Tuesday, May 13, 2014
Bacterial diseases
| Bacterial diseases | |
|---|---|
| Bacterial leaf blight and stalk rot |
Pseudomonas avenae subsp. avenae |
| Bacterial leaf spot |
Xanthomonas campestris pv. holcicola |
| Bacterial stalk rot | Enterobacter dissolvens = Erwinia dissolvens |
| Bacterial stalk and top rot |
Erwinia carotovora subsp. carotovora Erwinia chrysanthemi pv. zeae |
| Bacterial stripe |
Pseudomonas andropogonis |
| Chocolate spot |
Pseudomonas syringae pv. coronafaciens |
| Goss's bacterial wilt and blight (leaf freckles and wilt) |
Clavibacter michiganensis subsp. nebraskensis = Corynebacterium michiganense pv. nebraskense |
| Holcus spot |
Pseudomonas syringae pv. syringae van Hall |
| Purple leaf sheath |
Hemiparasitic bacteria |
| Seed rot-seedling blight |
Bacillus subtilis |
| Stewart's disease (bacterial wilt) |
Erwinia stewartii |
| Corn stunt (achapparramiento, maize stunt, Mesa Central or Rio Grande maize stunt) |
Spiroplasma kunkelii |
Friday, May 2, 2014
Many
efforts to reduce the environmental impacts associated with commercial
horticulture production have failed to influence the general public. For
example, one recent study showed that the use of organic fertilizers
offered no significant marketing advantage to producers of floral crops.
In contrast to the promotion of organic products, the use of
biocontainers (plant material-based, biodegradable pots) as alternatives
to conventional plastic containers has been shown to resonate with many
consumers.
The
authors of a new study say that, despite the positive public perception
of biocontainers' environmental benefits as alternatives to
petroleum-based plastic pots, the impact of biocontainers on commercial
greenhouse sustainability has not been thoroughly evaluated. The
researchers offer a first look at the overall sustainability of
biocontainers as part of a greenhouse production system. "Our work
adopted a grower's perspective and focuses on the environmental impacts
of container use during the plant production phase," explained Andrew
Koeser, corresponding author of the study published in HortScience (March 2014).
The team's "cradle-to-gate" study compared the secondary impacts that occur during the greenhouse production of plants grown in biocontainers. The life cycle assessment data for the study was obtained from interviews, published literature, propriety data sources, direct metering at the greenhouse facility, and original findings from a series of university greenhouse experiments. The authors noted that their work also offers an initial screening of commercially available biocontainers that could be used in future life cycle assessments that focus on manufacturing inputs and environmental impacts.
A conventional plastic container and nine types of biocontainers (bioplastic, coir, manure, peat, bioplastic sleeve, slotted rice hull, solid rice hull, straw, and wood fiber) were included in the life cycle assessments for greenhouse petunia production. The impacts were presented in terms of contribution to the carbon footprint or global warming potential (GWP) of a single finished plant in a 10-cm-diameter container.
Results showed that a traditional plastic container accounts for approximately 16% of overall carbon dioxide equivalents emissions during petunia production. However, electrical consumption for supplemental lighting and irrigation during plug production proved to be the leading source of CO2e emissions (more than 47%) in the model system. Differences in GWP when considering secondary impacts associated with the various biocontainers were minor, especially when compared with the other elements of production.
The researchers said that their results demonstrate that biocontainers could potentially be as sustainable as, or more sustainable, than plastic pots "once pot manufacturing and end-of-life data are considered." They emphasized that use of more efficient supplemental lighting sources may ultimately have the greatest impact on overall global warming potential for the production system assessed.
"Although biocontainers have been linked to reduced performance in plant growth, filling speed, shipping success, and irrigation demand trials, these differences do not have a dramatic effect on production sustainability from a global warming potential perspective," said the authors. "These results should be encouraging for growers and manufacturers looking to increase sustainability through the use and development of biocontainers."
The team's "cradle-to-gate" study compared the secondary impacts that occur during the greenhouse production of plants grown in biocontainers. The life cycle assessment data for the study was obtained from interviews, published literature, propriety data sources, direct metering at the greenhouse facility, and original findings from a series of university greenhouse experiments. The authors noted that their work also offers an initial screening of commercially available biocontainers that could be used in future life cycle assessments that focus on manufacturing inputs and environmental impacts.
A conventional plastic container and nine types of biocontainers (bioplastic, coir, manure, peat, bioplastic sleeve, slotted rice hull, solid rice hull, straw, and wood fiber) were included in the life cycle assessments for greenhouse petunia production. The impacts were presented in terms of contribution to the carbon footprint or global warming potential (GWP) of a single finished plant in a 10-cm-diameter container.
Results showed that a traditional plastic container accounts for approximately 16% of overall carbon dioxide equivalents emissions during petunia production. However, electrical consumption for supplemental lighting and irrigation during plug production proved to be the leading source of CO2e emissions (more than 47%) in the model system. Differences in GWP when considering secondary impacts associated with the various biocontainers were minor, especially when compared with the other elements of production.
The researchers said that their results demonstrate that biocontainers could potentially be as sustainable as, or more sustainable, than plastic pots "once pot manufacturing and end-of-life data are considered." They emphasized that use of more efficient supplemental lighting sources may ultimately have the greatest impact on overall global warming potential for the production system assessed.
"Although biocontainers have been linked to reduced performance in plant growth, filling speed, shipping success, and irrigation demand trials, these differences do not have a dramatic effect on production sustainability from a global warming potential perspective," said the authors. "These results should be encouraging for growers and manufacturers looking to increase sustainability through the use and development of biocontainers."
Thursday, May 1, 2014
Vitis vinifera
are common grapevines and are the world's favorite wine-producing
varietal. However, research has shown that grapevines are susceptible to
powdery mildew, a plant disease, which contributes to significant crop
loss for most commercial wine varietals that are cultivated each year.
Now, researchers at the University of Missouri have used frog eggs to
determine the cause of this disease, and have found that a specific gene
in the varietal Cabernet Sauvingon, contributes to its susceptibility.
"Powdery
mildew disease causes the leaves of the grapevines to lose their
chlorophyll and stop producing sugar," said Walter Gassmann, an
investigator at the Bond Life Sciences Center and professor in the
Division of Plant Sciences in the College of Agriculture, Food, and
Natural Resources at MU. "The grape berries also get infected, so the
quality and yield are reduced in multiple ways."
According to a report by the USDA, powdery mildew can cause major yield losses if infection occurs early in the crop cycle and conditions remain favorable for development. Powdery mildew appears as white to pale gray fuzzy blotches on the upper surfaces of leaves and thrives in cool, humid and semiarid areas according to the report.
Gassmann used unfertilized frog eggs to test and analyze genes found in the grapevine plants. He studied the biological role of a specific gene that contributes to grapevine's susceptibility to the fungus by incubating it in the frog eggs. Gassmann found that the fungus is able to trick the grapevine into providing nutrients, which allows mildew to grow and devastate the plant. His findings reveal one way that Vitis vinifera is genetically unable to combat the virus that causes powdery mildew.
"Not much is known about the way a grapevine supports the growth of the powdery mildew disease, but the frogs help us provide a reasonable hypothesis for what is going on and why Cabernet Sauvingon could be susceptible," Gassmann said.
Gassmann says this research will open the door for discussing techniques to breed more resistant grapevines in the future.
"The grapevine could be bred to prevent susceptibility and to keep the character of the wine intact," Gassmann said. "Isolating the genes that determine susceptibility could lead to developing immunities for different varietals and other crop plants and may contribute to general scientific knowledge of the grapevine, which has not been studied to the extent of other plants."
The study was funded by grants from the USDA National Institute of Food and Agriculture and was published in the journal Plant and Cell Physiology.
According to a report by the USDA, powdery mildew can cause major yield losses if infection occurs early in the crop cycle and conditions remain favorable for development. Powdery mildew appears as white to pale gray fuzzy blotches on the upper surfaces of leaves and thrives in cool, humid and semiarid areas according to the report.
Gassmann used unfertilized frog eggs to test and analyze genes found in the grapevine plants. He studied the biological role of a specific gene that contributes to grapevine's susceptibility to the fungus by incubating it in the frog eggs. Gassmann found that the fungus is able to trick the grapevine into providing nutrients, which allows mildew to grow and devastate the plant. His findings reveal one way that Vitis vinifera is genetically unable to combat the virus that causes powdery mildew.
"Not much is known about the way a grapevine supports the growth of the powdery mildew disease, but the frogs help us provide a reasonable hypothesis for what is going on and why Cabernet Sauvingon could be susceptible," Gassmann said.
Gassmann says this research will open the door for discussing techniques to breed more resistant grapevines in the future.
"The grapevine could be bred to prevent susceptibility and to keep the character of the wine intact," Gassmann said. "Isolating the genes that determine susceptibility could lead to developing immunities for different varietals and other crop plants and may contribute to general scientific knowledge of the grapevine, which has not been studied to the extent of other plants."
The study was funded by grants from the USDA National Institute of Food and Agriculture and was published in the journal Plant and Cell Physiology.
Story Source:
The above story is based on materials provided by University of Missouri-Columbia. The original article was written by Diamond Dixon. Note: Materials may be edited for content and length.
The above story is based on materials provided by University of Missouri-Columbia. The original article was written by Diamond Dixon. Note: Materials may be edited for content and length.
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