Mushrooms and Fairy Rings

By Bruce Wenning

 

Every fall I get questions from people who are worried about the appearance of mushrooms (toadstools) growing in their lawns and gardens. Some people feel that they are unsightly and sure that their presence indicates that something is wrong. Others welcome these fungi and are delighted when they learn that mushrooms serve an ecological purpose by helping in the decomposition of soil organic matter. Only one caller has mentioned that the mushrooms growing in her garden and lawn added interest as “colorful little plants.”

Mushrooms are fungi. Green plants (trees, shrubs, lawns and garden plants) contain chlorophyll in their leaves, and, by the action of photosynthesis, produce sugars and other compounds from carbon dioxide and water. Mushrooms, on the other hand lack chlorophyll and cannot undergo photosynthesis. They must derive their nutrients from dead plant and animal matter.

How do they do this? Mushrooms colonize organic debris in the soil by hyphae (fine branching tubes). As their hyphae grow and “seek out” organic debris such as buried wood chips, dead roots, pieces of wood, lawn thatch, etc., they gain more mass by branching outward and fusing together forming a larger structure called a mycelium. Mycelium is the body of the fungus and hyphae are its individual components.

As the mycelium moves or grows through the soil by way of multiple growing points, it increases in size as a diffuse, loosely combined fungal mass-producing various enzymes and other chemicals to digest or feed on organic compounds in the soil. Mushrooms and other decomposing fungi are important garden organisms involved with organic matter break down and nutrient recycling. They are welcomed additions to the organically-tended lawn and garden.

Mushrooms are the above ground portion of the underground growing mycelium. Mushrooms are the actual fruiting body or reproductive structure of the fungus. They are the “tip of the iceberg” of the entire fungus. In general, a mushroom is composed of a cap, gills, ring, stalk, cup and root-like extensions (rhizomorphs). Under the cap, spores are produced in the gills for release into the air. Boletes mushrooms release spores from pores instead of gills.

Spores, when released, can be carried by wind, rain, irrigation water from sprinklers, animals, insects and gardening tools that come into contact with the mushroom. For a spore to germinate into hyphae, the right combination of moisture, temperature, and available organic compounds must be present for growth and eventual development to occur. The process from spore to hyphae to a mycelium that produces a mushroom could take weeks to years depending upon the fungal species and environmental conditions.

Fairy rings are groups of mushrooms growing in lawns and pastures that form circular or semi-circular patterns. These mushroom rings occur during spring and fall in all types of grasses when temperatures range between 45 and 65 degrees F. Many species of mushrooms can form fairy rings, however these three species are the most common; Marasmius oreades (small, tan color), Agaricus campestris (edible, sold in grocery stores), and Chlorophyllum molybdites (large, white poisonous).

 

Fairy rings can vary from a few inches to more than 50 feet in length. The mycelium producing the fairy ring mushrooms can be as deep as eight inches or more, impeding water from reaching turfgrass roots. This is the reason why fairy ring fungi are considered a disease in lawns. Grass is killed inside the ring of mushrooms and grass. The outer ring of mushrooms and grass is alive with the grass exhibiting deep green color and a faster growth rate. This is due to the mushrooms’ decomposing soil organic matter and releasing nutrients to the grass as a natural fertilizer. It is not unusual for a fairy ring to resemble a bulls eye appearance similar to dog urine spots on a lawn. However, dog urine spots lack mushrooms.

Fairy rings spread outward from a few inches to several feet per year. According to Mass Audubon naturalist, Dan McCullough, if the fairy ring mycelium hits a rock, fence post, bird feeder post or some other impeding object, the ring will become interrupted, possibly loosing its circular or semi-circular pattern. Digging out the mushroom-mycelium mass and replacing with good topsoil will help eliminate this problem.

McCullough owns fourteen mushroom field guides and still has problems identifying certain species. He strongly urges the beginner to use caution when looking for edible mushrooms. Identifying mushrooms is not like identifying birds, where one bird guide may cover all the birds in an area. You must use several guides when trying to identify mushrooms and it is strongly advisable to take a class to sharpen your skills.

Bruce Wenning is the horticulturist-grounds manager of the Mass Audubon Society, Habitat sanctuary, Belmont and serves on the Board of Directors of the Ecological Landscaping Association. www.ecolandscaping.org

Nutrients help turn the Charles green

By Anna Eleria and Rebecca Scibek/Special to the TAB

 

 

While this summer was filled with warm, sunny days that encouraged recreation on the Charles River and in its parklands, it also saw an explosive growth of a potentially harmful algae in the Lower Charles. First identified in early August, the fluorescent green algal bloom extended from the Harvard/Massachusetts Avenue Bridge east to the Museum of Science, with dense, floating mats of algae most visible in lagoons, canals and along the river’s edge in Boston and Cambridge. 

Algal blooms have been a problem in the Charles River for years, but this year’

s bloom was remarkable for two reasons. First, it was the first time that the algae bloom was identified – a sample collected in early August was identified as microcystis, a type of blue-green algae that secretes toxins and grows naturally in fresh and estuarine waters. Second, the amount of algae was extremely large. The abundance of algae was due to heavy late spring and early summer rainstorms that brought an enormous influx of nutrients to the river, followed by a period of extremely warm water temperatures, creating perfect conditions for algae growth.

In early August, the density of sampled algae was ten times greater than the moderate health risk threshold designated by the World Health Organization (WHO). Samples taken the second week in September by Massachusetts Department of Conservation and Recreation (DCR) showed that algae levels had decreased significantly, close to the WHO low health risk threshold. CRWA sent water samples (with algae concentrations slightly above the low health risk probability threshold) to a laboratory at the State University of New York in Syracuse to determine if and how much of the toxin was released by the algae. The results showed that a small, but significant, amount of toxin was present in the water at that time. Exposure to the toxin at that level could lead to short-term health problems such as skin irritations, diarrhea, and nausea. 

To notify the public of the potential hazard, CRWA informed all boathouses involved in the Flagging Program, a daily water quality public notification system, of the algal bloom, and instructed those within the affected area to fly red “do not boat”

flags. DCR posted signs along the river warning people to avoid direct contact with the water. CRWA and state environmental and health agencies are continuing to work together to better monitor and understand the algae issue.

Algae is a natural and critical part of the Charles River ecosystem that provides food for fish and other small aquatic animals. However, too much algae drives the ecosystems out of balance, as it blocks sunlight from underwater plants, creates large day-night swings in oxygen levels in the water, produces scum and odor and may secrete large amounts of toxins. Upon die-off, algae consumes large amounts of oxygen, which can damage or kill fish and plant species that are dependent on dissolved oxygen in the water.

The primary cause of algal blooms in freshwater is excessive phosphorus, a nutrient found in wastewater treatment plant discharges and in stormwater runoff. The single greatest source of nutrients in the Charles River is run-off from high-density residential land, which comprises nearly fifty percent of Newton’s land. Lawn fertilizers, soaps and detergents are the main human sources of phosphorus. Other “natural”

sources of phosphorus from residential areas are decaying leaves, grass clippings, and pet waste, all of which increase the level of algae-inducing nutrients when they flow into the river through storm drains or small streams.

The property management practices of homeowners and municipalities have a dramatic impact of the amount of nutrients flowing into the Charles. Property owners should minimize fertilizer use, use only low phosphorus fertilizers, pick up and dispose of dog waste, and dispose of yard waste properly (not in the street or into storm drains). Cities and towns should minimize the use of fertilizers on public playing fields, parks and landscaped areas, provide yard waste pickup, enforce “pooper-scooper” laws, clean catch basins regularly, and build “green infrastructure”

wherever possible. 

Other factors, such as low river flow volume, warm water temperature and the presence of dams, magnify the impacts of phosphorus and increase algae growth.  CRWA continues to develop science-based solutions to tackle these problems, and to advocate for policies and programs that will help reduce algae levels and ensure cleaner, safer waters for fish, wildlife and the public. 

Anna Eleria is a CRWA Project Manager/Engineer, and Rebecca Scibek is CRWA Volunteer Coordinator.

A “Sticky” Issue: No More Vermont Maple Syrup?

By Susan Bellerose

 

Much has been written about climate change caused by the build up of carbon dioxide and other “greenhouse” gases that are the by-products of burning fossil fuels such as oil and coal.  Many of us have read about the melting of the polar ice caps, and the increasing incidence of insect-borne diseases and extreme weather-related events such as droughts, floods, fires and hurricanes that have been attributed to global warming.  A less well known but important local by-product of global warming is the reduction in maple syrup production in New England due to the northern migration of forests.

Over the next thirty to fifty years, the optimal growing range for many tree species is expected to migrate northward by as much as 100 to 300 miles to higher altitudes in response to the predicted doubling of greenhouse gases.  Trees can “migrate” to cooler, more tolerable growing climates when their seeds are spread by the wind or by animals.  Trees that have seeds that are spread by birds, such as oak trees, are able to migrate northward at a faster rate than those trees whose seeds are spread by the wind, such as maples.  Some tree species will have difficulty thriving in their current environment but may not be able to migrate quickly enough to survive, which will result in a reduction in biodiversity of both plants and animals.

In the Northeast, warmer, drier winters combined with other factors such as air pollution and pest infestations are putting stress on the sugar maple.  The sugar maple is not able to migrate quickly to adapt to the warmer climate because its seeds are spread by the wind.  Some scientists are hypothesizing that sugar maples may nearly die out in New England over the next century.  This will not only affect the brilliant colors that we see on the mountains in northern New England in the Fall, but will also have consequences for one of America’s favorite foods:  maple syrup. 

We are already seeing the effects of global warming on maple syrup production.  In the 1950’s, the U.S. produced 80% of the world’s maple syrup, and Canada produced the remaining 20%.  Due to climate warming combined with technological changes in how syrup is collected, this ratio has reversed.  Now Canada produces 80% of the world’s maple syrup, and the U.S., primarily New England and New York, produces only 20%.  Vermont in particular has been affected, as it has a sizeable seasonal workforce devoted to syrup production and relies on the income from sales of syrup and related products.

An explanation of how maple syrup is produced helps to understand how climate change is affecting the syrup business here in the U.S.  Maple syrup flows best when the temperature is below 25 degrees Fahrenheit at night, and above 40 degrees Fahrenheit during the day.  As air temperatures drop below freezing, the sugar maple pulls sap out of its branches and into the roots.  When temperatures move above freezing, the cycle is reversed, and sap flows out of the roots back into the branches, and out of any “wound” in the tree, such as the tap hole cut for syrup production.  In order for the tree to convert stored starch to sugar in the sap, there needs to be an extended period of below freezing temperatures.  As the climate in the Northeast has continued to warm, this has reduced the number of freeze-thaw cycles that are needed for sap to flow.  When the transition from winter to spring is accelerated with early spring warming, this causes the sugar maple buds to open early, resulting in bitter sap, and less syrup production overall due to a shorter sugaring season. 

It will be a pity if the sugar maples in New England die out because they are unable to adapt quickly enough to the warming climate.  Hopefully the next time we pour syrup over our pancakes or waffles, we will be reminded of how easily climate change can affect our everyday lives and the “sweet” pleasures in life that we take for granted!

Susan Bellerose holds degrees from Mt. Holyoke College and Columbia Business School and is a resident of Newton.

How to stop the spread of invasive plants

By Florrie Funk

 

Many of Newton’s residents are not aware of the crisis threatening biodiversity in our parks and their own back yards. Although there is no easy solution to the problem of invasive plants, here are some things that citizens can do to help:

·       Learn to identify invasive plant species and remove them from your property.

·       If your property abuts a park or wooded area, be sure that your non-native landscaping materials don’t spread beyond your property line. 

·       Never dump yard waste into parks or conservation areas.  Many common landscaping plants, especially ground covers such as English Ivy, Winter Creeper, Pachysandra and Vinca, reproduce vegetatively, so cuttings can root and spread aggressively. Walk along the boundaries of Newton’s conservation lands to see what happens when homeowner are careless about this.

·       Learn about native plants and use them in your landscaping. Your yard can be part of the solution to ecosystem fragmentation.

·       Encourage city officials to develop a plan to remove invasive plants and to reintroduce native plants on city property.  Learn from other communities how they trained personnel, organized volunteer efforts, and obtained funding.

·       Be aware that cautious and strategic use of herbicides may sometimes be necessary.  Many species resprout with renewed vigor even when they are cut down to ground level.  Removal of root systems can be impractical and destructive to soil structure and other organisms, and soil disturbance usually increases germination of invasive plant seeds. There is a small risk of unwanted side effects in the use of herbicides, but the alternative may be a devastating and irreversible loss of species. Check the National Park Service’s Fact Sheets (nps.gov/plants/alien) and The Nature Conservancy’s “Weed Control Methods Handbook” (tncweeds.ucdavis.edu)

 

Florrie Funk, florriemfunk@aol.com assisted with the 2006 Newton comprehensive plant survey. This article is a follow up to her March 2007 article “The importance of removing invasive plants”.

Listen to the howl

Mexican gray wolf reintroduced in the Southwest

By John Linehan and Brooke Wardrop

 

 

The howl of the Mexican gray wolf has not been heard in more than 30 years in the forests and fields of the Southwest. Once common throughout western Texas, southern New Mexico, central Arizona and northern Mexico, the Mexican gray wolf, the rarest and most genetically distinct subspecies of the North American gray wolf, was completely eliminated from the wild, surviving in only small captive populations.

Thanks to successful conservation programs throughout the past 27 years, a brighter future has been procured for these wolves, and their howl is beginning to be heard once again.

In a unique partnership between the U.S. Fish and Wildlife Service, state agencies, several zoos accredited by the Association of Zoos and Aquariums and other partners, Zoo New England is participating in a reintroduction program to release captive-reared Mexican gray wolves in remote parts of Arizona and New Mexico.

Zoo New England began participating in the Mexican Wolf Species Survival Plan (SSP) in 1998. The SSP is a consortium of institutions working together to breed captive Mexican wolves for reintroduction and recovery in the Southwest. Last year, a pair at Stone Zoo in Stoneham produced eight pups, all of which are thriving. The SSP has now reached its captive population goals, and soon Zoo New England will be translocating some members of its pack to other zoos.

In captivity, close bonds between wolves and keepers are avoided because of the reintroduction program. Their survival ultimately depends on active avoidance of human contact. The animals cannot become reliant on people for food. While in captivity, the wolves do not lose their natural instincts, but hunting skills need to be honed before being released into the wild. Wolves that are slated for release are sent to large pre-release centers with native prey. Typically, these wolves and their offspring are released into the wild together as a pack.

In 1976, the Mexican gray wolf was listed as endangered under the Endangered Species Act. Today, there are approximately 300 Mexican gray wolves in existence. Most were born in zoos and wildlife sanctuaries in the US and Mexico, and more are being born in the wild each year. The recovery of these animals has been given the highest priority.

Based on experience gained from other wolf recovery programs, scientists are optimistic about the program’s eventual success. Captive-reared wolves have learned to survive after release and successfully form groups, reproduce and raise their pups. They are also forming new pairs on their own, indicating a healthy wolf population.

There are still challenges. At the 2006 Mexican Gray Wolf SSP Annual meeting held in Alpine, Ariz., the heart of the wolf release area, attendees discussed the opposition to the reintroduction program by some area residents, particularly ranchers concerned that the program will increase predation on livestock and family pets.

The task of locating the radio-collared wolves is daunting. Biologists track the wolves in rugged, often steep, terrain. U.S. Fish and Wildlife agents must deal with wolves that leave the approved recovery areas, which do not have fenced boundaries. Sometimes it is possible to recapture and return the animals to the recovery area, but lethal removal is sometimes necessary to ensure the species’survival in the wild.

The Mexican gray wolf’s role in the ecosystem is filled by no other predators. Black bears and cougars roam these areas of the Southwest, but they don’t fill the wolf’s niche. Elk are a major source of food for the Mexican gray wolf. As the wolves disappeared, some areas suffered from an overabundance of elk, which led to environmental degradation. Keeping a balance between elk and wolves is crucial to the environmental health of those areas.

Mexican gray wolves weigh between 50-80 pounds and are about 5-feet long with a relatively large head. The coat is often mottled or patchy and varies from gray and black to brown and buff. They have complex social behavior, living in tightly organized packs and communicating through howling vocalizations, body posturing and scent marking. These animals work effectively together to adapt to most environments where there is prey, which includes deer, jackrabbit, mice and peccary.

As a critical predator, wolves have a profound effect on the ecosystem. When an ecosystem is out of balance there are a host of negative effects. Returning the wolves to their natural habitat helps to restore the environmental health of these areas.

John Linehan is President & CEO, Zoo New England and Brooke Wardrop is Publications & Grants Manager, Zoo New England

The importance of removing invasive plants

By Florrie Funk

 

An invasive plant is a non-native species capable of spreading aggressively and monopolizing essential habitat resources–

light, nutrients, water, and space, to the detriment of other species.

Our planet’s life forms co-evolved over millions of years as complex, interdependent communities of organisms called ecosystems. Each species within an ecosystem depends on other species to provide nutrients, circumstances necessary for reproduction, and limits to its expansion.

Many plants rely on fungi and other soil organisms to decompose dead plants and animals, thereby releasing nitrogen and other nutrients into the soil. Specific plants often depend on specific insect species to pollinate their flowers so that they produce seeds, and they depend on other animals to help disperse those seeds. The community of organisms that make up an ecosystem includes of a variety of herbivores, predators, fungi, bacteria and other pathogens that help an ecosystem stay in balance by preventing one species from increasing to the point of extirpating others. When biodiversity (the number of different species) is reduced, this compromises the ability of an ecosystem to withstand drought, blights and other environmental stresses.

In our suburban communities, native species are being weakened by loss of biodiversity caused by habitat fragmentation. Ever-smaller natural areas are being separated by ever-wider highways and developments. Small, isolated populations of plants and animals, unable to exchange genes with other populations, become inbred and eventually die out.

The introduction of alien organisms has seriously compounded this problem. Some alien species were introduced intentionally by horticulturalists and others arrived by accident in soil or imported products. Some of these species do not survive; others persist as benign members of the community. But others grow and reproduce rapidly, displacing whole communities of native plants, sometimes causing rapid reductions in biodiversity and the extinction of other species.

Worldwide, invasive alien species are the second leading cause of species extinction. (The leading cause is habitat destruction.) More than 28% of the world’

s native species are threatened or endangered. There are 4000 non-native species grown outside of cultivation in the US (including 200 species in MA). The economic cost is estimated at $137 billion dollars annually (mostly from lost crops) and has led to a decline of 42% of endangered and threatened species nationwide.

In Newton, the worst offending invasive plants are species planted as ornamentals, such as Norway Maples, Japanese Barberry, Burning Bush, Oriental Bittersweet Vine, Japanese Knotweed (sometimes called “bamboo”

), Common and Glossy Buckthorn, Asian Shrub Honeysuckles, and Tree-of-Heaven.  Many of the characteristics that make a plant a good garden choice – rapid growth, disease resistance, easy propagation – increase the chances of its becoming invasive. These plants all produce seeds that are carried by birds or wind into natural areas, roadsides and vacant lots where they germinate, grow quickly and reproduce. This vegetation often looks at first glance like nature happily doing what it is supposed to do.  But dense patches of Japanese Knotweed or monoculture groves of Norway Maples are actually heartbreaking reminders of the many dozens of species that are now gone:  wildflowers, ferns, grasses, shrubs, trees, plus the insects, birds and other animals that depend on them.

In the past, conservation areas were purchased and left alone, and nature took care of itself.  No longer.  Due to the proliferation of invasive species most forests and conservation areas must now be actively managed.  If invasive species are not controlled, overall species diversity will decline, and the loss will be irreversible.

The MA Department of Agricultural Resources “Massachusetts Prohibited Plant List” designates 141 plants, including many popular ornamentals that are now prohibited from being imported, sold or propagated.  This ban may help reduce the spread of invasive species, but in many cases the horse is already out of the barn.

Promising research is being done on biological controls, such as a beetle species that eats Purple Loosestrife (a highly invasive plant found in wetlands throughout North America), but these methods are still experimental and may entail ecological risks. To learn what you can do to help to limit the spread of invasive species, visit: newfs.org (New England Wildflower Society), tncweeds.ucdavis.edu (Nature Conservancy), nps.gov/plants/alien (National Parks Service) and www.newtonconservators.org (Newton Conservators).

Florrie Funk, florriemfunk@aol.com, has taught interpretive nature study programs in CA, FL, MO and IL and assisted with ecological research and habitat restoration at the Chicago Botanic Garden and in Highland Park. 

The Wonder of Green Roofs

By Clydia A. Davenport and Karen L. Weber, Earth Our Only Home, Inc.

 

 

The term green roof refers to a roof that is partially or completely covered with vegetation, usually with special membranes to protect the rooftop and hold the plants and growing media in place. Green roofs are a proven technology with significant potential to stabilize our climate by cleaning and cooling our air and reducing stormwater runoff.

Green roofs date back at least to 600 BC, to the Hanging Gardens of Babylon, one of the Seven Wonders of the World.  These were terraced structures that were built over arched stone beams, waterproofed with layers of reeds and tar, covered with soil and planted with trees and plants.  There are houses in the Orkney Isles of Scotland from 3600-2500 BC that appear to have had turf roofs. In Iceland, sod homes with grassy roofs were constructed hundreds of years ago. The idea spread throughout Scandinavia and other parts of Europe.  There is a green roof that was planted in 1914 in Switzerland on which an orchid (Orchis morio) thrives today that is otherwise extinct in the region, The Rockefeller Center in New York City has several green roofs that were installed in the 1930s.

Germany has been perfecting modern green roof technology since the early 1970s when the first complete green roof systems were developed and marketed.  These intensive systems require thick planting media of 8 inches or more to support a variety of plants and trees and can add upwards of 54 pounds per square foot.  In the late 1980s many green roof systems were developed for large flat roofs; these lighter and cheaper versions were designed to be self-irrigating and require minimal maintenance.  These systems are generally 3-5 inches in depth, weigh around 20-34 pounds per square foot and utilize various species of sedums, which are hardy succulent plants. 

Green roof systems can be incorporated into new construction or retrofitted onto existing buildings. 

They are usually found on commercial and public buildings, although they can be installed on smaller residential surfaces. Green roofs, unlike roof gardens, are applied as part of the roofing system and can be installed on a pitched roof. The components include the roof structure, a waterproofing membrane, a root barrier, a drainage system and/or water retention system, filter cloth to maintain the integrity of the green roof layers, a specially engineered lightweight growing medium, and plants. The cost of greening a roof starts at $11 per square foot, not including the structural analysis to determine the roof’s load capacity. 

Green roofs serve many environmental functions. They absorb carbon dioxide from the atmosphere in exchange for life-giving oxygen, they cool the air and they retain stormwater.  That means that once installed, they immediately reduce the urban heat island effect, reduce energy costs and reduce stormwater runoff. According to Prof. Brad Bass of University of Toronto, when a city installs enough green roofs to achieve a 1ºC drop in temperature, this will result in a 10% reduction in energy use. Green roofs also provide environmental services by creating new space for biodiversity to thrive, reducing allergens and asthma, diminishing air and noise pollution, and increasing roof longevity (which reduces the need for disposal of old roof membranes).

Nearly 10% of Germany’s building surfaces have green roofs, covering 50 square miles, and is currently adding 5 square miles of green roofs per year. North America lags far behind, with slightly more than 2 million square feet of green roofed space. Green roof installation is costly in the US, so the economic benefits are not always sufficient to motivate consumers.  Our local, state and federal governments need to provide incentives to accelerate the process.  In Toronto, the city subsidizes green roof installation by $2 per square foot. Germany offered large incentives during the initial years.  Tokyo passed a law in 2001 to require new buildings to green at least a fifth of their rooftops.  Chicago, a city with a celebrated green roof on its City Hall, has more than 200 green roofs, and is perhaps the greenest city in the US. It is now requiring developers to green all buildings that undergo city review.

When we cool our coastal cities with sufficient numbers of green roofs, we may even begin to cool our oceans by limiting freshwater runoff, and thereby slowing the rate at which coastal waters are being reduced in salinity due to human activity.  Some advocates feel that green roofs have the potential to keep the Atlantic’s thermohaline pump performing properly.

Green roofs limit greenhouse gas emissions, and therefore can help to slow global warming. The northeast corridor, from Boston to Washington, DC is contributing an enormous burden of CO2 to the atmosphere. Policymakers have an opportunity to turn our urban corridor into the Eighth Wonder of the World, a carpet of green roofs, and help preserve a livable world.

Earth Our Only Home, Inc. is a company led by three mothers committed to reversing the rate of global warming through green roof technology, www.earthouronlyhome.com

 

Biodiversity and Health: Locally and Beyond

By Yi Li

 

Dr. Edward O. Wilson, distinguished biologist and researcher at Harvard University, wrote nearly two decades ago that “biological diversity must be treated more seriously as a global resource.”  Wilson realized that the depletion of organismal variation was leading to a host of environmental and economic problems  Many scientists today share Wilson’s concerns about biodiversity; and this concern has only grown in the past few decades.  Biodiversity, defined as variation in life at all levels of biological organization, is quickly diminishing, and this erosion is being catalyzed by human pollution, consumption, and exploitation of our resources. 

In this area, one prominent example of the effects of loss in biodiversity can easily be observed.  Every fall in New England, incidences of Lyme disease increase as more people head outdoors to enjoy the weather and fall foliage.  Lyme disease is spread by small insects called ticks, and the disease is more prevalent in the northeastern United States because disease-bearing ticks and animals that serve as reservoirs for these ticks have become more prevalent as well.  This increase in the tick population and their hosts can be attributed to a recent decrease in their natural predators.   In the northeast, ticks are often carried by white-footed mice, and the predators of these mice – wolves and wildcats – have decreased in number over the years.  Additionally, the number of other small animals that may serve as targets for tick bites have decreased as well.  The synthesis of all of these factors leads to a rise in the number of cases of Lyme disease in the human population, serving as just one example of how the maintenance of biodiversity in our environment is so crucial to everyday health. 

Losses in biodiversity cause much environmental instability.  My arguments for the importance of biodiversity in health for human populations come mainly from two fields: a scientific argument based on the importance of environmental stability, and an economic argument based on the cost-effectiveness of preventative biodiversity measures. 

In scientific terms, throughout evolutionary history, when organisms become extinct or move away from their environments of origin, parasitic agents take over the niche that these organisms had inhabited.  These parasites often find new hosts, and when they jump from one host organism to another, new diseases begin to emerge.  Parasitologists postulate that this is the mechanism of emergence for new human diseases like West Nile Virus and the Avian Flu.  Currently, researchers still have a poor understanding of the exact roles that various identified parasites play in different diseases.  Research is still ongoing and is being aided by advances in fields such as molecular taxonomy.

The importance of biodiversity can best be illustrated through case-studies of diseases that have spread among human populations due to disruptions in biodiversity.  Deforestation in the Amazon and in remote regions of Africa has exposed people to diseases that originally inhabited wildlife; this is the proposed origin of diseases such as AIDS and Ebola.  Research by Dr. Peter Daszak, of the Consortium for Conservation Medicine, has also identified a connection between Chinese horseshoe bats and the outbreak of SARS in Asia.  Most poignantly, we may look back in history and see that the introduction of smallpox, typhus and measles by Spanish conquistadors to South American natives in the 15th century resulted in the deaths of nearly 50 million.  These examples illustrate how the introduction of disease-causing agents into environments where they were previously nonexistent can have profound consequences.

From an economic perspective, vast amounts of money and economic resources can be saved by taking a preventative approach to the loss in biodiversity, instead of a reactive one.  When SARS broke out in Asia, the economic losses from trade and travel totaled around $50 billion – a figure that hugely impacted the developing economies of the countries affected.  On top of that, 800 people died from the disease.  The costs of Lyme disease treatments in the United States total to nearly $500 million each year.  One can only imagine the magnitude of these figures for diseases such as AIDS where cost of care is staggering and new transmissions remain undiminished. 

A vastly better use of these economic resources is to take a preventative approach to these problems.  Scientists advocate for tougher regulations on trade, agriculture and travel as methods of reducing the spread of disease-causing agents and preventing the jump of diseases from wildlife to humans.  By protecting the environment, we prevent the catastrophic consequences of emerging disease and spend well below the current costs of reactive measures.  All of these benefits come in addition to the inherent benefits of preserving our natural resources and preventing organisms from extinction.  Many yet-unstudied and undiscovered organisms may hold the secrets to medical cures.  At one point, scientists believed that the Australian gastric brooding frog held the secrets to anti-ulcer treatments because these frogs incubate their young in their stomach only after shutting off digestive acids. Tragically, the frogs became extinct before scientists could study them – their secrets and mysteries died along with them.

As citizens of the metropolitan Boston area, with so many educational resources, we have many opportunities to learn more about the issues surrounding biodiversity.  The Harvard Center for Health and the Global Environment (chge.med.harvard.edu) and Wildlife Trust (www.wildlifetrust.org) are great online resources for more information on research, recommendations, and upcoming events.  We must also remain aware of legislation that will affect biodiversity locally and beyond.  Our actions begin with becoming aware of what organizations and companies to support, what initiatives to advocate for, and what political agendas to push for.  This approach to biodiversity maintenance requires a long-term vision, but the action must begin now.  We must take a stance on this issue before further diseases emerge as a consequence of our actions and before many more resources are depleted in the process.

Yi Li is a first-year student at Harvard Medical School. She served for two years as Editor-in-Chief of Duke University’s undergraduate Journal of Science and Technology.

Crabgrass: friend or foe?

By Bruce Wenning/ Special To The Tab

 

Undoubtedly you have noticed that crabgrass has invaded your lawn and is growing very well. You may be plotting against it, investigating herbicides. Perhaps you have been working on this problem for years. Crabgrass – and a weed-free lawn – may even have become an obsession. Crabgrass seeds can lie in the soil for years. This is why crabgrass suddenly appears after you turn over an unused garden bed or you renovate your lawn in spring or summer. The seeds are there, just waiting for the right amount of sunshine, heat and moisture to germinate and make you miserable.

Crabgrasses are coarse-bladed grasses with prostrate blades that spread at right angles to attached stems, reminiscent of the angular structure of a snowflake. They are lighter in color- and do not blend in with- finer bladed perennial turfgrass species and cultivars of Kentucky bluegrass (Poa pratensis), fine fescues (Festuca spp.) and rye (Lolium perenne). Two species of crabgrass, which can be found in the same lawn at the same time, are common in our area: large crabgrass (Digitaria sanguinalis) and smooth crabgrass (D. ischaemum).

Crabgrass is an annual; it spreads by seeds. At the first killing frost, crabgrass dies, turning brown against the green of more desirable species. However, it leaves behind in the soil seeds that will germinate the following late spring and summer, potentially filling in every available unoccupied space. Crabgrass seeds germinate every time you irrigate your lawn and after every rain. Compared with usual lawn species, crabgrass requires less water and fewer nutrients, and it spreads more efficiently in stressed areas, i.e. turf worn from foot traffic, compacted soils, dry soils, diseased and low nutrient lawns, and even areas under attack by white grubs! And because of its prostrate growth habit, crabgrass escapes the cutting action of the mower.

Fortunately, there is another way to look at this problem. Crabgrass can play a role in providing that inexpensive, green, maintenance – free lawn you have been striving for. It has the same utility as a fine home lawn. You can play on it, walk on it, complain about its appearance, not water or fertilize it and it will continue to grow with minimal care. Even if you cannot face the idea of a brown lawn after the first frost, you can still reduce the crabgrass population in your lawn without using herbicides.

Start by getting a soil test. Visit www.UMassGreenInfo.org for directions and costs. A soil test will determine the proper amount of lime to apply to correct soil pH (acidity) problems and allow you to select the right amount of organic fertilizer.

Be sure to water your lawn only one inch/week during the growing season (if there has not been sufficient rainfall); this encourages the growth of deeper roots. Lawns with deep roots have more resilience to environmental and biological stresses. Raise the mower blade height to at least two and a half inches; three is better. This will allow the grass to caste more shade on the soil below, thereby discouraging crabgrass (and other weeds) from germinating.

Throughout the growing season, remove crabgrass (and other weeds) by hand, which creates open spots where lawn grasses can spread. Then reseed your lawn between August 15-September 20, when nights are cool but the days, while still warm, are growing shorter, which inhibits weed germination and establishment. If you reseed your damaged lawn in spring or summer, the grass seed usually loses out to the quick germinating lawn weeds.

Bruce Wenning is the Environment Page Garden columnist. He is a horticulturist at the Mass. Audubon Society Habitat Wildlife Sanctuary, Belmont, and serves on the Board of the Ecological Landscaping Association.

This article is archived at www.greendecade.org/environmentpage

Controlling white grubs without chemicals

By Bruce Wenning/ Special To The Tab

 

White grubs are insect pests of home lawns, athletic fields, parks, gardens and anywhere their preferred hosts grow. They live in soil, are C-shaped, have six legs, chewing mouthparts, and feed on turfgrass roots and the roots of other plants. Lawns that are attacked by these pests show poor vigor, thin turf, smaller (or no) roots and bare spots susceptible to weed colonization.

The four white grub species of concern in our area are introduced pests and are very problematic on home lawns. They are Japanese beetle, Popillia japonica; Oriental beetle, Anomala orientalis; European chafer, Rhizotrogus majalis; and Asiatic garden beetle, Maladera castanea.

The life cycle for all four species is very similar: there is one generation per year, adult beetles are active during the summer, the grub (larval stage) is actively feeding on turfgrass roots in the fall (August through October) and again in the spring (April through May). It is too often assumed that all white grubs are the insecticide-susceptible Japanese beetles. They are not! And particularly as there are health concerns and environmental problems associated with the misuse and overuse of insecticides for the control of white grubs, it is very important to properly identify white grubs using a 10X hand lens, so that the least toxic control agents will be used. Unfortunately, landscape company personnel typically do not identify grubs by species.

·      The Japanese beetle grub has a small distinctive V-shaped rastral (spines) pattern, and a transverse anal slit on the 10th abdominal segment. These grubs are widely distributed in southern New England and are more susceptible (than the other species of white grubs) to chemical and nonchemical controls. Adult JBs feed on nearly 300 species of plants, including trees, shrubs and vines.

·      The Oriental beetle grub has a transverse anal slit (like the JB) but exhibits a unique straight and parallel rastral pattern. It is less susceptible to commonly used insecticides because it is quick to burrow down deeper into the soil during hot weather, where it is difficult to control.

·      The European chafer has a rastral pattern that is somewhat Y-shaped; rows of rastral spines look like an opening zipper near the anal slit. It is the most damaging to home lawns, causing turf to become easily dislodged from the soil. Sometimes called an “eating machine on lawn roots,” it’s the only grub that can feed during cold weather, causing root damage in the early spring and well into the fall, when the other grub species are inactive. It has even been detected feeding on lawn roots under snow in February. These grubs are hard to control with insecticides because they are larger in size than the other species and they have genetic characteristics that enable them to metabolize insecticides or avoid them.

·      The Asiatic garden beetle has a rastral pattern in the shape of a reduced semi-circle. Imidacloprid (trade name, Merit) is used for chemical control, but it has limited effectiveness. It is suspected that the spread of AGB is due to imidacloprid overuse: the chemical kills the other grub species and allows the expansion of this one.

Fortunately, there are biological control alternative to synthetic insecticides that can reduce the need for chemical control of white grubs. Although there is one commercially available type of nematode, Steinernema carpocapsae, that does not provide white grub control, another commercially available nematode, Heterorhabditis bacteriophora, has been shown by Dr. Albrecht Koppenhoffer (Rutgers University) to be an effective bio-control agent against Japanese beetle grubs. Dr. Patricia Vittum (University of Massachusetts) has demonstrated satisfactory control for all four species of white grubs using the HB nematode in late summer field trials, but the trials were limited in scope.

IPM Labs entomologist Carol Glenister notes that HB nematodes are most effective when the soil is warm in late summer (mid-August to early September) and the grubs are large. She does not recommend applying nematodes before then. She said that with the proper environmental conditions nematodes will reduce all grub species to varying degrees.

The HB nematode seeks out grubs for food and reproduction. When this nematode enters a white grub through a natural body opening, it releases a bacterium while it feeds on the grubs’ internal organs, and this eventually kills the grub. The nematodes then move through the soil to seek out more grubs.

The EPA exempts nematodes from the registration required for chemicals, and protective equipment is not needed to apply them. Commercially available nematodes are specific to pests stated on the label. Read and follow all instructions and be certain that the beneficial nematode matches the biology of the pest in question. To learn more contact: IPM LABS, Locke, N.Y. 315-497-2063, www.ipmlabs.com.

Bruce Wenning, the environment page garden columnist, is horticulturist and grounds manager, Massachusetts Audubon Society, Habitat Wildlife Sanctuary. massaudubon.org, and he serves on the Board of Directors of the Ecological Landscaping Association.

This article is archived at www.greendecade.org/tabarchive.asp.