Home / Resources and Writings / Weblog / Plant Diseases and Pests


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 | Comments (0)

 


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 | Comments (0)

 


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 | Comments (0)

 


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 | Comments (0)

 


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 | Comments (0)

 


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 | Comments (0)

 


Plant Insect Interactions of Ancient Times

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

Researchers are examining fossils from Patagonia and three sites in North America to gain insight into the historic biodiversity of the regions. Insect fossils are rarely found. By studying the damage caused by insects on the more abundant plant fossils, researchers are able to evaluate the type and level of insect feeding in prehistoric times. Life in Patagonia is among the most varied on the planet. The research shows that the region's biodiversity exceeded that of the other research sites as long as 52 million years ago.

Link: Fossil Patagonian plants show high insect feeding diversity 52 million years ago from EurekAlert

Posted by Eric La Fountaine at 5:56 PM | Comments (0)

 


Looking for Healthy Butternut Trees

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

Butternut trees (Juglans cinerea) are not common. Many people may have never tasted the nuts, which are prized in eastern N. America, where they are native. The tree is plagued by butternut canker, which has wiped out 80% of Juglans cinerea in some US states. To promote the tree researchers are searching the tree's native range for healthy stock to use in breeding research.

Continue reading "Looking for Healthy Butternut Trees"

Posted by Eric La Fountaine at 2:17 PM | Comments (49)

 


Managing the Effects of the Pine Beetle Infestation on BC’s Logging Communities

Category(-ies): Plant Diseases and Pests , Plant Legal News and Issues

More than seven million hectares of pine forest in British Columbia are now infested with the mountain pine beetle and there is no end to the spread of the pests in sight. BC’s logging industry is ramping up operations to harvest the glut of dead timber left in the wake of the infestation. The increased harvest is a boon to the economies of logging communities, but when the dead timber is depleted, many regions will need a new economic plan.

Continue reading "Managing the Effects of the Pine Beetle Infestation on BC’s Logging Communities"

Posted by Eric La Fountaine at 2:45 PM | Comments (0)

 


Smoke Jumpers Employed in “Bug Hunt”

Category(-ies): Plant Diseases and Pests

Asian longhorned beetles (ALBs) first arrived in N. America 9 years ago, inadvertently brought in from China in green-wood palettes. ALBs seriously threaten maples, birches, poplars, horse chestnut, willow, alders, birches and other tree species in Canada and the US. It is very difficult to spot trees infected with the beetles. To aid in the task, smoke jumpers, who normally fight western forest fires, have been brought in to work high in the treetops, where signs of infestation are most evident.

Continue reading "Smoke Jumpers Employed in “Bug Hunt”"

Posted by Eric La Fountaine at 4:57 PM

 


Moths Threaten Hemlocks in National Park

Category(-ies): Plant Diseases and Pests

A 'new' pest destroying hemlock trees concerned park managers in Nova Scotia's Kejimkujik National Park in 2002. It took forest ecologist Blair Pardy a year to identify the invader. It turned out to be a native moth that had not been seen since the 1950s. The pale-winged moth had not been known to seriously defoliate hemlocks before.

Park managers are watching for a return of the pest this year. They are developing a replanting strategy and hoping chemical controls will not be necessary.

Link: Moth outbreak threatens hemlocks at national park from the CBC

Posted by Eric La Fountaine at 4:43 PM | Comments (0)

 


Remote Sensing as an Agricultural Tool

Category(-ies): Plant Diseases and Pests

In the late 1920s, when local pilots reported that they could identify areas of disease in fields of cotton, scientists at Texas Agricultural Experiment Station realized that aerial photos could be used to assess and measure diseased areas in field crops. Over the years researchers realized that different wavelengths, including those beyond the visible spectrum revealed different conditions in plants. Images from above could indicate a problem in the field before the grower was even aware of it.

Continue reading "Remote Sensing as an Agricultural Tool"

Posted by Eric La Fountaine at 5:26 PM

 


Genome of Fungal Threat to Rice Crop Sequenced

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

Researchers at the International Rice Blast Genome Consortium at North Carolina State University have unravelled the genome of Magnaporthe grisea, one of the worst threats to the world�s rice crop. Scientists hope the work will uncover new methods of control for the pest. It is the first pathogenic plant fungus to have its genetic code sequenced.

Continue reading "Genome of Fungal Threat to Rice Crop Sequenced"

Posted by Eric La Fountaine at 4:48 PM

 


Watching for the Spread of Sudden Oak Death in the US Southeast

Category(-ies): Plant Diseases and Pests

Officials are asking residents in the southeastern US to be on the look out for signs of sudden oak death in camellias, rhododendrons and other ornamentals. The disease arrived in the region last year in shipments of ornamentals from nurseries in California and Oregon. Officials destroyed some of the shipments after finding the disease, but most had already been sold. Since sudden oak death was first discovered in California in 1995, it has killed thousands of native oak trees in the state.

Continue reading "Watching for the Spread of Sudden Oak Death in the US Southeast"

Posted by Eric La Fountaine at 4:04 PM

 


Hikers Spreading Sudden Oak Death?

Category(-ies): Plant Diseases and Pests

Research conducted by J. Hall Cushman, a biologist at Sonoma State University in California, seems to indicate that hikers and other recreational trail users are spreading the pathogen that causes sudden oak death. The pathogen was found along trails in grasslands and other uninfected forest areas, while samples a few metres from the trail turned up few or no spores of the disease.

Continue reading "Hikers Spreading Sudden Oak Death?"

Posted by Eric La Fountaine at 2:29 PM

 


Public Recall of Camellias in BC

Category(-ies): Plant Diseases and Pests

The BC Landscape and Nursery Association is working with the Canadian Food Inspection Agency to organize a public recall of recently-purchased camellias to halt the transmission of Sudden Oak Death, Phytophthora ramorum.

Continue reading "Public Recall of Camellias in BC"

Posted by Daniel Mosquin at 3:59 AM

 


Fungus causing sudden oak death distributed across US?

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

The San Francisco Chronicle has reported that spores of Phytophthora ramorum, the fungus that causes sudden oak death, have been discovered at Monrovia Nursery, the largest nursery in California. Monrovia was investigated after being traced as the source of infected camellias distributed to a small Washington state nursery.

Continue reading "Fungus causing sudden oak death distributed across US?"

Posted by Eric La Fountaine at 3:13 PM

 


And so it spreads...

Category(-ies): Plant Diseases and Pests

BBC News reports that sudden oak death (a fungus named Phytophthora ramorum) has infected several species of native trees in England: beech, horse chestnut and holm oak.

Continue reading "And so it spreads..."

Posted by Daniel Mosquin at 11:23 PM