Yard & Garden Line News Volume 4 Number 16                                                               October 1, 2002

Features this issue: It Might Be Worth Saving--Transplanting Trees and Shrubs - Part I: Preparing for the Move Apple Guide Now Available in Hmong and Spanish Plant Bulbs Now for Color Next Spring Minnesota Gardening Calendar Available Fall Clean Up Key To Healthy Plants Lady Beetles in Homes Spider Mites on Ash Editorial Notes

It Might Be Worth Saving
Transplanting Trees and Shrubs-Part I: Preparing for the Move
Gary R. Johnson, Professor, and Extension Educator, Urban and Community Forestry

Tree to save. Photo credit:  Gary Johnson

"I don't know anything about planting trees, but my neighbor told me that you shouldn't plant in the autumn in Minnesota." "I was at the local nursery last weekend and they had signs advertising "Fall is for Planting"." Who should you believe?

Part of this contradiction involves mythical information vs. factual information. A bigger part of the contradiction relates to the differences between planting and transplanting. Most of the mythical information revolving around the blanket statement "you shouldn't plant in the autumn in Minnesota" is a misunderstanding. Planting is literally placing a plant in the ground at its (hopefully) permanent growing site. Transplanting involves digging a plant from one site and transferring the tree or shrub to a new site. When planting is done, theoretically, no roots are lost. When transplanting is done, the majority of the tree or shrub's original root system is cut off during the process.

It's SHOCKING! The loss of roots during the transplanting procedure normally induces a health condition called transplant shock. This condition is actually less ominous than the term implies, and the vast majority of transplanted trees and shrubs fully recover in a relatively short amount of time. During this shock period, however, the abbreviated root system must recover and reestablish a more characteristic "root:shoot" balance. During this recovery period the tree or shrub exhibits retarded growth above ground (contrary to what's going on below ground), maybe a little branch or twig die-back, and often fewer and smaller leaf production.

As the tree or shrub is growing through this recovery period, it's more vulnerable to stressful weather and landscape conditions that healthy plants would normally be able to tolerate. Short-term drought, hot and windy weather, and early, deep freezes can result in some abnormal damage to the plants. Whether the plant is a native one or an introduced one, they're all vulnerable to transplant shock.

When the leaves are falling, the roots are growing. Autumn, especially early through mid-autumn, is actually an excellent time to transplant many trees and shrubs in Minnesota because of the aggressive root growth going on below ground. Normally, the autumn soil temperatures and moisture content in most Minnesota landscapes are ideal for root growth. That's why most field nurseries "root-prune" trees and shrubs in the weeks during late summer to early autumn. Warm soil temperatures + uniform soil moisture = new roots.

Spring is also an excellent time period for transplanting, especially if it can be done between ground thaw and leaf emergence. Both spring and autumn seasons present the advantage of moving largely dormant plants, and the disadvantage of not knowing what the following months will be like (weather-wise). Droughty, hot and windy summers can be just as stressful on newly transplanted trees and shrubs as early, windy, bitterly-cold and long winters.

Why take the chance and potentially waste all the efforts of transplanting something when it's easier to just buy a new tree or shrub? Good question!

Not worth saving. Photo credit:  Gary Johnson

Maybe the plant has some sentimental value, such as a memorial tree or a shrub that you propagated from your grandparent's garden?…GOOD REASON!

Maybe the tree has some historical significance, and is worth preserving, such as the "Eagan Oak" that was transplanting in 2001?…GOOD REASON!

Maybe it's a unique species, or a species that isn't normally found growing in Minnesota, such as the Japanese maple in Grand Marais, or a topiary juniper that has taken you years to develop?…GOOD REASON!

Maybe it's just a beautiful specimen, the most perfect potentilla you've ever seen?…GOOD REASON!

Maybe the tree or shrub is in pretty bad shape, unhealthy, unshapely, and a new site could improve its appearance?…BAD REASON!

As a rule of thumb, if the plant is in poor health or poor condition, it probably would be best to transplant it to the chipper and then to the mulch pile. You can do this during any season.

Okay, you've convinced me. Can I move anything, spring or fall? Well, yes, you can move anything, but it may not survive! Literally, just about any tree or shrub can be moved, but there are definite limits to success (a.k.a., the plant actually lives).

Smaller trees and shrubs transplant more successfully. They're younger and recover from the transplant shock much sooner and easier. Plus, there's a better chance that you will be able to transplant a larger percentage of the roots if the plant is smaller. For instance:

Root and Top Growth of a One-Inch Caliper Tree Following Transplanting (Reyes, 2002) A 1" caliper tree would have a root diameter of 4.5 feet. By nursery standards a root ball of about 1.5 feet would be moved. Less than 5% of the root system is transplanted.	Root and Top Growth of a Four-Inch Caliper Tree Following Transplanting A 4" caliper tree would have a root diameter of 18 feet. A root ball of 3.5 feet would be moved. Less than 5% of the root system is transplanted in the root ball.
First Year. The tree is under severe water stress soon after transplanting. With good care the stress diminishes, and the root system diameter should increase to 4.5 feet (100% of the original) by the end of the first year. Roots and top are now balanced and the tree should grow normally.	First Year. Root system diameter increases to 6 feet, 9% of original volume. With less than 10% of the absorbing roots to support a full crown (top), the tree is often under severe water stress, inhibiting top growth, including bud formation.
	Second Year. Root system increases to 9 feet, 23% of original volume. The tree is frequently under water stress, inhibiting current season growth.
	Third Year. Root system diameter increases to 12 feet, 41% of original volume. As root/top balance is gradually restored, the tree is exposed to less water stress and growth improves.
	Fourth Year. Root system diameter increases to 15 feet, 60% of original volume. The effective rate of root generation accelerates as the overall diameter of the root system increases.
	Fifth Year. Root system diameter increases to 18 feet, 100% of original volume. Roots and crown and the tree should grow normally.

Healthy plants transplant more successfully. It takes a lot of the plant's stored energy to establish a new, more characteristic root system. If a plant is unhealthy, it probably has a very poor, energy reserve system. Not only will it be more difficult for this plant to recover its root system from the shock of transplanting, the energy drain could push this tree or shrub over the edge from unhealthy to dead.

How do you know if it's healthy? If the foliage is undersized for the species, it may not be healthy. If the canopy (branches with leaves) is sparse for the species, it probably isn't very healthy. If there is a lot of branch die-back, it's probably not healthy. If there is decay in the stem/s, infestations of boring insects and/or infectious diseases of the stem or leaves…transplant it to the chipper.

SOME plant species just do better if moved in the spring:

Stick with Spring	Spring best, Autumn w/care	Early Autumn
Carpinus (hornbeam)	Acer rubrum (red maple)	Berberis (barberry)
Magnolia	Betula (birch)	Cotoneaster
Populus (poplar, aspen)	Cornus (dogwood)	Ilex (holly)
Quercus (most species) (oak)	Prunus (plum, cherry)	Pinus (pine)
Chamaecyparis (false cypress)	Pyrus (pear)	Rhododendron
Crataegus ( hawthorn)	Salix (willow)	Taxus (yew)
	Tilia tomentosa (silver linden)	Tsuga (hemlock)
		Viburnum

How can I improve the chances of a successful transplant?

Rootpruning completed. Photo credit:  Gary Johnson

Build up the health of the plant before the move. If you're planning on moving the plant in the spring, start with the health program the preceding autumn or summer. If it's nutrient-stressed, fertilize it. Don't allow it to become water-stressed…keep the soil uniformly moist. Control any insect pests or diseases. Prune out any dead wood and/or weakly attached branches. Mulch as much of the root zone as you can stand. This gets rid of grass competition, lessens the need for constant watering, and keeps the soil warmer into late autumn (for best root growth).

Root prune the plant, at least one season (spring or autumn) before the move. Root pruning woody plants encourages a more compact and dense root system. Therefore, when you finally move it, the tree or shrub will have a higher percentage of its most important roots contained within a smaller soil volume.

As a rule of thumb, for each inch of stem caliper, root prune at a distance of 10-12 inches out from the stem of the plant. For instance, if the tree has a one inch stem caliper, the diameter of the root pruned area would be 20-24 inches. Simply determine the appropriate distance from the stem, draw a circle around the stem with this distance as the radius, and sink the blade of your digging spade down as deep as you can go all the way around this circle. This one practice will dramatically reduce the transplant shock on the plant when it is finally transplanted the following season or year.

You've sold me on the idea of transplanting, but the tree is just too big for me to move it. Are there companies that specialize in transplanting large trees and shrubs?

Yup. There are several companies in Minnesota that specialize in transplanting large plants with various sizes of tree spades. However, these companies are busy, and it would be smart to include contacting them at least one season before the transplant date.

A Partial Listing of Companies That Transplant Large Trees and Shrubs:

A telephone survey of possible tree moving companies in the Twin Cities: Minnesota Valley Landscape, Shakopee, 952-445-4004 Halla Nursery, Chaska, 952-445-6555 Witzel Tree Moving, 651-459-4581, 651-769-1759 Strese's Tree Service, Dennison, Mn, 507-645-6137, cell 612-282-3526....variety of spade sizes. Bob Matiski Tree Moving, 651-436-1709, serving the St. Croix River valley, moves up to 5 inch caliper trees This list was compiled from the telephone book and someone called to verify. No endorsement is expressed or implied by the University of Minnesota Extension Service, the author, or Yard & Garden Line. Tree moving firms not included are invited to contact the author at grjonson@umn.edu for addition to the list.

In Part II, the actual transplanting process will be illustrated and outlined. In the meantime, start your planning!

References cited:
Reyes, Jonah. 2002. Arboriculture Myth Exposed: Bigger is Better? Tree Care Advisor Newsletter. Volume 9, No. 2. P.15-16.

Apple Guide Now Available in Hmong and Spanish
Jill MacKenzie, Commercial Fruit Specialist

Photo credit: U of Mn Extension Service

Apples for Minnesota and Their Culinary Uses, a newly revised publication by Professor Emily Hoover, Scientist David Bedford, and Extension Educator Doug Foulk has been translated into Spanish and Hmong, just in time for apple season. This folder describes 22 apple varieties and shows where in Minnesota they can be grown. It gives information on selection, storage, nutritive value, canning, freezing and drying.

"Apples for Minnesota" will be a great reference for apple growers and apple eaters, and especially for anyone who didn't grow up eating Minnesota apple varieties, since they aren't found anywhere outside our region.

Plant Bulbs Now for Color Next Spring
Deborah Brown, Extension Horticulturist

'Apricot Beauty' Photo credit:  Netherland Flower Bulb Info

If you admired beautiful bulb displays last spring, and wished your yard looked that way, this is a gentle reminder. The time to ensure fabulous color from spring-blooming bulbs is right now, before the weather turns too nasty. According to experts from the Netherlands Flower Bulb Information Center, the best time to plant spring bulbs is when night temperatures average between forty and fifty degrees – about six weeks before the ground actually freezes.

There's good reason to plant now. Soil moisture from watering and rainfall will encourage newly planted bulbs to develop healthy root systems. Even though they're storage organs, don't make the mistake of assuming the bulbs, themselves, are roots. Like onions, bulbs grow roots at their base. Without good roots, they're unlikely to survive the winter.

Buying bulbs
Shopping for bulbs is no time to pinch pennies. Always look for the largest bulbs, regardless of whether you're buying tulips, daffodils, crocus or other spring bloomers. Bigger bulbs yield larger stronger flowers and in some cases, more than one stem of blooms. A sack of inexpensive, smaller bulbs is no bargain, particularly if you have hopes of enjoying them for several years.

Choose bulbs that are firm, with crisp papery skins. A little mold on the papery covering is usually not a problem, but mold on the bulb itself is not a good sign. And finally, handle the bulbs with care – don't toss them around. Each contains a minuscule precursor to next spring's blossom; rough handling can destroy it so all you get is leaves.

Planting sites

Tulips in yard. Photo credit:  Deb Brown

There are several factors to keep in mind when choosing where to plant spring bulbs. First is personal preference. Where do you want to see them? From your kitchen window, as you sip your morning coffee? Or are you more interested in enhancing the most public part of your landscape, where their colorful flowers will be visible to people who walk or drive by? You might also consider tucking small groups of bulbs here and there into the landscape to create an element of surprise.

Viewed with bulb health in mind, it's important to choose locations where the soil drains well. Bulbs are "fleshy" and will rot quite easily when kept too wet. Steer clear of wet areas near downspouts or the base of a slope where water collects.

Most bulbs bloom best and come back better when planted in full sunlight – six to eight hours daily. Finding enough light can pose problems in mature shady landscapes, but it may be less difficult than it first seems. Many spring bulbs bloom before trees leaf out or cast much shadow. As long as their foliage receives about six weeks of good sunlight, they'll probably be set for the following year.

If your garden beds are shaded by buildings, but you have your heart set on spring bulbs, go ahead and plant them anyway. Because they had ideal growing conditions in production fields the year before, they'll bloom perfectly well. Just don't expect a repeat performance. Think of them as annuals, and replace them accordingly.

Soil preparation
Good soil preparation is critical, especially in new beds. Dig the soil thoroughly, so it's loose and easy to work. Go at least two or three inches deeper than you plan to plant the bulbs. (Follow guidelines that come with the bulbs to determine how deep each should be planted.) Incorporate well-rotted compost or other organic matter if you're starting a new bed or if the soil is either too sandy or clay-like.

Experts no longer believe it's necessary to add bonemeal to the soil. Modern bonemeal processing has reduced its usefulness. Worse yet, the scent of bonemeal may attract squirrels, moles, dogs, and other animals that will dig in the area, trying to unearth non-existent bones. Instead, work bulb fertilizer into the soil surface next spring, after flowers fade but before foliage yellows.

Planting schemes

'Prinses Irene', a fragrant tulip Photo credit:  Netherland Flower Bulb Info

To create the most visual impact, plant spring-flowering bulbs in clusters or drifts rather than in long lines or individually. Use one color or a blend of similar colors that look good together in each grouping.

The Netherlands bulb folks suggest you can fool your eye into seeing a larger mass of color by planting bulbs in a triangle pattern, with the narrow point of the triangle facing the direction you'll view them from, and the broad expanse positioned towards the back. They also suggest planting small bulbs in the soil, right on top of larger bulbs that will bloom at the same time, for a double-decker effect. (One of the most memorable sights at Monet's gardens in spring are deep pink tulips popping up through a mass of sky blue forget-me-nots. You could produce a similar effect using tulips and grape hyacinths.)

When bulbs bloom at approximately the same time, plant low growing bulbs in front of taller ones, so you can see and appreciate them all at once. However, if the shorter ones bloom earlier than the taller ones, plant them in back. You'll see them bloom first, then as they fade, the bulbs in front will come into their own, drawing attention away from the shorter, spent bulbs.

Try many types
Most spring bulbs are lovely. Take this opportunity to plant some that are unfamiliar, along with tried and true tulips, daffodils, hyacinths, and crocus. Alliums (ornamental onions) come in a wide variety of sizes and colors; Siberian squill (Scilla), glory-of-the-snow (Chionodoxa), and Puschkinia are small but often naturalize or spread on their own. Grape hyacinths are more graceful than their big cousins, just as species tulips are more delicate than large hybrids. You really can't go wrong.

Critter control
If you've had the experience of squirrels digging bulbs out almost as quickly as you plant them, be sure to lay chicken wire over the soil once you're done. Bulbs will grow through the grids, but squirrels will be thwarted. And be sure to clean up all bulb debris before you leave the site so its scent doesn't attract more critters.

Minnesota Gardening Calendar Available
Deborah Brown, Extension Horticulturist

Deb and calendar. Photo credit:  U of Mn Extension Service

The new calendar, Minnesota Gardening, 2003, may be found now at garden centers, book stores, and gift shops as well as local county extension offices throughout the state. Look for a close-up phot of a large purple clematis flower with a frilly center.

This new calendar features a page devoted to attracting butterflies to your garden, based on material provided by University Extension Entomologist, Vera Krischik. And as always, it has a map showing average spring frost-free dates along with a USDA plant hardiness zone map. The calendar also provides up-to-date information about the various organizations that serve home gardeners in Minnesota.

What distinguishes Minnesota Gardening from other similar calendars is the fact that it's written specifically with our climate and growing conditions in mind. Each month has a list of timely tips and suggestions for garden and landscape activities, including pruning advice, weed control, disease prevention, and dealing with insect problems effectively.

Though it is chock full of good information, the calendar is also very attractive with its colorful photos of flowers, trees, and landscapes. You can preview it at http://www.extension.umn.edu/distribution/horticulture/DG7690.html Pick one up for yourself and for your gardening friends and neighbors. You may also order the calendar directly from the U, toll-free, at 1-800-876-8636 (outside the Metro area) or 612-624-4900 (in the Metro.)

Fall Clean Up Key To Healthy Plants
Janna Beckerman, Extension Plant Pathologist

This year, clematis were infected with Ascochyta blight. Photo credit: Janna Beckerman

As the 2002 gardening year draws to a close, now is the time to ensure a successful gardening season next year. Sanitation is a cornerstone of integrated pest management and essential for good plant health management. Throughout the year, many of us have been plagued with unusually wet weather. This weather incited normally minor disease problems to epidemic levels, encouraged the development of new disease problems and made for a difficult year to garden. However, now is not the time to give up! Removing diseased plant material this fall will help prevent disease problems next spring. Many disease-causing organisms can survive the winter in infected plant debris. Plowing or tilling under crop debris can also help prevent over-wintering of plant disease causing organisms. Although this is a constant theme in all my columns, it bears repeating: Don't guess at your disease problems! Remember to accurately identify which pests you have and what crops they attack.

Evaluate and Investigate
Before you begin your sanitation program, bring out a notebook to take records of what did and did not work, what will need dividing in the spring, and what needs to be moved to a different site. Failure to divide perennials is a leading cause of crown rot in Sedums, Hosta and members of the mint family (bee-balm, catmint, etc). If you haven't started a gardening log, consider doing so. Make notes about problems and research potential solutions over the winter. If your gardening consists of annuals and vegetables, evaluate which varieties did well and which you should consider replacing. If all your tomatoes had blossom end rot, look for plants that carry the 'BER' label that denotes resistance to this disorder. Was powdery mildew a problem for your bee-balm? Consider moving it to a sunnier location in the spring (with better air flow) or remove it and replace it with a powdery mildew resistant variety, like ''Jacob Cline.'

Get Down and Dirty
After you've filled up several pages of notes, its time to put the notebook down, and put on the heavy gloves. Clean up leaves and crop residues from all gardens. As soon as crops are harvested, pull up and dispose of all plant material, including roots. After a the hard freeze, remove and compost all disease-free, but frost-blackened, tender annuals, such as morning glories, petunias and zinnia, to name but a few.

A common question asked by gardeners is whether diseased plants can be safely composted. The answer is NO! Do not compost diseased plants! In Minnesota, compost rarely reaches the temperatures required to kill most plant pathogens. Be sure to discard the material properly, by bagging it or by burning it if this is permitted.

Did you have really bad leaf spots on your coneflowers? After your perennials have died back, the leafy material can be removed. Carefully cut the tissue with shears or scissors and dispose of the infected leaves. Consider applying a copper based fungicide if leaf spots were particularly severe. There are many common leaf diseases that good sanitation practices will help control, such as leaf spot of iris, botrytis of peony and black spot on rose to name a few. Cut back late flowering perennials like asters and chrysanthemums to a few inches. Did your peonies develop spots? Pull out the shears! Peonies can be cut to the ground. Mulch the crowns with compost. If your coneflowers (or any other plants) had aster yellows, be sure to remove and dispose of infected plants.

We've received numerous calls and samples about clematis diseases this year. This "Queen of the Vines" commonly gets dethroned by a variety of fungal diseases, the most common and most serious of which is Ascochyta blight (Fig. 1). Remove infected vines and dispose of them. Mulch heavily with several inches of both soil and mulch-Because this disease commonly attacks at the soil line, by preserving the crown through deep planting or mulching, you can regenerate your clematis after infection-even severe infection, although the plant may take several years to recover. In the spring, consider preventative applications of a sulfur-based fungicide to minimize the likelihood of reinfection.

Clematis isn't the only plant to benefit from mulching: Add mulch to your perennials to create a protective layer that insulates plant roots from the freeze-thaw damage. Mulch also conserves moisture and improves soil structure. Straw, hay and compost are all excellent mulch materials. Leaves and grass clippings are less effective as mulch material because neither holds much air space for insulation, but the price is hard to beat! (Remember in the coming spring to remove the mulch layer promptly, to prevent crown rots from occurring.)

Avoid Colorado Purple Spruce Syndrome

Wrapping protects some trees in winter. Photo credit: Janna Beckerman

Wrapping protects some trees in winter. Photo credit: Plant Disease Clinic

Conserving moisture isn't enough, though. Be sure to thoroughly water all plants as we head into winter. Spruce, pine and other conifers can become desiccated by the harsh winter winds if a fall drought should develop. When symptoms develop in the spring (purple Colorado blue spruce, reddish brown white pines and red pines), nothing can be done to "cure" the problem. While watering the bigger plants, don't forget sheltered perennials, such as those under the eaves, or under the trees. Plants that become too dry in fall are less likely to survive the winter. And you won't know this until the late spring when they fail to return!

Install simple windbreaks, or cover the entire tree, or cover the trunk of vulnerable, thin bark trees with plastic "tree guards." to protect them from drying winter winds. Anything that encourages snow accumulation will help provide excellent protection against low temperature or wind desiccation. Questions regarding the use of anti-transpirants and evergreens need to be put to rest: Antitranspirants are tools that help plants endure stressful, short-term periods, like transplant shock. Only the most hardcore lover of snow and ice could define a Minnesota winter as "short term." For this reason, anti-transpirants are not a replacement for proper fall watering or proper plant selection

Rose Tipping
In Minnesota, winter injury to canes can be severe. Dave Zlesak did an excellent job describing how to protect your roses in last month's Yard and Garden News http://www.extension.umn.edu/projects/yardandgarden/YGLNews/YGLN-Sept1502.html#roses

Guarding the Garden
Because most disease organisms can survive the winter on garden debris if it is not properly destroyed, it is imperative to eradicate as much debris as humanly possible. Any material left over serves as inoculum for next years crop. In the garden, till and turn the soil to the depth of 6-8 inches after weeds and plant debris have been removed. Tilling buries any remaining infested plant debris and will be consumed by other soil microorganisms. You can encourage this process by amending the soil with compost. Compost introduces billions of microorganisms, eager to eat plant pathogens, in addition to improving the soil structure and nutrient profile.

Practice crop rotation to aid in the management of soil borne diseases. Grow a diversity of crops and rotate their locations in the garden every few years being sure to rotate between families (e.g., replacing the tomato growing area (Solanaceae) with beans (Leguminosae) not with in families (e.g., do not replace tomatoes with potatoes which are both members of the Solanaceae). Ideally, rotate susceptible crops with non-susceptible ones. If that cannot be achieved, be sure to use resistant varieties to minimize losses.

No Shears Here
If there weren't enough chores in the yard this time of year, there is one you should not be doing: Pruning fruit trees. In climates such as ours, pruning should be done in spring just as the buds begin to swell. Freezing injury and dieback can occur to fruit trees if they are pruned in fall or early winter. Even though you can't prune, you can remove fallen fruits, or hanging "mummies" (dessicated, infected fruit that often serves as an inoculum source for next years infection). Don't forget to protect trees with mouse/rabbit/deer guards. Wrap tree trunks with hardware cloth (¼ inch openings) up to the expected snow-line to provide the necessary protection. Be sure to remove this protection in the late spring to protect the crown of the tree as it continues to grow.

After the Bulbs of Summer Have Gone
Okay, that's not what Don Henley sang, but you get the idea. Don't forget to lift and harvest tender bulbs and corms (cannas, caladiums, gladiolas, dahlias and tuberous begonias) for next year. Lift after a good frost blackens their tops. Carefully dig bulbs/corms and place the bulbs in a well-ventilated location to dry for a two to three week period. This will prevent storage rot from destroying your bulbs. Stems can be cut off with a sharp knife or scissors (except for begonias-keep reading!) near but not at the point where they emerge from the bulb. Allow begonia stems to dry until they are brittle enough to break off from the bulbs. Store bulbs in a cool, dark place, preferably in vermiculite. Consider dusting the bulbs with a preventative fungicide, like Bordeaux mixture to prevent storage rot. Consider pouring yourself a fine Bordeaux wine to toast yourself and all the work that you've accomplished!

Lawns
Tired of digging? Of cutting or pruning? Then pull out the fertilizer spreader for a relaxing stroll. Don't forget to load it up with fertilizer, of course! Do your lawn a favor with a fall turf feeding, and it will return the favor with stronger and healthier growth that is better able to resist disease and weeds when spring finally arrives. Ideally, this is the time for the second fall fertilization. But, if nothing else, get that last fertilization in. In choosing a fertilizer, be certain that the nitrogen is mostly water insoluble nitrogen or controlled release nitrogen to prevent excessive top growth. As the month of October nears, the mowing height can gradually be reduced from 3" to the shorter, over-wintering heights in an effort to prevent snow mold problems.

Don't forget to rake and compost fallen leaves. Leaf litter left on lawn provides an infection court for snow mold. Be sure to sneak that last mowing in, too, as long grass provides an excellent place for snow mold, too. Finally, fall is a great time to reduce weed levels-besides, you want your fertilizer to go to your lawn. No one wins prizes for growing the biggest dandelions!

Lady Beetles in Homes
Jeff Hahn, Assistant Extension Entomologist

Asian Lady Beetles Photo credit: Jeff Hahn

One of the most common household insect pests over the last few years has been the multicolored Asian lady beetle. Also known as Halloween lady beetle and Japanese lady beetle, this lady beetle is about 1/3 of an inch long, a little larger than the average ladybug.

This lady beetle gets its name because its color and the size and number of spots on its wing covers are variable. When larvae have a diet rich with aphids it produces adults that are reddish. When larvae do not find enough aphids and supplement their diet with pollen they will be more yellow. When the temperature is cool and the insects remain as pupae for a longer period of time, they produce beetles with 19 full-sized spots on its wing covers. When it is warmer and the lady beetles stay as pupae for a shorter period of time, the size of the spots are reduced and in some cases the number of spots are reduced.

Multicolored Asian lady beetles are very beneficial as aphid predators but they can also become pests themselves when they congregate in large numbers around and inside homes. In its native Asia, the multicolored Asian lady beetles typically overwinter on cliff faces and rock outcroppings. Since these types of sites are not common in the U.S., these lady beetles have adapted by seeking shelter during the fall around homes. These beetles can also be a pest by staining surfaces with a defensive fluid (a process known as reflex bleeding), giving off a bad smell, and biting people. Some people may become allergic when high numbers of lady beetles are present.

A survey in Ohio conducted by Huelsman et al. examined factors that may attract these lady beetles to buildings. Over half (57%) of the people that responded to the survey live in a two-story house while 31% live in a one story home. The exterior of the buildings varied as 54% had wood, 43% had vinyl, and 23% had brick. The color of the house did not appear to influence lady beetle attraction as houses of light, medium, and dark colors were equally invaded. Also age did not appear to greatly influence lady beetle invasion.

The presence of trees in the landscape (over 50%) was a good indicator that homes may become infested in contrast to homes, farmland, and open areas. Once indoors, people most commonly found these lady beetles in living rooms (58%), bedrooms (53%), and kitchens (46%). The most common surfaces they were found on included windows (86%) and ceilings (64%).

Multicolored lady beetles generally start to enter homes some time in mid to late October. However, this is variable as last year lady beetle started moving into homes in late September. Researchers at Ohio State University have determined that multicolored Asian lady beetles are most likely to enter homes when temperatures are in the mid-60's F. after being preceded by temperatures at or near freezing. Some areas in Minnesota have already been at or near 32 degrees F. and the rest of the state may soon follow. Once temperatures sufficiently warm back up, expect lady beetles to move large numbers towards homes to overwinter.

Prevention is the most important method of keeping lady beetle out of your home. For the best results use several tactics in combination with each other as no one method will be totally effective by itself.

First, caulk and seal any visible cracks and spaces around the exterior of a home. Especially check around foundations, windows, doors, utility pipes and wires entering buildings, facets and other areas around buildings. Screen all vents and replace any damage screens (20 mesh maximum). This helps deter insects but it will not be enough on its own.

Control should be supplemented with an insecticide application. Homeowners should choose a product that is labeled for treating the exterior of buildings. Sprays should be concentrated along the roof lines, along windows and doors, and at the base of walls. Be sure sprays are applied before lady beetles attempt to enter buildings. Once they are in a home, there is little you can do to control them.

Insecticides available to homeowners for lady beetle control include bifenthrin (e.g. Ortho Home Defense Indoor & Outdoor Insect Killer5) and deltamethrin (e.g. Bonide's Household Insect Control). Both are very effective against multicolored Asian lady beetles. Cyfluthrin (e.g. Bayer Advanced Home Pest Control Indoor/Outdoor Ready) is moderately effective. Tralomethrin (e.g. Spectracide Bug Stop Spray), esfenvalerate (e.g. Ortho Bug-B-Gon Multi-Purpose Insect Killer concentrate), and permethrin (e.g. Bonide's Eight Yard & Garden Ready to Spray) can also be applied although the residual may not be as long.

Treating the exterior of a home can also be done by an experienced pest control service. They have access to many effective products including Demand CS (lambda-cyhalothrin) which is particularly effective against lady beetles. This product is not available to homeowners.

Once lady beetles get inside a home, there are few options but to vacuum them and then discard the bags. The use of insecticides indoors is of very limited value and does not prevent lady beetle from entering homes. Avoid crushing lady beetles as this can stain surfaces.

Spider Mites on Ash
Jeff Hahn, Assistant Extension Entomologist

Spider mites.<br>

Close up Photos: Jeff Hahn

It has been common to find webbing and large numbers of orange or yellow colored spider mites clustered together on the trunks and branches of hardwood trees, especially green ash. Concentrations of spider mites have also been found on basswood and American elm. The webbing usually starts at the base of the trunk but can move up the tree many feet. In one case spider mite webbing enveloped an empty bird house that was about 10 feet off the ground.

Despite its appearance, the spider mites are not feeding on the tree or causing any harm. The spider mites are clustering together as they prepare to overwinter. They eventually will move into the cracks and crevices of the bark and go dormant until spring. The presence of spider mites is not harmful to the tree and doesn't automatically mean the tree will have a problem with spider mites next year. Just ignore the spider mites for now and enjoy them as a curiosity. Watch trees next year for evidence of spider infestation and treat only if necessary.


Editorial Notes

Swallowtail on coneflower. Photo credit:  Beth Jarvis

In the November issue, Gary Johnson will finish his discussion of transplanting trees and shrubs. For December, I hope Michael Long will be able to take a break from his Ph.D research long enough to talk about plants that require acidic soils. Why are they different from other plants? Kathy Zuzek, rose breeder extraordinaire, from the Horticulture Research Center, has agreed to talk about the latest in her rose research. We'll get to enjoy that this winter. Lee Frelich, of Forest Resources, gave an eye opening presentation on the dangers of exotic earthworms at the state Master Gardener conference in Sept. He's agreed write about it for the March 1 issue. Doug Courneya, Regional Educator, Olmstead County, will write about buckthorn reduction some time this winter, also.

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.

Back issues Yard & Garden Line News are on the Yard & Garden Line home page at www.extension.umn.edu/yardandgarden/. Our 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.

Deb Brown answers gardening questions on Minnesota Public Radio's (MPR) "Midmorning" program on the first Thursday of every month at 10 a.m. Katherine Lanpher hosts the program that is broadcast on KNOW 91.1 FM, and available state-wide on the MPR news radio stations.

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: listserv@lists.umn.edu (note: the second E in listserve is omitted), leave the subject line blank, then in the body of the message, type: sub yglnewslist or to unsubscribe, enter: unsub yglnewslist

Happy gardening!

Beth Jarvis
Yard & Garden Line Project Coordinator


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