|Mahaffee, Walter - Walt|
Submitted to: American Journal of Enology and Viticulture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/2/2001
Publication Date: N/A
Interpretive Summary: Heavily infected grapevines were observed in conjunction with vine shelter use during the 1997 growing season in the Oregon Willamette Valley. This research examines the use of vine shelters in viticulture production and their effect on the development of grape powdery mildew. Five brands and four installation methods were examined. There was no difference in disease development among shelters but installation did impact disease development. Installations designed to increase airflow in the shelters resulted in disease development similar to no shelter control. Reduction in disease development was significantly correlated to prolonged exposures above 97 F. Horticultural traits were significantly affected depending on shelter brand and installation type.
Technical Abstract: Heavily infected grapevines were observed in conjunction with vine shelter use during the 1997 growing season in the Oregon Willamette Valley (personal observation). The influence of vine shelter use on the development of powdery mildew, Uncinula necator, was investigated in the field during the 1998 and 1999 growing season. Installations of vine shelters were examined for both incidence and severity of U. necator infection. Five brands and four installation types were examined. There were no significant differences among brands of vine shelters. The industry standard installation of 76 cm high tubes hilled with 7.6 cm of soil at the bottom to prevent airflow, resulted in significantly lower incidence of powdery mildew in both field seasons. Significantly increased disease incidence was observed in installations designed to increase airflow in the shelters. Reduction in incidence of disease on leaves was significantly correlated with prolonged temperatures above 36° within the vine shelters. Vine length was significantly increased depending on shelter brand and installation type in both years.