It’s that time of year when many of you are out and about scouting for the earliest signs of powdery mildew and implementing your vineyard spray programs throughout the state. Here’s a quick status update for powdery mildew forecasting and management.
The influence of atmospheric humidity on three aspects of sporulation of
Sphaerotheca pannosa (Wallr.) Lev. var. rosae Wor., which causes rose powdery
mildew, was studied on leaf disks of susceptible Rosa cultivar Samantha.
To study conidiophore production, leaf disks were inoculated on the adaxial
(upper) surface with conidia of S....
Published August 1935. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalog
Studies were conducted on pathogenic specialization and
heterothallism in Sphaerotheca pannosa var. rosae, causal agent of
rose powdery mildew.
Methods were developed for isolation and identification of
Sphaerotheca pannosa var. rosae races on rose. Monoconidial isolates were initiated on detached leaves, increased on host plants,
and inoculated to rose cultivars...
Published January 1944. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalog
An important disease of Vitis vinifera production in Oregon and all other commercial growing regions is powdery mildew of grape, caused by the obligate fungal pathogen Uncinula necator (Schwein.) Burril. Grape production can be characterized as a long-term investment in the establishment and maintenance of the vineyard. Establishment times have...
Podosphaera macularis causes one of the most important diseases, powdery mildew, of Humulus lupulus (hop). If left unmanaged, hop powdery mildew can cause total crop loss due to disease or browning of hop cones rendering the cones unmarketable to buyers. The Hop Powdery Mildew Infection Risk Index (HOPS) is heavily...
Grape powdery mildew (Erysiphe necator) causes economic damages to grape worldwide due to the cost of management and injury to berries. Each region where European grapevine (Vitis vinifera) is grown experiences a unique epidemic, and disease prediction models that are based on empirical correlations of weather data to disease fail...
Podosphaera macularis, causal agent of hop powdery mildew, is known to produce cleistothecia (syn. chasmothecia) in eastern North America and Europe, but ascocarps are not reported from the Pacific Northwestern region of North America. Reasons for the apparent absence of cleistothecia in the Pacific Northwest are unknown. We established that...
The Pacific Northwest has become one of the nation’s premier sweet cherry,
Prunus avium, production areas. As production of sweet cherries has flourished in
Oregon and Washington, so has powdery mildew, caused by the fungus
Podosphaera clandestina, which infects both foliage and fruit causing severe
economic damage to growers. Sweet...