become pest species.
§ The likelihood that an introduced arthropod will become established is extremely unpredictable, and we cannot predict what effect an insect species will have on the ecosystems it invades, although we tend to think it will generally be bad.
The following not-so-fun facts are based on information gleaned from the 1.4 million data records in the USDA/APHIS/PPQ Pest Interception Database since 1984 (McCullough et al. 2006).
§ Of all pest groups tracked in this database, (i.e., insects, mites, snails and slugs, plant pathogens, nematodes and weeds,) 78 percent of all exotic organisms that are intercepted by PPQ are insects.
§ Plants for propagation as cargo, e.g. imported nursery stock.
§ Plant products not for propagation as cargo, e.g. fruit and vegetables.
§ Miscellaneous cargo, e.g. machinery, ceramic tiles.
§ Plant material carried by international travelers.
§ Conveyances, e.g. ships, aircraft or railroad cars.
§ Mail.
§ Organism imports, e.g. live insects for butterfly houses.
§ 61 percent of intercepted pest were found in personal baggage and 31 percent were discovered in cargo.
But cargo is
considered riskier because…
§ Pests in cargo are tougher to detect.
§ Cargo is shipped to multiple sites.
§ Large volumes involved in cargo mean large infestations.
§
Only 2 percent of the cargo entering the
§ 73 percent of pest interceptions occur at airports.
§ 13 percent of pest interceptions occur at land borders.
§ 9 percent of pest interceptions occur on ships.
The most frequent
origins of intercepted pests are:
§
Central and South
§
§
North America (
§
§
§
The major means or pathways that are of highest concern
§ Nursery stock.
§ Wood packing materials.
§ Cut flowers.
§ Oddly, ceramic tiles and quarry products.
The following not-so-fun facts about exotic insects pertain only to forest insect pests. These were presented by Bob Rabaglia, Forest Health Protection, USDA Forest Service.
§
400 exotic species affecting forests and forest
products are established in the
Ecologically, these exotic
species…
§ Impact the structure and composition of our forests.
§ Aid other destructive forces that act upon our forests.
§ Impact wildlife and fisheries.
§ Impact water quality.
Economically, these
exotic species…
§ Reduce yield; the cause mortality and growth loss.
§ Affect quality of our forest products.
§ Impact recreation.
§ Increase management costs of our forests.
§ Homoptera (leafhoppers, aphids and scales)
§ Lepidoptera (moths and butterflies)
§ Hymenoptera (sawflies, bees, wasps and ants)
§ Coleoptera (beetles)
§ Cerambycidae (longhorned beetles)
§ Buprestidae (metallic wood boring beetles)
§ Scolytidae (bark beetles)
Bark beetles are the
most commonly intercepted beetle.
Exotic bark and wood-boring beetles that have become established since 1989
by family..
§ Scolytidae (25+)
§ Cerambycidae (4)
§ Buprestidae (2)
The most common pathway for these exotic bark beetles is solid wood packing material (SWPM) for tile, machinery, granite, ironware; seeds.
§ 117 different countries of origin.
§
The top 10 are
Some examples of the number of exotic bark beetle interceptions in solid wood packing material by state between1985 and 2000:
§
§
§
§
§
The number of first reports or detections of established
species of exotic bark beetle in
§ <1980: 29
§ 1980’s: 8
§ 1990’s: 10
§ 2000’s: 8
The continent of origin of established exotic bark beetles
in
§
§
§
§
§
In summary, one would have a hard time not thinking these not-so-fun facts about exotic insects paint a pretty grim picture for our forests and landscapes.
Steven Gower
MSU Diagnostic Services
Glyphosate-resistant horseweed (Conyza canadensis) has been confirmed in a Christmas tree
plantation in Mason County, Michigan. This detection represents the 16th state
in the
For the past several years, MSU Diagnostic Services has been screening
horseweed populations for glyphosate, ALS, triazine and PPO resistance utilizing
greenhouse whole plant assays. ALS-resistant horseweed has been documented in
35 field crop locations and seven Christmas tree plantations spanning 14
Christmas tree growers commonly use a soil-applied, residual
herbicide in early spring followed by one to several applications of glyphosate
during the season. The initial greenhouse screen of this
Horseweed plants were treated with glyphosate at 0.01X, 0.1X, 0.25X, 1X, 4X, 10X and 100X the labeled rate (0.22, 2.2, 5.5, 22, 88, 220, and 2200 oz/A Roundup WeatherMAX 5.5L, respectively, plus AMS at 17 lbs/100 gallons) when rosettes were two to three inches in diameter. Visual weed control ratings and dry weights were taken 21 days after treatment.
While GR50
values have not yet been tabulated, these experiments consistently show the
ability for this population to survive glyphosate at 1X, 4X and occasionally
10X the labeled rate. The accompanying picture shows representative plants for
each treatment and population.
If herbicide resistance is suspected in any weed species,
samples may be submitted to MSU Diagnostic Services for a resistance screen. In
most circumstances, a whole plant pot assay established from seed will be the
standard test for herbicide resistance confirmation. 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 seed in plastic!
Generally, 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. However, costs associated with horseweed samples
submitted by
Please contact Steven Gower (517-432-9693, sgower@msu.edu) with any questions regarding resistance confirmation or sample collection. Samples can be mailed to:
Diagnostic Services
101 Center for Integrated Plant Systems
Attn: Steven Gower
Jeff
Andresen
Agricultural Meteorology
Geography
Friday morning, May 11, the weak frontal boundary that
brought showers and thunderstorms to much of
Cool and dry weather is expected Saturday and most of Sunday behind the front, with brisk northeast winds. An area of low pressure will approach the region by late Sunday, bringing the next chance for significant rainfall overnight Sunday across far northern sections of the state and statewide Monday and Tuesday. Fair and dry weather is expected once again for the latter half of next week. Temperatures will fall back from daytime readings in the upper 70's and low 80's to the mid 50's far north to the upper 60's south Saturday. Low temperatures will generally range from the upper 30's north to the 40's south Saturday morning, falling back to the upper 20's and 30's Sunday morning. Some frost and freezing temperatures are possible Sunday morning across northern and interior central sections of the state. Daytime temperatures will rebound once again Monday ahead of the next weather system, with highs in most areas back into the 70's.
Medium range forecast guidance is suggesting the formation
of a ridging feature across the western