Yard & Garden Line News Volume 4 Number 2                                                               March 1, 2002

Features this issue: Strawberry Fields--Minnesota Style It's the Berries! Two New U Strawberries Solving Houseplant Problems Trappers Working Hard to Detect Gypsy Moths MDA Looking for Gypsy Moth Trappers For 2002 The Red Queen, the Black Currant, the White Pine and the Orange Rust that Binds Them Editorial Notes

Strawberry Fields--Minnesota Style
Beth Jarvis, Yard & Garden Line

WinonaTM. Photo credit: U of MN Extension Service

The University of Minnesota Strawberry Breeding programs has two new Minnesota-hardy cultivars for you to try. Both Mesabi™ and Winona™ are available through garden centers and catalogs this year.

Winona^TM is the Dakota Indian word for "first daughter"". It's an apt name as it marks the resurgence of the strawberry breeding program, a cooperative effort with the USDA Agricultural Research Service (ARS).

The first U strawberries were released 1920; there were three cultivars. Four more cultivars followed in 1921. Then several more were released in the mid 1940s then one in 1958, another in 1960, then nothing until 1982 when Northland was released. None of these are available commercially now.

It can take 12 years to produce a new strawberry cultivar and the average cultivar's life span seems to be about 20 years. The older ones fall from favor with the introduction of more disease resistant, hardier, better tasting or bigger fruited cultivars.

In 1980, the ARS, in Beltsville, Maryland, helped rekindle interest in developing Minnesota strawberries.

Dave Wildung checks plants. Photo credit: U of MN Extension Service

The ARS Fruit Laboratory had been approached by northern looking for cold hardy strawberries as those bred in Maryland weren't hardy enough. A cooperative venture was formed among several universities' breeding programs in colder sites. David Wildung, horticulturist, at the North Central Research and Outreach Center (NCROC), in Grand Rapids, became involved.

Crosses of prospective cold-hardy parents were made by fruit scientists in Beltsville. The seeds were sown and grown in Grand Rapids. Scientists from ARS traveled to Grand Rapids to conduct field evaluations.

Jim Luby joined the project in 1982 . He, David Wildung and a fruit scientist from ARS developed ideas for crosses. For example, how to combine the disease resistance of one cultivar to the flavor of another. The appropriate parent plants were shipped to ARS every fall, where the ARS scientist would make the crosses, harvest the seed and germinate the seedling to test for red stele. (Red stele is a disease that is very common in the east, as close as southeastern Wisconsin. Jim notes that it's not common here because our commercial strawberry industry is young--generally less than 10 years old, growers practice good sanitation, and there is more land to rotate crops.)

The seedlings were then shipped to Minnesota where they were planted out at Grand Rapids or Excelsior.

Today, ARS screens 10,000 seedlings for red stele and 5,000 resistant seedlings are planted in fields at Grand Rapids and Excelsior.

The second year, seedlings are evaluated for productivity, fruit quality, foliar diseases, cold hardiness, etc. Of the original 5,000 seedlings, only 50 to 75 are selected for further trials. These selections are dug for propagation.

In the third year, the selections are propagated and planted in short rows in observation trials in Grand Rapids and Excelsior.

Yield trials. Photo credit: U of MN Extension Service

In the fourth year, the plants are evaluated for yield, fruit size, fruit traits, and plant diseases. Only 10 to 20 of the selections are still in the running.

In year five, mulched and unmulched trials are planted in Grand Rapids, Excelsior and Morris. Over the next two years, one or two selections might be advanced for introduction. Or not.

The selections will be tested for virus and by the 10th year, they will be distributed to nurseries for field propagation and available to the public by the 12th year.

Virus testing:

When possible introductions are identified, obtaining virus-negative stock is accomplished following meristem culture and indexing.

Plants are treated to 110 degrees for several days, an almost killing temperature. It causes the plants to grow extremely quickly. The plant runners can outgrow the virus organisms. Then, only the meristem of the runner is harvested. That's the very tip that's ˝ mm. or less . The idea is if the plant grows fast enough, it outgrows the virus and so new tissue will not yet be infected.

This clean tissue is the propagated through tissue culture, which means tiny bits are placed, using sterile technique, into test tubes containing a clear gel that contains nutrients and plant growth regulators. These barest bits of plant are stimulated by means of additives in the gel, to produce shoots which are rooted and produce plants.

Viruses are a real concern, so the plants are then screened using an ELISA test or indicator plants. If no ELISA test is available, a leaflet is removed from the new plant and grafted onto a strawberry known to be highly susceptible to a particular virus. After several months, if the host plant show no signs of disease, the plants are considered healthy.

Jim selects potential new releases. Photo credit: U of MN Extension Service

Healthy plants are then shipped as plugs to strawberry nurseries who plant the plugs then harvest the daughter plants. Because the parents can become disease-infected after being planted outside, reputable purveyors sell plants no more than than 2 generations from tissue culture.

Raising strawberry plants is labor intensive. The daughter plants are dug, the soil is knocked off the roots and excess foliage is stripped off. The bare-root plants are graded, boxed and stashed in a cooler at near freezing temperatures.

Strawberry plants need to have their chilling requirement met to produce fruit. Strawberries are raised in Canada, northern US, and higher elevations (>7,000 ft.) in northern California.

What does a strawberry breeder want to see in a plant?
Jim said a strawberry breeder standing in a seeding field, wants to see:
1) healthy plants, that have survived the winter and are disease free.
2) "Lots of red", at least from a standing position. The red can be either lots of fruit or large fruit (or lots of big fruit). Bigger berries, in the medium to large range, are becoming more popular. Everyone says how much they love the flavor of wild strawberries but no one wants to pick them. Strawberry growers can't afford to spend their labor dollars on smaller fruit.

Then, when the strawberry breeder bends over to get a closer look at the fruit, he's no longer just looking. He touches. The fruit should have a firm texture, which he determines by gently squeezing then he rubs the skin to see how easily the skin bruises. Soft, thin skinned fruit would not stand a chance of getting out of the field these days.

MesabiTM. Photo credit: U of MN Extension Service

'Trumpeter', the 1960 U release, by today's standards would be a "soft, ugly berry". It doesn't travel well as it's too soft. Today's berry is a well- traveled berry that has to make it further than 100 ft. from backyard to kitchen.

Then, the strawberry breeder gets to taste the fruit. The texture should be smooth and creamy and it shouldn't feel "seedy" or stringy. Firm fruit is good, but NOT woody or crunchy. The color should go all the way through the berry. Jim says he's seen some fruit with white flesh.

The flavor can be "classic strawberry" or remind the eater of melon, mango, anise, peach or other tantalizing flavors.. There are a lot of good flavors to satisfy consumers.

Fruit should have some acidity but not too tart. If the fruit is lacking acidity, the sugar gets cloying.

Test winter:
Minnesota's diverse geography makes it a fine place to trial fruit for hardiness. Grand Rapids is in USDA Zone 3 while Excelsior and Morris are zone 4. Grand Rapids gets bitter cold and often a lot of snow. In Morris, add prairie winds to Minnesota winters.

Snow is a great insulator, so a really cold, open (snow-less) winter can play havoc on plants. Minus 30 in January with little snow can be as damaging as bitter cold in mid November before the strawberries have completely hardened off. An early spring followed by a sharp cold snap also raises havoc.

Potential strawberry. Photo credit: U of MN Extension Service

If the cold doesn't kill the plants, summer stresses, caused by heat and wind, might do it. With stress, comes disease. Jim notes there is more leaf spot in Grand Rapids because that foliar fungal diseases like cool and humid weather. In Morris and the Twin Cities, leaf scorch, encouraged by warm humid conditions is more common.

Where do the berries go?
The Minnesota strawberry crop was 90% pick your own 25 years ago. Now, only 2/3 is pick your own with the remaining portion sold as pre-picked at farm stands, farmers markets, small co-ops and grocery stores and local restaurants that feature local produce. You will not find Minnesota strawberries at your local mega-grocery.

Jim estimates that perhaps 5% of Minnesota strawberries are processed into pies and preserves on a small commercial scale, so commercial processing is less of a factor than home cooking. Many of us head out to a farmers' market to buy strawberries for homemade jams and as such need a little acidic flavor to offset the sugar used in jam making. Really red color is preferred to orange-red. When the berry is cut the anthocyanins, which color the berries red, leak out. In an "undercolored" berry, you get muddy grey fruit in your pie or jam.

A word for the sponsors:
The Strawberry Project is funded by USDA funds for the ARS part, the Minnesota Fruit and Vegetable Growers' Association, the University of Minnesota Agriculture Experiment Stations funds, gifts from nurseries and patent royalties.

To learn more:
For information on raising strawberries in the home garden, go to: Strawberries for the Home Garden

It's the Berries! Two New U Strawberries

Winona^TM (MNUS 210) Strawberry
A Large-fruited Late Season Variety

WinonaTM fruit. Photo credit: U of MN Extension Service

Parentage
Winona^TM strawberry was the first variety developed by a cooperative breeding program between the University of Minnesota and the United States Dept. of Agriculture-Agricultural Research Service from a cross of Earliglow x MNUS52(Lateglow x MDUS 4616). Winona is the Dakota Indian name for a first-born daughter.

Cropping Season
Winona™ strawberry is a late-season junebearing (short-day) type. It ripens later than Kent, Jewel or Glooscap and similar to Lateglow.

Fruit Characteristics
The fruit is very large with a bright orange- red color and a conical to conic-wedge shape. The flesh is also orange-red and smooth and creamy in texture. The flavor is moderately intense with classic strawberry flavors and, sometimes, a hint of peach. The flesh is very firm. The berry skin has been sufficiently tough under most conditions but skin breakdown has been observed during very wet and humid seasons.

Disease Resistance
Plants are resistant to 5 common eastern US races of the pathogen causing red stele and also have shown good tolerance to black root rot in Minnesota. The foliage has been clean with respect to leaf spot, leaf scorch, leaf blight and powdery mildew.

Horticultural value
Winona™ strawberry should be a useful winter hardy, late season variety in eastern Canada and the Midwestern and Northeastern US. It will likely be most suitable for u-pick and pre-picked on-farm sales.

Mesabi^TM (MNUS 248) Strawberry
A Very Productive Variety for Cool Climates

MesabiTM Photo credit: U of MN Extension Service

Parentage
Mesabi^TM strawberry was developed by a cooperative breeding program between the University of Minnesota and the United States Dept. of Agriculture-Agricultural Research Service from a cross of Glooscap x MNUS 99. Mesabi is the Ojibway Indian word for "giant".

Cropping Season
Mesabi™ strawberry is a mid-season junebearing (short-day) type. It ripens with the North American varieties Glooscap, Cavendish, and Kent.

Fruit Characteristics The fruit is medium to large in size with a glossy scarlet skin that does not tend to darken as much as Glooscap, and a uniform bright red interior color. The flavor is well balanced between sugars and acids with a characteristic strawberry aroma. The flesh is firm with a creamy, melting mouthfeel. The skin is medium to tough but tends to become weak in hot weather.

Disease Resistance
Plants are resistant to 5 eastern North American races of red stele (red core) root rot and have moderate resistance to the common foliar diseases, leaf spot and powdery mildew, and moderate to high resistance to leaf scorch.

Horticultural value
Mesabi™ strawberry has been among the most winter hardy and most productive of varieties tested in Minnesota and should be useful as a mid-season variety in areas with cool summers and cold winters. It will likely be most suitable for on-farm sales and local markets.

Solving Houseplant Problems
Deborah Brown, Extension Horticulturist

Yellow lower leaves. Photo 0credit: U of MN Extension Service

If you're like most gardeners, within a few weeks you'll be preoccupied with the plans and preliminary activities that accompany spring planting outdoors. Right now may be your best opportunity to spend some "quality time" with your houseplants....before you hear the siren's call of lawn and landscape, flowers and vegetables.

For houseplants, most of which originated in tropical or sub-tropical climates, Minnesota homes provide a hostile environment, especially in late fall and winter when days are short. Some houseplant problems develop due to low light, low humidity and high (or low) temperatures. Others result directly from the care -- or lack of it -- they're given.

Spring is a good time to resolve houseplant problems; longer days mean more sunlight for photosynthesis and more sugars produced for plant growth and maintenance. When you prune out weak-looking growth, plants should have the oomph to come back with healthier, more robust foliage. And if you need to remove some of the old soil and repot your plants into larger containers, the additional energy will allow them to grow more roots rapidly.

Here's a checklist of common houseplant problems and some of the most likely causes. Do any of your plants exhibit these symptoms?

* Lower leaves turn yellow and fall:

This is most likely from over-watering, but it could also be from lack of nitrogen. If you haven't fertilized for a long time, apply liquid houseplant food mixed half-strength; repeat in four to six weeks.

* Dry, brown leaf edges or tips:

Fertilizer build-up in the soil, often combined with allowing the soil to get too dry, usually results in these symptoms. Some plants (mostly with long, pointed leaves) are also sensitive to the fluoride in our water. Leach excess fertilizer by watering several times in rapid succession, using lukewarm water.

Dry leaf tips on diffenbachia. Photo credit: U of MN Extension Service

* Soft, weak growth that may be pale and spindly:

This develops in excessive heat, when there's not enough light for high levels of photosynthesis. It's not unusual in winter when our homes are warm, but light levels are low. You can prune this growth back once conditions have improved.

* Small leaves spaced far apart on the stems:

If, after several months in your home, a plants' new leaves are decidedly smaller and "further between" that when you bought it, the plant is suffering from lack of light. Move it to a brighter location or use supplementary lighting.
* Pale green or yellowish leaves throughout the plant:

This could simply be from light that's too bright (Swedish ivy typically turns pale in high light), or it may be a sign that the plant has a poor root system. If the plant is not growing in a really bright location, knock it out of its pot to check the roots.

* Yellowing and dropping leaves at various levels:

Drafts and chilling temperatures by windows and doors commonly causes this, So does poor soil aeration and drainage. Gas fumes are a more remote possibility, but one that's worth investigating if symptoms develop rapidly on many plants, particularly if you don't feel they've been chilled.

Trappers Working Hard to Detect Gypsy Moths
Jeff Hahn, Assistant Extension Entomologist

Gypsy moth Photo credit: James B. Hanson, USDA Forest Service

Gypsy moth is a serious defoliator of hardwood trees. It is known to feed on the leaves of over 300 species of trees and shrubs. They are particularly fond of oak, aspen, birch, and apple. Gypsy moth was first introduced into the United States in Massachusetts in 1869. One hundred years later, the first gypsy moth landed in Minnesota when eggs and pupae were found in Duluth. In Hennepin county in 1976, the first adult moths were discovered. Since then there has been an ongoing battle to eradicate gypsy moths from Minnesota.

In 2001, trappers working for the Minnesota Department of Agriculture (MDA) set out about 15,000 pheromone traps throughout the state. Areas designated as delimiting sites set up at least 16 traps (sometimes as many 36) per square mile. Delimiting sites were located in St. Louis, Lake, and Cook counties along the North Shore; Hennepin, Dakota, Ramsey, Scott, and Carver counties in the Twin Cities; and in Houston, Filmore, Winona, and Goodhue counties in the southeast section of the state. An area is designated for delimiting trapping by either 1) receiving multiple catches in a single trap from the previous year, 2) trapping single moths in the same trap in consecutive years, or 3) catching single moths in the same year in traps within a mile of each other.

Non-delimiting sites in southeast Minnesota and the seven county Twin Cities area set up one trap per square mile. The rest of the state is set up on a three to four year rotation schedule, using one trap for every four square miles. In 2001 the northwest and central areas of the state were trapped (with one trap per square mile set up in cities, towns, and incorporated areas). Also in 2001, for the first time, the USDA-APHIS, PPQ (United States Department of Agriculture-Animal and Plant Health Inspection Service, Plant Protection and Quarantine) set up traps at saw mills and pulp mills.

As a result of these efforts, 429 gypsy moths were trapped. This is the third highest number of trap catches in a single season. Gypsy moth numbers had peaked in 1998 at 953 moths. But then trap catches were significantly down in the next two years with 296 moths trapped in 1999 and 182 moths trapped in 2000 before trap catch numbers increased in 2001. Of the 429 gypsy moths trapped in 2001, 332 (from just 7 sites) were trapped in the delimiting trap areas. Four delimiting sites in Hennepin alone produce 285 moths (66% of the total moths trapped).

Gypsy moth trap contents. Photo credit: MN Dept. of Ag.

An egg mass survey was conducted in the fall at three sites in Hennepin county. In a southwest Minneapolis delimiting site, where 170 gypsy moths were trapped in 2001, hundreds or thousands of egg masses were found within a one block area. This site is under a state quarantine until after this area is treated this spring. A second egg mass search conducted in Golden Valley yielded 30 - 40 egg mass in a heavily wooded site. No egg masses were found in a survey conducted in Plymouth.

In addition to trapping, MDA plans to treat gypsy moth infested areas. The most commonly used product, especially in residential areas, is Bacillus thuringiensis (B.t.), a bacterial insecticide. This insecticide has very low impact on the environment, affecting only butterfly or moth caterpillars that consume leave tissue with B.t. on it. This product has essentially no effect on people or animals. The best time to treat gypsy moth is shortly after the eggs hatch.

Gypsy moth eggs generally hatch sometime from early to mid May. The larvae are hairy, very small (1/10th inch), buff colored at first before turning black. As the larvae become older, they develop light orange spots on the back half of their body. They eventually become a two inch sized caterpillar with five pairs of blue spots on its back near their head and six pairs of red spots further down their back.

These caterpillars finish feeding sometimes in late June or early July. At this time they pupate for about 10 - 14 days before emerging as adult moths. Males are about ˝ inch long and have dark brown wings with black markings. Females are a little larger with whitish colored wings with black markings and a two inch wingspan. Adults are active from mid July through the end of August. After mating with males, females lay an egg mass containing anywhere from 300 - 1000 eggs. These eggs mass can be found on tree trunks and branches and literally any other nearby object. Adults die shortly after mating and egg laying. There is one generation a year.

The public can help by being on the alert for gypsy moths. If you see caterpillars that you suspect are gypsy moths, contact MDA (651-296-8328). The University of Minnesota Extension Service can also help identify suspicious caterpillars. Keep in mind that there are other caterpillars that can look similar to gypsy moths. Eastern tent caterpillar and forest tent caterpillar are two good examples of caterpillars that may be confused for gypsy moths. However, these caterpillars will lack the five pairs of blue spots and the six pairs of red spots on its back that older gypsy moth caterpillars possess.

(Note: Trapping information is courtesy of the Minnesota Department of Agriculture)

MDA Looking for Gypsy Moth Trappers For 2002

Gypsy moth trap. Photo credit: MN Dept. of Ag.

The Minnesota Department of Agriculture is seeking people to help in their 2002 summer trapping program. The job position is as follows:
Job Description: The Minnesota Department of Agriculture is currently seeking qualified, self-motivated individuals to work as seasonal Gypsy Moth Trappers. Gypsy moths are exotic European insects that cause extensive damage to North American forests. Job responsibilities include assembling, setting, checking, and monitoring up to 650 gypsy moth detection traps within designated routes (see attached map for designated routes). Trappers will also be responsible for compiling and maintaining accurate data records and maps, including the use of a Global Positioning System (GPS) unit. Trappers must live within their designated work areas and work out of their homes. All work is performed from an automobile, and trappers must have a reliable vehicle for this purpose. State vehicles may or may not be available for assignments during the employment period. This position requires highly responsible and accountable employees.

Hourly Wage: $10.42 per hour

Commitment: Interested individuals must be willing to commit from June 6 through September 27 (depending on work area), working 40 hours per week from 8:00 am-4:30 pm. Trappers will have one week of scheduled unpaid leave during the months of both July and August, leaving 11 weeks of full-time employment.

Qualifications: Qualifications include post-high school education or a solid work history. This position requires driving up to 250 miles per day, working in ALL weather conditions, and setting traps at a rate of 25 to 30 per day. The position also requires attention to detail and good map-reading and navigation skills. Applicants must have a valid driver's license and enjoy working outdoors.

To Apply: For more information about these positions contact Valerie Cervenka at (651) 296-8578, e-mail Valerie.cervenka@state.mn.us . To apply, send a State of Minnesota Job Application (marked Ag Tech-Gypsy Moth) and resume to: Minnesota Department of Agriculture, Human Resources Division, 90 West Plato Blvd, St. Paul, MN 55107-2094.

Deadline for Applications is March 22, 2002.
The Minnesota Department of Agriculture is an Equal Opportunity Employer.

Get the low down on this month's insect pests at Insects http://www.extension.umn.edu/projects/yardandgarden/EntWeb/Ent.htm
The Red Queen, the Black Currant, the White Pine and the Orange Rust that Binds Them
Janna Beckerman, Extension Plant Pathologist

A key symptom of WPBR is the characteristic "flags"(orange branches) that identify infected branches. Photo credit: Bob Blanchette

The sign of WPBR is the buff to orange fungus that sporulates in late April through May. Photo credit: Bob Blanchette

On Ribes spp., the sign of WPBR is the characteristic orange pustules that cover the upper leaf surface. Photo credit: Todd Barnes

When the infected Ribes leaf is turned over, telial spore horns can be seen on the leaf underside. Photo credit: Todd Barnes

"…in this place it takes all the running you can do, to keep in the same place."
Lewis Carroll, Alice in Wonderland
The Red Queen Principle was developed by evolutionary biologist L. van Valen in 1973 as a way to explain what has been described as a "co-evolutionary arms race" between plant and pathogen, predator and prey. Like Alice's visit with the Red Queen, she runs and runs, but ends up going nowhere. This same phenomenon happens in the wild world of plant pathology, right under our noses and involves a fungus, white pine, currants and gooseberries.

When did this "co-evolutionary arms race" begin? At some point, the ancient ancestors to the white pine and Ribes spp (currants and gooseberries) had a feud and went their separate ways. The continent of Asia wasn't big enough for the two of them! Some ended up in North America, the rest remained in Asia. The Asian white pines and Ribes spp. met a fungus named Cronartium ribicola, the causal agent of white pine blister rust (WPBR). While hardly affecting the Asian Ribes spp., WPBR probably killed many of white pines. Over time, natural selection favored the resistant white pines and resistance became an established trait in the population. C. ribicola became a minor nuisance of the Asian white pines, currants and gooseberries. North America was still "undiscovered," and the Ribes spp and white pines reproduced without having to worry about resistance to C. ribicola.

In the 1700s, when Europeans "discovered" North America, they fell in love with the exotic vegetation. Numerous plants were brought back to Europe, including the North American version of the white pine, which often reached diameters as large as 6 feet across and heights of up to 220 feet! Lord Weymouth brought the white pine to Britain (where it was renamed 'Weymouth pine' to obscure its lowly, colonial origin) and it spread throughout Europe. In 1856, white pine blister rust was first reported in Russia.

At this point, C. ribicola had found a more accommodating host that had never evolved resistance. Unfortunately, the story doesn't end here, or end up being about an introduced host being destroyed by a native pathogen. Timber companies who had over-harvested Eastern forests were looking for fast-growing pines to re-plant and quickly harvest. The growing timber industry lobbied Congress to remove tariffs on imported plant material. Weymouth pines (a.k.a. Eastern white pine) were shipped back to the US, with its new "friend" C. ribicola. The blister rust also found its other "new best friends" that were the native currants and gooseberries who also never evolved resistance to C. ribicola The stage was set for an epidemic.

And epidemic it was. The Red Queen was no longer standing still but was now off and running! Ten years after the Chestnut blight epidemic starting killing all the chestnuts in North America, white pine forests valued in the millions of dollars appeared threatened. In 1912, the Federal Quarantine Act was passed to prevent additional plant products into the country. To control the problem that had already started, an eradication program began with zero tolerance for white pine blister rust. The government went after infected trees with little to no success.

They then implemented a tactic that was only marginally successful with wheat stem rust: Eliminate the alternate host. Thus began the eradication of all European currants within 1000 feet of a white pine in North America. Unfortunately, spores from the Ribes host are believed to travel up to 350 miles to white pine…Not only that, but the native currants were just as susceptible as their European counterparts. Thus, the Ribes Eradication Program against all native currants and gooseberries began from New York to British Columbia (Canada never subscribed to the Ribes Eradication Program). During the Depression, 11,000 men were paid to uproot or poison Ribes . Have you ever tried to pull up a gooseberry or currant? Think deep roots and heavy, sharp prickers! Add to that the fact that it produces berries that are loved by birds that freely disseminate them in a package of fertilizer, and you can imagine how incredibly unsuccessful the program was. The incidence of WPBR was reduced, but not eliminated. Since 1966, Ribes eradication has been implemented on a state-to state basis (17 states still have bans in place). To this day, many homeowners in other states are unable to import any cultivar of Ribes , or are restricted from planting the more susceptible black currant. Additionally, programs are in place to evaluate and select for WPBR resistance in white pines. These two resistance-breeding programs have played an important role in putting the Red Queen back on the proverbial treadmill for now.

In Minnesota, we don't suffer Ribes restrictions. But, because of the presence of white pine and WPBR, it is important that homeowners carefully consider what varieties of currant and gooseberry that they plant. Remember, WPBR is a problem to white pines; it does not severely affect the Ribes . Below is a list of WPBR resistant currants and gooseberries. This way, WPBR, like the Red Queen, will still be running, but going nowhere!

Currants and Gooseberries to Plant: Most currant and gooseberry varieties are considered hardy to zone three.

Black currants (R. nigrum) are considered the most susceptible to WPBR. Black currant fruit has a characteristic aroma. The scent can also be found in the leaves, which are commonly used in tea to impart the characteristic black currant flavor.

'Consort Crusader', 'Coronet': Considered immune to WPBR, these cultivars were released in Canada. Berries are considered very tart with a musky flavor.

'Titania Large', firm berries are produced on extremely vigorous plants. Resistant to PM and WPBR.

'Ben Alder' and 'Ben Sarek'. Medium to large berries are used for juice and desserts. Plants are moderately resistant to WPBR and very resistant to PM.

'Minaj Smeriou'. A new rust resistant release with a more classic black currant flavor. Performance has not been studied in Minnesota. Early reports are positive for both flavor and disease resistance.

'Viking' was erroneously reported to be resistant but is quite susceptible to WPBR

Red currants (R. sativum) are generally considered moderately resistant to WPBR.

'Red Lake' (developed at the University of Minnesota produces clusters of large, mild flavored red berries. It is considered to be one the best red currant variety.

White/Pink Currants (R. sativum) are considered albino forms of red currants, and as such are considered moderately resistant to WPBR.

'Pink Champagne'. Flavor is more delicate (less acid) than that of black currants and less tart than red currants. Plants have a vigorous, upright growth habit and excellent resistance to PM.

'White Imperial' (Geneva, NY) White fruit with a pink blush. Excellent flavor. Considered by some to be the best tasting of all currants. Moderately susceptible to PM, but resistant to WPBR.

Gooseberries (R. hirsutellum and R. grossularia), like red currants, are considered moderately to completely resistant to WPBR. Care should be taken to keep plants healthy to minimize the possibility of WPBR infection. Powdery mildew is capable of defoliating and killing gooseberries. For this reason, consider PM resistance when purchasing plants.

'Welcome'. WPBR and PM resistant, this cultivar is noted for high fruit yields of tart, red gooseberries.

'Pixwell'. Originated in North Dakota, 'Pixwell' is a heavy yielder of large, delicious berries. Often, it bears the year after planting. Moderately mildew resistant.

'Hinnomake Red', This variety from Finland combines excellent flavor and yield of dark red fruit. As an added bonus, it is considered mildew resistance.

Hybrid: Jostaberry. Considered by many to have the best traits of both parents (black currant and gooseberry); Still, others believe it inherited the worst traits of both parents. Plant and decide for yourself, but plants are resistant to both WPBR and PM.

Test your diagnostic savvy monthly with Disease Watch at: http://www.extension.umn.edu/projects/yardandgarden/PlantPathWeb/Plpa.htm
Editorial Notes

Chokecherry blossoms. Photo credit: Beth Jarvis

What a winter! Sounds like we'll have a dry summer with El Nino. So perhaps drought tolerance may be something to think about when planting the gardens this spring.

In April we'll hear about the annual flower trials and planting pear trees. I'm hoping to have a story about the work of a medical entomologist who studies Lyme disease, in time for tick season.

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 have gardening questions, please call the Yard & Garden Line at (612) 624-4771.

If you have gardening questions, please call the Yard & Garden Line at (612) 624-4771.

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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