Yard & Garden Line News
Volume 6 Number 1                                                               January 1, 2004
Features this issue:
 Guara and Lilies and Glads, Oh My!
More Easy-Care Houseplants; Try Succulents
Tree Care Advisor Training- St. Paul Sessions
Plant Disease Management with a Twist of Lime-Sulfur
Brown Recluse Spiders: Truth vs. Myth
Editorial Notes


Guara and Lilies and Glads, Oh My! A peek at long range projects in herbaceous flower breeding
Beth Jarvis, Yard & Garden Line

Gaura blooms. All photos: Neil Anderson
When he's not freezing mums, Neil Anderson is freezing ‘Blushing Butterflies' and their kin. No, this is not entomology run amok. The butterflies are Gaura lindheimeri 'Blushing Butterflies' and other Gaura species. It's all being done in the name of science in the U's Flower Breeding and Genetics Lab.

Gaura has become an increasingly popular plant over the last few years. It's been available from garden centers for 5-6 years and is already the 23rd most popular herbaceous plant in terms of US sales. What's not to love in a drought and heat tolerant, continuously flowering plant?

Unfortunately, Gaura lindheimeri is hardy only to zone 6, so it's not hardy in the Twin Cities (zone 4) but that doesn't stop an occasional retailer from stretching the truth a zone or two. But, there is a native, fragrant, hardy gaura, Gaura coccinea that might provide additional hardiness in future hybrids. Gaura calcicola has tall, fragrant flowers and grows in limestone soils, such as Texas.

So, where did all these gaura come from?

Funded by a grant from the Perennial Plant Growers Association, Neil Anderson and his Flower Breeding and Genetics Lab staff collected gaura ecotypes in California, Texas and Minnesota. Now they have the largest gaura species collection of any breeding program, anywhere. This is raw material for a plant breeding program. Crosses among potential parents will be tried and the results evaluated, for not only hardy garden perennials but as additions to the cut flower trade or potted plant industry.

Gaura calcicola
All the Minnesota and most of the Texas gaura ecotypes are tetraploid. Texas also has some diploid. G. lindheimerii is diploid.

Time out for Genetics:

Eggs or pollen from a parent contributes half or the haploid number of chromosomes; the offspring is diploid as it got half of its chromosomes from each parent. Triploids have 3 times the haploid number and are, reproductively speaking, sterile. (One well-known triploid is seedless watermelon.) Tetraploids have four times the haploid number, so they have twice as many as diploids.


Gaura lindheimerii has shown great tendencies to be invasive in California, eastern seaboard states and south Africa. It reseeds in Minnesota but the seedlings are not hardy.

Ever mindful of and concerned with potentially invasive plants, the U flower breeders are planning to select against invasive tendencies. One way they might do this is to create triploids, which would be sterile.

For the crosses currently under observation, emergent rhizomes will be counted to see if the field observation method (outlined in the December issue) works for guara as well.

And colors? Oh yes!! Neil's all excited about finding a yellow flowered gaura (they're usually white to rose) but, rather impishly, won't say what species it is. We'll just have to wait.

Behold the lilies of the field!

Lilium x formolongi
Back in 1999, students in a potted plant production class experimented with some Japanese lilies. They were using lilies grown from seed purchased from a Japanese firm. The Japanese raise these lilies strictly as cut flowers then pitch the plants.

The students were testing the effects of day length on flowering and discovered the Japanese lilies were totally insensitive to day length, a trait known as day neutrality. In short, the lilies started to bloom and kept going, sending up a new shoot as soon as the older one set a flower bud with as many as 10 flowers per stem. They also didn't need vernalization.

All lilies need vernalization-exposure to cool temperatures for six weeks or so and long days to set flowers and bloom. Garden lilies in the ground are vernalized by nature. Potted bulbs are vernalized in greenhouse coolers. Long days is accomplished by turning on the greenhouse lights for 4 hours from 10 p.m. to 2 a.m. to effectively break up long winter nights.

Commercial bulbs, both Easter lilies and cut flowers are grown under the "Dutch method" of culture. A traditional lily bulb takes 2-4 years to grow to a forceable size, then it's potted up, forced then tossed. (Many gardeners toss spend Easter lilies right into the garden and grow them outdoors in summer where they might bloom again. They're not reliably hardy and may only survive winter in protected sites.)

These Japanese lilies can be raised as Easter lilies and planted outside. They're an interspecific lilies cross between Lilium formosanum and L. longifolium, the Easter lily. It's named Lilium x formolongi.
Bluebeard--
Caryopteris incana
Because they're propagated from seed, the possibility of viruses being transmitted from a parent is largely eliminated. They bloom in 250 days from seeds. Due to extravagant bloom, they don't stockpile much in the way of food reserves in the bulbs, so the bulbs are small, yet they are frost tolerant and some of the bulbs are even hardy. Our flower breeders don't yet know how heritable each trait is–cold, reflowering, etc. While Neil doesn't hold the hybrid patent, he is able to patent newly discovered traits. Right now the project is pretty much lily-white because the only color is white, which is prevalent in the F2 and F3 hybrids. They are hoping to see color in the F4 hybrids, the great, great grand-lilies, er, children.

Glad all over!

Some day we will be able to plant gladiolus seeds that will produce flowers that summer, but not yet. The Flower Breeding and Genetics Lab folks have produced one cultivar, so they're in the very initial stages with years of breeding work to go.

They're working with South African gladiolus, some of the parents of modern-day garden glads. These glads are naturally dwarf, fragrant and come in a wide variety of colors, so the flower breeders will have a lot of desirable genetic options from which to choose.

Closer to home

Lastly, a mention of a forthcoming annual that you will see in garden centers in two to three years. It's Caryopteris incana, commonly called bluebeard. It's a member of the mint family, 18-24" tall, that is highly fragrant and highly floriferous--with lots and lots of blue flowers. Neil thinks it has excellent cut flower possibilities.

More Easy-Care Houseplants; Try Succulents
Deborah Brown, Extension Horticulturist

Aloe vera production. Photo credit Deb Brown
Usually when you hear the phrase "easy care houseplant" snake plant, pothos, and other plants with low light requirements come to mind. And with good reason. Light is the factor that most often limits plant growth indoors, particularly in fall and winter when our days are so short.

But there's another whole category of plants that are easy to care for indoors – not due to their modest light requirements, but because they can sit a long time between waterings with no ill effects. And they aren't sensitive to low relative humidity. I'm talking about succulents.

Succulents are defined by their specialized moisture-holding tissue that allows them, in nature, to conserve water for days, weeks, months, or longer. It's a survival mechanism that allows plants to survive and even thrive in harsh desert-like environments and situations where rainfall may be plentiful one season, then non-existent the rest of the year.

Cacti are perhaps the best known succulents. Their typical globe-like or cylindrical shape allows them a favorable ratio of moisture-holding inner tissue to outer tissue that can lose moisture more readily to sun and drying winds. In nature, opuntias (prickly pears) grow so their flat vertical "pads" are oriented to present the thin side towards the predominantly sunniest exposure.

The ridged or pleated appearance of many cacti allows them to expand and contract, depending on how much moisture they are storing. It also allows for a larger photosynthetic surface, while still enclosing a critical mass of moisture-holding tissue. Even their thorns, barbs, and wooly hairs are thought to collect morning dew and protect them from drying.

Though cacti are easy to grow indoors, most require lots of bright light to maintain their original shape. Almost all indoor gardeners have had the experience of buying a healthy, small cylindrical cactus (or receiving one as a gift), only to find the new growth that developed was noticeably slimmer than the original. While hardly the end of the world, it's not terribly attractive.

Cacti are only one group of succulent houseplants – albeit, a large group. The following list includes several other popular houseplants, all of them succulents with more modest light requirements than most true cacti. Each is definitely easy-to-grow.

* Jade Plant, Crassula argentaea

Jade plant Photo credit: Deb Brown
One of the most reliable houseplants you can grow, the jade plant often lives a very long time indoors, developing thick, almost woody stems. Needing only medium light, it often develops red leaf margins when grown in extremely bright light.

The key to keeping jade plants healthy lies in knowing when to water them. Begin to feel the leaves a day or two after you've watered the soil. They'll be nice and firm. Water thoroughly again as soon as those leaves begin to lose their turgidity. Never let the plant dry to the point that leaves actually wilt.... catch it as soon as they're a little rubbery feeling.

* Aloe vera, also called Medicine Plant, Aloe barbadensis

One gentle squeeze of aloe's spongy leaves will convince you of this plant's succulent nature. Watering it too frequently will cause its spongy leaves to rot at the base. Always water the soil thoroughly, but allow it to dry before watering again. Keep the plant in an east-facing window in summer, a west or south-facing one in winter.

Aloe veras enjoy a deserved reputation as medicine plants. People apply the viscous gel in their leaves directly to burns, bites, and other skin irritations, where its soothing action is thought to accelerate healing. Keep an aloe vera on your kitchen window sill, ready to treat minor accidents.

Assorted pepperomias Photo credit: U of M Extension Service
* Ovalleaf Peperomia, Peperomia obtusifolia

Peperomia leaves are more firm than aloe's, but if you've ever accidentally broken one in half, it's obvious how much moisture they hold. You'll find ovalleaf peperomias with solid green leaves as well as variegated types. They all require medium light, and will grow spindly in a low light situation. Be careful not to over-fertilize variegated forms or they tend to become greener. As with other succulents, wait until the soil dries before watering these plants.

* Snake Plant, also called Mother-in-law's Tongue, Sansevieria trifasciata

You may have heard it's impossible to kill a snake plant. That's only a bit of an exaggeration. Though too much sunlight fades the foliage to a yellowish green, this plant tolerates most forms of neglect. It needs only minimal light levels, and can be left unwatered for long periods of time. Of course, it will grow faster when watered regularly, and fertilized two or three times over spring and summer. Because its leaves are quite succulent you should allow the soil to dry each time you water.

If you're not particularly fond of the vertical spears typical of most sansevierias, look for the "birdsnest" form, instead. Growing as a compact rosette of four or five inch leaves, the birdsnest sansevieria is just as tough as its taller relatives.

ZZ Plant Photo credit:
Mark Zarr, U of Montana
* Ponytail Palm, Nolina recurvata (Beaucarnia recurvata)

Ponytail palms are not really palms at all. They have tough, leathery leaves, but if you break one open, it's apparent they don't hold much moisture. Instead, they're known for their large, swollen bottle-shaped stem or caudex. This caudex can store enough moisture to hold large plants for months on end in their native environment. Of course, their foliage would deteriorate under these conditions, so you don't want to try depriving them of moisture for too long indoors.

There are a number of difference caudiciform plants with swollen stems or tubers, but most are considered rare, or at least unusual, "collector" plants. Only ponytail palm is commonly available. Give it medium to bright light and allow the soil to dry before watering. Though insects are not usually a problem, periodic cleaning both sides of the long, strap-like leaves with a damp rag will prevent dust build-up and remove any potential egg deposits.

* ZZ Plant; Zamioculcas zamiifolia

The ZZ plant is a relatively new houseplant with thick, leathery, compound leaves and even thicker succulent stalks. It's related to philodendrons, peace lilies, and Chinese evergreens, but you'd never guess by looking at it. ZZ plant will grow in low light, but is said to do better in medium light. It's okay for high light, too, but would require additional watering. Typically, you need to allow the soil to become completely dry before you water the ZZ, which means like other succulents, it's very undemanding when it comes to daily care.

Tree Care Advisor Training - St.. Paul Sessions
Dave Hanson, Urban and Community Forestry

Proper pruning  is one part of the class. Photo credit:
U of M Extension Service
Announcing the 2004 Tree Care Advisor (TCA) Training! The TCA Program is similar to the Master Gardener program in that volunteers pay a fee, $80 this year, and receive 30 classroom hours of both hands on and in class training with local experts.

The training takes place in Green Hall on the St. Paul campus of the University of Minnesota from 8:30 am - 3:30 pm on February 21st, February 28th, March 6th, March 13th, and March 20th. The classes focus on tree and shrub care within an urban environment. Topics covered include, but are not limited to: plant selection based on site, how to prune, common tree insects and diseases, and diagnostic procedures.

In exchange for the training and support, volunteers are expected to perform 50 hours of community service the first year and 25 hours each additional year. Often, these volunteer hours are consistent with Master Gardener volunteer activities and are not in addition to required Master Gardener hours. In order to keep you up to date on current tree related research and news you continue to receive a quarterly newsletter, a website with tons of resources, and quarterly update training sessions on "hot topics."

Interested? Please visit the website at http://www.mntca.org to find out more about the program. While there you can fill out the online application or print one off to mail in. You can also call Dave Hanson at 612-624-1226 for program assistance. We look forward to hearing from you.

Plant Disease Management with a Twist of Lime-Sulfur
Janna Beckerman, Extension Plant Pathologist

Roses benefit
from a dormant treatment. Photo credit:
Beth Jarvis
Sulfur has been used for the control of plant disease since ancient times. Although it did fall out of favor after the discovery of Bordeaux in the late 1800's, the re-discovery of lime-sulfur in the early 1900's (almost 100 years after its initial discovery), and the resulting enthusiasm for it continues through this day.

Why did sulfur fall out of favor? The key may be in the notes of William Forsyth 'Gardner to His Majesty [King George IV].' In his book 'Treatise on the Culture and Management of Fruit Trees,' Forsyth advises that when faced with a possible powdery mildew outbreak, one should "wash or sprinkle the trees well with urine and lime-water mixed…take tobacco one pound, sulphur two pounds, unslaked lime one peck and about a pound of elder buds…It should then stand two or three days to settle; then take off the scum and it is fit for use." It may be modern day prudishness, but I don't believe it was the sulfur that made this concoction fall out of favor!

As you can imagine, sulfur must be a fairly effective fungicide. Why else would people tolerate the rotten-egg odor? The key to its efficacy is that it prevents spore germination. For this reason, it must be applied prior to disease development for effective results. It kills the pathogens through direct contact. In addition to being sprayed, it is often burned in a greenhouse setting as a fumigant to kill powdery mildew.

Sulfur is available as a dust or can be purchased in liquid form; it is also available as a wettable powder, which allows you to decide how you wish to apply it. Sulfur for use as a fungicide is available under many trade names (e.g., Bonide Sulfur, Monterey Sulfur 90W, Fertilome Rose, Flower and Vegetable Dust). When properly used, the micro-fine wettable sulfurs or flowable sulfurs result in less burn to foliage and fruit than liquid lime sulfur. However, their use during hot weather (above 80 degrees F) may result in some leaf burning and/or fruit russeting. Sulfur-based fungicides are very effective for control of powdery mildew on most fruit crops. They are not highly effective for control of most other fruit crop diseases.

Do NOT use on gooseberries Photo credit:
Beth Jarvis
Sulfur is very toxic to foliage of certain grape varieties (mainly American grapes) including Concord, Chancellor, and Foch. Care, if not avoidance of sulfur for newer American vinifera-hybrids, should be the rule until reputable studies demonstrate the safety and efficacy of sulfur for control of powdery mildew and other diseases. In the case of grapes, or other fruit for wine purposes, sulfur may pose problems during fermentation, and impart a bouquet of rotten eggs to the finished wine. Other sulfur-shy plants include varieties of gooseberries, currants, apricots, raspberries, and cucurbits. Sulfur is relatively safe on most other plants. Do not use sulfur if you have applied an oil spray within the last month--the combination is phytotoxic (plant-killing). Likewise, remember to NOT use sulfur when temperatures are expected to exceed 80°F. The compatibility of sulfur with other products, except oils, is considered good. Of course, to every rule, there is an exception: Lime-sulfur is a great dormant spray to apply prior to tipping roses. Because roses are dormant at this time, this is the one instance when you can mix oil with lime-sulfur.

As with copper in Bordeaux mixture, lime reduces the toxicity of the sulfur to the plant, while increasing it lethality to the fungus. Lime-sulfur is formed by mixing hydrated lime (to help it penetrate plant tissue) and sulfur with water. This mixture is then boiled and the clear liquid is extracted for use. It is important to note that simply mixing the hydrated lime with elemental sulfur will not result in calcium polysulfide without boiling. Hopefully, the thought of toxic sulfur fumes (which are corrosive, too!) and unbelievably smelly are enough to convince the enterprising home chemist from ever attempting such a thing! Fortunately, lime-sulfur can be easily bought at most nurseries and chemical supply companies. It is most commonly sold as a premixed liquid concentrate of 30% calcium polysulfide. Although this is probably its most stable configuration, it is not a very stable fungicide. For this reason, you should only buy what you can use within the growing season.

Plum pockets (light green ovals mid-photo). Photo credit:
Beth Jarvis
Lime-sulfur is commonly used as a dormant season fungicide or as a growing season spray. Dormant season applications must be applied in late winter or early spring when temperatures are above freezing, but before leaves are present on the plant to prevent the possibility of phytotoxicity. When using lime sulfur during the growing season, care must be taken to apply the product in the early morning or late afternoon to avoid burning. Never apply lime sulfur during dry weather, or when temperatures reach or exceed 80 degrees F in a 24 hr period. Both lime and sulfur are corrosive, and damaging to the eyes, in addition to being harmful if swallowed, inhaled, or absorbed through the skin. As always, thoroughly read the label before purchasing, handling, or applying lime-sulfur.

Liquid lime-sulfur fungicide is often used for organic disease management of fruit crops. It can be used at high concentrations as a dormant spray on plums for control plum pockets, on raspberries for cane blight, spur blight and anthracnose. At high concentrations, it should be used only when plants are dormant. It can cause severe damage if applied after green foliage appears. Lime-sulfur is only moderately effective against apple scab. Because of its lack of efficacy, wettable sulfur is not recommended for control of apple scab.

A final word of caution: Users of sulfur and sulfur-based fungicides should remember that sulfur is lethal to some beneficial insects, such as spiders and mites. Just as there are beneficial fungi, beneficial insects often prey upon insect pests that affect your yard and garden. Indiscriminate use of sulfur can result in the killing of these beneficials. Finally, when used appropriately, sulfur is not injurious to honeybees.

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


Brown Recluse Spiders: Truth vs. Myth
Jeff Hahn, Assistant Extension Entomologist

Brown recluse spider Photo credit: Entomology Dept.
U of MN
(Note: Some of the following information was taken from Richard Vetter's spider web site at the University of California, Riverside to help write this article. Richard Vetter is an expert on brown recluse spiders having studied them for many years. Please see his site, http://spiders.ucr.edu/ for more information on brown recluse spiders and their bites.)

Every year there are people in Minnesota that believe that have been bitten by a brown recluse spider. This diagnosis is based on the presence of a necrotic wound or ‘bite', (a lesion with localized dead tissue). Any time a necrotic wound is encountered, many people assume that it must be the result of a brown recluse spider as they are known to be a common cause of such lesions. This conclusion may be further confirmed or reinforced by a physician from just an examination of the wound. Unfortunately, in most cases this is inaccurate.

Despite unconfirmed reports of brown recluse spider bites in Minnesota, a positively identified brown recluse has never been found biting someone here. There is confusion as to what a brown recluse looks like. It is not a big spider which surprises most people when they see an actual specimen. The body measures only 1/4 - 1/2 inch long. It is brown with a dark colored violin shaped marking behind its head. Brown recluse spiders characteristically have six eyes while most spiders have eight. You usually need magnification to see the eyes.

Range of spider. Graphic credit: Richard Vetter, Univ. of California, Riverside.
The issue of bites is further complicated by the fact that these brown recluse spiders are not native to Minnesota. They are found in the south central states, from eastern Nebraska south to eastern Texas and east to southern Indiana, western Kentucky and Tennessee, and northern Georgia. Brown recluse spiders may be found in Minnesota but they must be transported here from an endemic area. It is possible but rare. The reality is there has only been one confirmed brown recluse spider specimen found in Minnesota in the last 60 years.

Brown recluse spiders and shy and infrequently encounter people. They typically establish themselves in basements but typically do not move beyond. Brown recluse spiders are communal and when they are in a favorable area, you will find many of them -- it would be very unusual to find just a single brown recluse. The presence of high numbers does not seem to increase bites. There are many cases where rooms have been infested by brown recluse spiders without residents ever being bitten. Because of their shy nature, bites usually only occur when the spiders become accidentally trapped between a person and bed sheets, clothing, shoes, or something similar.

Despite claims to the contrary, brown recluse spider bites do not result in ongoing, ulcerating wounds. The vast majority of brown recluse bites heal on their own within two to three months without medication and with little scarring. There has never been a confirmed death in North America attributed to a brown recluse spider bite.

If brown recluse spiders are unlikely suspects in creating necrotic lesions then what is causing these wounds? There are many medical problems that can affect the skin that have been reported in the medical literature, including but not limited to, any infection with Staphylococcus or Streptococcus species, Lyme disease, infected and chronic Herpes simplex, Herpes zoster, fungal infection, diabetic ulcer, Pyoderma gangrenosum, chemical burn, and poison ivy/oak.

You can not identify a brown recluse spider bite from just an examination of the wound, especially if you are in an area where the brown recluse does not occur. The bottom line is in Minnesota you must have a spider positively identified by an expert as a brown recluse and it must have been seen or strongly implicated in creating the bite before you can call it a brown recluse spider bite. Otherwise, keep an open mind and explore other possibilities to properly diagnose the problem.

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


Editorial Notes

Annuals at Arb Photo credit:
Beth Jarvis
Ah, the days are getting longer!! Perhaps we're only gaining seconds per day but they are longer.

To get you thinking spring big time, next issue Pete Moe, the operations manager at the Arboretum, will share a peek into a day in the life at the Arb. I took the photo, at left, at the Arb a few years ago. This flower bed borders the sidewalk to the Snyder Building.

I'm still hoping the folks at the North Central Research and Outreach Center, formerly the NC Experiment Station, in Grand Rapids, will tell us about themselves.

I'm also hoping to introduce you to Dr. Tim Kurtti, who does deer tick research.

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 the components of the Yard & Garden Line, such as Bell Museum of Natural History, INFO U and the Soil Testing Lab. There are new links to the Insect Journal, Plant DIsease Diagnostics, Disease Watch and now the Urban Forestry Resources clinic.

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.

The Yard & Garden Clinic closed December 12, 2003 due to budget cuts. Questions from the general public will no longer be accepted. Samples will not be accepted.

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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