Proceedings of the sudden oak death second science symposium: the state of our knowledge

Abstract

The Forest Service of the U.S. Department of Agriculture is dedicated to the principle of multiple use management of the Nation's forest resources for sustained yields of wood, water, forage, wildlife, and recreation. Through forestry research, cooperation with the States and private forest owners, and management of the National Forests and National Grasslands, it strives-as directed by Congress-to provide increasingly greater service to a growing Nation.The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, age, disability, and where applicable, sex, marital status, familial status, parental status, religion, sexual orientation, genetic information, political beliefs, reprisal, or because all or part of an individual's income is derived from any public assistance program. (Not all prohibited bases apply to all programs.) Persons with disabilities who require alternative means for communication of program information (Braille, large print, audiotape, etc.

Proceedings of the Sudden Oak Death Fourth Science Symposium

“…Taken together, these experiments indicate that aerial dispersal is very limited and above-ground plant-to-plant pathogen transfer requires direct contact. Similar evidence for short distance aerial dispersal in a mock nursery setting was observed by Tjösvold and others (2006). In contrast to short distance aerial dispersal, splash dispersal from water films (on non-infiltrating growing surfaces) and direct inoculation during tipping over of plants seem to play an important role in pathogen spread.…”

“…Approximately 16 percent of the samples were positive for P. ramorum, while P. citricola was the dominant species (> 70 percent). Dominance of P. citricola was also observed in the dispersal experiments of Neubauer and others (2006). Distribution of P. ramorum was not linked to clear disease foci, although the incidence was higher in specific cultivar blocks and was probably linked to the susceptibility of the given cultivars.…”

“…Studies of plant-to-plant spread in nursery settings have been limited. Tjösvold and others (2006) observed no spread beyond 30 to 50 cm, but the leaf area of the detector plants in their study was limited. Neubauer and others (2006) were not successful in observing spread of P. ramorum in a nursery experiment due to a rapidly spreading P. citricola co-infection.…”

“…Tjösvold and others (2006) observed no spread beyond 30 to 50 cm, but the leaf area of the detector plants in their study was limited. Neubauer and others (2006) were not successful in observing spread of P. ramorum in a nursery experiment due to a rapidly spreading P. citricola co-infection. Werres and others (2007) observed spread from irrigation water, but their study did not focus on plant-to-plant spread.…”

“…PAU was often found in soil, asymptomatic plants, and areas where PAA does not occur. Ioos and others (2006) suggested that PAU and PAM might have existed for a long time on or in the vicinity of alder trees before the recent emergence of large-scale death of alder in Europe. Thus the occurrence of PAU or PAM in the past might not have been noticed because of the lack of conspicuous symptoms or death of whole trees.…”