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Orange tentacles ooze from a cedar-apple rust gall. Nancy Rose
Aliens Found in Local Juniper!
They may not be from outer space, but when the brown cedar-apple rust galls on juniper branches suddenly sprout a tangle of gelatinous bright orange tentacles in spring, well, it sure looks alien.
Cedar-apple rust (Gymnosporangium juniperi-virginianae) is a common fungal disease that requires two separate host species in order to complete its complex 2-year life cycle. One host group is apples and crabapples (Malus). Fortunately not all varieties are susceptible. On this host the fungus can infect the leaves, eventually showing as orange spots with dark centers. Apple and crabapple fruit can also be infected.
Mature spores from apples blow in the wind, landing on junipers in late summer and early fall. Common host species in Minnesota include Eastern red cedar (Juniperus virginiana) and Rocky Mountain juniper (J. scopulorum). The next spring, the disease starts as a small swollen area on the needles. By fall the infection has become a round woody growth called a gall. These galls can be an inch or two in diameter.
The next spring it's showtime! In wet weather the galls swell repeatedly and send out those alien orange tentacles, more properly known as telial horns. Fungal spores are shed from the horns. These spores can travel a mile or more on the wind. If they land on a susceptible apple or crabapple, the fungus has completed a full lap and the disease cycle begins again. In home landscapes, you can reduce the problem by pruning rust galls out of your junipers before galls produce orange horns in the spring. --Nancy Rose & Michelle Grabowski
Is frost predicted tonight or in the extended forecast? This is an ongoing question that keeps gardeners glued to the local weather forecast, especially during April and May. For most of us, the answer strongly influences our gardening activities and priorities. It can help us determine if we will hold off on planting frost sensitive transplants, or whether we need to declare a gardening emergency and rush out to cover frost sensitive transplants already in the ground. Fluctuating spring temperatures may even set us to protecting established favorites already in active growth in order to avoid damage to flower buds and tender new foliage. Unfortunately, freezing damage (ice crystal formation that can rupture plant cells) is not all we should be concerned with. Chilling injury is also possible and is something gardeners rarely consider. Chilling injury is common especially on warm season annuals and plants from tropical and subtropical regions. Chilling injury can occur at temperatures from near freezing (32°F) up to about 45 to 50°F.
Tropical flowers like these New Guinea impatiens are easily injured by chilling temperatures. Nancy Rose
Symptoms of chilling injury
Typical symptoms include overall slowed or stunted growth; watersoaked, wilted or dead regions on leaves, flowers, and fruit; and altered texture or flavor of susceptible fruits. Symptoms of chilling injury, especially stunted or slowed growth, can go undetected or be confused with other potential causes. Symptoms of chilling injury vary based on susceptibility of plant species and plant tissue, the degree of acclimation of plant tissue, the exact temperature(s) encountered, and the duration of exposure to chilling temperatures. Chilling injury is common in Minnesota especially on bedding plants during stretches of cool spring temperatures and especially cool nights. It is also common in Minnesota with tropical or sub-tropical fruits and potted plants during winter months and primarily occurs when the plants are in transit. Plants may or may not recover from chilling injury depending on how much damage has occurred.
Unfortunately, many gardeners trying to get a head start on the growing season by planting their warm season bedding plants early may actually lose the advantage of an extended growing season as plants use precious time trying to recover from chilling injury. Commonly grown plants that are particularly sensitive to chilling injury include tomatoes, peppers, squash, dahlias, and impatiens. In fact, sometimes early planting may result in such delayed growth from chilling injury that smaller, later planted transplants may surpass earlier planted transplants suffering from chilling injury. I have especially noticed this with squash. The squash I direct seeded in the garden in late May have typically outgrown my earlier transplanted squash seedlings even though I try to protect my transplants from cold nights and chilling injury.
What is happening when plants experience chilling injury?
The primary site of chilling injury is thought to be cell membranes. Cell membranes are rich in lipids (fats) and control what materials pass into and out of regions of the cell. Lipids differ in their degree of saturation--how many hydrogen atoms are connected to the carbon chain. Typically, the more hydrogen-saturated the carbon chain is, the higher the temperature needed for the lipid to turn into a solid. For instance, margarine is hydrogenated vegetable oil and at room temperature margarine is a solid and vegetable oil is a liquid. Hydrogenation results in margarine being more saturated than vegetable oil (more hydrogen on the carbon chain) and so it remains solid at a higher temperature than vegetable oil.
The lipids in cell membranes of tropical and subtropical plants tend to be more saturated than the lipids in membranes of plants from more temperate regions. In order for the membranes to work best, lipids must be somewhat fluid and not solidify. The lipids in chilling sensitive plants change from their relatively fluid state to becoming gelatinous or semi-solid at chilling temperatures. When this happens membranes become damaged and their function is impaired. It takes significant time and energy to repair the damage to cell membranes as well as the subsequent damage that occurred as a result of disrupted cell function. The longer and colder the chilling exposure, the greater the potential for damage and the longer it will take to repair the injury. Sometimes severely damaged plants are not able to recover and die.
Ways to get a head start on the growing season and avoid or reduce chilling injury
As we keep our eyes on the weather forecast, it is important be on the lookout for temperatures that can cause chilling injury. Taking action to prevent or minimize chilling injury for our chilling sensitive plants can help us truly gain a head start on the growing season.
Honey bee colonies in the U.S. are overworked and under-appreciated. They are the world’s most important pollinators of many fruits, vegetables and seed crops, contributing billions of dollars in value to agriculture and our diet. Bees also pollinate wildflowers in our natural ecosystems and much of what we plant in our home gardens. Without honey bees, and other bee pollinators, the produce section in our grocery stores would have about 1/3 fewer fruits and vegetables and it is impossible to estimate how many flowers would not set seed.
Honey bee on peach blossom. Z. Huang, Michigan State Univ
Honey bees in the U.S. are maintained by beekeepers who keep them as a hobby, as a side-line profession, or commercially as a livelihood. All beekeepers harvest honey from their colonies, a wholesome and healthful product. Some harvest other products such as beeswax, pollen, royal jelly, and propolis, which are used to make candles and cosmetics, or serve as nutritional supplements and medicine. Beekeepers keep their colonies of bees in cities, suburbs, and the countryside. Some maintain their colonies in one location year round, and some transport their colonies long distances to follow the blooming plants for honey and to provide pollination service to crops. Some beekeepers propagate “nursery” stock (more bee colonies and queen bees) for sale around the country.
Unfortunately, honey bees are subject to diseases and parasitic mites. The mites were inadvertently introduced into the U.S. in the 1980s. These maladies weaken colonies and can lead to the collapse and death of colonies. Beekeepers are careful to control these pathogens and pests in their colonies, but it has become increasingly difficult because the diseases and mites have developed resistance to some of the treatments. New treatments are currently available which reduce the risk of the pests developing resistance. Fortunately, colonies that die from diseases and mite parasites can be replaced with nursery stock, but overall, the number of bee colonies in the US, and the number of beekeepers, has been drastically reduced over the last 20 years.
In addition to the stress that diseases and mites place on the immune system of bees, our environment is not as friendly to bees as it was in the past, which also adds to the overall stress on bees. Urban sprawl and agricultural practices have limited the amount of bee “pasture” (flowers such as clover, alfalfa) available to the bees for their food. The use of pesticides on crops to kill pest insects can have the negative side-effect of killing beneficial insects such as bees. Many pesticide applicators choose pesticides with low residual and low toxicity to bees. But new classes of pesticides, such as those that are systemic (move through plant tissue) may contribute to the stress on bees’ immune and detoxification systems because the pesticide may be incorporated into the pollen and nectar. While we know that pesticides can adversely affect bee health, GMO (genetically modified organism) crops have not been shown to directly affect honey bees.
Bee hives in almond orchard.
U of M Bee Lab
Finally, the beekeeping heroes that transport their colonies across the nation to pollinate crops for our nation’s food supply face extreme difficulties in supplying bees that are strong and healthy enough for pollination. Often, a large number of bee colonies are required to pollinate a particular crop. For example, over 1 million bee colonies are required to pollinate almonds in California during late February and March. Moving such large numbers of colonies into a relatively small area places even more stress on bees. In these conditions, the bees may become nutritionally stressed, they may be at increased risk of pesticide exposure, and definitely are at increased risk of disease and mite transmission among colonies.
It is no wonder bees are suffering. But the biggest question is: Is the collapse of honey bee colonies this year due to yet another factor? Is there a new disease afflicting bees? Are the effects of new classes of pesticides contributing to bee deaths? Why are the bees leaving the colony and not returning? What is the so-called Colony Collapse Disorder? Scientists across the nation are trying to figure this out. At this point, it is unclear why so many bee colonies are dying, and the name Colony Collapse Disorder is a placeholder until its nature can be determined for certain. Most likely, the bees are dying from a number of contributing factors that collectively place an enormous burden on the immune and detoxification systems of bees, eventually putting them “over the edge.”
What can you do?
To help protect honey bees, gardeners can eliminate or reduce pesticide use. If using pesticides, select one with low toxicity to bees (such as insecticidal soap) when possible. Also, time pesticide applications carefully to avoid daily bee activity.
What else can a gardener do? Become a beekeeper! Gardeners who also keep a colony or two of bees will gain a deeper understanding and appreciation of honey bees and all bee pollinators. As a beekeeper, you become aware of what is blooming both in your garden and within a 3 mile radius of your bees as that is their foraging range. You can observe the bees collecting their first pollen of the season in April from willow and maple trees, before any other flowers are in bloom in Minnesota. You will appreciate the dandelions, wild mustards, clover, and other weedy plants that grow on roadsides because they supply pollen for the bees and lots of nectar for the bees to convert to honey. You will both watch and listen to the black locust and basswood trees as they blossom and are covered with bees collecting nectar. In late summer, you will appreciate the asters, sunflowers, and even ragweed as these flowers produce an important source of pollen and nectar for the bees to help them survive the long winter months. You will learn about the fascinating and complex social behaviors of bees, and you will even learn not to be bothered by a few stings here and there.
Beekeeping is not easy but it is highly rewarding. It is an art and science and requires learning effective management techniques and ways to keep bees healthy. Our apiculture research and extension program at the University of Minnesota focuses on keeping bees healthy. We teach several classes to the public, including keeping bees in northern climates, and raising and breeding queen bees. A new on-line course will be available soon that deals exclusively with beekeeping management techniques that can be used to prevent and mitigate disease and mite transmission. The Bee Lab web site has education materials on how to protect bees from pesticides, as well as materials on many general beekeeping practices. Our research efforts concentrate on breeding bees for "hygienic behavior" - a mechanism of resistance against bee diseases and parasitic mites. We are also researching ways to bolster the immune system of bees. Please take a few minutes to navigate our web site for more information: www.extension.umn.edu/honeybees/
Editor’s note: Marla and Gary will write about another important pollinator, the bumblebee, in a future issue of the Yard and Garden News. A newly published manual on rearing local bumblebees is available on the Bee Lab web site.
Understanding the terminology
When the determination is made that an herbicide is needed to control a population of weeds, it is always best to get the weeds properly identified so that appropriate products can be chosen that will be effective at controlling the weeds and be safe for surrounding vegetation.
In the process of identification, one will usually learn something about how they grow and how they could spread from one area to another. That information along with knowing the name of the plant is an important first step in choosing the correct control product.
For lawn weed control applications, there are 2 major categories of herbicides: preemergence and postemergence. Preemergence products are directed at controlling the germinating weed seed before it emerges from the ground. These products are applied as either a liquid or granular product and usually require a small amount of watering-in (1/4 to 1/2 inch water) following their application to be effective. These products set up a “barrier” at the soil surface that kills the weed seedling as it contacts this barrier but before emergence. See Figure 1. It is important to remember that these materials do not kill seeds that do not germinate. The seed must begin to grow and contact the material before it is killed.
Postemergence products are directed at controlling those weeds fully emerged from the ground and are easily visible. This group of materials is further divided into two other categories: selective and non-selective. Selective materials are able to selectively remove certain weeds while not harming others in the same area. Examples include the ability to remove broadleaf plants (e.g., dandelions, white clover) from lawn grasses, or remove grass plants from broadleaf plants such as shrub borders or flowering perennial beds. Another form of selective control would be the use of preemergence herbicides to selectively remove annual weedy grasses (e.g., crabgrass) from existing lawns. Non-selective materials are used to destroy all of the vegetation in an area. Examples of non-selective control include killing off all of the weeds from an area prior to seeding or sodding or, doing the same strategy but where a new perennial bed or shrub border is to be located.
Preemergence Herbicides
One of the most common uses of preemergence herbicides is for control of warm season annual grasses, such as crabgrass, in lawns. In recent years, most of the herbicides used for this purpose came from a family of herbicides with similar chemical structures but varying levels of longevity and effectiveness. Some of the commonly available homeowner products included in this family are balan, trifluralin, pendimethalin and prodiamine. This family of preemergence herbicides has enjoyed many years of successful crabgrass control in home lawns. However, they must be applied prior to any emergence of crabgrass seedlings. Once crabgrass seedlings poke through the soil these products are ineffective in killing the emerged seedlings. Hence these materials have a very narrow window of effectiveness. If you miss that window of application time, you will have missed any chance at control.
Balan and trifluralin are combined together under the trade name of Team. This trade name is often listed on the product label. Trifluralin is packaged by itself under the Preen label, but it is not for use on lawns.
Several years ago, the product dithiopyr was introduced as a preemergence material that also had some very early postemergence effect as well. That is, even if the crabgrass seedling had emerged from the soil but only had 1 to 2 leaves, dithiopyr (Trade name: Dimension; also sold under the Preen label as a crabgrass preventer) would still be able to destroy the seedlings. While this gives a little bigger window of control, it too must be applied before the seedlings get much beyond the 1 or 2 true leaf stage. For homeowners, dithiopyr is usually packaged with granular lawn fertilizers and sold as “weed and feed” products.
None of the above mentioned products can be used at the time of seeding a new lawn or overseeding an existing lawn. The problem is that they do not discriminate between the seeds of weedy grasses or the seed of desirable lawn grasses. These products will kill either one equally well. However, there is a product that will control crabgrass and other weedy summer annual grasses but will not affect seeds of our bluegrasses, fine fescues or perennial ryegrass. The product’s chemical name is know as siduron and is sold under the trade name of Tupersan. This is the only preemergence that homeowners can access and safely use at the time of seeding our cool season lawn grasses. Thus, if you need to do some seeding during the mid-May through mid-July period, using siduron will help provide some short term control of the annual weedy grasses while not interfering with lawn grass establishment.
Another newcomer to the preemergence scene is that of a natural organic known as corn gluten meal (CGM). This is a by-product of the corn processing industry and is used as a feedstock for some animals. However, in the early nineties, Dr. Nick Christians and his staff at Iowa State University discovered this material also had some weed control properties. This material destroys the seedling root system shortly after it emerges from the seed. Hence, once the root system is damaged the plant cannot continue to grow and consequently dies. This material is available under several different trade names and is becoming more readily available for homeowner use. In addition, this product acts much like a traditional “weed and feed” material as it contains 10% nitrogen, all in an organic form, in addition to its virtues as a preemergence material. Its one downside is that control can be quite variable, especially the first year it is used. Therefore, it’s important to have a little patience with this product as control usually continues to improve each year that it is used.
Regardless of which product is chosen, it is important to always read the label directions for proper use and application information. The label is considered to be federal law and hence any use other than that described on the label is a violation of that federal law. It should also be remembered that weeds are present because there is not any grass growing in that spot. Thus, the first step in any weed management program is to provide the necessary inputs and cultural practices to ensure a healthy, vigorous lawn. That is your best first defense against weed invasion into your lawn.
The information provided in this publication is for educational purposes only. References to commercial products or trade names do not imply endorsement by the University of Minnesota Extension nor is criticism or bias implied of those products not mentioned.
Starry white flowers are followed by white to pale blue fruit.
Garden Glow has luminous chartreuse foliage.
Red stem color adds winter interest. All three photos: Dave Hansen
Garden Glow™ dogwood is a luminous result of the U of M’s woody plant research efforts. Since its selection in 1988, Garden Glow™ has been extensively evaluated under a range of growing conditions. It is adaptable to a range of soil conditions and is very cold hardy. In controlled laboratory freezer tests, Garden Glow™ withstood –47°F without injury in midwinter. Today, northern gardeners can trust Garden Glow™ will be winter hardy, insect and disease resistant, and display delightful ornamental qualities.
Garden Glow™ dogwood grows slower than most red-osier (Cornus sericea) cultivars. It is similar to Tatarian dogwood (C. alba) but smaller in size. Mature shrubs are typically 5-6 feet tall and wide but can be maintained at a smaller size by cutting plants back in early spring. The multi-stemmed, irregularly rounded form provides a natural and somewhat informal appearance. Smaller size and pleasing shape make Garden Glow™ very manageable and attractive for residential landscapes.
Lush, chartreuse to golden yellow-green foliage covers the plant in spring and summer. While most plants with brightly colored or variegated foliage require full sun for optimal performance, Garden Glow™ dogwood is ideally suited for low-light situations and will add brightness and a luminous glow to shade gardens. Garden Glow™ is not recommended for full or afternoon sun because the golden leaves tend to burn or bleach under high light conditions. This dogwood will tolerate heavy shade, but foliage color turns a darker green. Dappled, light shade, or full morning sun followed by afternoon shade, will produce the brightest, glowing, yellow-green colored foliage.
In addition to its attractive summer foliage, Garden Glow™ bears white summer flowers which are followed by white to pale blue berries. In mild, extended falls, leaves turn an attractive rosy red to burgundy color. Red stems and twigs add eye appealing color to the landscape throughout the winter.
Contact your favorite nursery, grower, or garden center and ask for Garden Glow™ Dogwood.
To learn more about the U of M’s expertise and wide range of cold hardy varieties, including Cardinal and Isanti dogwoods, please visit www.maes.umn.edu/MNHardy/.
Spring has no sooner been welcomed back into our yards and gardens when the many kinds of insects and related creatures that live in those sites have started to become active. One in particular, the house centipede, not only is abundant outdoors but actually seems to like living in our homes. I don’t believe I have lived in a house where house centipedes were not common.
House centipede (Scutigera coleoptrata). Jeff Hahn
Related to insects, centipedes belong to the class Chilopoda. While centipedes have mandibles and antennae like insects, they do not have three distinct body regions (like insects) and they have 15 or more pairs of legs, one pair per body segment (unlike the six legs insects have). Centipedes are generally flattened and are often found in protected places on the ground, such as under leaves, loose bark, and logs. Centipedes use poison jaws to prey on insects and other invertebrate animals.
A house centipede, Scutigera coleoptrata, is yellowish brown with three dark stripes running down its back and dark and light colored bands on its legs. It is usually between one to two inches long and with long slender legs that make it appear even larger. And they are fast. Even the stoutest amongst us have jumped just a little when a house centipede has scurried past.
While house centipedes’ natural habitat is outdoors under objects, they are perfectly content to enter homes, taking advantage of any small crack or crevice around doors, windows, or other areas at ground level to do so. They are often found in damp areas indoors and are particularly common in basements. However, they can range away from these sites when looking for food and can be found in any room of a home. It is not unusual to find house centipedes in sinks, basins, or tubs. Despite the appearance, they do not come up drains. Instead, they have fallen in while they were seeking moisture and were unable to climb back up on the slippery surface.
Fortunately, house centipedes do not damage our property or eat our food. They rarely bite and are considered harmless to people. Although they are beneficial, because of the insects they eat, many people consider them nuisances while some are even frightened of them.
Ignore house centipedes if you only find one here and there. If you prefer, you could also kill them with a broom or rolled up newspaper. You can also put out sticky traps (like a Roach Motel®). There isn’t anything in the trap that attracts the house centipede to it but it relies on chance that as house centipedes move around they eventually will blunder into one. Place traps in areas where you see them most commonly.
If you find large numbers of house centipedes, inspect the outside of your home and seal any obvious cracks or spaces you find around doors, ground-level windows, and the foundation to help keep house centipedes out. Also remove leaves, brush piles, firewood piles and other sources of cover that are close up to the house to reduce potential hiding places.
Indoors, dry out damp areas with a fan or a dehumidifier. You should also remove boxes, bags, and other items when possible in order to minimize clutter and reduce the number of potential hiding places. If another insect is abundant, that insect may act as a food source for house centipedes. Controlling those insects helps reduce house centipede numbers.
You can supplement these measures with an insecticide application. A ready‑to‑use spray labeled for indoor insects should be effective against house centipedes. Treat areas where centipedes are common, especially behind baseboards and other cracks and crevices where centipedes may hide. However do not attempt spray the entire home for house centipedes.
The word organic is seen all over grocery stores, in garden centers and in advertisements. But what does “organic” really mean? Many people assume that organic means that no chemicals have ever been applied to these fruits, vegetables and plants. This is not necessarily true. Certain pesticides are allowed to be used when producing organic crops but there are restrictions as to which pesticides can be used and in what situations they can be used.
More information about the NOP can be found at http://www.ams.usda.gov/NOP/indexNet.htm
To start out, it is important to know that “organic” has been officially defined by the USDA (US Department of Agriculture) in the National Organic Program Rule (NOP). This definition applies primarily to producers and distributors of organic products. If a grower plans to label his produce “organic” it must be grown according to the NOP rules and be certified by an outside agency. Many organic gardeners choose to follow some or all of the NOP rule in their gardening practices, even though they will never be inspected by a certifying agent.
The NOP states that “preventative, cultural, mechanical, and physical methods must be the first choice for pest control”. This includes practices like planting resistant cultivars, picking off insect pests by hand, pruning out diseased branches, and killing weeds with a garden hoe. These are all solid pest control practices, which many gardeners use even if they don’t call themselves organic.
These labels are used on products acceptable in Organic production. Not all companies choose to use these labels.
The NOP does recognize that in some situations, cultural control is not enough to control the pest. In those situations, organic producers are allowed to use pesticides with an active ingredient that is natural or on the national list. These pesticides must also have inert ingredients (everything in the bottle besides the active ingredient) that are of minimal concern to public health and the environment. Although the majority of landscape pest problems can be managed without chemical control, in the few situations that do require more than cultural control practices, gardeners could use pesticides listed by the NOP and still consider their gardens “organic”. Below are listed a few organic pest control products commonly available to home gardeners. For more information visit http://www.omri.org/.
Organic Products for Disease Control
Examples of organic pesticides. Michelle Grabowski
Organic Products for Insect Control
Organic Products for Weed Control
Please read Salad Dressing or Weed Control? An Organic Non Selective Weed Control Product Evaluation by Bob Mugaas in the March 2006 edition of the Yard & Garden News.
Organic Products and Safety
Many people also assume that if a pesticide is accepted in organic production it is safe. This is not true. Some organic pesticides have very low impact on the environment and human health (e.g. potassium bicarbonate); other organic pesticides can be toxic to people and/or certain ecosystems (e.g. copper and rotenone). In addition every garden will have unique concerns. If it is in sandy soil or near open water, water quality might be an issue. If children and pets play in the garden, health concerns might be the most important factor. The best way to determine the safety of a pesticide, regardless of if it is organic or conventional, is to read a report from Extoxnet (http://extoxnet.orst.edu) or NPIC (http://npic.orst.edu/). These web pages report information about health and environmental impact of common pesticides and have useful information about general pesticide use and safety. They are run by major universities and the Environmental Protection Agency.
Whenever using any pesticide product, read the label completely and follow all of the instructions listed there. The label will tell you how to use the product effectively, safely and legally.
The information provided in this publication is for educational purposes only. References to commercial products or trade names do not imply endorsement by the University of Minnesota Extension nor is criticism or bias implied of those products not mentioned.
Carl Linnaeus: The Father of Modern Taxonomy
Carl Linnaeus. The Swedish Museum of Natural History
Born on May 23, 1707, in the Swedish province of Småland, Linnaeus is known as the “father of modern taxonomy” and the creator of our current binomial system for plants and animals. Though originally destined for the clergy like his father, Linnaeus’ parents redirected their son toward medicine under the advice of one of his teachers. Linnaeus entered the University of Uppsala in 1728. The university was established in the late 1500s and is the oldest and most prestigious university in Sweden. It has produced many great minds in natural science and medicine including Anders Celsius, who invented the Celsius measurement, and Linnaeus’ professor and mentor, Olof Rudbeck, for whom Linnaeus later named the plant genus Rudbeckia.
At the time, botany was part of a physician’s training since doctors were expected to produce medicines from plants. Over the years, Linnaeus made visits to areas throughout Europe including the then unknown region of Lappland. In a trip there in1732 Linnaeus made extensive observations about the flora and fauna of Lappland as well as the culture of the people. Campanula serpyllifolia (named by Caspar Bauhin in 1596) was described by Linnaeus as a “lowly, insignificant” plant. He renamed it Linnaea borealis after himself in a sort of self-mocking tribute.
Linnaeus wrote numerous books including the first edition of his most famous and now multi-volume Systema Naturae, the first book to consistently use the binomial classification system for animals and minerals. While in Holland he also published Bibliotheca Botanica and Fundamenta Botanica in which he reduced all of botany down to 365 Latin principles expressed in a few words or phrases (aphorisms).
He was awarded a professor’s position in 1741 at Uppsala University and took over teaching of natural science and botany. He also continued restoring the botanical garden at the University and arranging plants according to his controversial system of classification based on the plants’ reproductive structures. It was in this garden that Linnaeus gave demonstrations and lectured about the various plants, drawing many faculty and students to hear him speak. A small group of students – Linnaeus’ “disciples” - made botanical explorations to Japan, America, Australia, Asia, and the South Pacific, bringing back plant specimens for classification and study. Between teaching, lecturing and researching, Linnaeus continued expanding Systema Naturae to a multi-volume work, modifying his concepts as he studied collected specimens. In 1753 he published Species Plantarum, a work that standardized his binomial system of classification for plant names in the scientific community.
Throughout his life, Linnaeus held several esteemed appointments including physician to the royal family and secretary of the Royal Swedish Society of Sciences. He was also one of the founders of the Swedish Academy of Sciences in Stockholm. Linnaeus was dubbed to knighthood in 1753. In 1761 he was granted nobility and changed his name to Carl von Linné. His son, Carl, succeeded his father as a full professor of botany at Uppsala University after his father’s death in 1778.
The Linnaeus Garden at Uppsala University
The Botanical Garden at Uppsala University today. Uppsala University
The original botanical garden at Uppsala University, also called the Linnaeus Garden, is the oldest botanical garden in Sweden. It was first designed and planted by Olof Rudbeck in 1653. Located near the river Fyrisån, the area was swampy in Linnaeus’ days and not well-suited to a garden. By 1700, it held more than 1,800 species, many being grown in Sweden for the first time. In 1702, an intense fire killed many of the plants and the garden went into disarray for 40 years. Appointed by Rudbeck, Linnaeus took on responsibility for the garden when he was appointed a professor in 1741. He expanded the garden area and had a large orangery designed and built by architect, Carl Hårlemann.
In 1807, King Gustaf III donated the nearby Uppsala Castle to the University as the basis for a new botanical garden, today’s Uppsala Botanic Garden. All the plants and animals from the original garden were moved to the castle grounds and re-installed and the new garden was dedicated on May 21, 1807. Thanks to Linnaeus’ accurate records, lists and maps, the original garden at the University was successfully restored in 1917 by the Swedish Linnaeus Society. The Society took over care of the garden, and it is once again a place of learning for horticulture enthusiasts.
Eastern tent caterpillars cause webbing in branch forks. Jeff Hahn
Webbing in the forks of branches, especially of fruit trees, is due to eastern tent caterpillars. Despite the appearance, they normally do not injure healthy, vigorously growing trees. If you wish, you can spray the leaves with BT (Bacillus thuringiensis) which will kill the caterpillars when they eat the foliage. BT does not affect most beneficial insects, including bees. You can also wait until evening and pull out the webbing, along with the caterpillars. Destroy the webbing and caterpillars.
Protect your onions and cabbage and related plants from root maggots, especially if you have had problems with them in the past, by erecting a floating row cover or similar barrier over your crops. This barrier should reach the ground and should allow sunlight and rain in. Set up a floating row cover in your garden by the time adults flies are laying eggs which is usually early to mid-May. Keep the barrier in place until the end of the month when the flies are finished laying eggs. There are no insecticides available to home gardens for treating root maggots.
Blue Heaven™ little bluestem. University of Minnesota
Cut back warm-season ornamental grasses like miscanthus, little bluestem, switchgrass, and Indian grass before they start to grow. These grasses typically start growth in late May or early June. Tie the previous years growth in a bundle, then cut it all off at the base. You can then remove it in one neat bunch. You can cut back close to the ground, since the growing point is deep in the plant at the root/shoot junction.
Cool-season grasses like featherreed grass, tufted hairgrass, fescue and blue oatgrass start to grow in April so they will already be showing new green leaves. You can still comb or rake out the old foliage and cut back around the new growth.
Sedges need the least spring cutback. Many of these are small and their foliage melts away, similar to hosta. All of these ornamental grass and sedge clippings can go into your compost pile.
Finish cutting back other herbaceous perennials, being careful not to cut off any new growth.
Seed cool-season vegetables when garden soil is workable. Cool-season vegetables include radish, lettuce, spinach, other salad greens, peas, and carrots. Hardened-off transplants of broccoli, cabbage, and Brussels sprouts can be planted several weeks before the last-frost date in your area.
Wait until night temperatures are consistently in the 50s or higher before transplanting warm-season vegetables like tomatoes, peppers, and eggplants.
Cold-tolerant annual flowers such as sweet peas, calendula, bachelors’ buttons, corn poppy, larkspur, forget-me-not, and California poppy can be seeded directly outdoors now.
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Deb Brown will answer gardening questions as a recurring guest on the Midmorning show on MPR. 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.
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Happy gardening!Nancy Rose
Editor
Regional Extension Educator - Horticulture
Home « Gardening News « May 1, 2007