Treesearch

Phytophthora cinnamomi (Phytophthora crown and root rot, or ink disease) is now known to infect several hundred plant species in the world and is especially linked to the widespread death of mature chestnut (Castanea) and evergreen oak (Quercus ilex L.) trees in southeast United States. With an expanding geographical distribution of P. cinnamomi in Northern America, and coupled with the chestnut blight disease (caused by Cryphonectria parasitica) that initially decimated the 4 billion-strong American chestnut population (about 30 percent of trees in the Appalachian mountains), P. cinnamomi...

Port-Orford-cedar (Chamaecyparis lawsoniana (A. Murray) Parl.) (POC) is an economically and ecologically valuable tree in the forests of southwest Oregon and northern California and in the horticultural trade worldwide. Phytophthora lateralis, the aggressive, invasive cause of POC root disease, was introduced to the native range of POC about 1950, and has since killed trees along roads and streams throughout the forest area where the tree grows. The federal forest management agencies responded with an integrated disease management program designed to slow further spread of the pathogen in...

A major limiting factor for the culture of true firs as Christmas trees is their susceptibility to Oomycete species belonging to the genus Phytophthora. In North Carolina alone, the Fraser fir (Abies fraseri [Pursh] Poir.) Christmas tree industry loses 6 to 7 million dollars annually to root rot primarily caused by Phytophthora cinnamomi. Because no resistance has been found in Fraser fir, in 2003, the North Carolina State University (NCSU) Christmas Tree Genetics (CTG) Program conducted an extensive resistance screening of 32 Abies species (50 unique taxa) from around the world.

The balsam woolly adelgid, Adelges piceae (Hemiptera: Adelgidae) (BWA), first reported on Fraser fir, Abies fraseri (Pursh) Poiret, on Mount Mitchell in 1955 (Amman 1966, Boyce 1955), is a major pest in Christmas tree plantations and in native stands. Nearly all Fraser fir Christmas trees produced in North Carolina need to be treated one or more times during their 5- to 10-year rotation to prevent or lessen damage caused by this adelgid. These chemical treatments cost the industry over 1.5 million dollars per year (Potter et al. 2005) and may compromise the effectiveness of integrated pest...

American chestnut (Castanea dentata (Marsh.) Borkh.) once was a primary hardwood species in forests of the eastern United States. Sometime during the late 18th century, it is speculated that Phytophthora cinnamomi, which causes Phytophthora root rot (PRR) on many woody plant species, was introduced to the southeast region of the United States, and this pathogen spread as people moved inland from the coast (Zentmyer 1980). In the 1800s, PRR (also known as ink disease) caused extensive mortality to American chestnut trees in the southern portion of its range (Freinkel 2007, Zentmyer 1980)....

Beech bark disease (BBD) is an insect-disease complex that has been killing American beech (Fagus grandifolia Ehrh.) trees since the accidental introduction of the beech scale insect (Cryptococcus fagisuga) to Canada around 1890. Insect infestation is followed by infection with Neonectria ditissima or N. faginata. Mortality levels in the first wave of the disease can be as high as 50 percent, with consequent loss to stand health, merchantable timber, and many wildlife and ecosystem services. It is currently estimated that between 1 and 5 percent of the native American beech are resistant...

Butternut (Juglans cinerea L.) is being killed throughout its native range by an exotic fungus Ophiognomonia clavigignenti-juglandacearum (Ocj). In recent years, many disease-free trees have been determined to be complex hybrids with an admixture of Japanese walnut (J. ailantifolia). Recently developed molecular and morphological characterizations allow us to accurately identify and separate hybrid and pure butternut progeny. Disease-free-trees, from across butternut's native range, are the basis of our breeding program in the Central Hardwood Region of the eastern United States. Our first...

Laurel wilt is a highly destructive disease of redbay (Persea borbonia (L.) Spreng.) and other Lauraceous natives in the southeastern United States. The disease and associated vector, the redbay ambrosia beetle (Xyleborus glabratus), has spread through the United States coastal plain. The presence of surviving and asymptomatic individuals in severely-affected stands illustrates the possibility of natural resistance by surviving redbays. In 2008, a field survey was initiated to locate and identify healthy, asymptomatic redbays in areas of severe mortality. Six heavily-affected sites were...

Eucalyptus plantations cover about 1.5 percent of the agricultural area in Brazil, and contribute to 4 percent of GDP and 3 percent in exports of forest products. Technological and research advances in silviculture and genetic improvement have increased productivity up to 80 m³ of wood/ha/year, with an average of 35 to 45 m³/ha/year. The greatest challenge to the introduction and commercial use of exotic species is the adaptation of species to climatic conditions. Even when maladapted species are able to survive, they are subjected to continuous stress that limits the expression of their...

In a greenhouse trial to examine genetic resistance among seedling families (half-sib, full-sib, and selfed) of Port-Orford-cedar (Chamaecyparis lawsoniana (A. Murr.) Parl.) to the root pathogen Phytophthora lateralis, the root tips of seedlings were inoculated, and the subsequent mortality was followed over a 3 year period. Mortality among families at the end of the trial varied from 0 to 100 percent, with continuing mortality for some families occurring throughout the trial period. A preliminary examination of mortality curves for the families indicated that some families were highly...