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Poplar trees (genus Populus, not to be confused with yellow-poplar, Liriodendron tulipifera) are among the fastest-growing trees in the world, and represent a diverse wide-spread genus of trees. Poplars are grown in plantations for pulp and paper, and have great potential as feedstock for biofuels production.
Poplars have a lot of advantages as experimental plants, as they grow clonally from cuttings and are easy to hybridize. The poplar genome has been sequenced, making poplars even more attractive as research subjects and for advanced breeding.
Gary Coleman and his colleagues at the University of Maryland and Bowie State University have just received a $3.2 million grant from the National Science Foundation to take advantage of the poplar genome map to try to improve the prospects for poplars as a biofuel feedstock.
Coleman’s group will use the poplar gene map to examine details about how poplars store and use nitrogen. Nitrogen is often the most limiting element in crop productivity, and trees are already fairly efficient at nitrogen use. Understanding the molecular details of how poplars use nitrogen may help increase productivity of poplar plantations with minimal nitrogen input.
Poplars already have advantages over more familiar biofuel crops such as switchgrass and Miscanthus. Poplars can grow on marginal farmland unsuitable for food production, minimizing competition between biofuels and food crops. Increasing the nitrogen efficiency of poplar plantations is an important step in making biofuel production economically viable.
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The goldspotted oak borer, Agrilus coxalis Waterhouse (Coleoptera:Buprestidae), is adding to the woes of California’s magnificent oak forests.
While sudden oak death is killing oak and other trees in the northern part of the state, the oak forests of the southern part of the state have escaped damage due to the dry conditions that prevent spread of the disease.
Now, the goldspotted oak borer is causing oak mortality in the southern part of the state. Like other Agrilus beetles, such as the emerald ash borer and twolined chestnut borer, the goldspotted oak borer kills trees when the larvae feed on the phloem and cambium.
The borer, first identified during oak mortality surveys in 2004 in San Diego County, has been found attacking coast live oak, Quercus agrifolia, canyon live oak, Q. chrysolepis, and California black oak, Q. kelloggii, on the Cleveland National Forest. It is now considered a major cause of oak mortality in Southern California.
The goldspotted oak borer is native to parts of southern Arizona, Mexico and Guatemala. It has not previously been considered a major pest in those areas. While the borer may have extended its range naturally, is it likely that it was introduced into southern California by movement of firewood, as with the emerald ash borer.
It remains to be seen how significant a pest this will turn out to be. Major mortality was not seen until 2008 in Cleveland National Forest, and it will take some years to assess the extent of the outbreak. A risk assessment by the US Forest Service (click map for details) shows that oak forests throughout California are at risk from this pest.
Additional information: USDA Forest Service Pest Alert: Goldspotted Oak Borer. (pdf, will open in new window)
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The annual maple sap flow has begun early in parts of Maine. According to the Bangor Daily News, mild day and night temperatures and a lack of snow is having a strong effect on Maine’s maple syrup industry. The average start date for sap flow in Maine is March 20, with central Maine beginning March 7-10.
This year, sap flow is already strong in parts of the state, while daytime temperatures are still too low in other areas. The forecast for this year’s production is unpredictable because of the strange weather patterns.
Sap flow in maples occurs when warm days and cold nights stimulate conversion of starch to sugar, and the osmotic potential created by high sugar concentrations in sap draws water in from the soil. This creates a positive pressure in the xylem, allowing sap to flow from cuts in the stem.
Global warming is predicted to drive sap production further north, as spring weather warms more quickly. Average night-time temperatures are increasing throughout New England, and this does not bode well for the long-term prospects for the US maple syrup industry. However, 2009 was a record year for syrup production in Maine following a disastrous 2008.
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Pawpaw, Asimina triloba, is a small understory tree very common in Appalachian forests. The fruit, prized by people and possums alike, has a custardy texture and flavor. The fruit, as well as the tree, is called Hoosier banana, at least in Indiana. Pawpaw is a member of the family Annonaceae, an important family of mainly tropical trees and shrubs. Pawpaw has many tropical characters, from its strange purple flowers to its broad, undissected leaves.
Here are some photos of the amazing flowers and young fruit of pawpaw. Click the pictures for really big images. The purple flower is especially glorious at full screen.
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