Yard & Garden Line News Volume 8 Number 5                                                               April 15, 2006

Features this issue: All-America Selections-Vegetable trials Voles: Lawn Varmints Problem of the Polka-Dot Lawns Ash Flower Galls Are Unsightly But Not Harmful April Garden Calendar Editorial Notes

All-America Selections -Vegetable Trials
Jackie Smith, Carver-Scott MG Coordinator

Do you recognize any of the following variety names - Improved Perfecto Cantaloupe, Sunshine Calendula, Colorado Cucumber, Confidence Pea, Scarlet Dawn Tomato? How about Straight 8 Cucumber, Imperator Carrot, Golden Gleam Nasturtium, or Sensation Cosmos? All of these varieties had the distinction of winning All America Selections Awards in the 1930's, but many of them are completely forgotten today, while others are still grown in many gardens throughout the country.

The AAS was established in 1932 as a way for home gardeners to learn which new varieties are truly improved and likely to do well in their gardens. New varieties are tested at official AAS sites throughout the country and winners have been introduced each year since 1933.

But it is obvious that some of the “new, improved” varieties have been superseded by better varieties as the years pass.

Each year, Master Gardeners in Minnesota test several of the newest AAS winners. Among other things, participants are asked if they would purchase the variety again for use in their home garden. Following is a list of varieties tested 2000 through 2005.They are listed in order of their ranking based on how many MGs are willing to purchase.
     

2003	Squash, Summer	Papaya Pear	O	100%	Purple Majesty millet
2003	Millet*	Purple Majesty	X	96%
2005	Gaillardia	Sundance Bicolor	O	96%	Sundance Bicolor
2005	Swiss Chard	Bright Lights	O	93%
2002	Rudbeckia	Cherokee Sunset	O	92%
2002	Vinca	Jaio Scarlet Eye		92%
2005	Gaillardia	Arizona Sun	X	92%
2001	Portulaca	Margariet Rosita	O	91%
2003	Squash, Summer	Sunburst	O	91%
2005	Zinnia	Magellan Coral	O	91%
2001	Nicotiana	Avalon Bright Pink		90%
2000	Cosmos	Cosmic Orange		89%
2003	Rudbeckia	Indian Summer	X	89%
2004	Celosia	Fresh Look Yellow		89%
2001	Pepper	Giant Marconi	O	88%
2002	Basil	Siam Queen	X	88%	Siam Queen
2003	Rudbeckia	Prairie Sun	X	88%
2005	Tomato	Juliet		88%
2004	Celosia	New Look	X	87%
2004	Hollyhock	Queeny Purple	X	86%
2001	Zinnia*	Profusion Bright White	O	85%
2003	Agastache	Golden Jubilee	X	85%
2004	Squash , Winter	Sunshine		85%
2004	Watermelon	Sweet Beauty Hybrid		83%
2005	Gaillardia	Red Plume		83%
2000	Sunflower	Soraya		81%
2005	Vinca	First Blueberry Kiss	O	78%
2001	Sweetcorn	Honey Select Hybrid	X	77%
2002	Pepper, Ornamental	Chilly Chili		76%
2003	Gaillardia	Sundance Bicolor	O	75%
2003	Rudbeckia	Cherokee Sunset	O	75%
2004	Celosia	Fresh Look Red	O	75%
2005	Squash	Sweet Mama Hyb	X	75%
2005	Squash	Bonbon		75%
2003	Squash, Summer	Eight Ball		72%
2000	Sweetcorn	Indian Summer		70%
2002	Pumpkin	Sorcerer		69%
2005	Eggplant	Fairy Tale		68%
2005	Tomato	Sugary		68%
2002	Pumpkin	Autumn Gold		67%
2002	Squash, Winter	Bush Delicata		64%
2005	Gaillardia	Yellow Plume		64%
2003	Kohlrabi	Grand Duke		60%
2002	Pumpkin	Orange Smoothie	O	59%
2002	Cucumber	Diva		58%
2000	Cabbage	Savoy Express		56%
2003	Melon	Angel		55%
2002	Basil	Magical Michael		53%
2000	Vinca	Stardust Orchid		50%
2001	Sunflower	Ring of Fire		50%
2001	Tomato	Jolly Hybrid		50%
2003	Squash, Summer	Peter Pan		50%
2005	Squash , Winter	Sunshine		50%
2001	Salvia	Strata		39%

* = gold medal winners – given to plants considered to be a breakthrough in breeding.

Three other varieties received 100% ratings, but were unfortunately tested by only a few of our members, so results are not statistically significant.They are Sparkler Blush Cleome, Melody Pink Dianthus, and Gypsy Deep Rose Gypsophila.

In some cases, a variety was tested more than once in this time frame. It is interesting to compare ranking to see if the variety becane more or less popular as time passes.

As an addicted variety tester, I have grown many of these varieties several times over the years. Of the varieties listed above, I have marked with a “X” those that I personally consider excellent, and with an “O” those that I still consider good (not necessarily better than similar varieties) choices for the garden – until something better comes along.

Voles: Lawn Varmints
From the Ask A Master Gardener Archives

Voles, also known as meadow mice, live and feed on the soil surface or just below the surface. Although voles are sometimes confused with moles, the two do not have much in common except their capacity to be a nuisance in yards and gardens. Moles are silver gray and most voles are rusty to chocolate brown.

Moles push up conical piles of soil and develop conspicuous networks of raised tunnels as they dig their burrows and search for soil insects.

Vole trails in lawn. Photo credit: Beth Jarvis

Voles often leave little evidence of their presence apart from damage they do to trees, shrubs and vegetables. They feed primarily on plants. When populations are high, networks of shallow burrows and grassy trails are evident. Tiny rows of shredded plant materials that mark winter feeding tunnels sometimes remain on lawns after the snow melts and the shallow nests are also typical of voles. Voles seldom enter homes but are sometime found in farm buildings or garages where grain or hay is stored.

Vole populations run in two to five year cycles. Some years there might be great numbers of them and then suddenly the population dies off.

Controls include habitat modification, barriers, trapping and bait stations.

Habitat modification

You may be able to reduce the number of voles in your area by keeping the lawn mowed to three inches or less, removing garden litter, and keeping vacant lots, ditches or other open areas free of weeds and tall grass. Eliminating thatch will discourage voles from nesting in your lawn.

If you feed birds, it is a good idea to clean up spilled seed. This removes a source of food for the voles.

Barriers

Place hardware cloth cylinders (1/4 inch mesh or finer) around the trunks of young trees and shrubs. The cloth cylinder should be dug into the ground at least six inches and should extend well above the anticipated snow level. Wrap tree trunks with plastic tree guards.

Wire or metal barriers, at least 12 inches high, with a mesh size of 1/4 inch or less will exclude voles from a garden area. Bury the bottom edge 6 to 10 inches to prevent voles from digging beneath the barrier.

Traps

Some people report success using wooden snap-type mouse traps baited with peanut butter. When you find the tunnel in the lawn, set the traps perpendicular to the grassy runway.

Bait stations

Rodenticides may be placed in a foam cup tipped on its side for a bait station. Use a bait formulated for voles. Set these at right angles to the runways.

Traps and bait stations do pose a threat to pets, children and non target animals so it is important to monitor them carefully. Concealing the traps or bait stations under a shingle or a small box with a hole near the bait or trap may help reduce the risk.

Check these sites for more information a about voles and how to control them:
http://www.extension.umn.edu/info-u/environment/BD596.html
Controlling Vole Damage
What's Digging Holes in my Yard?
Moles: Tips for Mole Trappers
Ask A Master Gardener FAQ Index
Ask A MG archives
Ask A MG
 
Problem of the Polka Dot Lawns
Michelle Grabowski, Regional Extension Educator, Horticulture

Snow mold Photo credit: Beth Jarvis

With the snow finally melted away, many of us are gasping in surprise at the state of our newly revealed lawns. What was green and uniform the previous fall is now covered in dry pink, grey or straw colored spots, some of them quite large. These are likely caused by snow mold, a fungus that thrives in cool wet turf. Snow mold is caused by two different fungi, Microdochium nivale and Typhula sp. Both of these fungi grow very well at temperatures just around freezing and need high levels of moisture to thrive. Snow cover is not a requirement for growth for pink snow mold. This past year's winter was mild and wet for long periods of time, creating the perfect environment for snow mold in even the best cared for lawns.

The good news is that snow mold rarely causes permanent damage to home lawns. As days warm up and lawns dry out the fungus will go dormant and the grass will recover. To assist in this process, home owners should rake over the diseased patches to fluff up matted down grass and increase air circulation. A light fertilizer (1/2 - 2/3 lbs N/ 1000sq. ft) could be applied to help the lawn recover. Do not over apply N at this time of year, however, as it will cause excessive shoot growth at the expense of root growth.

Reducing thatch and compaction by dethatching and aeration in either spring or fall can help to reduce conditions that favor snow mold and create a healthier, happier lawn all around. Next fall rake up leaves and any other debris on the lawn. Continue mowing until the grass goes dormant. Long turf can become matted down and create humid pockets where snow mold thrives. Also avoid putting N fertilizer on your lawn in late September and early October. Fertilizing this time of year causes a flush of new leaf growth that will be very susceptible to snow mold in winter months. Instead, wait until late October or November before applying fertilizer. By that time of the season plant growth will have slowed down and nutrients will go into the roots and crowns rather than into new leaves. This will make a healthier plant the following spring and will reduce problems with snow mold.

Contributors: Nancy Rose Patrick Weicherding Bob Mugaas

Bud break Photo credit: Beth Jarvis

Trees and Shrubs:

Now's a great time to finalize planting selections. Look at the Extension pubs for ideas:
Trees, Shrubs and Vine for Minnesota Landscapes
Tough Trees and Shrubs for Tough Sites
Recommended Trees for: Northern Tallgrass
Recommended Trees for: Northwest and Central Minnesota
Recommended Trees for: Southeast Minnesota
Recommended Trees for: Southwest Minnesota

Remove tree wrap off now

If you spot bare root materials that has broken bud, pass it by. Bare-root trees and shrubs that have been kept dormant can be pla nted pretty much any time.

Do not prune oak in April-June, the high risk period. Best time is late winter.
Elms should NOT be pruned until fall.
If you didn't get apples, hawthorns, mountain ash pruned by now, just wait until August.
It's OK to prune out dead branches on anything but they must be dried up-dead if you prune oaks or elms. Avoid live tissue of oaks and elms. The scent of fresh sap attracts idsease carrying insects.

It's ok prune shrubs that bloom late in season as they bloom on new wood. Shrubs such as lilacs, forsythia and weigela are best left until after they bloom.

Renew mulch as you do yard clean up.

What about dividing shrubs?
Foresters' and horticulturists' first response is "Huh? Why?" (I've asked.) Yet it's a question that crops up at least once a year. The short answer is foresters and horticulturists don't recommend it. It's hard on the plant. It can be time consuming. There are easier ways of adding more plants, such as taking stem cuttings, layering or simply shopping a sale for more plants.

Not all shrubs shoulld even be considered. The most likely to survive the treatment include:
Hydrangea arborescence/smooth hydranges, lilacs, sumac,red stem and grey dogwood, grow-low fragrant sumac, symphorocarpus, and privet. Suckers from shrubs like lilac and sumac should be snipped free of the clump and left in place to develeop more roots before transplanting. This could be a fall project with transplanting done in the spring. Plants, like privet, that root readily where they touch the ground can be easily rooted. For some plants, slicing a chunk from one side of teh planting is the only option.

Possibly if they're clump formers but it's really not recommended. It will set the plants back.

Anyone who wants to divide a shrub needs to understand they could be killing it instead.

Lawns:

Lawn care recommendations are now focusing more on soil types than calendar dates. Sandy soils warm up more quickly than heavier, clay soils.

Once the soil in your yard dries enough that you can walk on it, it's ok to rake lightly to clean up debris.

Deposits of sand from the boulevard may be brushed into the gutter and swept up from there. Depending on your city's street sweeping policy, they might collect it when the sweep the streets.

As the grass greens up, you you may wish to aerate your turf. Three passes with a core aerator are recommended. Remember you want the kind of aerator that removes cores, not the kind that pokes holes. (Those "sandals" are worthless.) Areating should be done before the weather really warms up as the grass roots are damaged.

As we get to first part of May, sandy soils will be warm enough for a pre-emergent herbicide application. Heavier soil, northern slopes, soils slower to lose snow are slower to warm so there's more time. Folks living north of St. Cloud may wait until May 15th or so. But it all depends on the soil types and the weather. If temperatures remain above average, an earlier application is fine. A cold, wet spell will mean a delay.

We could be mowing our lawns for the first time by the end of April. A light dose of fertilizer, either less than one pound of N per 1,000 square feet or a slow-release (eg: organic) fertilizer is suitable. Don't force growth with the normal one pound N/1,000 sq. ft. In spring, we want to keep an even slow growth and healthy plants. High N pushes growth too much. Succulwent plants are susceptible to diseases.

If we don't continue to get at least 1/2" of water per week, we will need to irrigate to make up the difference. Spring is an important natural growth period for the lawn. We don't want to saturate the lawn, we just want sustained growth. We don't need the full inch that is recommended later in teh summer when it's warmer and there's more evaporation loss.

Hold off on treating broadleaf weeds like dandelions, and creeping Charlie. Weeds need to be actively growing to take up herbicides. Latest research indicates that creeping Charlie responds best to triclopyr when the plant is in full bloom, in May.

Flowers, Fruit and Veggies:

Early tulips Photo credit: Beth Jarvis

As soon as the garden is dry enough to till, you can direct seed early cold tolerant crops, such as lettuce, spinach, carrot, peas, green onions, pearl onions plus by the end of April, put out hardened-off transplants of broccoli, cabbage, and related cabbage members. Onion sets may be planted as well.

Warm season veggies go in about May 15th in the TC and May 31 in northern Mn. Peppers go in about May 31 in TC.

It's time to direct-seed bachelors buttons, sweet alyssum, calendula, snapdragons, nemesia, and sweet peas.

You may start to uncover strawberries. Keep the mulch handy just in case.

You may uncover tipped/winter protected roses.

If you're raising only a fall crop of fall bearing raspberries, you may cut the canes down to the ground now. Otherwise, leave them be. Any canes that set fruit this summer may pruned out once fruiting is done. Those canes are all done.

Ash Flower Galls Are Unsightly But Not Harmful
Jeffrey Hahn, Assist. Extension Entomologist

Ash flowers in early spring Photo credit: Jeff Hahn

Ash, particularly green ash, is a commonly planted woody ornamental in our urban landscape. A common and conspicuous problem that we find on these trees is the ash flower gall. These galls are unsightly abnormal deformities that result from the feeding of an eriophyid mite, Eriophes fraxinivorus, on the developing flower buds. These mites only affect the staminate (male) flowers of ash. Since ash trees are either male or female (seed-bearing), you will only find ash flower galls on male trees.

These mites spend the winter on ash trees under the bud scales or in cracks in the bark. These mites are extremely small, measuring about 200 - 230 microns long, i.e. approximately 1/125th inch long making them essentially microscopic. If you could see an eriophyid mite, they are a distinctly elongate shaped. They only possess two pairs of legs which occur near their head which differs from other mites which possess four pairs of legs.

When the weather becomes warm, generally in April, these mites become active and move to feed on the developing flower buds. Although they do this before the flower is fully expanded, they are so small they don't have any problem penetrating into the structure of the flower. As they feed, affected flowers become distorted, forming lumpy, small green distortions. These galls become larger as summer progresses turning into broccoli-like green growths. The green of these galls blends in with the leaves and are generally not as conspicuous as they will become later. Although there is variability between trees, generally more ash flower galls occur in the top of the tree than in the middle or bottom levels of the crown.

These growths remain attached to the tree throughout the summer. New mites appear and continue to feed inside these abnormal growths. By the end of summer, these galls start to dry out and the mites leave to find overwintering sites on the tree. The ash flower galls change color from green to dark brown to black. They continue to remain on the trees through the winter and are much easier to see then. Ash flower galls remain on trees for one to two years before finally falling off.

Old ash flower galls. Photo credit: Jeff Hahn

While most people find these galls quite unsightly, they are fortunately not harmful to trees. This was confirmed through the research of Rob Wawrzynski while he was an M.S. student in the Dept. of Entomology, Univ. of Minnesota during the late 1980's. He examined tree vitality through three methods, measuring root starch, diameter of the tree at breast height (dbh), and shigometry measurements (examining the resistance to a pulsed electrical current as it passes through wood). He found that the vitality of ash trees when measured by these three different methods were independent of the presence and number of ash flower galls. While the galls probably have some impact on ash, it does not appear to be important to its health (for more information on this research, see: Wawrzynski and Ascerno. 1990. Journal of Arboriculture 16(7): 182-185).

Still, some people are interested to reduce the number of galls on their ash trees even if it only affects the trees' appearance. Ash flower galls can be persistent and can reappear on a tree year after year. However, treatment and reduction of these galls are difficult and challenging. Reasonably effective insecticides include carbaryl (Sevin) and bifenthrin, a type of synthetic pyrethroid. Horticultural oil has also been suggested against these mites as the oil coats and suffocates small soft-bodied insects or mites on plants. However, unlike carbaryl or bifenthrin, horticultural oil does not have any residual activity and the eriophyid mites have to be present at the time the oil is applied to kill the mites. It will also not affect those mites that move to the flowers after the application.

However, even if these insecticides are 100% effective against eriophyid mites (which they aren't), correct timing and good coverage of the trees, particularly the top of the ash, are critical for success against ash flower gall mites. The mites are moving into the flowers before they are fully open. Ash flowers typically blossom sometime during mid - late April, a time when people are generally not thinking about treating trees. However, depending on the spring this can occur even sooner. This season, the ash flowers had already opened in St. Paul by at least the beginning of the week of April 9th. While it's necessary to treat the flower buds about 7 - 10 days before they are expected to open, that is difficult to predict. If you miss this window and the flower buds are already open, it is already too late to treat your trees.

If you have a problem with ash flower galls, it is probably best to just ignore them. If you wish to attempt management, remember it must be done early in the spring. It is already too late for 2006.

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

Editorial Notes

Crocus Photo credit: Beth Jarvis

Bob Mugaas just told me about some mole bait called "Talpirid" of which he's seen favorable results. Talprid resembles earthworms, the moles' main food. These ersatz worms each pack a lethal dose of rodenticide. Birds can't get at them because they're inserted in the runs. It's not a restricted use rodenticide so anyone can legally buy it though the manufacturer seems to want to sell it to pest control operators. I priced it on the web. These lethal gummy-worms were going for about $47 for a box of 20. I'm waiting to hear from our wildlife people to see what they know about them and happy I don't have moles in my yard.

Nancy Rose has provided an article on "blue" trees that I'll run in the May 1 issue. This article provides some alternatives to Colorado blue spruce,a popular landscape tree yet a poor landscape choice due to their disease susceptibility. I'm delighted to tell you that I've been granted permission to publish a series of articles dealing with legal issues surrounding landscape plants and plant care. You could call it a "landscape and lawsuits" series. Lorrie Stromme, attorney and Hennepin Co. Master Gardener, has written the series for her Master of Ag degree.

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 Friday 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. (Scroll down for map.)

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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