Yard & Garden Line News
Volume 6 Number 14                                                               September 1, 2004
Features this issue:

What's Wrong with My Maple?
Early Autumn Tips for Yard and Garden
Ripening Tomatoes Indoors
Downy Mildew of Viburnum
Multicolored Asian Lady Beetle Update
A Weird and Strange Gall
September Garden Tips
Editorial Notes


What's Wrong with My Maple?
Patrick Weicherding, Regional Extension Educator, NRE

Recognize this
maple? Photo credit:
Patrick
Weicherding
"What's wrong with my tree?" Homeowners by the hundreds ask us this question every year but this year's hue and cry seems to be "What's wrong with my maple?" Many callers report symptoms of early fall coloration, reduced foliage growth, reduced twig growth, dead branches in the upper canopy, or even death of the tree. The symptoms are appearing primarily on sugar maple (Acer saccharum) and red maple (Acre rubrum) and less frequently on Norway maple (Acer platanoides).

The symptoms noted above are the classic characteristics of a much larger problem commonly known as "maple decline." Long time USDA Forest Service researcher, Dave Houston, coined the term in 1967 and described it as "a progressive disease condition that begins when the trees are altered initially by stress and continues as they become invaded by organisms of secondary action." The maple decline Houston observed in the '50's and 60's was not new at the time; stag-headed maples were described as early as 1917 in Massachusetts forests and their dieback was attributed to drought. What is new is that today, maple decline is much more prevalent in urban areas where maple trees struggle to remain healthy in the sometimes harsh city conditions.

Paul Manion, in a book titled Tree Disease Concepts, provides an excellent description of tree decline (non-host specific) as a "disease complex." He believes tree decline is "caused by the interaction of a number of interchangeable, specifically ordered abiotic and biotic factors to produce a gradual general deterioration, often ending in the death of the tree." Manion cites three sets of factors in complex decline diseases.

According to Manion, "The first set of factors are generally static or non-changing factors such as the climate, the soil type or site, the genetic potential of the tree, and the age of the tree. These are the predisposing factors that weaken a plant growing in the wrong location. Such factors put a permanent stress on the plant and predispose it to the actions of other factors.

The second group of factors are called incitants. These are short in duration and may be physical or biological in nature. Examples of incitants include insect defoliators, late spring frost, drought, and [de-icing] salt spray. These generally produce a drastic injury. The plant attempts to recover but has difficulty because of the predisposing stress of the environment.

Stressed urban trees Photo credit:
Patrick
Weicherding
The third group of factors, called contributing, finally begin to appear. Bark beetles, canker fungi, root and sap rot fungi, viruses, and mycoplasmas produce noticeable symptoms and signs on the weakened host. These organisms are persistent and are often blamed for the condition of the host. They are better understood as indicators of weakened hosts. Eventually the plant dies or is rendered useless as an ornamental or forest tree."

What does all of that discussion about" tree decline" and "disease complexes" have to do with our dying maples?

First, consider one of the predisposing factors, maples as a species and their basic soil requirements. Sugar maples (Acer saccharum) are native in the eastern United States and Canada and west to Texas. Their brilliant red, orange, and yellow fall coloration is the foundation of nature's autumn display. Sugar maples are slow growing with dense oval crowns. Mature height in the landscape is 60 to 70 feet with a spread of 40 to 60 feet. These trees grow best in well drained, evenly moist, fertile soil that is slightly acidic. They do not like crowded conditions (limited soil root volumes) with compacted soil. And, according to our research at the TRE Nursery on the St. Paul Campus regarding planting depth and stem girdling root formation, they do not like to be planted too deep in the landscape. In other words, they do not perform well in the tight, poor soil conditions typical for street trees in urban areas. Since they are not trees for high-stress environments, they should only be planted in large yards or parks where they have good soil and ample room to grow. The simple fact is that sugar maple, by its very nature is often predisposed to decline in urban areas.

Red maple (Acer rubrum) has green leaves in summer, red fall color, and light gray-colored bark. Mature height in the landscape is 40 to 60 feet with variable crown spread. Red maple can be tolerant of wet soils but they prefer slightly acid, moist, sandy loam soil. Red maple does not grow well on alkaline soils (pH above 6.7) where it may develop chlorosis from manganese deficiency. With the right selection (Trees should be obtained from northern sources so winter hardiness is assured.) and in the right location it can be an outstanding tree. However, red maple is generally considered to be not particularly "urban tolerant" given most urban soil conditions. Again, we have a species which, is by its nature, is predisposed to decline on inappropriate sites in urban areas.

Norway maples (Acer platanoides) are planted extensively as street and landscape trees in Minnesota communities, however, commonality breeds contempt and many gardeners have tired of Norway maple for street and urban use. A large number of cultivars are available including red cultivars ('Crimson King' and 'Deborah"), green cultivars ('Emerald Queen'), and variegated cultivars ('Harlequin'). Norway maples are shaped like lollipops with mature height of 40 to 50 feet and similar spread. Norway maples are tolerant of a wider range of environmental conditions than sugar or red maple but stress tolerance of the species is now being questioned. They appear to withstand sandy as well as clay soil texture, acid to alkaline soil reaction and hot, dry planting sites. On the negative side, frost cracking of the trunk is fairly common when Norway maple is planted in poorly drained soils. In addition, Norway maple appears to be genetically prone to stem girdling roots. Finally, the species has become invasive in natural areas because of its excessive seed production in the fall. While Norway maple may seem better suited to the urban environment, its questionable stress tolerance may be a predisposing factor leading to decline on individual planting sites.

Healed frost crack. Photo credit:
Patrick
Weicherding
Next, consider one of the inciting factors leading to tree decline, namely drought. In Minnesota we have had a string of unseasonably cool, moist springs followed by hot, dry summers and even drier autumns leading to soil moisture deficits approaching winter. Add to that winters with little or no snow cover and deep frost penetration and you can see that there might be reason to be worried about our maples (see the article by Dave Hanson, Urban Forestry Research Specialist in the previous issue of Yard & Garden News). Many of the early fall coloration symptoms we're currently seeing on maples are related to drought and winter injury to tree root systems. The trees are struggling to recover but because of the predisposing factors they are headed for a downward spiral to decline and death.

Finally, we're beginning to see evidence of contributing factors in the third stage of maple decline. Heart, butt, and root rotting fungi are beginning to appear with regularity on the stems and root collars of declining maples. These fungi can cause dieback of the crown but they also affect trees structurally, making them unsafe or "hazardous."

How do you know if your tree is suffering from maple decline?

Begin by checking your tree against the following symptomology:

·Reduced twig growth - Yearly twig growth varies considerably between trees and even within the canopies of individual trees. If the distance from bud scar to bud scar is less than or equal to five cm (approx 2") on a non-shade twig (check the ends of the branches), the tree may be in trouble.

· Reduced foliage growth - Keep in mind the normal, healthy appearance of the particular maple species' foliage. Foliage that is sparse, light green and/or marginally scorched signals that the tree may be declining.

·Early fall coloration - Maples normally begin showing fall color after the first frost or in mid-to-late September. When fall color develops earlier than normal, in late July or early August, the maple is suffering from decline.

·Dead branches in the upper canopy - Small dead branches seen in tree tops in late spring or early summer are indicative of decline. Over time, larger, more visible branches and limbs will die back. The more numerous the dead twigs or branches are, the more severe the decline condition.

·Poor root condition - If roots can be examined, look for stem girdling roots. Also, look for reduced occurrence of smaller fibrous roots at the drip line of the tree crown; brittle roots and decaying roots are indicators of root decline which severely affects the root/shoot ratio of the tree. A balanced root/shoot ratio is necessary for good tree health.

What can be done to save my maple?

By the time the symptoms are noticed, the tree is probably beyond being restored to its original healthy state. However, this may be the time to think about replacing the declining maple. If you still want a maple in that spot consider one of the more "urban tolerant" cultivars. A naturally occurring hybrid or cross of red maple and silver maple (Acer saccharinum) known as a Freeman maple (Acer x freemanii) is a good urban tree. These hybrids have the beauty of red maple and the fast growth of silver maple, but lack the silver maple's problems and the pH sensitivity of red maple. One of the better cultivars for Minnesota is 'Autumn Blaze'™ but there are others available including 'Red Sunset' and 'October Glory'.

For additional information regarding the content of this article, check the following references:

Dirr, Michael A. 1997. Dirr's Hardy Trees and Shrubs: An Illustrated Encyclopedia. Timber Press, Inc., Portland, Oregon. 493p.
Manion, Paul D. 1981. Tree Disease Concepts. Prentice-Hall, Inc., Englewood Cliffs, New Jersey. 399p.
Pokorny, Jill D. 2003. Urban Tree Risk Management: A Community Guide to Program Design and Implementation. USDA Forest Service, Northeastern Area, State and Private Forestry

 Early Autumn Tips for Yard and Garden
Deborah Brown, Extension Horticulturist

Iris rhizomes ready to be divided. Photo Credit: Lynn McNaughton
Though the gardening season is winding down, there are still lots of lawn and landscape activities you can do, both to prepare for winter and to get a leg up on next spring. Rather than looking at these activities as "chores," think of them as opportunities to savor those last few weeks of beautiful weather before we head for the inevitable deep freeze.

Fall is a Good Time for Planting

* Overseed thin parts of the lawn. Grass seed that's planted by the middle of September should grow a strong enough root system to make it through most winters. As an added bonus, you won't find weed seeds sprouting along with the grass when you plant this time of year. Seeds must make contact with soft, receptive soil to grow well, so be sure to power rake, aerate, or manually scruff up the soil immediately before you plant.

* Divide and transplant perennials early this month. They need a good three weeks of mild growing conditions after you plant them, to become re-established sufficiently to make it through winter. You'll also need to pay special attention to mulching these perennials as the soil begins to freeze. Cover them with several inches of straw, or rake about a foot of leaves on them. (Straw is better because the stems are hollow and trap insulating air; leaves tend to mat down, excluding insulating air pockets.)

* Add evergreen trees and shrubs to your landscape for winter interest. Cooler fall temperatures create less demand on their roots to supply moisture. The sooner you plant, the better. You want plenty of time for those roots to begin to grow and become established before harsh weather sets in.

Routine Maintenance Nets Better Growth Next Spring

Tree mulch
ring Photo Credit:
Permascape
* Fertilize the lawn. Use a standard high nitrogen lawn food to help your lawn develop strong roots and runners. Grass that is fertilized in fall will come back thicker and greener next spring. You may choose to follow up with a second application of fertilizer in mid to late October. Though top growth will have slowed or stopped because of cooler temperatures, the underground portions remain active several weeks longer.

* Core aerate compact soils. If your soil is heavy and clay-like, or it has become compacted over the years from kids or dogs romping on it, make a habit of core aerating every year or two. Rent a machine that takes plugs out of the soil and throws them onto the lawn's surface. They'll crumble and "topdress" the soil with microorganisms to help break down thatch. The holes will also allow moisture, fertilizer, and oxygen to penetrate into the root zone, resulting in healthier grass.

* Renew mulch around young trees and shrubs. Shredded bark, woodchips, and other organic mulches break down where they contact the soil. They also settle over time. Check to see that mulching materials are about three inches deep over the root ball area of young trees and shrubs. This mulch will protect them from extreme cold as well as early spring thaws. Be sure to leave a small space between the mulch and your plants' trunks or stems to avoid moisture damage.

* Water evergreen trees and shrubs regularly. Unlike deciduous plants that lose their leaves, evergreens keep their leaves or needles throughout the winter. This means that they're more vulnerable to drying from winter sun and strong winds. Allowing them to go into cold weather stressed for moisture will increase the likelihood these plants will suffer disfiguring winter "burn" or browning.

Prepare Indoor Plants for Winter

Forced
hyacinths Photo Credit: Deb Brown
* Bring houseplants indoors. Don't wait for more frost warnings before bringing in your tender, tropical plants. The transition will be easier for them if you move them indoors while night temperatures are still relatively warm. Do wash houselants carefully before placing them near others, though, as they may harbor mites or insects from outdoors. Repot any plants that put on lots of new growth this summer.

* Order extra-large hyacinth bulbs for forcing. Bigger and costlier than ordinary hyacinth bulbs, the largest bulbs will put on a colorful, fragrant display in the dead of winter. Plant them in a shallow container, water them, then put them in your refrigerator or an unheated basement or attic. After about twelve or thirteen weeks, move them to a sunny but cool location. They should bloom within several weeks.

* Allow your amaryllis bulbs to go dormant. Put them in a dark, relatively cool location, and withhold water. Check them periodically for spontaneous sprouting. Sometimes the flower bud shows up first; sometimes, leaves. If two or three months go by with no sprouting and you'd like to begin forcing your amaryllis to bloom, bring a pot out into a warm, sunny room and resume watering. The bulb should awaken from its "rest" and bloom within six to eight weeks, depending on the temperature in your home.

For more garden and landscape tips specifically geared to our northern climate, pick up a copy of the 15th anniversary gardening calendar, Minnesota Gardening, 2005, available at garden centers, book and gift stores, Extension Offices, and Regional Outreach Centers across the state. You can also order them on line, directly from the University. Go to http://www.extension.umn.edu/distribution/horticulture/DG8101.html

Ripening Tomatoes Indoors
Deborah Brown, Extension Horticulturist

Tomatoes taste best when allowed to ripen on the vine, but unusually cool summer has left us with lots of tomatoes that have been slow to mature. The question is, what can be done with them?

You can pick any that have begun to ripen, then finish the process safely indoors. They won't be as tasty as vine-ripened, but they'll still taste good. Choose only fruit that have already turned distinctly lighter green (on their way to pink, and finally red), not ones that are still dark green. The dark ones may be fried or made into relish, but they'll never ripen properly indoors.

To ripen tomatoes in your home, keep them out of direct sunlight. Ideally, temperatures should range between 60 and 70 degrees. If it drops below 55 degrees, flavor will be significantly compromised. (For that reason you should never refrigerate tomatoes, even though they're ripe.) Wrap the fruit individually in tissue paper so if one begins to decay, it won't spread to others.

Another way to ripen tomatoes is to pull entire plants out by the roots, then hang them up indoors out of direct sunlight. This works particularly well with cherry tomatoes, as the fruit is lighter weight. Check them every few days and remove any tomatoes that looks ripe. Be sure to cull out any that have soft spots or are rotting, so as not to attract fruit flies.

If outdoor temperatures are expected to drop only a little below freezing, you can cover the plants with old sheets or blankets to trap warmer air around them over night, then uncover them as the day warms up. If daytime temperatures remain cool, though, you'll probably get better flavor by picking the tomatoes and ripening them indoors.

Downy Mildew of Viburnum
Janna Beckerman, Extension Plant Pathologist

Downy mildew symptoms include angular lesions. Photo Credit: Janna Beckerman
Turn over a leaf on a humid day to see the tell-tale signs of downy mildew. Photos: Janna Beckerman
Viburnums are a large and varied group of shrubs that are grown primarily for their showy and often fragrant flowers, attractive fruit, or fall foliage color. In Minnesota, the most well-known viburnum is the old-fashioned snowball bush that is covered in white flowers in late May. Other popular viburnums include the high-bush and low-bush cranberry. Normally not bothered by many diseases, our cool and humid summer has created an outbreak of downy mildew on viburnum.

Downy mildew is a generic description of several closely related, but distinct pathogens. Downy mildew should not be confused with powdery mildew: These diseases are caused by two very different groups of organisms. Powdery mildews are true fungal pathogens that produce white, flour-like colonies on the upper leaf. Downy mildews are not even fungi, but are members of the Chromista, a group of organisms that have characteristics of plants, animals, and fungi. Downy mildew produces grayish fuzzy looking spores and mycelium on the lower leaf surfaces. The distinction between these two pathogens is important as the fungicides effective against one are not usually effective against the other.

Symptoms and Signs

The variability of lesions, and the severity of infection makes this disease difficult to diagnose. On the upper leaf surface, grayish- brown spots are delimited by leaf veins, and develop into angular lesion that can be easily misdiagnosed as bacterial leaf spot. As lesions coalesce and large amounts of tissue become damaged, leaves drop. On the underside of the leaves, beneath the areas of upper leaf discoloration, the signs of whitish to grayish downy fungal growth of the pathogen (Plasmopara viburni) are seen.

Management

Unfortunately, the severity of this year's infection means additional work to keep your plant looking healthy next year. Whenever possible, reduce overhead water, and keep leaves as dry as possible. Implement a good sanitation program, by cleaning up infested leaves, and removing blighted shoots where the overwintering stages of the fungus reside. Fungicides labeled for home use for control of downy mildew include active ingredients of copper, fosetyl-Al, and mancozeb. These should be applied in the spring to prevent downy mildew from becoming established.

Learn more about the Chromista at: http://www.ucmp.berkeley.edu/chromista/chromista.html

Please check out the new diagnostics web pages at
http://www.extension.umn.edu/projects/yardandgarden/diagnostics/


Multicolored Asian Lady Beetle Update
Jeffrey Hahn, Assist. Extension Entomologist

Lots of ladybeetles Photo credit: Gail Felton
Last March and April may seem like a long time ago, but for those Minnesotans that were besieged with multicolored Asian lady beetles (MALB) inside their homes, it is a recent memory. Whether they were a problem for you last spring or not, it won't be long before they start the whole process over again. So the big question is ‘how are the lady beetles doing this year?'

A quick survey throughout the state has shown that MALB numbers are down. A large part of that seems to be the small number of soybean aphids in soybeans. This is significant as these aphids have proven to be an important food source for MALB. On the other hand, corn has been infested with a fair number of cornleaf aphids which have attracted and helped support MALB.

While there are few adults being seen in some areas, there are a fair number of mature larvae and pupae. Their numbers could rebound somewhat by the end of summer but overall their numbers are still likely to end up to be less than what we saw last year. These lower numbers are undoubtedly attributable to the cool spring and summer we have experienced.

Interestingly, not all lady beetle species numbers are down. The sevenspotted lady beetle, Coccinella septempunctata is doing well in many areas as well as twelvespotted lady beetles, Coleomegilla maculata. Fortunately, these lady beetle species do not invade and overwinter in buildings.

So does fewer numbers of MALB mean we won't see lady beetles invading homes this fall? Not quite. Their numbers are low but MALB are still present so expect them to some degree just not as overwhelming as there were last season. Their presence in our homes will probably be more like 2002 when smaller numbers of MALB and a lack of an Indian summer produce relatively few complaints about lady beetles.

An interesting question was asked when areas of Minnesota experienced frosts earlier in August. People wondered whether this premature cold weather would be a signal to lady beetles to begin their flights from trees and fields to homes and other structures. We have observed in the past that when temperatures drop to or near freezing during fall and then bounce back to the 60's or 70's degrees F that that is a cue to lady beetles to start their search for harborages to spend the winter.

But it is likely that a more complicated set of signals tell MALB when to begin their aggregation towards buildings. In addition to dramatic changes in temperature, they probably also need to experience a combination of shorter day lengths and differences in food quality. That it is too early for MALB to invade our homes has been corroborated by the total lack of any reports of nuisance lady beetles so far this summer. Typically, MALB do not begin to move until sometime in October. Last year, their flights began on the first Sunday in October.

Regardless of how many lady beetles we expect, if you want to protect yourself from MALB, NOW is the time to act. Prevention is the best control. Keep these lady beetles out using a two pronged approach. First seal as many opening as possible that may allow lady beetles into your home. Concentrate along doors, windows, fascia boards, where utility lines enter buildings and similar places. Seal any openings 1/8 inch or larger. This should be done by the end of September before lady beetles start to enter homes.

Physical exclusion should be supplemented with a residual insecticide treatment. Make any applications before insects begin to enter buildings, usually late September or early October. Spray the insecticide around doors, windows, and roof lines, paying particular attention to the south and west sides where the insects are most common. You can treat your home yourself or contact a licensed pest control service to do it for you. The following are common examples of effective insecticides available to the public:

* bifenthrin
* cyfluthrin
* cypermethrin
* deltamethrin
* permethrin

These steps are not always going to keep 100% of the lady beetles out but they will reduce the number that get inside. Once lady beetles get into your home, you have few options to control them. They will remain trapped until they die or are removed. Some of these lady beetles will get into walls and attics and will periodically emerge during mild winter days and again in the spring.

 A Weird and Strange Gall
Jeffrey Hahn, Assist. Extension Entomologist

Noxious oak gall Photo credit:
Jeff Hahn
An interesting gall was recently seen on a young swamp white oak, Quercus bicolor. Going by the ominous name of noxious oak gall, it affects the twigs, petioles, and leaves of new growth. The galls on the twigs form dark-colored, irregularly shaped warty growths encircling the woody tissue. On some of the petioles, you can find smaller, green galls. Affected leaves are stunted and cupped. These galls are the result of a tiny cynipid wasp called Neuroterus noxiosus attacking the oak in the spring.

The observed tree was throughly infested with these galls. Although the tree's appearance is affected, these galls will not kill it. If you have a tree infested with these galls, the best bet is to prune out infested twigs before next spring before the overwintering wasps can emerge. If there are many infestations in a tree, is may not be practical to prune them out. Insecticides treatments have no effect once the galls are formed. Spraying the trees in the spring would be marginally effective at best and could possibly make the problem worse by killing natural enemies.

Get the low down on this month's insect pests at Insects http://www.extension.umn.edu/projects/yardandgarden/EntWeb/Ent.htm


September Garden Tips
Beth Jarvis, Yard & Garden Line

Normal fall color of peonies Photo credit:
Beth Jarvis
Compiled from conversations with Patrick Weicherding, Bob Mugaas and Bob Olson, Regional Extension Educators.

(These recommendation are based on Twin Cities temperatures. Adjust for northern Minnesota..)

Lawns:
You can still seed new lawns, over-seed and lay sod. Remember that site preparation is very important to getting grass seed or sod established quickly.

If you've been itiching to give perennial weeds the old heave ho, now is a fine time to start applying perennial broadleaf weed control. The cooler temps are prompting plants to translocate foods down to the roots, so pack a little herbicide along!

Give up on the crabgrqass and other warm season weed control. Frost and winter's cold will wipe them out soon enough. They'll be back from seed next spring.

Labor Day weekend is a great time to get a fall fertilizer application down. Use the rate of 1 pound of nitrogen per 1,000 square feet. For help with fertilizer calculations: http://www.extension.umn.edu/distribution/horticulture/components/1731-18.html

Water, water water. Even though temps have cooled off some, the soil can still be dry and plants need water.

September is a great time to dethatch/power rake and/or core aerate your lawn. Grass needs 6-8 week of recovery time. Core aerating isn't as hard on the grass plants so they can recover a bit faster.

Then everything you ever wanted to know about lawn care and repair can be found at the Sustainable Urban Landscape Information Series website at: http://www.sustland.umn.edu/maint/index.html. Click on lawn maintenance and scroll down to the lawn care calendar for timing.

Coneflowers and black-eyed Susans Photo credit:
Beth Jarvis
Flowers
Those of you who got hit with a hard freeze are well on your way to getting fall chores done.

Tender bulbs can be lifted once the frost has killed off the vegetation. Dahlias, 4 o'clocks, glads, caladium, cannas, callas, begonias are all tender bulbs. They don't *need* the frost "to reset their biological clocks", so if you've not had a frost, you can wait. We'll see frost in about month, most likely.

It's ok to cut back any perennial foliage that has turned yellow or orange as the growing season winds down.

Trees and Shrubs:
Water, water, water, in hopes of preserving/saving what you have.

Fall color is 2 weeks early due to cool weather.

Adequate soil moisture is critical now when trees and shrubs are begnning to going dormant for winter. Evergreens will need to be watered until the ground freezes. If you need a reminder on how to water trees, see: http://www.extension.umn.edu/yardandgarden/YGLNews/YGLN-Sept0103.html#water

We really shouldn't be pruning oaks, yet. According to US Forest Service research findings over over the last few years, July, August, September are the 2nd highest period of oak wilt transmission/infections due to picnic/sap beetle activity. However, this research has yet to make its way into updated fact sheets, etc.

Vegetables and Fruits:

Save the Best; Forget the Rest
Bob Olson, REE

As this dismal growing season winds down, it's time to face the reality that all of those unripe fruits on our garden crops will not mature. With growing degree days cut nearly a month short, those green vines and small fruits are not likely to yield ripe tomatoes, pumpkins, or other late-maturing produce.

In an effort to "force" ripening of some of the fruit, get out the pruning shears and remove all of the small fruits and some of the foliage. This is a difficult task for most gardeners to accomplish, but we have to face the music. By removing the fruits that have no chance of maturing we divert energy to the remaining, salvageable fruits. The plants have an active, full-sized root system that can now support fewer "sinks". With a little luck, those remaining fruits will be larger and mature quicker.

Investing in "Blankets" may pay off
Bob Olson, REE

As the air turns chilly, thoughts turn to the concern about when that first killing frost will occur. We apologize to those of you that already experienced the first frost, many of you on the morning of August 21. For those of us that lucked out, take the time to sniff out deals to purchase a variety of protective "blankets" that can be used to cover our garden crops when the next frost warning occurs.

Face it, we've all scrambled to pull out every blanket, bedsheet or tablecloth in the house to lay over the garden or flower bed after we listen to the 10 o'clock news. Wouldn't it be a good idea to have some more effective coverings ready to go? Experience generally indicates that we can often get several weeks to a month of extended growing season if we protect our plants just that one cold night. In a year like this, covering your plants might mean the difference between harvesting a crop or nothing at all.

Plants grown in rows and supported by stakes or posts can easily be draped by inexpensive tarps that drape over the plants and can be lightly anchored. Take your fall raspberries; even in a good year we're pushing the first frost. This year, without some season extension, the fall crop will almost surely fail. Why not invest in some tarps that can cover 20 feet of row at a time? Besides, those tarps can be used for a multitude of other yard and garden tasks as well.

Some years we gardeners are relieved that the frost wraps up our season because we're sick of all of the produce and the work it entails. But this year abating the first frost might be just what the doctor ordered.


Editorial Notes

Pumpkin and zucchini Photo credit:
Beth Jarvis
My heart goes out to everyone who has lost cash crops and gardens to our freaky frosts! The cold seems to have done a number on eggplant crops (total dud). Tomatoes have most folks' attention as there are plenty of green fruits if only they'll ripen soon. Zucchini seem to be holding their own this year, but don't they always?

The photo at left is from several years ago. A friend gave me French red pumpkins and I planted them planning to let them climb on the fence. I planted a couple of summer squash in front of them. Much to my surprise, squash vine borers raised total havoc with the pumpkins and totally ignored the usual target, as you can see here.

Some of the Master Gardeners expressed interest in high tunnels, those walk-in cold frames, that are being tested in northern Mn. Bob Olson, Regional Extension Educator , Horticulture, will be penning a piece on the high tunnels for the Sept. 15th issue. Bob Mugaas, Horticulture, will be writing about how fall sets the stage for turf grass to flower the following spring. That will be published Oct. 1. I've asked a couple of grad student to write a piece on the physiological changes plants, other than turf grass, undergo in order to flower. Patrick Weicherding, Regional Extension Educator, Forestry, mentioned new research finding on the timing of pruning trees for disease prevention and to prevent pruning damage. He will write about that soon, as well.

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/.

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

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: 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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