As spring continues to advance, more woody plants are showing damage from this past winter. Several county offices have received an increasing number of inquiries about damage to roses and boxwood.
While it’s not uncommon to see extensive dieback on hybrid
tea roses, this year we’re also seeing damage to shrub roses, including hardy
Canadian and Buck roses. Boxwood damage varies from a few branches to the whole
plant. Even the newer, hardier hybrids out of
While these plants tolerate our Zone 5 cold temperatures, it’s the swing in winter temperatures that caused the damage this past winter. When plants are subjected to long periods of warm weather in the winter, they are fooled into thinking it’s time to wake up and start growing. They start to lose their cold temperature tolerance. Then, when the cold temperatures return, these plants cannot withstand the cold temperatures they could before the warming period. Bottom line: plant tissue is damaged.
Many of these plants are pushing out new growth and should survive. Prune out the dead and damaged wood to maintain plant health and vigor. For pruning tips, refer to Tom Fernandez’s article in the April 13, 2007, Landscape Alert.
Downy mildew, Peronospora sparsa is a serious disease that attacks all types of roses both in the greenhouse, nursery and the landscape from potted miniatures to landscape-size roses and even shrub roses. The disease can be quite severe under cool moist conditions and will defoliate rose plants within a day or two in the greenhouse or in a polyhouse. The optimal temperature for rose downy mildew is 64°F with a relative humidity of 85% or greater. Making sure your humidity, especially overnight, is below 85% is effective at preventing the disease. Sudden temperature drops at dusk in greenhouses or polyhouses can significantly increase humidity around the plant and lead to conditions that favor downy mildew.
Look for purple to black spots on the stems and flower peduncles, first symptoms are on the leaves near the top of the plant (see photos). As the spots develop, the leaf may yellow and even look like a leaf burn that may be confused with pesticide toxicity.
No mycelia appear on the upper leaf surface as with powdery mildew. Downy mildew under very humid conditions will form mycelia on the underside of the leaf under the purple to black spots. As mentioned if you are forcing roses under plastic, keep the foliage dry to prevent this disease.
The following fungicides are labeled and effective for downy mildew control on roses: Heritage, Stature, Cygnus and Fen-stop. Read the label and follow directions as indicated. A severe infection cannot be arrested by fungicides. You should consider dumping severely infected rose plants.
Henbit (Lamium amplexicaule L.), family: Lamiaceae (Mint).
Life cycle: Square-stemmed winter annual.
Leaves: Cotyledons are oval in outline and notched at the base where the hairy petioles attach. Opposite, circular to heart-shaped, hairy leaves have rounded teeth along the margins. Prominent, palmately veined leaves give a crinkled leaf surface. Lower leaves are attached by long petioles; upper leaves lack petioles and encircle the stem.
Stems: Square, hairy, spreading stems with many ascending branches from the base can root at the lower nodes. Stems are up to 16 inches tall.
Flowers and fruit: Pink to purple flowers in a two-lipped tube form in whorls in the upper leaf axils. Each flower produces four egg-shaped, one-seeded, grayish brown and speckled nutlets.
Reproduction: Seeds.
Similar weed: Purple deadnettle (Lamium purpureum L.). Differs by having more triangle-shaped leaves, upper leaves with petioles and red to purple coloration.
Control: Henbit and purple deadnettle are winter annual
plants that flower and produce seed in early spring. Typically, these seeds
will emerge in the fall, overwinter and then resume growth in early spring.
Control of henbit and purple deadnettle will depend upon location. Timely
applications in the fall and/or preemergence products can work very well in
landscape beds. Once in flower, however, herbicide applications are usually not
recommended as seeds will quickly mature on the plants. For now, just enjoy
their beautiful flowers.
Note: Identification information for more weeds is available in the new field guide An IPM Pocket Guide for Weed Identification in Nurseries and Landscapes. To order, call 517-353-6740 or visit: http://www.ipm.msu.edu/pdf/pocketGuidesLandsc07.pdf
European chafer grubs are about done feeding this spring. If your lawn sustained some grub injury last fall or early this spring, it is better to wait and apply GrubEx, Season-long Grub Control or another product containing imidacloprid in July. This will protect your lawn against grubs in late summer and fall. Most areas of the state have good soil moisture now and the turf is growing fast. This will allow the turf to out-grow any late spring feeding damage from grubs.
Some golf course superintendents like to treat fairways, tees and greens with Merit or Arena in May, so they can get some spring and early summer help with Ataenius, Aphodius and ants, as well as adequate control of Japanese beetle in late summer and fall. This is fine for those that have an on-going Japanese beetle problem and want to get the most out of their grub treatments. However, for golf courses that have a problem with European chafer in the rough, you will get much better grub control if you wait until July to use the Merit or Arena in the rough.
I’m a skeptic, it’s just my nature. When someone tells me about the latest miracle grass or secret lawn potion, I usually smile, listen, wish them luck, and tell them to call me when they have some research data that backs up their claim. Recently I stumbled across some interesting facts during an early morning Google episode on the web. Listen to this!
New miracle herb revealed!
This herb will reportedly when eaten as part of your daily diet:
§ Prevent or cure liver diseases.
§ Cleanse your skin and eliminate acne (teenagers take note!).
§ Lower blood pressure.
§ Reduce acid indigestion (how do you spell relief?).
§ Improve bowel function (no comment necessary…).
§ Assist in weight reduction!!!!!!
The best part of this story is that you don’t even have to go to the local drug store to secure your supply. Just go outside and look at the sea Taraxacum officinale, that’s right dandelions. There may truly be gold in those dandelion fields. Just a reminder from last week’s issue, if you’re looking to control dandelions, the puff ball stage should be arriving soon and this is an effective time to try and suppress the dandelion population.
The best time to seed turfgrass is in the autumn when temperatures are cool and rainfall is hopefully plentiful. However, in many situations turfgrass areas are now being seeded either to recover from some malady from last season or just to establish a new area. For any seeding project make sure to ensure good seed to soil contact, maintain adequate soil moisture during establishment, apply a starter fertilizer to supply nutrition to the young seedling, and avoid all herbicide applications until the turf has been mowed at least a couple times. Make sure to be careful when selecting fertilizers this time of year as there are many fertilizer herbicide combo products that contain either a preemergence or broadleaf herbicide.
Now is the time to begin managing the two Douglas fir
needle-casting diseases called Rhabdocline needle cast and Swiss needle cast
and the needle-casting disease of spruce called Rhizosphaera. The fungi causing
the needle-casting diseases of Douglas fir and spruce require free moisture and
warm temperatures very typical of May and early June in
While monitoring spores of Rhabdocline in 2006, we saw the spores of Rhabdocline come in two distinct waves, early in May and later in early June. Therefore, it would be best to design your spray schedules to accommodate these times. At least two sprays should be applied to manage these two spray release waves. If you have planted the Douglas fir seed-source called Shuswap which is resistant to Rhabdocline needle cast, you should still determine the amount of Swiss needle cast infection the trees are carrying. Generally, sprays for Swiss on Shuswap, can be made two years prior to the potential harvest date.
To determine if your trees warrant chemical management, look for signs of the fungal fruiting bodies on the needles. These fruit bodies are producing the spores that will infect the new needles as they break bud. With a hand lens, scan the discolored needles. For Rhabdocline on Douglas fir, look for needles with elongated brown splotches and on the bottom side of the needle, look for areas where the outer portion of the needle’s epidermis (skin) appears raised. If you see these, then examine two-year-needles on 50 or more trees scattered throughout your plantation. If you find fruiting bodies on 20 percent or more of the trees, consider treating the plantation.
In the case of Swiss needle cast
of Douglas fir and Rhizosphaeria of spruce, randomly select 20 or more trees
scattered around the plantation, and remove three sample branches from each
tree. Examine the white rows of stomata on 2-year-old needles and if half of
the branches have fruiting bodies on more than 10 percent of the needles,
considering treating the entire plantation. Two sprays are more effective than
one.
If growing Douglas fir, consider planting the Rhabdocline resistant seed source Shuswap to reduce Rhabdocline needle cast problems.
Gypsy moth - egg hatch
Cooley and Eastern Spruce Gall- first galls visible
Eastern pine shoot
borer – first adult active
European pine
sawfly – first larvae
Pine bark adelgid -
egg hatch
Pine Needle Scale –
first egg hatch
Spruce spider mite
– egg hatch
Balsam twig aphid – stem mothers present
Cooley spruce gall adelgid – first nymphs on Douglas fir
Gypsy moth- egg hatch
Eastern pine shoot borer – first adults active
European pine sawfly – first larvare
Spruce spider mite – egg hatch
Balsam gall midge – adults laying eggs
Balsam twig aphid – stem mothers present
Cooley spruce gall adelgid – first nymphs on Douglas-fir
Cooley and eastern spruce gall adelgids – first adults active
White pine weevil – first adults
Zimmerman pine shoot moth – first larvae
Cooley and Eastern spruce gall adelgids
We are finding balsam twig aphids on Fraser and in the expanding buds of concolor fir in the Hart area. Once you find the aphids inside the expanding bud and they are well protected from insecticides. Spraying will not prevent damage to the current-year foliage. Late sprays will, however, harm beneficial predatory.
The first cottony masses can be found on the underside of
the needles of Douglas-fir. If you look closely you will find cream-colored
adelgid eggs that will 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. Looking at Douglas-fir in
We are still seeing cold temperature injury to conifers appear in the last few weeks (See color photos on the Internet version of this newsletter.). The concolor firs have been especially hard hit. The needles will appear reddish to bleached cream on the last year’s growth.
Last week we introduced the new gypsy moth spray window zone map. Growers should note that spray windows dates have been identified for zone 2 – all compounds and zone 3 – Dimilin.
Each year Michigan Department of Agriculture and MSU
Extension evaluate the progress of gypsy moth egg hatch in order to set the
opening and closing dates for the gypsy moth spray window. This year we have
refined the process using historical degree day accumulation data available
online through MSU IPM Resources at: http://www.ipm.msu.edu/landscapeipm/gddlandchart.htm
. The state has been divided into five gypsy moth spray window zones that
roughly correspond to historical degree day trends. These zones are comprised
of the counties shown below.
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.
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.
|
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 (projected) |
June
21 (projected) |
June
27 (projected) |
|
4 |
May
14 (projected) |
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.
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.
Boxwood, Buxus
spp., is gaining popularity in
Boxwood leafminer, Monarthropalpusi flavus (Diptera:
Cecidomyiidae) is the most serious insect pest of boxwoods. This
small fly is native to Europe and widely distributed throughout the
Both littleleaf boxwood, B. microphylla and common boxwood,
B. sempervivens, are commonly attacked, but there is resistance found in
individual varieties of both species. Common boxwood cultivars with reported
resistance are ‘Handworthiensis’, ‘Pyramidalis’, ‘Suffruticosa’ and ‘
The larvae are yellowish-white and a little over 1/8 inch
long. The adult boxwood leafminer is an approximately 1/10 inch long, delicate,
orange-yellow to red, gnat-like fly. The partly grown larvae overwinter within
their mines within the leaves. The larvae grow rapidly as the weather begins to
warm. In early to mid May, when weigela blooms, they turn into orange-colored
pupae and emerge as a fly. After mating, the female inserts her eggs deep into
the leaf tissue and the eggs hatch approximately three weeks later. The larvae
grow slowly as they eat away inside the leaf. In
Control of the
boxwood leafminer should begin with the selection of the more resistant
varieties mentioned above. Pruning the foliage before adult emergence or after
egg laying ends will help to reduce the overall population of egg laying
adults. Chemical control is difficult
because the application must be timed with the emergence of the adult flies. An
application of an insecticide spray when the adult flies emerge (This
corresponds to when weigela is in bloom.) can reduce populations. Insecticide
sprays containing bifenthrin (Talstar), carbaryl (Sevin), cyfluthrin (Tempo or
Bayer Advanced Garden Insect Control), or malathion are among the recommended
materials that can be applied to control the adult flies. Imidacloprid, a
systemic insecticide (Merit or Bayer Tree and Shrub Insect Control) will
control the larvae inside the leaves and does not require precise timing. This
product should be applied in mid to late April.
The boxwood mite, Eurytetranychus buxi, is a spider mite that feeds on the undersides of leaves and is difficult to see even with a hand lens. Infested leaves appear to be pin-pricked or stippled with tiny white or yellow marks. The boxwood mite is a pest of both European and American boxwood varieties. Japanese boxwood is less susceptible. The application of high nitrogen fertilizers may lead to higher numbers of this mite.
Like most other spider mites that plague
Control of boxwood mites follows that of other spider mite pests. One can try washing mites from the foliage with a stream of water. Summer rates of horticultural oil is also effective. A more aggressive approach includes treating with abamectin (Avid), bifenthrin (Talstar), malathion, or oxythioquinox (Morestan) during the first two weeks in May.
The boxwood psyllid, Cacopsylla busi is a less serious pest that occurs wherever boxwoods are grown. It causes cupping of leaves and may affect twig growth, but the damage caused is purely aesthetic and not as destructive as other boxwood pests. The boxwood psyllid is a common pest of all boxwoods but the American boxwood (Buxus sempervirens) is most susceptible.
This insect overwinters as a tiny, orange egg deposited in the bud scales. The eggs hatch in the spring when the buds of the host plant open. The nymphs immediately begin to feed and develop white waxy strands over their bodies. Winged adults appear by early June. After mating, the female deposits her eggs between the bud scales of the host plant.
There is one generation each year.
The nymph stage damages the host plant by feeding on newly developing foliage, causing the leaves to become cupped. This cupping conceals the psyllid, and provides protection while feeding; however, the damage to the host plant is purely aesthetic.
This minor pest can be controlled with many of the insecticides mentioned above for other boxwood pests. An application should be made when young psyllids are present, in early May.
It seems that in most years the lab starts getting in ticks toward the end of May. But this year, we received our first ticks before the first of May. The tick we see most often in the lab is the American dog tick, Dermacentor variabilis (Acari: Ixodidae). Also, we are seeing an increase in tick submissions from the mid-Michigan area.
The American dog tick
is the most commonly found tick in
Mice appear to be the preferred hosts of immature stages of the American dog tick while the adults prefer to feed on dogs and other large mammals. Dog ticks can live for over a year without food. 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, also apply duck tape around pants cuffs to keep ticks from crawling up the legs. If an attached tick is found, it should be removed by placing tweezers near the head and gently pulling it off. Be careful not to squeeze the tick as this can inject more toxins into the wound. Keep in mind that ticks cannot feed immediately after attaching. They require several hours to imbed their mouthparts deep enough to take a bloodmeal. An unfed tick (unengorged) tick is quite small and flat, but a fully engorge tick looks like a small grape. Yuck! If you are unsure about the identity of your tick, save it in a vial of rubbing alcohol and sent it to the lab for identification.
Editor’s note:
This article is gleaned from a web site hosted by Jim Harding, wildlife
specialist at the
Moles, along with their relatives the shrews, are members of the mammal order Insectivora, which literally (and appropriately) means "insect eater." Moles are specially adapted for a life underground—they have short thick fur (that can lie comfortably in any direction), tiny eyes, and ear openings that are hidden under the fur. Their bodies are rather narrow and compact, their snouts are pointed, and they have large claws on the toes of their powerful, shovel-like front feet. Under the right soil conditions, moles can tunnel at a speed of 15 feet per hour – No wonder it seems like they can ruin a lawn almost overnight!
There are two species of moles in southern
In warmer, damper weather, eastern moles make their well-known feeding tunnels just under the surface; they push up the soil to form the long, winding ridge that most annoys homeowners. In drier weather, and in winter, they create deeper tunnels, at times over 2 feet down; the excess soil may be pushed upward, forming the well-known "molehills." Both mole species can create surface-breaking tunnels and "spoil" hills and (contrary to popular belief) you cannot always discriminate between the species on the basis of the shape or size of these hills, though in general eastern moles tend to create larger, more irregular hills, while star-nosed moles create lower, more neatly rounded hills, at least in wetter soils.
Typically in May a female mole gives birth to 3 to 5 naked babies in a cozy nest usually in one of the deeper burrows. They grow quickly and leave the nest in about a month, and are independent and making their own burrows by late summer or fall. Eastern moles tend to be rather solitary animals, and possibly territorial. Though it may seem like your yard must be inhabited by hundreds of moles, it is more likely that the maze of tunnels criss-crossing your lawn was made by only a few moles, and quite possibly only one.
Moles have huge appetites, and may eat up to a third of their weight in food each day. The diet includes mostly earthworms and adult and larval insects, along with a few centipedes, spiders, slugs, snails and a bit of vegetable matter such as roots and seeds. Moles occasionally attack the underground nests of yellowjackets and other wasps.
All in all, moles are beneficial animals, consuming numbers of potential insect pests and aerating the soil. However, there is no doubt that they are highly attracted to the bounty to be found in well-watered and fertilized lawns, and here they become quite a nuisance. So how can you eliminate or at least discourage moles in the yard?
Repelling eastern moles from an area is often possible using one of the castor oil-based liquid products (such as Mole-Med® and Scoot-Mole®). These are sprayed on the lawn with a standard garden or hose-end sprayer (follow label directions). Noticeable results may occur after several days; heavy rains will dilute the effect and necessitate reapplication. These products are thought to be relatively non-toxic to people, pets, and wildlife when used as directed. Other repellent methods may also be effective in small garden areas, including devices (like "mole windmills") that vibrate the ground, and the dense planting of certain plants like "gopher purge" (Euphorbia), castor bean, marigold and Fritillaria.
Some other often-suggested remedies are usually ineffective and often unsafe; these including placing human hair, "chewed" bubble gum, broken glass, engine oil or mothballs in the mole tunnels, or trying to flood out the moles with a garden hose.
Cats and dogs sometimes learn to catch moles; cats are poor at digging and more often catch shrews on the surface. Certain dog breeds take great joy in digging out moles, but often cause considerable additional damage to the lawn in the process.
Direct killing of moles will certainly help the problem, but catching them is not easy.
Sometimes by flattening mole tunnels and then patiently watching for active digging, you can locate the mole and quickly flip it out of its burrow with a shovel. Activity is usually greatest (or at least most observable) at dawn and after sunset.
Trapping is a bit tricky, but can be effective. There are several trap types on the market; the two most common styles are the "harpoon" trap (with several long, sharp metal spikes on the business end) and the "choker" type (which grabs the critter with a metal loop). Start by stamping down sample sections of the mole tunnels in your yard and noting which ones are quickly pushed back up each day; these are the ones to target. Follow the directions of the trap manufacturer. In hard, dry ground, the harpoon traps may not work unless the soil is loosened or the trap is staked down. Once the trap is set, place extra soil over any openings over the tunnel, as light shining in will scare the mole. Star-nosed moles can be trapped by digging into the tunnel below one of the mounds; refill the hole with loose dirt and set the trap over the hole.
Fumigation of mole tunnels using smoke cartridges is another option, but this tactic rarely achieves full control without frequent and time-consuming reapplication. Follow package instructions for cartridge placement and ignition, and keep children and pets away during use. A number of the cartridges must be introduced simultaneously into the active tunnels, perhaps every 5 to 10 feet, and tunnels must be re-sealed after ignition to prevent smoke from escaping.
Reducing the mole's food supply by using lawn insecticides may discourage moles by reducing the numbers of beetle grubs and other insects that attracted the moles to the area in the first place. However pesticides must be used judiciously and with due caution - nearly all involve certain risks, even when used as directed.
Other stronger, mole-control substances, including poison baits and toxic fumigants, may be available for use by licensed pest control companies, but are generally not available to the homeowner. Again, no poisonous substance is completely risk-free, and one should weigh carefully the choice of introducing these chemicals into the home environment to eliminate an annoying but otherwise harmless pest. It is always wise to start with the least risky control methods for any pest, and then gradually "escalate the battle" as necessary.
Did you know that southern
On June 15 an on-site workshop will be held at the MSU
MacCready Reserve, near
This one-day event will be held at the MSU MacCready
Reserve, located 15 minutes south of
Additional field day information and registration forms are available at: www.msue.msu.edu/jackson
For more information contact: Anna Fiedler, MSU Department of Entomology, fiedlera@msu.edu.
Upper air ridging and high pressure were entrenched across
the Great Lakes region Friday (May 4) and will bring another day of mostly
sunny skies and seasonable temperatures to
Medium range forecast guidance currently suggests an upper
air troughing pattern across the western
Further ahead, the new