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Archive for November, 2010

Canada’s harsh climate is often responsible for severe damage to landscape plants. Winter sun, wind, and cold temperatures can bleach and desiccate evergreen foliage, damage bark, and injure or kill branches, flowerbuds, and roots. Snow and ice can break branches and topple entire trees. Salt used for deicing streets, sidewalks, and parking lots is harmful to landscape plantings. Winter food shortages force rodents and deer to feed on bark, twigs, flowerbuds, and foliage, injuring and sometimes killing trees and shrubs. All is not bleak, however, as landscape plants can be protected to minimize some of this injury.

Cold Damage

Cold temperatures can damage plants in several ways. Plants that are not hardy in Canada will be killed or injured during the winter unless protected in a microclimate. Plants that normally grow in hardiness zone 3  and hardiness zone 4  may also be injured if winter conditions are abnormally severe or if plants have been stressed by the environment. Injury is more prevalent and more severe when low temperatures occur in early fall or late spring, when there is little or no snow cover during the winter or when low temperatures are of prolonged duration. Pronounced fluctuations in temperature can be extremely detrimental to plants throughout the fall, winter, or spring.

Sun Scald

Sun scald is characterized by elongated, sunken, dried, or cracked areas of dead bark, usually on the south or southwest side of a tree. On cold winter days, the sun can heat up bark to the point where cambial activity is stimulated. When the sun is blocked by a cloud, hill, or building, bark temperature drops rapidly, killing the active tissue.

Young trees, newly planted trees, and thin-barked trees (cherry, crabapple, honey locust, linden, maple, mountain ash, plum) are most susceptible to sun scald. Trees that have been pruned to raise the lower branches, or transplanted from a shady to a sunny location are also sensitive because the lower trunk is no longer shaded. Older trees are less subject to sun scald because the thicker bark can insulate dormant tissue from the sun’s heat ensuring the tissue will remain dormant and cold hardy.

Sun scald can be prevented by wrapping the trunk with a commercial tree wrap, plastic tree guards, or any other light-colored material. The wrap will reflect the sun and keep the bark at a more constant temperature. Put the wrap on in the fall and remove it in the spring after the last frost. Newly planted trees should be wrapped for at least two winters and thin-barked species up to five winters or more.

To repair sun scald damage, cut the dead bark back to live tissue with a sharp knife, following the general shape of the wound, rounding off any sharp corners to facilitate healing (Figure 1). Wrap the trunk in subsequent winters to prevent further damage. Do not use a wound dressing. Spraying the area with a fungicide may help prevent fungal infection of the wound.

sun scald damage image

Figure 1. Repairing sun scald damage.

Winter Discoloration of Evergreens

Browning or bleaching of evergreen foliage during winter occurs for four reasons:

  1. Winter sun and wind cause excessive transpiration (foliage water loss) while the roots are in frozen soil and unable to replace lost water. This results in desiccation and browning of the plant tissue.
  2. Bright sunny days during the winter also cause warming of the tissue above ambient temperature which in turn initiates cellular activity. Then, when the sun is quickly shaded, foliage temperature drops to injurious levels and the foliage is injured or killed.
  3. During bright, cold winter days, chlorophyll in the foliage is destroyed (photo-oxidized) and is not resynthesized when temperatures are below 28° F. This results in a bleaching of the foliage.
  4. Cold temperatures early in the fall before plants have hardened off completely or late spring after new growth has occurred can result in injury or death of this nonacclimated tissue.

Foliar damage normally occurs on the south, southwest, and windward sides of the plant, but in severe cases the whole plant may be affected. Yew, arborvitae, and hemlock are most susceptible, but winter browning can affect all evergreens. New transplants or plants with succulent, late season growth are particularly sensitive.

There are several ways to minimize winter injury to evergreens. The first is proper placement of evergreens in the landscape. Yew, hemlock, and arborvitae should not be planted on south or southwest sides of buildings or in highly exposed (windy, sunny) places. A second way to reduce damage is to prop pine boughs or Christmas tree greens against or over evergreens to protect them from wind and sun and to catch more snow for natural protection.

Winter injury can often be prevented by constructing a barrier of burlap or similar material on the south, southwest, and windward sides of evergreens (Figure 2). If a plant has exhibited injury on all sides, surround it with a barrier, but leave the top open to allow for some air and light penetration.

protecting evergreens image

Figure 2. Protecting evergreens
from winter burn with a burlap screen.

Keeping evergreens properly watered throughout the growing season and into the fall is another way to reduce winter injury. Never stress plants by under- or overwatering. Decrease watering slightly in September to encourage hardening off, then water thoroughly in October until freeze-up. Watering only in late fall does not help reduce injury.

Anti-desiccant and anti-transpirant sprays are often recommended to prevent winter burn. Most studies, however, have shown them to be ineffective.

If an evergreen has suffered winter injury, wait until mid-spring before pruning out injured foliage. Brown foliage is most likely dead and will not green up, but the buds, which are more cold hardy than foliage, will often grow and fill in areas where brown foliage was removed. If the buds have not survived, prune dead branches back to living tissue. Fertilize injured plants in early spring and water them well throughout the season. Provide appropriate protection the following winter.

Dieback

Deciduous trees and shrubs can incur shoot dieback and bud death during the winter. Flower buds are more susceptible to injury than vegetative buds. A good example of this is forsythia, where plant stems and leaf buds are hardy, but flower buds are very susceptible to cold-temperature injury.

Little can be done to protect trees and shrubs from winter dieback. Plants that are marginally hardy should be planted in sheltered locations (microclimates). Plants in a vigorous growing condition late in the fall are most likely to suffer winter dieback, so avoid late summer pruning, fertilizing, and overwatering. Fertilize in the spring on sandy soil or in the fall on heavy soil after the leaves have dropped.

Root Injury

Roots do not become dormant in the winter as quickly as stems, branches and buds, and roots are less hardy than stems. Roots of most trees and shrubs that grow in Canada are killed at temperatures at or below 0 to +10°F. These plants survive because soil temperatures normally are much higher than air temperatures and because soil cools down much more slowly than air temperature.

Many factors influence soil temperature. Moist soil holds more heat than dry soil, so frost penetration will be deeper and soil temperatures colder for sandy or dry (drought) soils. Snow cover and mulch act as insulators and keep soil temperatures higher. With newly planted trees, cracks in the planting hole backfill will allow cold air to penetrate into the root zone, reducing fall root growth or killing newly formed roots.

To encourage fall root growth and to reduce root injury, mulch new trees and shrubs with 6 to 8 inches of wood chips or straw. If the fall has been dry, water heavily before the ground freezes to reduce frost penetration. Check new plantings for cracks in the soil and fill them with soil.

Frost Heaving

Repeated freezing and thawing of soil in fall or spring causes soil to expand and contract, which can damage roots and heave shrubs and new plantings out of the ground. A 4- to 6-inch layer of mulch will prevent heaving by maintaining more constant soil temperatures.

Snow and Ice Damage

Heavy snow and ice storms cause damage by bending and breaking branches. Multiple leader, upright evergreens, such as arborvitae and juniper, and multiple leader or clump trees, such as birch, are most subject to snow and ice damage. Relatively small trees can be wrapped together or the leaders tied with strips of carpet, strong cloth or nylon stockings two-thirds of the way above the weak crotches (Figure 3). These wrappings must be removed in spring to prevent girdling, and to allow free movement of the stem. Proper pruning, to eliminate multiple leaders and weak branch attachments, will reduce snow and ice damage. For trees with large wide-spreading leaders or large multi-stemmed trees, the main branches should be cabled together by a professional arborist.

protecting trees image

Figure 3. Protecting trees from snow or ice damage.

Salt Damage

Salt used for deicing walks and roads in winter can cause or aggravate winter injury and dieback. Salt runoff can injure roots and be absorbed by the plant, ultimately damaging the foliage. Salt spray from passing autos can also cause severe foliar or stem injury.

To prevent salt damage, do not plant trees and shrubs in highly salted areas. Avoid areas where salty runoff collects or where salt spray is prevalent, or use salt-tolerant species in these areas. Burlap barriers (Figure 2) may provide protection to some plants from salt spray.

Animal Damage

Mice, rabbits (rodents), and deer can all cause severe damage to plants in the winter. These animals feed on the tender twigs, bark, and foliage of landscape plants during the winter. They can girdle trees and shrubs and eat shrubs to the ground line. Deer can cause significant injury and breakage by rubbing their antlers on trees during the fall.

Rodents

Trees can be protected from rodent damage by placing a cylinder of ¼-inch mesh hardware cloth around the trunk. The cylinder should extend 2 to 3 inches below the ground line for mice and 18 to 24 inches above the anticipated snow line for rabbit protection (Figure 4). Hardware cloth can be left on year-round, but it must be larger than the trunk to allow for growth. For small trees, plastic tree guards are also effective. You can protect shrub beds from rabbits by fencing the beds with chicken wire; however, check such fenced areas frequently to ensure a rabbit has not gained entrance and is trapped inside.

protecting trees from rodents image

Figure 4. Protecting trees from rodents.

If you have many trees or shrubs to protect, using screens and wraps may be too expensive and time consuming. In such situations, repellents may be the best solution. Remember that a repellent is not a poison; it simply renders plants undesirable through taste or smell.

The most effective repellents for rodents are those containing thiram, a common fungicide. You can either spray or paint repellents on trees and shrubs. Repeat applications are necessary particularly after heavy precipitation.

If these methods are ineffective, commercial baits containing poisoned grain are available. However, baits may be hazardous to humans, pets, and beneficial wildlife. Injury or death can result for animals that eat the bait directly and for animals that consume bait-killed rodents. Shelter or containerize baits so they stay dry and are accessible only to targeted rodents. Beverage cans laid on their sides work well for this purpose. Trapping and shooting, where legal, will also control rodents.

Deer

Deer feed on and damage terminal and side branches of small trees and shrubs. Repellents containing thiram provide some control if feeding pressure is not extremely heavy. Plants can be sprayed or painted with the repellent; however, the most effective procedure is to hang heavy rags near the plants to be protected that have been dipped in concentrated repellant. Repeated plant applications or dipping of rags is necessary. Deer can also be successfully excluded with fencing. To be effective, fences must be high and constructed properly. If deer are starving, there is little that will prevent feeding. Providing a more palatable forage may help, but it may also attract more deer.

Conclusion

Although plant cold hardiness and winter injury are common concerns associated with Canadian winters, appropriate plant selection, selecting the proper site, proper cultural practices, and preventive maintenance will significantly reduce or prevent severe injury or loss of landscape plants.

Even though plants respond differently to winter stress and each winter provides a different set of stressful conditions, plants possess a remarkable ability to withstand extremely severe winter conditions. Canadian winters should not discourage planting of traditional or new plant species.

Learn to take advantage of microclimates to enable interesting or different plants to be grown.

Source


Bert T. Swanson, Professor
Department of Horticultural Science, University of Minnesota

Richard Rideout, City Forester
City of Milwaukee, WI

Reviewed by: Jeffrey H. Gillman, Nursery Management Specialist
Department of Horticultural Science

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Have you ever given a thought to why do men shave? Considering that there is no medical reason behind this daily ritual undertaken by them, the main reason could be that they want to appear presentable, especially in front of women. A close shave adds to the sex appeal of a man. No wonder they spend a considerable amount of time shaving.

Although electric shavers reviews have been quite good, men still prefer the good old blade to shave. However, they are often confused about the kind of razor to use. Let’s compare safety razor vs straight razor on various parameters and try to eliminate this confusion.

Safety vs Straight Razor

Safety Razor vs Straight Razor: Definition
A straight razor, also known as cut throat razor, is a razor with a permanent single blade and a handle. Like in a pocket knife, the blade of a straight razor can be folded inside the handle cavity. Straight razor blades are either made of stainless steel or high carbon steel.

A safety razor as the name suggests is designed in such a way that only the edge of the blade is exposed to the skin of the user, thereby protecting him from any kind of injury. Cartridge razors and disposable razors fall under this category.

Safety vs Straight Razor: Usability
A safety razor is very easy to use. Even a first time user can produce good shaving results with them. On the other hand, using a straight razor for hair removal requires a great deal of practice and patience. Proper method of shaving has to be learned while using a straight razors as it involves a lot of skill, steadiness and training. This might take days or sometimes even months.

Safety Razor vs Straight Razor: Smoothness
Both straight razor shaving and safety razor shaving make your skin equally smooth. However, safety razors might cause hair ingrowth. The multi-blade cartridge pulls out the facial hair from the hair follicles in the skin before actually cutting it. Certain part of the hair can sometimes remain uncut inside the skin and the hair can grow beneath the first layer of the skin, thus causing ingrown hair. The straight razor has a single blade, so no such problem arises while using them. Read more on shaving tips for men.

Safety vs Straight Razor: Utility
In case the facial hair is very long and coarse, using a straight razor for shaving is the only option. A safety razor might not be able to shave a long beard. Read more on how to shave a beard.

Safety Razor vs Straight Razor: Safety
In safety razors, multi blades are used. These safety razor blades can cause skin irritation as the same area of the skin is shaved again and again. Straight Razors are safe once the user has learned how to shave properly. A first time shaver however, should be prepared for some small cuts here and there. Read more on shaving tips for sensitive skin.

Safety vs Straight Razor: Time consumption
Shaving with a safety razor is less time consuming as it is a ready-to-use razor while a straight razor needs to be sharpened with a razor strop before every use. Straight razor sharpening does take a few extra minutes every day.

Safety Razor vs Straight Razor: Environment friendliness
Safety razors are a hazard to the environment. So many cartridges are thrown each year by numerous users which are a sheer waste. Even the plastic packs in which they come, add to the already difficult-to-dispose off plastic waste.

Safety vs Straight Razor: Expense
A straight razor is a one time investment as the blade does not need to be changed and usually lasts for a couple of years. A straight razor with inscriptions might cost a little more but simpler straight razor designs do not cost much. Safety razors, on the other hand are quite expensive as the cartridges have to be changed frequently. The cartridges of safety blades sold are usually overpriced by the manufacturers as the user has already bought the razor and is unlikely to change it in spite of the high cost.

In safety razor vs straight razor debate there is no clear winner. Shaving facial hair by either of these two, has its pros and cons. Buy a safety razor set complete with a safety razor stand and a shaving brush, if it is convenience what you are looking for. However, if you are the “masculine types” who is proud of his steaks and beer, who loves to take risks and derives satisfaction from doing things himself, buy yourself a straight razor set. As Anne Frank once said, “Laziness may appear attractive, but work gives satisfaction.

Source

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By Warren Karlenzig – president of Common Current

Vancouver, Canada’s new mayor Gregor Robinson is making good on his campaign promise to make Vancouver “The Greenest City on the Planet.”

Forget trying to be Canada’s greenest city as Toronto has aspired to be, or North America’s greenest city as Portland, San Francisco and Chicago have vied for. If it succeeds beyond its plans, the Vancouver region will have the makings of the world’s first modern Eco City-State.

Mayor Robertson announced ambitious plans Tuesday at this week’s Resilient Cities conference.

Whatever the outcome, Vancouver will be transformed by the process in reputation and mindshare. This plan should provide the city of 615,000 with an opening to make significant sustainability improvements to its economic competitiveness, infrastructure and use of resources.

With the 2010 Winter Olympics coming to town next February, Vancouver will be able to use an international media platform that key sponsors such as Coca Cola and General Motors are targeting for launches of new “sustainability” products and messaging. Besides the release of GM’s forthcoming Chevy Volt, I’ve been told that Coca Cola is trying to completely reposition its brand in the face of climate change, bottled water rebellion and anti-soda obesity regulations.

As a result of such marketing, and with Olympic Village plans for operations under the Global Reporting Initiative on sustainability, the 2010 games might make history as the first international event associated with sustainability.

Corn syrupy water and automobiles aside, Vancouver is putting forward some serious plans and goals in its quest. Yesterday, I chatted with Melina Scholefield, Vancouver’s Sustainability Group manager, and learned that the city as part of its Greenest City Plan will:

  • Set up a low-carbon economic development zone to attract private equity investment in the green economy, with the goal of creating 20,000 new jobs.
  • Try to increase its walkability, bikability and public transit ridership to more than 50 percent. The city currently has a rate of about 20 percent combined walking and cycling for commuting, one of the highest such rates in North America. Boston, for example, has a combined walking/cycling commute rate of 16 percent, the highest in the US.
  • Develop its own green building standards, which are stricter and more thorough than existing standards such the US Green Building Council’s LEED rating system or the US EPA’s Energy Star rating system. The goal is to have all construction in Vancouver be carbon neutral by 2020.
  • Reduce the amount of solid waste that goes to landfills or is incinerated by 40 percent.
  • Provide all city residents with easy access to green space, so that by 2020 everyone would be within a five-minute walk of a park, beach or greenway.
  • Reduce the per capita consumption of water by 33 percent.
  • Reduce the carbon footprint of food production by 33 percent.
  • The big one: reduce the ecological footprint of Vancouver by 33 percent. This means reducing the amount of arable land needed to support each citizen from 7 hectares to 5.7 hectares by 2020.

Eventually Vancouver wants to reduce its “four planet” Ecological Footprint down to “one planet.” (Tuesday night, I gave a talk on urban resilience at the conference with the co-founder of the Ecological Footprint, William Rees, a professor at the University of British Columbia: our Post Carbon Institute-sponsored talk will be broadcast on 15 radio stations and available here on an MP3 at the EcoShock radio site.)

Vancouver’s performance-based goals are impressive in that they are tangible and measureable. Having measured the sustainability performance, projects and capabilities of the largest 50 US cities in my book, How Green is Your City? The SustainLane US City Rankings, I am looking forward to seeing how Vancouver will pull off developing transparent and verifiable results.

Already the city claims the lowest greenhouse gas emissions per capita of any city in North America, at just under 5 metric tons, with New York City being at about 7 metric tons and the US average being close to 25 metric tons. Vancouver claims 90 percent use of renewable energy, with much of it in hydropower, though I was unable to verify whether that hydropower is small-scale enough to qualify for accepted renewable energy standards, such as that used by the state of California.

Now comes the real test. How will Vancouver plan, manage, construct and fashion a more sustainable future so it can complement its already world-famous quality of life with new technology jobs and opportunities in urban agriculture and food production?

Vancouver will have to compete with clean tech clusters emerging in California, Boston, Austin and Toledo, Ohio, creating green job growth in renewables, green building and advanced materials, advanced transportation (beyond its already-leading fuel cell industry cluster), and water/ energy efficiency.

A final challenge surfaced yesterday afternoon during a panel discussion at the Resilient Cities conference with Scholefield and other members of the Greenest City Action Team (including Gordon Price, Robert Safrata, and Moura Quayle).

Vancouver’s Greenest City Plan has yet to provide details on the participation of its surrounding metropolitan area, though the leadership of West Vancouver, a suburb of 44,000 appeared to be on board when I discussed the plan with its mayor Pamela Goldsmith-Jones and councillor Trish Panz.

Regional collaboration will be vital to ensuring effective land use and transportation planning, not to mention scaling up regional food and regional energy production, particularly biomass, wind, biofuels and small-scale hydro power.

“We’ll start at the core with the hope that action in the core city will move the outer area along” said Price, Director of the SFU City program, in response to a question about the lack of sign-on from Metro Vancouver, a group of 22 communities in the region.

That strategy might work to kick things off. At some point soon, however, Vancouver will need to more fully enlist the metro area and the Cascadia bioregion to take on an active partnership and even select ownership of Greenest City plan elements. Mayor Robinson did meet with Portland, Oregon mayor Sam Adams, who came to Vancouver this week with a contingent to the Resilient Cities event–the two were said to hit it off well and spent much time together privately.

If Vancouver accomplishes its formidable goals, it would within ten years begin to more closely resembles the Eco City-State concept devised by William Rees.

The city would then be at the center of a regional economy capable of producing most of its own energy, along with a significant amount of its goods, services and food, while protecting its water, wildlife, biodiversity and cultural resources. And this would be without contributing further to the acceleration of global climate change.

Call it resilience, sustainability, or just getting ready for what’s to come.

SOURCE: Warren Karlenzig is president of Common Current, an international consultancy focused on  urban sustainability strategy and metrics.

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