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Restoring the American Chestnut

Category(-ies): Plant Conservation , Plant Diseases and Pests

Once an estimated 4 billion trees strong, the American chestnut was almost wiped out by chestnut blight. Efforts are underway to help partially restore the species, by interbreeding the American chestnut with its disease-resistant Chinese relative. The end result of a hybridization program yielded a "new" American chestnut that contains approximately 94% genetic similarity to the original American parent, but confers resistance to the blight. Tens of thousands of the trees have been planted, with (so far) an 80-90% survival rate.

Posted by Daniel Mosquin at 3:39 PM

 


Why is Rye as a Cover Crop an Effective Weed Killer?

Category(-ies): Plant Diseases and Pests

And another from Claire...

John Teasdale from the USDA's Sustainable Agricultural Systems Laboratory has teamed up with Cliff Rice from the USDA's Agricultural Research Service to investigate the science behind why rye works as a cover crop against weeds. Rye is often used on organic farms as an alternative to herbicides, because of its ability to prevent soil erosion and block sunlight, thereby suppressing weed invasion. Teasdale and Rice have tested whether organic compounds found in rye, called benzoxazinoids, are also responsible for weed suppression. Their results suggest that benzoxazinoids do affect soil chemistry in ways that enhance the weed-suppressing abilities of rye and are worthy of further study.

Links:

Posted by Daniel Mosquin at 7:00 AM

 


Sweet Potato Protection is More Than Skin Deep

Category(-ies): Plant Discoveries , Plant Diseases and Pests

Thank you again to Claire Thompson for providing another entry:

Researchers from the USDA's Agricultural Research Service have found beneficial compounds in sweet potatoes that provide protection against plant diseases. The research team found measurable amounts of protective compounds called caffeoylquinic acids, which act as antioxidants against several types of plant fungi.

Links:

Posted by Daniel Mosquin at 1:42 PM

 


Australia's Wild Wollemi Pines Threatened by Disease

Category(-ies): Plant Conservation , Plant Diseases and Pests

Wollemi pines were thought to be long extinct until a park ranger discovered two small groves of the trees in 1994. Fewer than a hundred trees were found. Researchers have kept the location of the wild population secret. Although the scientists have been very careful not to introduce pathogens, an infection of Phytophthora cinnamomi, believed to have been brought in by a hiker, has recently been discovered in the groves. Although propagations of the trees now grow in gardens around the world, the wild groves are important to research and prized for their extreme rarity and remarkable survival.

Link:
Disease hits Australia’s ‘dinosaur’ trees from Aljazeera

For background see this earlier weblog entry: Auction of Jurassic Trees Brings in Over a Million Dollars

Posted by Eric La Fountaine at 12:44 PM

 


Fungi Share More than a Taste for Cocoa

Category(-ies): Plant Diseases and Pests

Two of the most troubling pests for cocoa farmers, witches' broom and frosty pod rot, were thought to be very different types of fungi. The morphology of the two is quite different; one lives in the branches and forms structural shoots and fruiting bodies, the other forms a cottony coat on the pod and has no apparent fruiting bodies.

Some researchers suspected that the two pathogens might be related because of similar symptomology. Modern DNA analysis of the fungi confirmed that they were not only closely related, but that the two form a new genus, yet to be named.

Link: Fungal Threats to Cocoa Share an Ancient History from the Agricultural Research Service of the US Department of Agriculture

Posted by Eric La Fountaine at 2:52 PM

 


How Plants Resist Powdery Mildew Infection

Category(-ies): Plant Diseases and Pests

Powdery mildew is a common fungal disease that infects more than 9,000 plant species. Recent research found that plants use various genetic defenses against the infection. The plant's first line of defense against the pathogen is at the cell wall. Scientists, working with arabidopsis, have identified two genes, called PEN1 and PEN2, that block the fungus from entering the cell. Each works in a different way, and although the mechanisms are not yet understood, researchers think the process is relatively simple.

Powdery mildew and other fungal diseases cause growers great losses each year. Scientists hope to use the arabidopsis genes to develop new crops that are resistant to fungal infections.

Link: Genetic defenders protect crops from fungal disease a news release from the Carnegie Institution

Posted by Eric La Fountaine at 3:15 PM

 


Bacteria "Sniffs Out" Plant Wounds

Category(-ies): Plant Diseases and Pests

Crown gall is a disease of many woody species caused by a common soil bacterium, Agrobacterium tumefaciens. The disease causes considerable losses for fruit and wine grape growers. New research shows how the pathogen infects its hosts, using a protein sensor to "sniff out" compounds emitted from plant wounds. The findings will help scientist develop controls for the gall tumours.

Continue reading "Bacteria "Sniffs Out" Plant Wounds"

Posted by Eric La Fountaine at 10:49 AM

 


Weeds Harbour Grape Disease

Category(-ies): Plant Diseases and Pests , Plant Relationships

New research indicates that one of the most destructive diseases of grapes, Pierce's disease, is present in many of the common weeds found in California vineyards. Insect pests spread the bacterial infection to grapes. The level of infection varied greatly among host species in different environmental conditions. Scientists are evaluating the individual responses of weeds to the disease. The findings suggest that better weed control in fields and adjacent areas will aid in suppression of the disease.

Link: Vineyard Weeds Found to Host Pierce’s Disease of Grapes from Newswise

Posted by Eric La Fountaine at 10:00 AM

 


Urgent Action Needed to Combat Emerald Ash Borer

Category(-ies): Plant Diseases and Pests

The emerald ash borer (EAB) has killed at least 8 million trees, since it was first discovered in Michigan in 2002. Authorities in the affected areas have set up quarantines and pesticide programs for uninfected trees, but fear that the destruction of all ash trees in the region will be necessary. If the pest cannot be contained it could wipe out all Fraxinus species in N. America.

Frank W. Telewski of the W. J. Beal Botanical Garden and Campus Arboretum at Michigan State University has initiated a conservation effort for native Fraxinus spp. with Dave Ellis of the Plant Genetic Resources Preservation Program to collect and store seeds as a precaution in case efforts to exterminate the pest are not successful. To read the letter posted to the American Association of Botanical Gardens and Arboreta Listserv by Dr. Telewski see Call to action re: Emerald Ash Borer.

Links:

Posted by Eric La Fountaine at 12:08 PM

 


Clinging Perennial Weed Problem Grows

Category(-ies): Plant Diseases and Pests

As agriculture adopts low tillage methods, perennial weeds are becoming a growing problem. One of the worst is redvine, Brunnichia ovata, a perennial woody vine, whose deep roots make control difficult. Researchers studying the mechanisms that allow the vine to climb have made two new discoveries. When the tendrils of redvine rub against an object, phenols in the plant react with polyphenol oxidase to form a sticky adhesive that the vine uses to cling. Secondly the researchers found that cells in the vine's tendrils produced lignin fibre, previously found only in trees. The lignin appears after coils form in the tendrils, allowing them to fix their position, ensuring a tight clasp on the host.

Link: New Insight into a Clinging Vine from the Agricultural Research Service of the US Depsrtment of Agriculture

Posted by Eric La Fountaine at 11:52 AM