Above & Beyond Tree Service LLC has been notified that we have been awarded Angie’s List’s 2011 Super Service Award in the following category(s): Tree Service

We want to specially thank all of our customers who actually made this possible! It is our honor to serve you and continue this high level of service we provide to all of you! Thanks for a great 2011 and we at ABOVE AN BEYOND TREE SERVICE look for an even better 2012! Happy new year friends!

Sincerely,

Geoff Mongeon
Owner

Wood Energy Economics and Heating Security

Comparing Firewood to Conventional Heating Fuels

Fuelwood is unlike any other mainstream heating fuel, in that users are engaged physically and mentally in its consumption, and for many, in its production as well. Users of oil, gas and electric heating are typically involved only in paying energy bills and adjusting thermostats. As a result, any cost comparison of wood with other fuels is likely to be inaccurate, if not misleading, because it cannot account for either the labour costs or the intangible benefits of wood heating.

Householders considering a switch to wood heating would find it useful to know how much money they might save compared to the use of conventional fuels, in the same way that other major purchases are evaluated. The problem with this approach is that the cost-benefit analysis of wood heating is not easily reduced to a simple matter of money. Considering the rising prices of conventional fuels, it is probably accurate to say that households located outside major urban centres where there is significant forest cover could save money using firewood on a strictly heat-energy-per-dollar basis. But how can the other less tangible costs be evaluated? These costs might include:

• the space required to store a winter’s supply of firewood outside the house and space inside the house for a few day’s supply
• the physical strength and stamina required to split, move and stack firewood
• the time consumed in managing the fuel supply, tending the fire and dealing with regular maintenance tasks like ash removal
• the impact of the inevitable ‘mess’ of wood chips, bark and wood ash on the time consumed by household cleaning

The intangible benefits are equally difficult to evaluate in monetary terms.

• the satisfaction one feels in having mastered home heating largely by personal labour and ingenuity
• the sense of security both in terms of energy price stability and in the ability to remain comfortable in the home during electrical power interruptions
• the beauty and ambience created by a fire burning behind clear glass doors
• the special kind of warmth given off by a wood stove located in the main living area (this may be debatable in terms of physics, but it is mentioned by most users of wood fuel as an important benefit)

Several online sites offer fuel cost comparison methods. The calculations are fairly complex, accounting for local fuel pricing, housing type, climate zone, fuel type, appliance type and efficiency. However, a good indication of the imprecision of these calculation methods is that only whole-house heating to an even temperature throughout can be considered. This type of calculation cannot accommodate a wood stove used as a partial or complete heating replacement for a central furnace using conventional fuel. Compared to central heating, the use of a wood stove for space heating, especially if it is located in the main living area, can mean a reduction in heat energy needed by up to 25 percent, regardless of the cost of either fuel.

How Wood Heating Strengthens the Local Economy

Let’s look at some real-world examples of how people save money by heating with wood. Some families buy their firewood already split so their work only involves stacking it to dry. They might spend $250 for each cord (4’x4’x8’), the equivalent of almost $440 in fuel oil at $2.75 a gallon. That family’s savings wouldn’t be large, but they would gain all the tangible and intangible benefits of wood heating.

Small-scale harvesting and processing equipmentSomeone working in his woodlot, harvesting trees and processing them into firewood can save most of the cost of heating using other methods. For him the cost of a winter’s firewood is two week’s work and a few gallons of gas for the saw, splitter and pickup truck. Harvesting and processing the household’s heating fuel can save two or three thousand dollars every year.

What if dozens of households in a small town decided to save money by heating with wood instead of oil? Each of the twenty households would have a few hundred to a few thousands of dollars more to spend around town this year. Every dollar saved through wood heating is another dollar of spending that strengthens the local economy.

Rural areas tend to have large ‘trade deficits’ on consumer goods and most commodities. Their ‘exports’ are usually based on their natural resources such as mining, agricultural and forest products. Revenue from external sources is commonly in the form of tourism and recreation expenditures by non-residents. Overall, as population, industry and political decision-making concentrates in large cities, rural areas have not fared well economically.

A household that produces its own fuelwood supply saves $2,000 or more each year, an amount that can be used to reduce expenses in a household of marginal income, or that can be spent on other goods and services like home improvements. This household trades its own labour for big savings in household operating expenses.

A woodlot owner who produces and sells firewood provides employment and income to the area. If that same producer practices effective management, the quality and value of the woodlot are enhanced at the same time. When a local household buys its winter fuel supply from a neighbour, that transaction has a multiplying effect by keeping the money circulating within the community, increasing local incomes and job creation.

Local economic activity, including jobs and incomes, is increased through the use of fuelwood as a substitute for fuels purchased from outside the community. In a time of uncertainty about the future price and security of supply of conventional energy sources, fuelwood provides some price stability for residents of rural areas, as well as a sense of security because, if necessary, each household could produce its own fuel supply with a relatively small outlay of cash.

Energy Return on Energy Invested

Looking at the energy cost of energy

Economists focus on the money cost of energy, but the energy costs of energy can provide better insights into environmental costs and the underlying reasons for the money cost. For this reason, the energy return on energy invested (EROEI) should be included in any appraisal of the quality, impacts and appropriateness of various energy sources. Here is a sample EROEI analysis for fuelwood compared to other energy sources. Note that the value of labour is not included in the calculation.
Assumptions:

• hardwood fuel example: 24 million btu per cord of sugar maple
• 1 gallon of gasoline: 115,000 btu
• average round trip for fuel delivery:  50 miles
• fuel consumption of pick up truck: 15 mpg
• two round trips per cord = 6.7 gallons
• chainsaw fuel per cord: 0.5 gallon
• log splitter fuel per cord: 1 gallon

Total fossil fuel consumption: 8.2 gallons/cord x 115,000 = 943,000 btu
Calculation: Energy content per cord: 24 M btu divided by fossil fuel input: 943,000 btu.
Energy return on energy invested: 25:1

An EROEI of 25:1 may not be worst case for fuelwood, but it is close for rural areas. Harvesting from their own woodlot, some people probably produce firewood at an EROEI of 30 to 40:1.

For comparison, back in the heyday of oil, when discoveries were peaking and consumption was just ramping up, one barrel invested would yield about 100 barrels for sale, a cheap energy bonanza if there ever was one. Today, gushers are a thing of the past, most of the biggest oil fields are in decline and the ‘new’ oil fields are tiny and found under oceans. The EROEI of oil and gas has now fallen to 10:1 to 20:1, depending on age, type and location of the field. So-called unconventional oil such as the bitumen extracted from the Canadian tar sands has an EROEI of as low as 1.5:1 to a high of 4:1, depending on how the calculation is done and who does the calculating.

The green bars are the minimum EROEI and the baige parts are the observed range.

The chart at right was developed by Professor Charles Hall and his colleague John Day. Note that firewood is asigned an EROEI of around 30:1, which is a similar result to the analysis done for this paper.

Wood, in the form of natural firewood, compares favorably with other fuels regarding the amount of net energy realized after processing and transportation. This bodes well for a degree of price stability for fuelwood in the future. Price stability is not likely for the fossil fuels because as the easily accessible deposits are consumed the EROEI rises dramatically, as does the retail price.

Sustainable forestry

What if everyone heated with wood?

This beautiful graphic was created for RSF-ICC, a fireplace and chimney company. Used with permission.Critics of wood heating like to say that if everyone decided to heat with wood, the air would be polluted and every forest in the country would be mowed down to produce firewood. Maybe, but the whole idea is pretty silly, considering that wood is a lousy urban energy source and is best used locally. Even the most ardent defenders of wood heating would never promote it as a universal energy source.

Large parts of the country are relatively thinly populated and have highly productive forests. These are the regions where wood heating makes sense. Foresters have said that wood heating could easily double or more in many regions without putting undue stress on the forest resource. Our forests do need to be managed sustainably, but the methods are well known and can be summarized in a single sentence: Uneven-aged selective harvesting, thinning of dense stands and removal of poorer quality trees, while leaving seed trees of all present species and ages, and some standing dead trees to provide wildlife habitat.

Many woodlots in farm country can offer a striking model of sustainable forestry. The careful work by generations of farmers and other woodlot owners, visible in healthy, productive woodlots that have provided generations of owners with their heating fuel and other products, provides the stewardship model that others can follow.

And while many woodlot owners understand and practice sustainable forest management, others exploit the resource for short-term profit. Unfortunately, some farmers have maximized short term profit by clear cutting their woodlots and converting the land to cash crop production. Some companies and individuals have made a practice of buying large parcels of unused forest land, stripping them of all the commercial trees and then reselling the depleted parcels. These profiteers do meet the definition of woodlot owners, but they do not maintain ties to the lands they buy and sell.

A healthy, well-managed woodlot can provide firewood and other products indefinately.It has long been said that a healthy, well-managed woodlot can yield half a cord of wood per acre per year forever – one full cord being a pile eight feet long, four feet wide and four feet high – and that a ten acre woodlot could sustainably produce enough firewood each year to heat a house. Although that guideline is old and not very precise, it still holds true. In fact, it takes a lot less than five cords of wood, and therefore less than a ten acre woodlot, to heat a new energy-efficient house using a modern wood stove. There is some evidence that carefully designed and built houses can be heated with as little as 1.5 cords of firewood.

Despite its considerable advantages, fuelwood is not a good solution for all households to the problems of high home heating costs and global warming. Fuelwood is not a suitable energy source in all locations, such as densely-populated urban areas, because its air emissions tend to be higher than other options, and the air is already burdened with pollution from industry and transportation. A winter’s supply of wood takes up a lot of space, and the price of firewood in urban areas is normally too high to achieve savings. Successful heating with wood also requires a level of physical fitness and the learning of a special set of skills. Clearly, wood heating is not for everyone.

Advanced Wood Burners Cut the Smoke

The new wood burning technology found in EPA certified stoves goes a long way toward solving all three wood smoke problems: airshed contamination, nuisance wood smoke and indoor air pollution. These advanced stoves, inserts, fireplaces and furnaces cut wood smoke by up to ninety percent compared to older so-called ‘airtight’ stoves, and also spill less smoke into the indoor air because fires don’t tend to smoulder in them, the condition that most contributes to smoky indoor air.

Smoke emissions from older conventional wood stoves average at least 25 grams per hour of operation, while the emissions from older wood-fired outdoor boilers range from 50 g/h to well over 100 g/h. In contrast, the EPA regulation limits emissions of certified wood stoves to no more than 7.5 g/h. However, since the regulation was first established in 1988, the average emissions of certified stoves have declined steadily due to advances in technology and competition among manufacturers. Today, most current wood stove models emit only 2 to 4 g/h.

Although the EPA emissions limits are stated as solid particles (particulates) collected on filters, other detailed testing has shown that the emission of the scary-sounding polycyclic aromatic hydrocarbons like fluorene and benzo (a) pyrene, as well as volatile organic compounds like benzene and xylene are all far lower in the exhaust from advanced wood heating equipment than from old style wood burners.

Despite what some anti-wood heating activists have claimed, the technology is effective in reducing pollution. The reduction in smoke emissions has been a significant technological breakthrough in wood burning and is noticeable at the top of the chimney where no visible smoke is seen.

Advanced equipment is more efficient too

Just as noticeable to users, however, is the increase in efficiency that results from burning and not wasting the energy-rich smoke. Conventional wood stoves range in efficiency from a low of about 35 percent for a cast iron box stove or furnace to a high of as much as 55 percent for a 1970s era ‘airtight’. Most older outdoor boilers are less than 50% efficient. In contrast, EPA certified wood stoves average around 70 percent and none are less than 60 percent efficient. The new breed of emissions certified outdoor boilers are also much more efficient.

The difference in efficiency between conventional wood burning equipment and the advanced low-emission models is so significant that users can immediately see the difference when they upgrade and begin using a new stove. The reduction in fuelwood consumption by up to one-third is significant for each household that uses the new technology, but it also has the potential to increase the number of houses that can be heated based on the sustainable harvesting of a given area of forested land. Another significant factor that reduces a wood-heated household’s impact on the forest resource is the lower heat energy requirements of modern housing. Together, the increase in wood burning appliance efficiency and improvements in housing energy conservation can roughly double the number of dwellings that can be heated by the yield from a given woodlot compared to just 25 years ago.

An outdoor boiler firing up.Community-wide smoke problems are uncommon in areas where level topography does not produce the same number or severity of winter inversions that trap smoke close to the ground. While community level smoke problems are relatively rare, nuisance smoke caused by thoughtless neighbours has been identified as a problem in dozens of towns. One technology in particular has been the focus of many complaints. Outdoor wood-fired boilers (OWB), which look like metal garden sheds and send hot water to one or more buildings through buried pipes, have become notorious for the dense smoke they produce. Small towns have enacted bylaws restricting the installation of outdoor boilers by either banning them from residential areas or placing limits on their proximity to property lines.

The source of the problem is that central heating furnaces and boilers, including OWBs, were exempt from the original EPA emission rules back in 1988 on the basis that there were too few of them to bother regulating. Well, that was then. Now OWBs are very popular and as a result a new smoke emissions test for OWBs has been approved and certified models are now on the market. On paper the new breed of OWBs look much better than the older, smokier versions. Time will tell if they are clean burning enough to satisfy regulators and reduce public complaints.

An Essential Resource

By any measure, wood is an important residential energy resource, especially outside large urban areas. Over 10 million US households, just under 10 per cent of the total, use wood as their main heating fuel or to supplement other heating fuels. Over 25 per cent of Canadian households burn wood.

Well-stacked piles of firewood are a comforting sight.A drive through small towns and down country roads in forested regions confirms that fuelwood is a significant energy resource. The long lines of piled firewood standing in yards serve as proof. Every winter the wood is cut from woodlots and every spring it is split and stacked to dry in the summer sun. In the fall it is moved to the house and stacked again, and in winter it keeps families cosy warm. It is a seasonal ritual that has recurred year in and year out for decades, for generations.

Firewood for home heating is an indigenous, renewable energy resource that helps families stretch their household budgets and strengthen their local economies. And yet an increasing number of vocal activists are clamouring to have wood burning banned from their communities because of air pollution, and even some environmentalists warn against the increased use of firewood fearing negative impacts on our forests.

A balanced assessment of firewood for home heating is long overdue. This paper explores how wood burning contributes to the prosperity of rural communities, the health and well-being of their inhabitants, and to the environmental sustainability of our society. It also tackles the problems of wood smoke pollution and forest resource impacts.

Smoke Emissions

Wood smoke pollution is the most serious knock against wood heating, so it is best to deal with it first.

The problem of smoke pollution from residential wood burning has been debated since the resurgence of wood as a fuel after the oil crisis of the 1970s. Because it contains toxic chemicals and known carcinogens, wood smoke is unhealthy to breathe in high concentrations and even in low concentrations can be harmful to children, the elderly and those with lung diseases or allergies. There are three aspects of wood smoke pollution that can be considered: nuisance smoke caused by a neighbor, airshed contamination caused when many households make too much smoke in a confined area like a river valley, and indoor air pollution caused when a wood burning appliance spills smoke into the house.

Firewood was seen as a renewable resource, but now it is linked to pollution.

In the aftermath of the first oil crisis in the late 1970s, governments supported the public’s return to wood as a home heating fuel. At the time it was seen as one strategy to reduce dependence on expensive imported oil. However, a gradual policy shift has occurred since then. Positive statements about firewood’s status as a renewable energy source and its role in reducing net greenhouse gas emissions are less common and more qualified in government documents than previously. To the extent that governments deal at all with the issue of wood heating, the concern tends to be more with pollution abatement than with encouragement.

Statements by both government and nongovernmental health agencies frequently include lengthy statements about the hazardous chemical constituents of wood smoke. They offer lists of compounds like polycyclic aromatic hydrocarbons, dioxins and furans and acrolein. The use of intimidating technical terms without offering contextual information makes these detailed statements quite beyond the ability of the average reader to comprehend or interpret. For example, context could be provided in the form of a list of chemicals emitted by a city bus or a backyard barbecue, which are similarly odious sounding. Government personnel insist that statements listing the chemicals found in wood smoke are simply intended to inform the public, but it might equally be said that this communications tactic reveals an underlying intention to dissuade the public from using wood fuel, especially considering that no other energy source receives this kind of treatment in public information.

It is not the intention here to minimize the environmental impacts of wood heating or attempt to deflect concerns by highlighting pollution from other energy sources. But a balanced assessment of benefits and risks is called for when any energy source is evaluated or compared to other sources, especially by government agencies. Too often, those who have concerns about the wisdom of wood heating fail to understand or communicate that all energy sources, including renewables like wind and solar, have impacts on the environment. To single out one energy source for condemnation without providing supporting evidence or contextual information is unhelpful and unlikely to sway a justifiably sceptical public.

The haze of wood smoke across a highway in the morningThe problem of wood smoke from residential heating is serious in some places and under some conditions, and it is important that the public understand the risks and the ways to minimize them. The three dimensions of wood smoke pollution – airshed contamination, nuisance neighbours, and indoor air pollution – should be addressed through public information and, where necessary, regulation. To be successful in changing minds and behaviours, any government action should be developed in full recognition that people who heat with wood tend to be sceptical of experts or governments meddling with their personal wood heating practices.

Up next, part 3: Advanced burners and equipment.

Please contact us using our convenient webform, as we sell various types of product depending on your needs. Or visit our dedicated website for FIREWOOD PURCHASES.

Please use this form to submit your application. We look forward to hearing from you!

Geoff Mongeon
Owner & Operator.

What makes wood heating different from all the other options?

Judged by coverage in policy discussions about our energy future, wood heating is virtually nonexistent. Most politicians don’t debate its merits or plan for its strategic use. The one area in which wood burning does attract attention is the problem of air pollution. As a result, wood burning has become most often identified as a problem to be solved rather than as an opportunity to be harvested. The one thing that almost no governments do is encourage householders to heat with wood. Fuelwood is the only renewable energy resource that most governments don’t seem comfortable with.

The low profile of wood heating in energy policy discussions and in the media reflects the fact that policy – even rural policy – is developed in big cites, and that the large media outlets are all urban in location and outlook. That and the fact that no large corporations are involved in wood heating and therefore no high-priced lobbyists or special interest groups prowl the halls of legislatures pleading the case of wood burning. So, despite the fact that millions of families burn wood at home, its role as an energy source rarely appears on government and media radar.

The refining of wood fuel is often done manually with hand tools.In a world of touch-screen convenience, pocket-sized computers, and automatic climate-controlled environments, wood heating is in every way rough, basic and steadfastly hands-on. People who heat with wood seem out of step with the modern world swirling around them. Have wood burners and those who labour to supply them with fuel slipped through a crack in the cozy consensus of modernity? Or are they onto something meaningful that has been missed by the mainstream?

The producers and consumers of fuelwood are engaged in an activity that reduces net greenhouse gas emissions while others merely fret about global warming. The fuelwood fraternity use a renewable energy resource, taking pressure off dwindling supplies of ever-pricier and scarce fossil fuels. Buyers of fuelwood create jobs close to home and strengthen their local communities. They know more about the cause-and-effect relationships of energy production and consumption than those who simply pay utility bills. The story of wood heating early in the twenty-first century is about average families making decisions based on how they see their future unfolding.

Heating with wood is about a lot more than home heating. It is a tangible expression of self-reliance, of the courage to buck the trends and to resist the appeal of sedentary, push-button convenience. Heating with wood reinforces links to the land and is a willing submission to the cycle of the seasons. It provides stability and security in a turbulent world.

To its owner, the woodlot is a living community in constant evolution, while to the urban observer it may be seen as a museum in which the removal of a tree exhibit renders it diminished. The woodlot owner watches its quality improve over the years, even as it yields products and creates employment. The owner’s household earns part of its income by being a fuel supplier to the neighbours. It is a gentle way to produce energy compared to mountain top removal coal mining and nuclear reactors.

Fuelwood is the ultimate populist energy resource, the most easily accessed and affordable of all renewable energies. The major environmental impact of wood heating is visible for all to see in the form of smoke emissions, making everyone who uses it instantly accountable for their actions. The families that heat with wood and those that supply them with fuel do so privately, without fanfare or acknowledgement. It seems they wouldn’t want it any other way. Heating with wood is its own reward. This is a private activity in which virtually everyone involved is content to remain anonymous, quietly keeping their families warm through their own labour and ingenuity.

But with so few individuals and groups speaking up to defend the responsible use of wood fuel, the families that depend upon it may soon be faced with unreasonable restrictions. Those who want to see wood heating banned are gaining influence and more governments are treating wood heating as a pollution problem and not as a renewable energy resource that needs to be improved.

Up next week: AN ESSENTIAL RESOURCE & SMOKE EMISSIONS

Please contact us using our convenient webform, as we sell various types of product depending on your needs.

Or visit our dedicated website for FIREWOOD PURCHASES.

Defects in Urban Trees

The following are defects or signs of possible defects in urban trees (see figure):

1. regrowth from topping, line clearance, or other pruning
2. electrical line adjacent to tree
3. broken or partially attached branch
4. open cavity in trunk or branch
5. dead or dying branches
6. branches arising from a single point on the trunk
7. decay and rot present in old wounds
8. recent change in grade or soil level, or other construction

Defects in Rural Trees

The following are defects or signs of possible defects in rural trees (see figure):

1. recent site construction, grading and tree removal, clearing of forests for development
2. previous tree failures in the local area
3. tree leaning near a target
4. forked trunk; branches and stems equal in size
5. wet areas with shallow soil

Managing Tree Hazards

An arborist can help you manage the trees on your property and can provide treatments that may help make your tree safer, reducing the risk associated with hazardous trees. An arborist familiar with hazard tree evaluation may suggest one or more of the following:

• Remove the target. While a home or a nearby power line cannot be moved, it is possible to move picnic tables, cars, landscape features, or other possible targets to prevent them from being hit by a falling tree.
• Prune the tree. Remove the defective branches of the tree. Because inappropriate pruning may weaken a tree, pruning work is best done by an ISA Certified Arborist.
• Cable and brace the tree. Provide physical support for weak branches and stems to increase their strength and stability.
• Provide routine care. Mature trees need routine care in the form of water, fertilizer (in some cases), mulch, and pruning as dictated by the season and their structure.
• Remove the tree. Some hazardous trees are best removed. If possible, plant a new tree in an appropriate place as a replacement.

Recognizing and reducing tree hazards not only increases the safety of your property and that of your neighbors but also improve the tree’s health and may increase its longevity!

Ensuring Quality Care for Your Tree

Trees are assets to your home and community and deserve the best possible care. If you answered “yes” to any of the questions in the tree hazard checklist or see any of the defects contained in the illustrations, your tree should be examined by an ISA Certified Arborist. Contact Above and Beyond if you need help with your trees.

Recognizing Tree Hazards

Trees provide significant benefits to our homes and cities, but when trees fall and injure people or damage property, they are liabilities. Taking care of tree hazards makes your property safer and prolongs the life of the tree.

Trees are an important part of our world. They offer a wide range of benefits to the environment and provide tremendous beauty.

However, trees may be dangerous. Trees or parts of trees may fall and cause injury to people or damage to property. We call trees in such situations hazardous, to signify the risk involved with their presence. While every tree has the potential to fall, only a small number actually hit something or someone.

It is an owner’s responsibility to provide for the safety of trees on his or her property. This brochure provides some tips for identifying the common defects associated with tree hazards. However, evaluating the seriousness of these defects is best done by a professional arborist. Regular tree care will help identify hazardous trees and the risk they present. Once the hazard is recognized, steps may be taken to reduce the likelihood of the tree falling and injuring someone.

Hazardous Trees and Utility Lines

Trees that fall into utility lines have additional serious consequences. Not only can they injure people or property near the line, but hitting a line may cause power outages, surges, fires, and other damage. Downed lines still conducting electricity are especially dangerous. A tree with a potential to fall into a utility line is a very serious situation.

Tree Hazard Checklist

Consider these questions:

• Are there large dead branches in the tree?
• Are there detached branches hanging in the tree?
• Does the tree have cavities or rotten wood along the trunk or in major branches?
• Are mushrooms present at the base of the tree?
• Are there cracks or splits in the trunk or where branches are attached?
• Have any branches fallen from the tree?
• Have adjacent trees fallen over or died?
• Has the trunk developed a strong lean?
• Do many of the major branches arise from one point on the trunk?
• Have the roots been broken off, injured, or damaged by lowering the soil level, installing pavement, repairing sidewalks, or digging trenches?
• Has the site recently been changed by construction, raising the soil level, or installing lawns?
• Have the leaves prematurely developed an unusual color or size?
• Have trees in adjacent wooded areas been removed?
• Has the tree been topped or otherwise heavily pruned?

to be continued….

Diseases

Three things are required for a disease to develop:

• the presence of a pathogen (the disease-causing agent)
• plant susceptibility to that particular pathogen
• an environment suitable for disease development

Plants vary in susceptibility to pathogens. Many disease-prevention programs focus on the use of pathogen-resistant plant varieties. Even if the pathogen is present and a susceptible plant host is available, the proper environmental conditions must be present over the correct period of time for the pathogen to infect the plant.

Diseases can be classified into two broad categories: those caused by infectious or living agents (diseases) and those caused by noninfectious or nonliving agents (disorders).

Examples of infectious agents include fungi, viruses, and bacteria. Noninfectious diseases, which account for 70 to 90 percent of all plant problems in urban areas, can be caused by such factors as nutrient deficiencies, temperature extremes, vandalism, pollutants, and fluctuations in moisture. Noninfectious disorders often produce symptoms similar to those caused by infectious diseases; therefore, it is essential to distinguish between the two in order to give proper treatment.

Insects

Some insects can cause injury and damage to trees and shrubs. By defoliating trees or sucking their sap, insects can retard plant growth. By boring into the trunk and branches, they interfere with sap flow and weaken the tree structure. Insects may alsocarry some plant diseases. In many cases, however, the insect problem is secondary to problems brought on by a stress disorder or pathogen.

It is important to remember that most insects are beneficial rather than destructive. They help with pollination or act as predators of more harmful species. Therefore, killing all insects without regard to their kind and function can actually be detrimental to tree health.

Insects may be divided into three categories according to their method of feeding: chewing, sucking, or boring. Insects from each group have characteristic patterns of damage that will help you determine the culprit and the proper treatment. Always consult a tree care expert if you have any doubt about the nature of the insect problem or the proper treatment

.

Chewing insects eat plant tissue such as leaves, flowers, buds, and twigs. Indications of damage by these insects is often seen by uneven or broken margins on the leaves, skeletonization of the leaves, and leaf mining. Chewing insects can be beetle adults or larvae, moth larvae (caterpillars), and many other groups of insects. The damage they cause (leaf notching, leaf mining, leaf skeletonizing, etc.) will help in identifying the pest insect.

Sucking insects insert their beak (proboscis) into the tissues of leaves, twigs, branches, flowers, or fruit and then feed on the plant’s juices. Some examples of sucking insects are aphids, mealy bugs, thrips, and leafhoppers. Damage caused by these pests is often indicated by discoloration, drooping, wilting, leaf spots (stippling), honeydew, or general lack of vigor in the affected plant.

Boring insects spend time feeding somewhere beneath the bark of a tree as larvae. Some borers kill twigs and leaders when adults feed or when eggs hatch into larvae that bore into the stem and develop into adults. Other borers, known as bark beetles, mate at or near the bark surface, and adults lay eggs in tunnels beneath the bark.

Treatment

The treatment method used for a particular insect or disease problem will depend on the species involved, the extent of the problem, and a variety of other factors specific to the situation and local regulations. Always consult a professional if you have any doubt about the nature of the problem or proper treatment.