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A distinctive nose-shaped burl. Michelle Grabowski
Burls are odd lumps, bumps, and bulges that develop on tree trunks. Some take on distinctive shapes, like “The Nose”, pictured here. Their exact cause is something of a mystery. Some suggest that burls form in response to insect damage or a disease pathogen, but no specific pest or pathogen has been proven to be the cause. Some burls seem to develop from a proliferation of bud tissue that keeps multiplying instead of developing shoots. Redwood burls are a bit different - they act as a source of stem tissue that can produce new shoots if the main trunk is cut or damaged.
Burls continue to grow as the tree grows. While burls do not kill trees directly it does seem that they can reduce a tree’s vigor. This can make the tree more susceptible to insects and diseases and ultimately reduce the tree’s lifespan.
The unusual swirling grain pattern found in burls makes them prized by woodworkers. Entire burls can be carved into bowls or art objects, and thin veneers of highly patterned burl wood is used on musical instruments such as guitars.
Nancy Rose
The oak burl coffee table (near window) and other Nakashima furniture in the AHL. Nancy Rose
George Nakashima, a famous American woodworker, is known for his craftsmanship and reverence for wood. Did you know that the Andersen Horticultural Library at the University of Minnesota Landscape Arboretum houses furniture designed and built by this famous craftsman? In the early 1970s former Governor Elmer L. Andersen and his wife Eleanor commissioned Nakashima to built furniture for the library they had endowed. Mrs. Andersen first encountered Nakashima furniture at the Smithsonian's Renwick Gallery which had an exhibit featuring American woodworking. Hearing how pleased the libraries at Princeton University and the city of Seattle were with their Nakashima furniture, they commissioned him to design and build tables, chairs, a desk, bookcase ends, and display cases for the Arboretum library.
Black walnut bookcase ends show trunk edges. Nancy Rose
The Soul of a Tree
Nakashima furniture is massive, rich in grain with wild knots and the remnants of the bark and cambium layer still visible. Unlike other furniture, the wood is chosen for its unique qualities. A piece with even grain and uniformity was not as interesting to Nakashima because it reveals nothing about its previous life. He considered the “personality” and history of each plank of wood to determine what type of furniture it was best suited for.
The Andersen Library’s tables are made from American black walnut (Juglans nigra) and are large book-matched pieces that reveal the history of the tree’s growth. Beautiful butterfly inlays reinforce the wood. Our chairs are hickory (Carya spp.) and the simple yet elegant design is surprisingly comfortable. The coffee table is from the burl of a majestic English oak (Quercus robur). It is a honey-colored map of worm holes and weathering – a testament to its previous life. The library cases, periodical shelves and desk are also black walnut and the storage cases are covered with pandanus cloth. The Andersen Library has a yearly furniture care event called “Miserable Day.” Staff and volunteers clean each piece with a clean, damp cloth. This includes every inch of wood, even underneath each table and chair. Then linseed oil is rubbed on the wood. These unique pieces of furniture are a “must-see” for Arboretum visitors who appreciate the beauty of natural wood.
The Life of George Nakashima
George Nakashima was born in 1905 in Seattle, Washington. His youth was spent hiking in the Pacific Northwest, enjoying the solitude and experiencing a kinship with nature. He studied Forestry at the University of Washington and earned a Master’s degree in Architecture from the Massachusetts Institute of Technology. After graduation he lived in Paris for a time and explored the French countryside on bicycle.
It seemed logical that Nakashima would be drawn to Japan, the home of his ancestors. He visited his grandmother’s ancestral home as well as many relatives in pre-war Japan. At this time he was hired by Antonin Raymond, an architect who had an office in Japan. His job was to design a dormitory in Pondicherry, India for Sri Aurobindo Ashram. (He also designed simple furniture for the rooms.) The silence and meditative atmosphere appealed to him. However, after two years he left and moved back to the United States and married Marion Okajima in 1941. At this time his interest in making furniture grew.
With the bombing of Pearl Harbor, people of Japanese descent were sent off to internment camps. Nakashima, Marion and his newly born daughter, Mira were sent to the desert area of central Idaho. In spite of the bitterness toward his country, Nakashima was fortunate to hone his skills as a woodworker through his friendship with a Japanese carpenter, Gentauro Hikogawa, who taught him how to sharpen a chisel on a traditional Japanese waterstone.
At this time his former employer, Antonin Raymond, invited Nakashima and his family to New Hope, Pennsylvania. They lived in a three sided outbuilding that would eventually be used as a furniture building workshop. In exchange for work, they were offered three acres of land. At one point they lived in a tent while they built a house. The family faced many challenges, yet it was an ideal location for them, with beautiful, undeveloped wooded areas and a population of artists and writers.
As his studio grew, he employed more artisans. Nelson Rockefeller commissioned Nakashima to design and build two hundred pieces for his house in Pocantico Hills, New York. One of his most famous pieces is a massive walnut Altar for Peace which is in the Cathedral of St. John the Divine, in New York City. In 1983 he was honored with the Third Order of the Sacred Treasure award from the emperor and the government of Japan. This was his most prized achievement. He died in 1990 while recovering from a stroke. His daughter Mira, who studied and worked with her father for many years, continues to design and build furniture at the Nakashima studio in New Hope, Pennyslvania.
Andersen Horticultural Library hours and other information:
http://www.arboretum.umn.edu/library/index.htm
Recommended Reading:
George Nakashima, The Soul of a Tree: A Woodworker’s Reflections, 1981, Kodansha International
Selected quote: “Years ago, a parcel of logs were available in London. Ragged but huge, they were laid out in neat rows in a log yard on the edge of the Thames. These were of English walnut and other species – majestic trees, now lying dead and held for commerce. Their future, their karma was in limbo. They could be used creatively or they could be degraded by the forces of the marketplace, ending up at best as paper-thin wood sheets decorating the dashboards of fine automobiles.”
Figure 1. Two of three littleleaf lindens dying due to severe stem compression from SGRs. Gary Johnson
Stem girdling roots (SGRs) are roots that grow in contact with tree (or sometimes, shrub) stems. Eventually they enlarge to the point where stem conductive tissues (xylem and phloem) become so compressed that sap and water flow is retarded to some degree (moderate to severe). For this reason, SGRs are considered to be primary predisposing agents, much like long-term drought, extremes in soil pH levels, or chronically water-logged soils. Figure 1 shows two out of three littleleaf lindens that are dying or almost dead due to severe stem compression from SGRs.
SGRs also affect the physical condition of a tree by creating a stem weakness that worsens each year. As the SGRs enlarge in diameter, stems may grow up and to a degree over them, creating a depression in the stem. As the tree continues to grow, this depression becomes more pronounced and eventually the diameter of the stem at the depression may only be a fraction of the diameter above the point of compression.
To envision this weak link, imagine blowing up a long, skinny, party balloon. Now squeeze the middle of the balloon with your hand. Note how the diameter above (and below) is significantly larger than the area that is being squeezed, a.k.a., girdled. When storm winds blow, this compressed point is literally “the weakest link in the chain,” and is the point where many trees break off under the loading pressure of wind storms.
SGRs as Predisposing Agents
“Tree decline” is a fairly common piece of jargon that tree health specialists throw around. What exactly does it mean? When trees are chronically stressed (long-term drought, repeated defoliation), their normal reserves of chemical energy (primarily starches or fats) are slowly depleted. Each year as the trees come out of dormancy, they emerge in a weakened state due to this energy depletion and find it difficult to re-leaf, grow, and deal with the harsh realities of urban landscapes on a normal basis. It takes a tremendous amount of chemical energy just to push out new leaves and shoots, recover from accidental wounds on the stems, or produce flowers and fruit.
As the energy reserves continue to decline and indirectly affect the ability to capture and store new energy (photosynthesis), the entire system is affected and begins the “decline spiral” to premature death. So decline actually refers to the ability to deal with life’s normal stresses. A tree in decline may suddenly die from an unusual winter (lack of snow fall), a short-term summer drought, or a defoliation from insects or hail. The other plants in the landscape tolerate the damage and survive, but the predisposed trees – those in decline – are unable to recover from the damage.
SGRs impede normal water movement and sap flow, indirectly affecting energy reserves by directly and indirectly affecting photosynthesis. Some of the first symptoms of SGRs impacting tree health include leaf scorch or leaf wilting…when no other plants in the area are showing the same symptoms. There may be adequate moisture in the soil, but the tree’s ability to move water throughout the system is thwarted by the area(s) of compression. Soon, this water stress evolves into early leaf drop in the autumn, late leaf-out in the spring, and much earlier leaf coloration…in the summer!
More is Not Better
Early SGR studies conducted by the University of Minnesota were in response to unexplained tree decline in urban areas. From 1994 through 1996, 220 declining and dying trees were diagnosed. In 80.2 percent of the cases, stem girdling roots were the only causal agents isolated from the “patients.” More specifically, these trees had been planted in the previous 12 to 20 years and had significant stem compression (greater than 50 percent of the stem circumference) from SGRs. In all cases, these SGRs were well below ground (range of 4 to14 inches)…out of sight, out of mind (Figure 3).
In subsequent studies of the effects of soil depth over first main order roots, and surveys conducted by the University of Minnesota, it has been demonstrated that the deeper tree stems are in the soil or mulch, the more likely they are to have multiple “layers” of SGRs. In a nutshell, the more soil or pre-soil (organic mulches) that are piled over the root systems and burying the stems, the more likely the tree will decline or fail due to multiple conflicts with SGRs.
SGRs as Car-Crushers
Quite honestly, there weren’t many sympathetic ears when the news was released that SGRs shortened the lives of landscape trees 12 to 20 years after planting. For some reason, many people still feel that 30 years is a normal lifespan for trees. To put that in perspective with reality, the normal life for a boxelder is around 100 years. For a jack pine, around 80 years.
It wasn’t until the Tree Failure in Wind Storms research was conducted that a broader picture of SGRs effects on landscape trees was exposed. From 1995 through 2005, over 1,500 “tree autopsies” were conducted on trees that had failed during wind-loading events in Minnesota. These trees were not those from the centers of severe wind-loading events such as straight-line winds or tornados. Rather, they were victims of thunderstorms or those at the edges of severe wind events.
From that data, the destruction and economic losses from premature tree failures due to SGRs were determined, and it was startling. The most common tree size category for boulevard tree failures was the 6 to 10 inch d.b.h. range (stem diameter measured 4.5 feet above ground). Of those trees, 50 percent snapped off at compression points from SGRs, at a depth of 4 or more inches below ground! The Achilles’ heel was a compression root that couldn’t even be seen because the stem was buried so deeply. Further, littleleaf lindens (Tilia cordata) were grossly affected by SGRs. Tilia cordata ranked as the third most common species for total failure during those years (the tree went down completely) and 73% of those Tilia cordata snapped off at below-ground SGRs.
How Often do Trees Die from SGRs?
Good question and most likely unanswerable. Most often when trees die or suddenly fail during a wind storm, diagnosing the problem below ground isn’t even considered. The trees are hastily removed and replaced. Weather is often blamed for the death or, in the case of storms, discounted as an “act of god.”
What is known is that many landscape trees live very short lives. J. Kielbaso from Michigan State University published a very controversial research study in the late 1980s. From his surveys of several U.S. cities, it was determined that the average lifespan of a tree in an urban landscape ranged from 7 to 35 years, depending on whether it was in a sidewalk pit in a downtown area, or a desirable landscape in a suburb.
In randomized landscape surveys conducted by the University of Minnesota Department of Forest Resources (1997 – 2004), five species of trees were investigated in three different communities. All trees were growing in public spaces: boulevards, schools, government centers, parks. Species surveyed included hackberry, littleleaf linden, sugar maple, honeylocust, and green ash. The trees were randomly selected and then evaluated for health and condition, and then examined for depth of soil over the main order roots and the presence of stem encircling or girdling roots. The results were a bit depressing.
Most sugar maples were buried too deep (over 90 percent). The species that had the highest percentage of trees planted at the correct depth (roots within one inch of the soil surface) was hackberry. Of the 100 hackberries surveyed, 45 percent were planted at the right depth! That was the best! And as expected, the results from all plants showed that the deeper the stems were buried the more frequently they were impacted by stem encircling and stem girdling roots.
What to do, what to do?
Figure 7: As the piled mulch turns to soil, this is an SGR-affected tree in waiting. Gary Johnson
Figure 9: Give up and start over. Tim Teynor
1. Don’t plant trees that are already buried too deep. Assume that trees in containers are buried 4 to 6 inches too deep, and you’ll need to remove that extra soil and root mass before planting. Figures 5 and 6 demonstrate a quick method for correcting deeply buried containerized trees.
Figure 8: Now that the dysfunctional root system is exposed, stem encircling and stem girdling roots can be removed with a pruning saw and the excess soil removed far away from the stem. Gary Johnson
2. Plant trees, don’t bury them. If stems aren’t buried, it’s not likely that SGRs will become a problem. They can still occur with correctly planted trees, but much less frequently than buried trees.
3. Don’t pile mulch against stems. Organic mulch is basically pre-soil. It will result in a buried stem and a wonderful environment for SGRs to develop.
4. When suspicious, investigate. Root collar exams are not all that difficult to perform. If you have a trowel and a wet-dry vacuum, you can perform a non-destructive root collar exam. If you find offending roots during the exam, remove them. Also, remove all that extra soil. If you do nothing, it will only get worse.
5. If the tree’s stem is severely impacted, greater than 50% of the stem’s circumference is compressed, it’s probably best and safest to remove the tree and start over.
For more information see:
Stem Girdling Roots: The Underground Epidemic Killing Our Trees http://fr.cfans.umn.edu/extension/urban_com/sgr%20book
%20sm%20file.pdf
Stumps of common buckthorn show yellowish wood color. Nancy Rose
As a wood carver, I am often asked what my favorite wood is. Gardening audiences often do a doubletake when they hear my response: My favorite wood for carving kitchen spoons, salad tongs, and cribbage boards is, without question, buckthorn (Rhamnus cathartica).
Many gardeners think of buckthorn only as spindly, fast-growing saplings with vigorous root systems that sprout from seed all over the garden and particularly under other trees where birds excrete the seeds from black buckthorn berries. If not removed, though, these invasive saplings can grow to tree size. The wood I covet comes from buckthorn trunks or branches at least 3 inches in diameter. I have worked with some buckthorn that measured nearly 1 foot in diameter, as has fellow woodworker Wayne Keifer of Shakopee. He has carved bowls from these large buckthorn trunks. (See some of Wayne’s bowls on display at the University of Minnesota Landscape Arboretum gift shop.)
In addition to buckthorn, I have carved ironwood, American elm, butternut, black walnut, white ash, bur oak, red oak, honeysuckle, lilac, cherry, plum, pagoda dogwood, and Russian olive.
Go with the Grain
“Basic wood-grain types include:
Hardwood or Softwood?
Buckthorn not only has attractive color and grain but it’s also an extremely hard wood, which I value for the kinds of crafts I work on. In my experience, the only Minnesota wood that is harder than buckthorn is ironwood (Ostrya virginiana), also known as hop hornbeam. Earlier this summer, I helped a friend clear buckthorn from his lakefront property in Meeker County and he rewarded me with a half dozen ironwood logs that will keep me busy for most of this winter. Growth rings reveal that these 8-inch diameter ironwood logs were from trees more than 75 years old. The ironwood trees we cut down were dead and had continued standing upright in the shady woodlot. One reason ironwood is such a hard wood is that it prefers to grow in deep shade, which means that it grows extremely slowly, so growth rings are barely perceptible from one year to the next.
The use of the terms “hardwood” and “softwood” can be confusing to people who don’t spend time working with wood. I grew up on a Carver County farm and my father grew up working in the woodlot, harvesting wood to heat his early 20th-century home. Dad knew wood in a practical sort of way and, consequently, I knew that when Dad said “hardwood,” he was generally referring to oak, ash, sugar maple, or ironwood. When he said “softwood”, he meant poplar, cottonwood, silver maple, or pine. His definition worked for me, but it wasn’t technically accurate.
This explanation is from the Extension publication “The Preservation of Wood”
http://www.extension.umn.edu/distribution/naturalresources/components/6413ch1.html
“The terms softwood and hardwood do not refer to the hardness or density of the wood. Softwoods are not always soft, nor are hardwoods always hard. Mountain-grown Douglas fir, for example, produces an extremely hard wood although it is classified as a "softwood," and balsawood, so useful in making toy models, is classified a "hardwood" although it is very soft.
In biological terms, softwoods are gymnosperms, which are trees that produce "naked seeds". The most important group of gymnosperms are the conifers. All species of pine, spruce, hemlock, fir, cedar, redwood, and larch are softwoods. Hardwoods are angiosperms, which are trees that produce seeds enclosed in a structure like a fruit or nut. The hardwood category includes the oaks, ashes, elms, maples, birches, beeches, and cottonwoods.
Though there are many more hardwood species than there are softwoods, the softwoods produce a larger share of commercial wood products, particularly those used for structural applications. This is evident by the dominant use of a few softwood species such as the southern yellow pines, other pines, Douglas fir, hemlocks, spruces, and true firs from the west, all of which play crucial roles in construction.”
What is Wood?
The following information is from the Extension publication “The Preservation of Wood”
http://www.extension.umn.edu/distribution/naturalresources/components/6413ch1.html
“Wood may appear to be a very simple material, but its make-up is quite complex. All wood is composed of four chemical components: cellulose, lignin, hemicellulose, and extractives, which combine to form a cellular structure. Variations in the characteristics and volume of the four components and differences in cellular structure result in some woods being hard and heavy and some light and soft, some strong and some weak, some naturally durable and some prone to decay. Four primary reasons account for the great variation in wood and its properties.
For me, woodworking is a winter hobby. From April to early November I derive too much pleasure from being outdoors in the garden to turn on the saw or sand wood surfaces. But now, as the growing season gives way to plummeting temperatures, blowing snow, and reduced daylight, my thoughts return to working with wood. I know that interesting challenges and pleasures await inside the buckthorn and ironwood logs stored in my woodshed and basement, so bring on the snowflakes.
For more information:
Minnesota Woodworkers Guild: www.mnwwg.org/
A list of Minnesota woodcarving clubs can be viewed at: http://www.woodcarvingillustrated.com/clubs_MA_SD.php#MN
Oystershell scale on apple. Jeffrey Hahn
Two apples were submitted from Douglas County at the end of September that were infested with small, 1/8 inch long, brownish or grayish scale insects. This was not easy to identify at first as there aren’t any common scales that attack the fruit of apples in Minnesota. However, after checking with a couple of colleagues, the problem was discovered to be oystershell scale.
This common scale is known to attack a wide variety of hardwood trees, including apple, typically feeding on branches and twigs. It uses piercing-sucking mouthparts to feed on the sap from plants. Small numbers of this insect are not likely to cause much damage, although heavy infestations can discolor and stunt the leaves and weaken and even kill branches.
The literature does describe oystershell scale as occasionally attacking the fruit of apples as well. Although this scale does not seem to damage the fruit too much, its appearance does mar the surface of the apple. When oystershell scale are found on apples at this time of year, there are not many options. You could try to remove scales from individual apples but that could still leave them unappealing to eat. There aren’t any practical options to treat these insects at this time of the year.
Fortunately, this is not a common problem and it is unlikely a home orchardist will have an ongoing issue with oystershell scales. If a gardener is faced with a persistent infestation, the best management is to treat the scale when the immature crawlers hatch and are active which is generally in the spring about late May or early June.
Brown recluse spider. Martin E. Wolfe, MD, Dept. of Emergency Medicine, Mayo Clinic, Rochester, MN
A short article appeared in the October, 2007 Annals of Emergency Medicine detailing a confirmed brown recluse spider bite in southern Minnesota. The article was written by Drs. Torry Laack, Latha Stead, and Martin Wolfe from the Dept. of Emergency Medicine at the Mayo Clinic in Rochester, MN.
A 46-year-old man was working in a warehouse when he felt something crawling under his shirt. This was quickly followed by a sharp pain on his back. He discovered and captured a spider that had gotten under his clothes. Two hours later, he went to the emergency room complaining of a localized pain on his back which was accompanied by a reddened, raised rash. He was treated “conservatively”. A week later, this lesion was unchanged and he was put on a more aggressive treatment (10 days on cephalexin). The wound satisfactorily healed in about three weeks.
Brown recluse spiders are not native to Minnesota and are rarely encountered here. Being bitten by a brown recluse is even more rare. The warehouse where this man works receives shipments from the south central areas of the U.S., where the brown recluse is a native. This explains how the spider made its way into Minnesota. However, even when a brown recluse is inadvertently brought into an area outside of its native range, it virtually never is able to establish itself.
Because the spider was captured and saved it could be verified as a brown recluse. It is critical when diagnosing a lesion as a brown recluse bite, especially when it is outside the south central U.S., that an offending spider is found that was directly associated with the wound and is positively identified as a brown recluse. There are a variety of other causes that have been misdiagnosed as brown recluse bites, including bacterial, viral, fungal, lymphoproliferative, and vascular diseases, reaction to drugs, and arthropod induced diseases, including Lyme disease (for more information, see http://spiders.ucr.edu/necrotic.html).
While it has been demonstrated that it is not impossible for a brown recluse to be transported into Minnesota and bite someone, this is still a very rare occurrence. The vast majority of spiders we see in Minnesota are harmless to people. And even those that are capable of biting people are reluctant to do so. None of our native spiders are considered dangerous to people.
Figure 1: White pine blister rust on Ribes leaf. Michelle Grabowski
Figure 2: White pine blister rust pustules on the lower leaf surface of a Ribes plant. Michelle Grabowski
Figure 3: Thread like teliospores produced on Ribes leaves in response to shorter and cooler days. Michelle Grabowski
As temperatures drop and days get shorter, most Minnesota gardeners are cleaning up perennial beds and raking leaves. This is typically not the time of year that gardeners worry about plant diseases. One important tree disease, however, is stimulated by the moist, cool conditions in late summer and early fall to make its move from one host plant to another. This disease is white pine blister rust, caused by the fungus Cronartium ribicola.
Cronartium ribicola needs two different host plants to complete its life cycle. On currants, gooseberries, and other plants in the genus Ribes this fungus infects leaves. Light yellow leaf spots may be present on the upper leaf surface (Figure 1) and raised orange pustules can be seen on the lower leaf surface (Figure 2). In some cultivars infected leaves fall off the plant. During the warm summer months, these leaf spots produce powdery orange spores that start new leaf spot infections on Ribes species. As day length shortens and temperatures drop, these same leaf spots produce threadlike orange spores on the lower surface of the leaf (Figure 3). If temperatures are below 69°F and moisture is present in the air for 60 hours or more, clear single-celled spores will be released from these leaf spots into the cool night air.
These sensitive little spores are carried on air currants to the fungi’s second host plant, the white pine (Pinus strobus). White pines typically have to be located near the infected Ribes plant in order to become infected. In some situations, however, spores have been known to travel up to a mile to infect a white pine tree.
There must be moisture in the air and on the pine needles for the fungal spores to survive and start an infection. If conditions are right, the fungi will enter the plant through stomates on the needle (natural openings for air exchange). A yellowish red spot or band can be seen on the needle at the infection point, but it is so small that it commonly goes unnoticed. In fact it may be several years before the gardener notices a problem with the pine tree.
Figure 4: Blister rust flag. Jason Smith
Figure 5: Fungal blisters of white pine blister rust pushing through infected bark in spring. Michelle Grabowski
Figure 6: White pine killed by white pine blister rust. Jason Smith
The fungus travels from the infected needle into the twig where it grows between the plant cells in the bark and sapwood. The fungus only grows at a rate of about 3 inches per year through the twig or branch. Eventually the fungus will girdle the branch and the needles of the infected branch will die and turn a rusty red color. These dead branches are commonly called blister rust flags, since they stand out so brightly against the green foliage on the rest of the tree and alert the gardener to the problem (Figure 4). Several years after the initial infection, white to yellowish orange blisters will push through the bark of the infected branch and release powdery orange spores in the springtime (Figure 5). The presence of these fungal blisters is a definitive sign of white pine blister rust.
If this infection is allowed to continue, the fungus will eventually make its way to the main trunk of the tree. When it finally girdles the main trunk, all of the branches above the infection will die. This can be fatal to young trees and severely disfiguring to older trees. (Figure 6)
The good news is that white pine blister rust can be managed through a series of cultural control practices. Resistant varieties of currant and gooseberry are available to gardeners who wish to grow these plants near white pine trees. See the article on ‘New Fruits’ in the June 15th, 2006 newsletter (http://www.extension.umn.edu/
yardandgarden/YGLNews/YGLNews-June1506.html) Since the fungal spores need cool, moist conditions to start an infection, avoid planting white pine trees in areas where cool air and dew tend to collect. This includes small openings in forested areas, locations at the base of a slope, and low-lying areas. Planting new white pine trees underneath the canopy of older trees can reduce the risk of white pine blister rust, since the older trees will shelter the new pine from the evening dew.
In the spring, inspect white pine trees for blister rust flags and fungal blisters emerging from the bark. If infected branches are found, prune them out immediately. The fungus can actually be present in the bark several inches beyond what is visible from the outside of the bark. Pruning cuts should be made at least 4 inches beyond the discolored infected area of the stem to remove this hidden fungus. This will completely eliminate the existing infection, although new infections may come in later. If the infection on the branch is within 4 inches of the main trunk, it is too late to prune out the infection. The fungus will have already reached the main trunk. (Figure 7)
The new 2008 Minnesota Gardening Calender.
2007 is rapidly disappearing. Get ready for the new year with the 2008 Minnesota Gardening calendar. This colorful calendar makes a great gift for gardening friends, relatives, or yourself. Give it as a gift at holiday parties - your host/hostess will appreciate that it requires no watering or refrigeration!
As always each month’s page is loaded with great gardening tips written by Deb Brown, horticulture professor emeritus. Find answers to vital questions like when to fertilize spring bulbs, how to get amaryllis to rebloom, when to aerate and fertilize the lawn, and where to find reliable gardening information online. And the 2008 special feature shows you three terrific new U of M plant introductions for your yard and garden.
Harvest late carrots before the ground freezes. Nancy Rose
Rake excess leaves and mow the lawn one last time if needed.
If you haven't made a final lawn fertilizer application get it done in early November. Be sure to sweep up any fertilizer spilled in streets, sidewalks, or driveways, and thoroughly water in fertilizer if rain doesn't do the job.
Dig remaining root crops like parsnips, fall radishes, and carrots before the ground freezes. Cold-tolerant crops like Brusells sprouts, Chinese cabbage, spinach, and some other greens will tolerate temperatures in the mid to upper 20s, but harvest them when colder temperatures threaten.
Empty and store clay pots - they can break outdoors when freeze/thaw cycles occur. Scour the yard for stray garden tools. Clean and store tools and other garden ware.
Add a winter mulch of straw, hay, or leaves to bulb and perennial beds after the ground starts to freeze. Winter mulch helps moderate soil temperatures and prevent heaving from spring freeze/thaw cycles.
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Happy gardening!Nancy Rose
Editor
Regional Extension Educator - Horticulture