Yard & Garden Line News
Volume 1 Number 8 August 1, 1999
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Guess Who's Coming For Winter!
James R. Kitts, Ph.D.
Extension Wildlife Specialist
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Fox squirrels: They don't want to live with you.
Photo credit: Skip Rither |
Have you noticed that the days are getting shorter. No? Well wild
animals have, so maybe it's time to plan for their arrival at your house
'cause winter is on the way!
Below are a few recommendations to ease your
anxieties relative to some types of invading wildlife. Keep in mind that
critters do not recognize legal property boundaries. They only respond
to available habitat or what they perceive as habitat(food +water +cover +space). Whether you live in an urban area, the suburbs, or in a rural location you can expect that wild animals will check your property (yes, your house is part of their property) for its usefulness to them as habitat. Some of these critters might be delightful to have as outdoor visitors (bats, chipmunks, shrews, even squirrels), but you'll probably want to discourage them from settling indoors.
Mice and Their Look-Alikes
Mice are some of the most common small mammals living in Minnesota. The house mouse (Mus musculus) was imported from Europe and Asia. It can
survive in the wild, but does better and prefers to live close to humans.
These are probably the most common mice found in our homes and buildings.
They are good climbers and feed on a wide variety of items including dried
fruits, grains, dried meats, dairy products, nuts, etc. They are not fond
of fresh fruits or fresh vegetables. House mice breed year round at
intervals of 18-21 days.
In wooded locations or areas close to woods expect to find deer mice or
white-footed mice (Peromyscus species). Peromyscus can be distinguished from other mice by their striking bicolor pattern. They are always all white underneath from the tip of the long tail to the tip of the chin.
Their sides and back usually appear as gray-brown or brown. These are
native mice and they are excellent climbers. They inhabit woods and
shrubby areas throughout Minnesota--even in many inner city areas. These
mice feed mostly on seeds, nuts, buds, fruits and insects. They can breed
year round but usually do not reproduce during the winter months. Where human dwellings are involved these mice seem to prefer to enter during late summer or early fall and often depart again in the spring.
Finally, in the grassy, meadow, marshy, and shrub areas of Minnesota we find voles (Microtus species). These stubby appearing mice are always
dark colored either brown, brown-gray, or red-brown and they have rather
short tails--always shorter than the combined length of body and head.
These mice are not good climbers and seldom seek entry to human dwellings.
They will, however, occupy barns and sheds especially where hay or straw
is stored. Voles feed mostly on plant stem and leaf material, but they do
consume seeds, nuts, and insects. While voles can reproduce throughout the year they usually do not reproduce during winter months.
Shrews
Often mistaken for mice, shrews are actually predators. They feed on a
wide variety of insects, worms, snails, small reptiles and amphibians,
birds, and on mice when and where they can. Shrews are not good climbers,
but they are strong burrowers and in light soils their excavations often
resembles those done by moles. The shorttail shrew (Blarina brevicauda)
might be the most often encountered species. It is slightly smaller than
the meadow vole and similarly dark in color, but always black to dark gray. The shorttail shrew has toxic saliva which functions to paralyze prey. It will also add to the pain if you're bitten. The shrew profile is streamlined with a pronounced pointy snout, no visible ears and tiny, dark eyes and 5 toes on their front paws (most rodents have only 4 visible). Shrews produce one litter each year. Often they can be distinguished from mice simply by their rolling gait and pungent odor.
Habitat management is the key to reducing damage from all of these
critters. The best habitat management includes elimination of food
sources and hiding places. The supply of naturally occurring foods such
as seeds, nuts, and insects will vary depending on circumstances such as
wind, rain and temperature patterns. However, homeowners have control
over such foods as birdseed, animal feeds, etc. These sources, bird and
pet feeders, are often the means for inviting wildlife too close to our homes. Trash cans, dog food dishes, etc. left outside supply additional habitat. Always store seeds or animal feeds in hard containers (metal or glass).
Other Rodents
Tree Squirrels
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Grey squirrel contemplating a move.
Photo credit: Beth Jarvis |
Although nesting is a prime squirrel concern in the spring and summer, fall is the time for selecting a safe den site. What better place to spend the winter than in the eaves/attic of your house? They'll be warm, isolated, and close to a consistent supply of easy to obtain food such as bird feeders.
Of the five species of tree squirrels that inhabit Minnesota, only fox squirrels (Sciurus niger) do not, with some regularity, invade our
houses. In most other areas, in particular our urban areas, gray squirrels (Sciurus carolinensis) are the most common violators. Red squirrels (Tamiasciurus hudsonicus) and flying squirrels (Glaucomys species) will also den in our dwellings, but with considerably less frequency than gray squirrels. Because of their great abilities to climb and gnaw, it is difficult to prevent squirrels from invading buildings once they have decided to enter.
The best preventive techniques usually involve trimming trees and large shrubs so they do not overhang the roof; keeping animal feeders more than
50 feet away from buildings; keeping roof vents and eaves in good repair;
opening all large birdhouses (duck boxes, etc.) after the nesting season
so squirrels do not occupy them as winter dens; and finally, removing from the
population any squirrels found climbing on the building (they didn't take
the other hints).
Chipmunks
Chipmunk
Photo credit: Skip Rither
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Two species of chipmunks occur in Minnesota, Eastern chipmunk (Tamias
striatus) and the least chipmunk (Eutamias minimus). These small critters are excellent climbers and strong burrowers. Look for them on the ground, in rock retaining walls, under bird freeders, and climbing in shrubs and trees to harvest nuts and fruits. Their major foods are nuts, seeds, fruits, buds, fungi, occasional birds and their eggs and young, voles,
amphibians, small reptiles, and some insects and their eggs and larvae.
One litter a year is standard with the least chipmunk, but the Eastern chipmunk regularly delivers two litters.
Problems with these animals are few, but when they occur they can be
severe. Since chipmunks like to burrow soil erosion can be a major problem around houses or landscape features located on steep slopes or loose soils. Chipmunks that gain entry to buildings can cause damage to insulation as well as the structural building materials as they gnaw to expand entry points or to establish internal travel routes. Rodents gnawing on electrical wiring in houses have been responsible for starting fires.
Prevention of damage from chipmunks is a matter of degree. Do not expect
to attain 100% control. Begin by altering the habitat. Move bird feeders
to level ground and well away from buildings and the house to minimize problems from their burrowing. Select landscape plantings that do not produce fruits, nuts, or seeds. On slopes use landscape blocks to build retaining walls rather than boulders, stone, or railroad ties.
Crawling Things
Salamanders
Although not all suburban dwellers will experience the migration of salamanders, those who do find it interesting. Tiger salamanders (Ambystoma tigrinum) are native to Minnesota and are found in and around our marshes and the adjoining uplands. In the spring adults migrate from their upland hibernation sites to aquatic areas for breeding and summer
hunting. In late summer they migrate back to their upland wintering
areas. During their migrations these large salamanders are often trapped
when they fall into window wells and ground level swimming pools. Here
they can accumulate in large numbers since they cannot climb out. Inside
corners on houses also pose problems for these animals where they are seemingly unable to "think" their way out.
Tiger salamanders are not dangerous although the mucus they secrete when
threatened can be irritating to eyes and tender skin . Major foods include earthworms, grasshoppers, crickets, small fish, other salamanders,
small snakes, frogs, and small mice.
They do no damage to humans. If you live in an area through which these
creatures migrate, be certain to cover your pool during cloudy, rainy days
in the spring(April) and late summer(September). It would also be
desirable to cover any window wells that do not have well edges protruding
6 or more inches above surrounding soil, mulch, or grass. Finally, place
a board or some other device on the ground as a barrier across any inside
90 degree corners along the exterior of your house. This will serve to
divert the salamanders away from the corners.
Snakes
Probably the most commonly encountered snake is the garter snake Thamnophis species). These snakes are harmless to humans. They inhabit nearly all of the vegetation types found in Minnesota, but have a fondness for water and are often found near it-ponds, streams, marshes, or pools.
Their major foods include earthworms and amphibians as prime choices, but
they also eat other snakes, fish, mollusks, small nesting birds, small
mammals, and carrion.
These snakes are traditional hibernators, preferring to return to the same
den year after year. Day length triggers the hibernation response and
snakes begin congregating at their dens beginning in late summer
(September). They sun themselves on warm days and seek the warmth of the
den on cold days and throughout winter. Spring emergence can occur in
early April at which time they will be seen basking in the warm, sunny
locations close to their den. As the soil and air temperatures rise, the
snakes begin to disperse for their summer of hunting. Garter snakes give
birth to live young, 10-25 is the typical litter size. Depending on the
timing of events (migration away from the hibernacula and delivery of
young) these young could be delivered at the hibernacula or in the
surrounding fields and woods. Newborn garter snakes are about the size of
wood pencils (5-6" long and 1/4" in diameter).
These snakes do no harm to humans, save the occasional start one gets when
suddenly encountering a snake in the garden or in the house. Hibernation
is the winter survival technique that assures continuation of the species.
Successful hibernation requires avoidance of direct exposure to frost.
These snakes seek harbor underground via natural entrances-animal burrows,
decaying tree root systems, etc. On occasion they discover exposed portions of septic drain fields, foundation drains, heaved or cracked concrete (walkways, porches, patios, etc.). Successful control of most snake problems involves control of their access to hibernation sites. It is not necessary to spend time, energy or money killing garter snakes--eliminate the dens and you control the snakes.
Flyers
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Little brown bat
Image: Don Luce |
Bats are truly wonders of nature. They represent the only flying mammals
(flying squirrels glide but cannot fly). The sonic, directional, object
detection ability not only serves them well while flying, but it was
studied as a part of various research projects during the development of
radar and sonar. Bat species in Minnesota are primarily insectivores.
They feed on a wide variety of flying insects, mostly small beetles,
moths, mayflies, and flies of several species. Contrary to some popular
information and superstition, they do NOT consume significant numbers of
mosquitoes (if you want mosquito control promote dragon flies). Bats
breed but once a year and depending on the species, females deliver one or
two pups. By early August the young are flying along with the adults,
but, until then, they are confined to the roost while the adult females
fly in and out to hunt and feed their young. Males live separately from
females until the fall migration when the sexes mingle and spend the
winter together at their hibernation sites.
Only two species of bats the Big Brown Bat (Eptesicus fuscus) and the
Little Brown Bat (Myotis lucifugus) are any threat to man. Individuals
from these species will enter houses in the spring and fall. During the
spring where attic and eve temperatures hover between 90 and 103 degrees
F, female little brown bats can use the areas as a nurseries for raising
their young. Big brown bats prefer slightly cooler locations for their nurseries. Also big brown bats can tolerate much colder winter temperatures and are active later into the fall than are the little browns. Both species, however, require fairly constant temperature and humidity during the hibernation period. Little browns are likely to hibernate in caves where the temperatures stay above freezing. Big brown often successfully hibernate in attics, eve areas, abandoned bird houses, etc. where temperatures may fall to below 0 degrees F.
Both species of bats can enter very small openings. Any circular opening
the diameter of a nickel will allow their passage. It is more common for
them to enter buildings via more accessible routes such as broken attic
windows, unprotected roof/gable vents, along side exterior masonry chimneys, sprung corners on eves, where dormers meet the main roof, etc.
Look for droppings adhered to roofing or siding as clues to detect
entry/exit points. Another practice is to enter the attic on a sunny day
and observe all of the points where light enters. Examine these carefully
both from the inside and outside of the building. With all of the
openings located, permanently block the least accessible openings but
leave some of the larger, accessible openings. Over these place devices
that allow bats to exit but restrict reentry. Temporary flapper valves
can be made from 1"x4" (or larger if needed) cedar and a 2" square piece
of truck tire inner tube. Drill a 1 1/4" hole in the wood block. On the
exterior side staple the piece of inner tube over the hole with two
staples through the top only. Screw or nail the valve device over the
hole. Check the device(s) at sunset to determine if they are functioning
properly. If so, wait 2-3 days for the bats to clear the roost, check
the roost after the 3rd day and if clear, remove the devices and complete
permanent repairs. Except in documented medical emergency situations
there is no need to spend time, energy, or money to kill bats.
Are you ready? Well then, let the animal parade begin! Have a great fall
and winter.
Plant, Divide Iris Soon
Deborah Brown, Extension Horticulturist
Iris
Photo credit: Deb Brown
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This is prime iris planting time. It's also time to lift and
reset older clumps of iris that have been growing undisturbed for
three or four years. Allowing them to become too crowded will
result in fewer flowers each spring.
Despite their delicate-looking blooms, iris are really quite
tough. Lifting them allows you to trim away any woody or soft,
rotted portions of their rhizomes (the thick, underground storage
organs). It also gives you an opportunity to improve the soil by
adding peatmoss or well-decomposed compost, along with some 5-10-10 fertilizer before replanting.
Dig iris carefully to avoid piercing their rhizomes. Trim leaf
fans back to about four or five inches and inspect the rhizomes
carefully for signs of soft rot, which can occur anywhere, or
woodiness, which is found in the oldest part of the rhizome.
Slice these portions away with a clean, sharp knife, and let the
rhizomes "skin over" or seal before putting them back in the
soil.
Choose a site that's both sunny and well-drained. Set your iris
rhizomes just below the soil surface in clusters with the fans of
leaves oriented towards the viewer or facing outwards in a
circle. Water them thoroughly, then only sparingly until new
leaves appear. Depending on the size of the rhizomes you plant,
you should be enjoying beautiful blooms in your garden next
spring or the spring following, at the very latest.
Drying Flowers
Deborah Brown, Extension Horticulturist
Dried flowers
Photo credit: Deb Brown
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Flowers have been so lovely this year many people want to
preserve them for dry arrangements. Air drying is easiest, but
it results in an attractive finished product only for certain
specific flowers. All other methods (silica gel, glycerine,
microwaving) require a fair amount of practice to develop the
skills needed to do a good job..... but, hey, it's fun!
To air dry flowers strip off their leaves, then hang them in
small bunches upside-down, using rubber bands to hold the stems
together. If you want stems that arch gracefully, make a vase-like cylinder of hardware cloth (metal mesh) with chicken wire
over the top. Prop the flowers in it to dry, allowing them to
curve naturally over the cylinder. Either way, keep the flowers
in a well-ventilated, dark location till they're ready. Sunlight
will fade their colors.
Favorite flowers for air drying include globe amaranth, larkspur,
goldenrod, mealycup (blue) sage, celosia, and statice. Grains
and grasses also air dry easily.
Most bookstores and libraries stock references on preserving
flowers that will detail the use of sillica gel on all sorts of flowers and glycerine for flexible (albeit, tan to brownish) dried materials.
Brighten Your Home and Garden with Sunflowers
Deborah Brown, Extension Horticulturist
Sunflower
Photo credit: Deb Brown
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Golden sunflowers have been trend-setting blooms the past few
years. As Minnesotans we're accustomed to driving past acres of
sunflowers, giant plants grown not for their cheery flowers, but
the oil content of their seeds, but they're popular in home
gardens as well.
You can buy sunflowers at florist's shops and flower stalls at
the farmers' market..... and they're not cheap! Why not make a
mental note to plant your own sunflowers next year? Not all
varieties are eight feet tall (though mammoth varieties are a
real hit with children). And they couldn't be easier to grow,
particularly if you've got a garden location that's sunny most of
the day.
Actually, you have a choice of many new sunflower varieties, some
as short as one to three feet, some with smaller flowers, some
that branch and have many flowers per plant, and some that
produce neither pollen nor seeds. In addition to the traditional
golden color, sunflowers are also available in pale cream, lemon
yellow, bronze, mahogany, and even a purplish hue.
The desirability of short stature plants is obvious. Tall
varieties such as Giganteus, grown primarily for seeds, take up
lots of garden space. And they may require staking as they grow
top-heavy with the weight of the mature flowers. Shorter plants,
while less dramatic, can provide lots of color..... as well as a
multitude of cut flowers for indoor use.
You might wonder though, why anyone would choose to grow sterile
sunflowers that don't produce pollen or seeds. If you plan to
use the flowers for bouquets and floral arrangements, their lack
of pollen can be a real benefit. Not only will pollen stain
tablecloths and clothing, it may cause an allergic reaction in
some "hayfever" sufferers.
If you want sunflowers for bouquets, treat them as you would any
fresh garden flower. Pick them early in the morning while
they're full of moisture, and place them immediately in a clean
container of warm water and floral preservative. Be sure to
strip off any foliage that will remain under water. Keep them in
a relatively cool location for several hours to "harden" them
before arranging them for display.
If you plant varieties that develop large seeds to harvest for
snacks and baking, you'll want to protect the flowers as they
mature in the garden. Cover each flower with cheesecloth when
birds or squirrels start to nibble at them. There's usually
plenty to allow some to remain for the animals.
'Chianti'
Photo credit: Deb Brown
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Check seed catalogs next winter to see the wide diversity of
sunflowers that are available. Here are just a few:
* Sunspot: giant flowers on short plants, tasty seeds
* Velvet Queen: velvety red petals, 5 ft. plants
* Teddy Bear and Orange Sun: shaggy, fully double
flowers, 2 to 3 1/2 ft. tall
* Sunbeam: golden petals, green center, pollen-free
* Chianti: deep wine-red blossoms, 3 to 4" on a multi-
branched plants, 4 to 5 ft. tall; no pollen
* Italian White: ivory petals, dark center, 4 ft. tall
* Music Box Mix: 4" flowers, yellow to mahogany
* Sunrise and Sunset: 6" flowers, lemon yellow or mahogany tipped with gold, excellent for cutting
* Mammoth: enormous flowers on 12 ft. stalks
Time for Second Corn Gluten Meal Application
Deborah Brown, Extension Horticulturist
Common chickweed, a winter annual.
Photo credit: Beth Jarvis
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If you're among the growing number of people relying on corn
gluten meal products to prevent weed seeds from sprouting in your
lawn, it's time for as second application (early to mid- August).
Last spring's application will have lost its effectiveness by
now. A new application will prevent weed seeds sprouting now and
more importantly, prevent weeds known as winter annuals from
sprouting this fall, then returning next spring.
Apply corn gluten meal at the same rate you used in spring; 20
pounds per thousand square feet. Water it into the lawn to
activate it. Corn gluten meal also provides slow-release
nitrogen which should help grass thicken this fall, and come back
even better in spring.
Remember, corn gluten meal is effective against a wide variety of
seeds. It cannot discriminate between weed seeds and seeds from
desirable turfgrasses, so if you're planning to overseed the lawn
this fall, do not spread any corn gluten meal in that area. Wait
until spring when the new grass plants are growing vigorously
before you apply it again -- probably late April or early May.
Lace Bugs
John F. Kyhl, Entomology Technician
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Lace bug adult
Photo credit: U of M Entomology Dept. |
This time of year we commonly see lace bug damage. Lace bugs are pests of a wide variety of
trees and shrubs in Minnesota, including hackberry, walnut, basswood, white oak, bur oak,
willow, chokecherry, hawthorn, serviceberry, and cotoneasters.
Lace bugs are 1/8 to 1/4 inch long, have light colored bodies, and elaborate, ornate, lacy wings
that look broad and flat from above. Lace bug damage is recognized by small white or yellow
spots on the surface of the leaves. Heavy feeding can cause striking leaf discoloration and early
leaf drop. Other signs of lace bugs are dark, varnish-like fecal deposits and shed skins on the
undersides of leaves.
Lace bug feeding damage is most noticeable in mid to late summer as populations increase. Lace
bug feeding degrades the appearance of plants but does not normally threaten their health.
However, lace bugs can damage trees and shrubs if heavy feeding occurs over several consecutive
years, or if the plants have recently been transplanted or stressed.
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| Lace bugs and fecal droppings |
It is best to tolerate lace bugs when possible, because natural enemies, such as lady beetles and
other predators help keep lace bugs in check. If control is needed on small plants, start with a
high-pressure water spray from a garden hose. The water spray acts much like a heavy rain,
knocking young lace bugs (nymphs) off the plant. Since nymphs can not fly back to the plant, they
are less likely to survive. Direct the spray at the undersides of the leaves where most lace bugs
are found.
Insecticides can be effective in reducing numbers of lace bugs on plants. Use insecticides
judiciously, as they kill natural enemies as well as lace bugs, and can make lace bug problems
worse. It is best to use the least toxic products first. Insecticidal soaps (e.g., Safer's), horticultural
oils, and pyrethrins are insecticide products with relatively low toxicity, and are relatively safe for
many beneficial insects including natural enemies. Other products to manage lace bugs are
acephate (e.g.,Orthene), carbaryl (e.g., Sevin), chlorpyrifos (e.g., Dursban), or permethrin. When
using insecticides, good coverage is critical, so be sure to spray the undersides of the leaves where
lace bugs are normally found.
These Adelgids Really "Gall" Spruces
John F. Kyhl, Entomology Technician
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Cooley spruce gall
Photo credit:
Whitney Cranshaw |
Many spruce trees are now showing curious fleshy, elongate cone-like growths toward the end of
their branches (see figures). These are most likely Cooley spruce galls. These interesting and
highly recognizable galls are cause by aphid like insects called adelgids. Cooley spruce galls
occur on white and Colorado blue spruces. Females overwinter under bark scales near the
terminal twigs. In the early spring, females emerge and lay their eggs. The young
adelgids(nymphs) settle at the bases of young needles and begin feeding. Theneedles grow and
quickly enclose the nymphs. The nymphs develop inside the host tissue until they emerge in late
August or early September. Cooley spruce gall adelgids generally do not threaten the health of
thehost plant, though they can cause them to look unsightly. The best control method is to prune
off galls before they open in the late summer. Since these insects are protected within the plant for
most of the growing season, most applications of contact insecticides are not effective. For
successful chemical control, apply insecticides before the buds begin to form in early April, or
after the galls have opened up and the adelgids have left the gall in late August or September.
Insecticidal soap is suggested against this soft- bodied pest, as are acephate (e.g., Orthene),and
carbaryl (e.g., Sevin). Given the minor damage that this insect causes, insecticidal treatment is
generally not recommended.
Aphids, a Perennial Pest
John F. Kyhl, Entomology Technician
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Aphid
Photo credit:
U of M Extension Service |
Aphids are common insects, occurring on almost all plants in Minnesota, from trees to shrubs to
annuals and perennials. Aphids are small (2-4 mm long), pear-shaped, soft-bodied insects that
occur in many colors (green, red, black), and are easily recognized by the presence of cornicles
(tail pipes) on their abdomen (see figures). Aphids tend to cluster on unopened flower buds, the
underside of young leaves, and developing stems.
Aphids have an enormous reproductive capacity. They can give birth to live young without
mating. Aphids are capable of reproduction within a week of birth. As a result, aphid populations
can build to enormous levels in a short period of time. Aphids suck plant juices through a fine,
needle-like stylet and feed on many plant parts. Damage from feeding is quite variable, ranging
from no apparent damage to off-color foliage, twisted and curled leaves, gall formation, poor
plant growth, and branch dieback. Most healthy plants are able to tolerate aphid feeding, even
when there are many feeding individuals. However, large aphid populations that persist can
significantly weaken recently transplanted or stressed plants.
While aphids often go unnoticed, their waste, called honeydew, is more conspicuous. Honeydew
is a clear, sticky liquid that coats bark, leaves, and objects beneath the plant. Honeydew is easily
seen on car windshields and lawn furniture, and can be difficult to remove.
There are several options for aphid management. The first option for aphid management is
tolerance, since aphid populations are naturally regulated in many ways. Natural enemies, such as
lady beetle adults and larvae, green lacewings, damsel bugs, syrphid flies, parasitic wasps, and
certain fungi can all lower aphid populations. Additional natural control is provided by the
weather, such as heavy rainfalls. In the absence of these natural controls, aphid numbers can build
rapidly. One reason that aphid populations can become very large is that they reproduce much
more quickly than their natural enemies, and can quickly rebound from harsh weather.
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Aphids and lady beetle immature
Photo credit:
U of M Extension Service |
Remember that leaving aphids alone generally causes little damage to the unstressed plant, and
has the added benefit of giving natural enemies the chance to exert natural control. High pressure
water spray from a garden hose is also a good option for aphid management on smaller plants.
The water spray acts much like a heavy rain, knocking the aphids off the plant.
Insecticides are effective in reducing aphid numbers. It is best to use the least toxic products first.
Insecticidal soap (e.g., Safer's), horticultural oils (e.g., Sunspray) and neem (e.g., BioNeem),
made from an extract of the neem tree, are effective against aphids. These products are examples
of 'biorational insecticides' because they kill pests with minimal impact on natural enemies. In
other cases, aphids can also be managed with insecticides such as acephate (e.g., Orthene),
malathion,diazinon, permethrin, or chlorpyrifos (e.g., Dursban). Keep in mind that these
insecticides kill the natural enemies as well as aphids, and can make aphid problems worse.
Get the low down on this month's insect pests at Insects http://www.extension.umn.edu/projects/yardandgarden/Ent.htm
Gifts from Our Feathered Friends
John F. Kyhl, Entomology Technician, and
Jeffrey D. Hahn,
Assistant Extension Entomologist
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Bird mites
Image credit:
Roger Moon |
Some of the more interesting calls to the clinic lately have been small
(about 1/32 inch long) spider-like creatures entering homes. In some
cases, these are bird mites. Bird mites are associated with many
different species of domestic and wild birds, particularly pigeons,
sparrows, and robins. In most cases, there is a nest somewhere within or
near the home. In our most recent cases, nests have been atop window air
conditioners, outdoor lights, or in soffits. If a bird dies or the nest
is abandoned, the remaining mites seek out other hosts. While searching,
they can enter nearby structures in large numbers. When inside, they can
bite people, but are not able to complete their life cycle when feeding on
humans alone. Bites can sometimes cause discomfort and skin irritations,
but rarely transmit diseases or are a health hazard.
The first step in control is to remove any dead birds that you find. If
nests are empty (i.e. no eggs or young birds in them), remove and dispose
of them. If eggs or young are found in nests of federally protected
songbirds (which includes nearly all birds in Minnesota), do not disturb
them. If the nesting season is over and only adults remain, you may remove
the nest, provided the birds are not harmed. Only pigeons, starlings, and
house sparrows are not federally protected; you may remove their nests
regardless of the circumstances. If mites enter your home, wipe them up
with a moist cloth or remove them with a vacuum. After vacuuming, remove
and freeze (or discard) the vacuum bag because mites can survive a trip
through the vacuum. To reduce bird mites that may migrate indoors, spray
an insecticide effective against mites, such as chlorpyrifos (e.g.
Dursban). Treat outside around windows, doors, and other possible points
of entry.
Renovating Red Raspberries
Doug Foulk, Extension Educator
University of Minnesota Extension Service, Ramsey County
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A renovated raspberry row before growth begins in spring. .
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Left unchecked, a summerbearing red raspberry patch quickly can become an unproductive, unattractive thicket. An overcrowded raspberry planting produces lower per-cane numbers of small, poorly flavored fruit. In addition, the decreased sunlight and air circulation results in a greater likelihood of fungal disease, including anthracnose and spur blight. Finally, an overgrown raspberry patch is just plain difficult to reach into, making harvest an unpleasant chore.
How can you keep your summerbearing raspberry plants at their productive, healthy best? The answer is annual renovation and the procedure is amazingly simple.
- Renovate summerbearing raspberries any time from late summer after harvest is finished until late March of the following year, before spring growth begins. While late summer renovation results in slightly more vigorous canes and larger fruit, a March renovation is preferable in areas where hardiness is a concern and canes may be lost to winter damage.
- To renovate, simply remove all canes that have already produced fruit (the floricanes), then thin all broken or weak first year canes (the primocanes). Those canes that have fruited are easy to spot at this stage as they sport numerous side branches. The primocanes, on the other hand, are relatively unbranched. The actual number of canes left in the row after renovation, unlike previously believed, is unimportant. What is important is that the canes left to grow are sturdy and strong.
- After thinning the old, weak and broken canes, check your row width. Raspberry rows should be no wider than 12" wide in order to maximize sun penetration and air circulation (figure 1). Removing canes that grow beyond that 12" width--and they will grow outside the row, constantly--requires frequent attention. Some people hoe or prune the extra canes out, while others mow them as they sprout.
Summer is not a good time to fertilize raspberries--wait until early spring when growth begins to apply nitrogen. Summer is a fine time, however, to apply 2-4 inches of organic mulch, if the existing mulch is getting thin.
Fallbearing raspberry types, including the cultivars 'Heritage,' 'Redwing,' and 'Autumn Bliss' may be renovated as described above, or, if only a fall crop is desired, may be cut entirely to the ground during the dormant season. The latter method effectively prevents fungal disease without the use of fungicides.
Rust Diseases Of Apple And Hawthorn
Chad Behrendt, Extension Plant Pathologist
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| Cedar apple rust teliospores |
Photo credit:
Dept. of Plant Pathology
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Rust diseases are generally not considered economically important or life threatening to ornamental crab apples, apples, and hawthorns in the home landscape. However, these rust diseases can be intriguing to first time observers. Rust diseases require cool, wet conditions in early spring, similar to the environmental conditions required for apple scab. As a result of the wet spring this year, we have observed an increase in the number of apple and hawthorn rust infections.
Although several different rust fungi infect apple and hawthorn, they all infect the same alternate host, eastern red cedar. The most common rust fungi include cedar-apple rust, cedar-hawthorn rust, and cedar-quince rust, with cedar-apple rust being the most serious. All of these fungi require two hosts in order to complete their life cycle, alternating between cedar and apple or hawthorn. All of these rust fungi produce similar symptoms, and have a similar life (reproduction) cycle.
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| Hawthorn rust on leaves. |
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| Hawthorn rust on fruit. |
In the spring, all of these rust fungi produce orange, gelatinous structures called telial horns on the leaves or branches of cedar. A special type of spore, called a basidiospore, is splashed by rain from the telial horns to the leaves and fruit of apple and hawthorn. Cedar-apple rust produces orange-yellow (rusty) spots on the upper surface of infected apple leaves shortly after bloom, and longer, finger-like projections (aecia) on the underside of the leaf tissue in late summer. Cedar-apple rust may also infect apple fruit, but formation of aecia on the fruit is rare. Cedar-hawthorn rust produces similar symptoms on the leaves of hawthorn, as well as apple, but rarely on the fruit. In contrast, cedar-quince rust rarely infects leaf tissue, but frequently infects both hawthorn and apple fruit. Infected hawthorn fruit commonly produce the finger-like aecia, similar to those on the underside of apple and hawthorn leaves (see photo).
In late summer and early fall, spores produced on the leaves and fruit of apple and hawthorn are splashed by rain to the leaves of eastern red cedar, where they initiate new infections. The cedar-apple rust fungus takes two years to complete its infection and produce orange telial spores. One year after infection, brown woody galls appear on the branches. These galls produce orange, gelatinous horns the following spring and can remain on the tree for several years.
To manage apple and hawthorn rust diseases, remove all cedars from the immediate area, when practical. This disrupts the disease cycle and helps prevent disease. Since spores can be wind-blown for several miles, infection may continue after the removal of nearby cedars. If you do not want to remove the cedar, you can try pruning out the brown woody galls that produce spores in the spring. If rust fungi continue to cause severe problems, fungicide sprays are available. However, fungicides are not usually recommended for ornamental purposes.
Willow Scab
Chad Behrendt, Extension Plant Pathologist
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| Canker on willow |
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| Conidia on leaves |
Recently, the Yard and Garden Clinic has received several willow samples with dead leaves and shoots. Symptoms typically included brown, shriveled leaves and stem cankers. Infected stems appeared blackened and curled, with a distinct division between infected (blackened) stem tissue and healthy tissue. Leaves on severely infected trees gradually dropped.
The disease responsible for these symptoms is called willow scab, but is often referred to as willow blight. Willow scab is caused by the fungus Venturia saliciperda. A second disease called willow black canker, which is caused by a distinctly different fungus, sometimes occurs simultaneously with willow scab. Both of these diseases cause similar symptoms, and are difficult to differentiate without evidence of the fungal organism.
Willow scab is easily identified by the conidial spores produced on infected leaf tissue. Masses of olive-brown to olive-gray spores usually form along the veins on the underside of the leaf, a few days after infection (see photos). During wet periods these spores become active and are splashed by rain to the current year and adventitious growth. Only the current year’s growth is infected.
The fungus survives the winter in infected twigs and becomes active in the spring during wet periods. Spores produced on infected twigs initiate new infections on nearby leaves. These leaves later produce masses of spores, which cause secondary infection. Wet springs cause severe infections, while dry springs inhibit infection. The severity of infection also decreases as leaves mature and develop resistance.
Willow scab is a common disease on susceptible varieties of willow such as black, white, golden, pussy, shining, and silky willows, while purple, osier, and weeping willows are more resistant. To manage this disease maintain healthy, vigorous trees, rake infected leaves in the fall, and prune infected shoots. In severe cases a fungicide may be applied. Few fungicides are listed for this disease, but Bayleton or copper-based fungicides may be tried. Always read the label before applying fungicides.
Birch Anthracnose/Maple Leaf Scorch
Chad Behrendt, Extension Plant Pathologist
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| Anthracnose |
As a result of the extremely wet spring this year, we have seen a lot of common diseases, as well as uncommon diseases. One of the uncommon diseases observed was birch anthracnose. This disease appears as a spotting on the leaf tissue (see figure) and may cause some defoliation. Since this disease is rare and usually of little importance, the recommendation is simply to maintain tree health.
As a result of the recent extreme heat and sporadic rainfall, we have observed leaf scorch on maple. This common problem is caused by a lack of water, strong winds, and extreme temperatures. It appears as a marginal and interveinal burning (drought-like symptom) on the leaf tissue. Watering trees on well-drained sites during dry periods may help reduce leaf scorch.
Test your diagnostic savvy monthly with Disease Watch at: http://www.extension.umn.edu/projects/yardandgarden/Plpa.htm
Editorial Notes
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Clemens Gardens,
St. Cloud.
Photo credit: Beth Jarvis
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When a friend and I visited Munsinger and Clemens Gardens in St. Cloud in mid-July, we were told to come back to see the mums in the fall. Today, 7/30, with noontime temperature at 91 and heat index at 111 degrees F., fall seems a long way off.
But as Jim Kitts' told us, the critters know fall's coming. Doug Foulk says now's a great time to renovate raspberry beds. Next issue, Neil Anderson. who heads the Minnesota Mum Project will give us a guided tour, timely as mums take center stage in gardens as well as garden centers. Coming soon, to coincide with fall lawn fertilizing, we'll hear from the Soils Testing Lab. Mike Zins, from the Arboretum, has promised to wax rhapsodic about overwintering tips for marginally hardy trees and shrubs. Patrick Weicherding, Extension Educator from Anoka Co., will expound on preventing winter injury in trees and shrubs. As a former forestry prof, Patrick will concentrate more on tree physiology than burlap.
I'm still collecting suggestions for articles for the near future or even for next year. Drop me a note if you have ideas.
I put up a small webpage with the Yard & Garden Line promotional items that are available, at no charge, of course. It's at: http://www.extension.umn.edu/projects/yardandgarden/YGLpromos.html.
Deb Brown will be the regularly scheduled guest on Minnesota Public Radio's MPR) "Midmorning" program on the first Thursday of every month. Katherine Lanpher hosts the program that is broadcast on KNOW 91.1 FM, and available state-wide on the MPR news radio stations. Although she's been a guest at MPR numerous times, she'll start as a regularly scheduled guest on July 2.
Back issues Yard & Garden Line News are on the Yard & Garden Line home page at www.extension.umn.edu/projects/yardandgarden/. Our newly revised home page has clickable links to most of the components of the Yard & Garden Line, such as Bell Museum of Natural History, INFO U and the Soil Testing Lab. You'll also find links to the current issue of the
Plant Health Care Update and back issue archives. Plant Health Care Update is a newsletter
written by Master Gardeners for Master Gardeners. The authors have completed advanced
training to earn the designation Plant Health Care Advisors.
We publish the Yard & Garden Line News twice a month during the gardening season, on
the 1st of the month and the 15th of the month.
Please feel free to cut and paste any of the articles for use in your own newsletters. All we ask is that you give our authors credit.
For plant and insect questions, visit http://www.extension.umn.edu/askmg. Thousands of questions have been answered, so try the search option in the black bar at the top left of the board for the fastest answer.
If you would like to receive an e-mail reminder when the next issue of the Yard & Garden Line News is posted to the web, just send an e-mail to:
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Happy gardening!
Beth Jarvis
Yard & Garden Line Project Coordinator
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Chipmunk
Iris
Dried flowers
Sunflower
'Chianti'
Common chickweed, a winter annual.
