December 18, 2006, 4:48 AM CT

Christmas Dinners Depend On Control Of Plant Diseases

The British Society for Plant Pathology are asking you to spare a thought this Christmas for how plant diseases caused by pathogenic fungi, bacteria and viruses could affect your celebrations.

Why? Because the 12,000 tonnes or so of potatoes eaten have to be protected against the devastating potato blight, likewise Brussels sprouts from ring spot and white blister, carrots from cavity spot. Even the stuffing is under threat with blight of chestnut trees. Less obvious accompaniments include the wine (grape mildew), beer (barley mildew), coffee (coffee rust), and if there is any room left after the meal, the chocolates are from cocoa bushes that survived or were protected from the well-named witches broom or black pod diseases.

These "basics" are all taken for granted but are only there by controlling a whole range of diseases. Also our homes really wouldn't be complete at Christmas without the 'trimmings' of 7.5 million conifer trees, potentially susceptible to Dothistroma needle blight; this would cause needles to drop even before you collected the tree! These comments apply of course to any meal, celebratory or not and is applicable worldwide. A number of cultures are heavily dependent on rice for example, which succumbs to Magnaporthe rice blast, arguably of equivalent importance in those producing countries to potato blight. Our research makes sure that only high quality produce, free from diseases, makes it into your home and onto your plate.........

Posted by: Tom      Permalink         Source

December 11, 2006, 9:36 PM CT

Plant One Tree And Save The Earth

Can planting a tree stop the sea level from rising, the ice caps from melting and hurricanes from intensifying?

A new study says that it depends on where the trees are planted. It cautions that new forests in mid- to high-latitude locations could actually create a net warming. It also confirms the notion that planting more trees in tropical rainforests could help slow global warming worldwide.

In the first study to investigate the combined climate and carbon-cycle effects of large-scale deforestation in a fully interactive three-dimensional climate-carbon model, researchers from Lawrence Livermore National Laboratory, Carnegie Institution and Universite Montpellier II observed that global forests actually produce a net warming of the planet.

The study provides a holistic view of the deforestation issue. "This is the first comprehensive assessment of the deforestation problem" said Govindasamy Bala, lead author of the research that will be presented on Dec. 15 at the American Geophysical Society annual meeting in San Francisco.

The models calculated the carbon/climate interactions and took into account the physical climate effect and the partitioning of the carbon dioxide release from deforestation among land, atmosphere and ocean.

Forests affect climate in three different ways: they absorb the greenhouse gas carbon dioxide from the atmosphere and help to keep the planet cool; they evaporate water to the atmosphere and increase cloudiness, which also helps keep the planet cool; and they are dark and absorb a lot of sunlight, warming the Earth. Climate change mitigation strategies that promote planting trees have taken only the first effect into account.........

Posted by: Tyler      Permalink         Source

December 1, 2006, 4:27 AM CT

Seagrass ecosystems at a 'global crisis'

An international team of researchers is calling for a targeted global conservation effort to preserve seagrasses and their ecological services for the worlds coastal ecosystems, as per an article reported in the recent issue of Bioscience, the journal of the American Institute of Biological Sciences (AIBS).

The article "A Global Crisis for Seagrass Ecosystems" cites the critical role seagrasses play in coastal systems and how costal development, population growth and the resulting increase of nutrient and sediment pollution have contributed to large-scale losses worldwide.

"Seagrasses are the coal mine canaries of coastal ecosystems," said co-author Dr. William Dennison of the University of Maryland Center for Environmental Science. "The fate of seagrasses can provide resource managers advance signs of deteriorating ecological conditions caused by poor water quality and pollution."

Among its findings, the study analyzed an apparent disconnect between the scientific communitys concerns over seagrass habitat and its coverage in the popular media. While recent studies rank seagrass as one of the most valuable habitat in coastal systems, media coverage of other habitats including salt marshes, mangroves and coral reefs receive 3 to 100-fold more media attention than seagrass systems.........

Posted by: Jessica      Permalink         Source

November 28, 2006, 4:54 AM CT

Biocontrol of wavyleaf thistle being studied in Texas

Wavy leaf thistle was difficult to find along Panhandle highways five years ago. But now the noxious weed can be found moving into pastures, said a Texas Agricultural Experiment Station researcher.

Dr. Jerry Michels, Experiment Station entomologist at Bushland, along with Nagendra Earle, a West Texas A&M University graduate student, began looking at controlling the intruding noxious weed with natural controls about two years ago.

Michels' entomology team travels the highways to Colorado frequently each year to monitor biocontrol work with the U.S. Fish and Wildlife Service. At first, they noticed wavyleaf thistle growing in small clumps along roadsides, Michels said, but in the past few years it seemed to be spreading.

Deciding they wanted to look at possible control measures, he submitted a proposal for a grant to the Joe Skeen Institute for Rangeland Restoration. His team received funding for two years.

In spring 2005, Earle began mapping the infestations across the Panhandle. The highest concentrations were found in the northern Panhandle down to U.S. Interstate 40, he said. Wavyleaf thistle has been found along I-40 from New Mexico to Colorado, but not much to the south.

"Our idea was that it was coming in through vehicle traffic, because it is common in Colorado, Nebraska and Wyoming," Michels said. "Also, thistles love disturbed areas, so any road work could have increased the infestation".........

Posted by: Jessica      Permalink         Source

November 1, 2006, 4:18 PM CT

Old Leaves Need To Die In Time

In a study from the recent issue of The American Naturalist, scientists Alex Boonman and co-workers from the Netherlands show that it is beneficial for plants growing in a dense stand to shed their oldest, lower leaves once these become shaded. By using transgenic tobacco plants that do not shed their lower leaves, they were able to show that shaded old leaves become a burden to a plant because they no longer photosynthesize but still require energy to be maintained.

Moreover, the nutrients in these leaves can be more usefully employed by the plant when re-allocated to new leaves at the top of the canopy, where more light is available and higher photosynthetic rates can be attained. Previously, theoretical modeling has been extensively used to investigate how plants should distribute their leaf area and nutrients to maximize their photosynthesis and fitness. However, a direct experimental test was lacking till now.

"Keeping up with the neighbors is important for plants in leaf canopies" Alex Boonman states, "because failure to project enough leaf area at the top of the canopy means that some other plant will do it, with shading and therefore diminished photosynthesis as the consequence." The transgenics, which were originally developed by Susheng Gan and Richard Amasino at the University of Wisconsin, indeed produced less leaf area in the upper canopy layer than normal plants and performed less well in competition exeriments.........

Posted by: Jessica      Permalink         Source

October 24, 2006, 7:27 PM CT

New Theory For Mass Extinctions

A new theory on just what causes Earth's worst mass extinctions may help settle the endless scientific dust-up on the matter. Whether you favor meteor impacts, volcanic eruptions, cosmic rays, epidemics, or some other cause for the worst mass extinction events in Earth's history, no single cause has ever satisfied all researchers all the time for any extinction event. That may be because big extinctions aren't simple events.

The new Press/Pulse theory gets around the controversy by rejecting the all-or-nothing approach to mass extinction, calling instead on a combination of deadly sudden catastrophes - "pulses" - with longer, steadier pressures on species - "presses".

"What we wanted to do is move away from the idiosyncratic approach to extinction mechanisms and look for what these intervals had in common. If you have A and B you will get a mass extinction," said Ian West, a 2006 graduate of Hobart and William Smith Colleges in Geneva, NY.

West and Hobart and William Colleges paleontology professor Nan Crystal Arens are scheduled to present their work on the Press/Pulse theory on Wednesday, 25 October, at the Annual Meeting of the Geological Society of America in Philadelphia.

Using databases that chart genera of marine organisms and their extinctions through the fossil record, West and Arens divided the last 488 million years of geologic history into four groups: times of suspected impact events (Pulses), times of massive volcanic eruptions (Presses), times when neither Presses nor Pulses occurred, and times when Press and Pulse coincided. They compared average extinction rates in geologic stages in each of these groups.........

Posted by: William      Permalink         Source

October 12, 2006, 7:55 PM CT

Plants Become Air Quality Detectives

What does a garden have to do with the chemistry of the atmosphere and air quality? One of the newest exhibits at NASA Goddard's Visitor Center, Greenbelt, Md., is a project related to NASA's Aura satellite. Aura is currently studying atmospheric chemistry and air pollution from space. The new Aura Ozone Monitoring Garden is used to study air quality from the ground by seeing how ozone in the air damages the leaves of certain plants.

During the summer months of intense sunlight, the air surrounding major urban areas undergoes dramatic changes. Ozone is formed when chemical pollutants that are by-products of human activities such as biomass burning and the combustion of fossil fuels react in the presence of sunlight. Ozone is a molecule that at ground level is a harmful air pollutant in high or prolonged concentrations.

Ozone tolerance among plants and people varies. According to research at the Great Smoky Mountain National Park and elsewhere, many common species of plants are sensitive to high concentrations of ozone. The Aura Ozone Monitoring Garden features plants that are known to be ozone sensitive, such as white dogwood (Cornus florida) and cardinal flower (Lobelia cardinalis).

Many of the plants that have been found to be ozone sensitive thrive in a wide range of the temperate environments within the continental United States. Aura education personnel at Goddard chose a variety of plants for the garden that represent different growing environments, from agriculture to horticulture.........

Posted by: Jessica      Permalink         Source

October 8, 2006, 6:49 PM CT

Rearing An Army To Save Wheat

With wheat stem sawfly natural enemies in demand, Montana State University entomologists are investigating ways of increasing their availability.

This fall, the entomologists are concluding a two-year study that involved mass-rearing parasitic wasps that attack wheat stem sawfly larvae that tunnel the interior of developing wheat plants. The team includes entomologists David Weaver, master's graduate Godshen Pallipparambil-Robert and undergraduate Melissa Frazier of Kalispell.

Pallipparambil-Robert's work, as part of his completed master's degree, used large cages placed over wheat at the Post Agronomy Farm west of Bozeman. He deliberately infested the enclosed wheat with wheat stem sawflies, and then introduced the parasitic wasps. His research explored whether supplemental food provided as nectar from flowering plants or as honey water increases the number of parasitic wasps produced in each cage. Another part of his thesis project examined whether using special ultraviolet and visible light-transmitting windows increases the number of parasites.

"After two years, the research shows that the added light consistently causes small increases in the number of parasitic wasps, while the food supply is probably not important in these mass-rearing cages, because the parasitoids were added in large numbers, and attacked the available sawflies before the need to feed may have become critical " Weaver said. At lower parasitoid densities, supplemental food might be much more important, and research from other systems suggests that this is definitely true in natural settings. However, the goal of the research is to find ways to increase the supply of parasitoids from a controlled system to Montana wheat growers.........

Posted by: Jessica      Permalink         Source

October 4, 2006, 10:09 PM CT

Tree Rings Provide A 200-year-old Hurricane Record

Scientists have shown that an age-old "database"--tree rings--contains surprisingly accurate information about hurricane activity that occurred hundreds of years ago. By measuring different chemical forms of oxygen present in the rings, researchers identified periods when hurricanes hit areas of the Southeast more than 100 years before modern records were kept.

The technique allows scientists to extend from decades to centuries the time-frames of intense hurricane cycles and may help determine if the increase in the number of hurricanes hitting the Southeast since the mid-1990s is part of a regularly occurring cycle or due to causes such as global climate change.

Their research is being published in the Sept. 18, early online edition of the Proceedings of the National Academy of Sciences. It was funded by grants from the National Science Foundation and the University of Tennessee (UT).........

Posted by: Jessica      Permalink         Source

October 4, 2006, 8:23 PM CT

Light On Evolution Of Life Cycles

In the history of life on earth, one intriguing mystery is how plants made the transition from water to land and then went on to diversify into the array of vegetation we see today, from simple mosses and liverworts to towering redwoods.

A research team led by University of Michigan evolutionary biologist Yin-Long Qiu has new findings that help resolve long-debated questions about the origin and evolution of land plants. The work will be published online this week in the Proceedings of the National Academy of Sciences.

Two major steps kicked off the chain of events that helped land plants prosper, forming the basis for modern land-based ecosystems and fundamentally altering the course of evolution of life on earth, said Qiu. The first step was the colonization of land by descendents of aquatic plants known as charophyte algae. That event opened up a vast new world where the sun's intensity was undiminished by passage through water and where carbon dioxide-another essential ingredient for plant life-was abundant.

The second event was a key change in plant life cycles. Plants exhibit a phenomenon known as alternation of generations, in which two alternating forms with different amounts of DNA make up a complete life cycle. One form, known as a sporophyte, produces spores, which grow into individuals of the other form, called gametophytes. Gametophytes produce gametes-eggs and sperm-which unite to form a fertilized egg capable of becoming a new sporophyte, thus completing a life cycle. While all plants exhibit alternation of generations, some spend most of their life cycle as sporophytes, and others spend more time in the gametophyte phase.........

Posted by: Jessica      Permalink         Source