Disease detection through traditional techniques such as scouting fields on foot, molecular assays, or morphological identification of plant pathogens is time consuming and costly. Disease diagnosis in the field can be extremely subjective, and largely depends on the experience and knowledge of pathogen identification and disease quantification. This thesis provides...
Sweet corn (Zea mays L.) yields in the Willamette Valley of Oregon have been declining since the early 1990’s. Studies were done to determine if there is a relationship between ear weight and several disease parameters including necrotic crowns or stalk nodes, nodal root rot, radicle root rot, and sub-crown...
Commercial radish seed producers in the Willamette Valley of Oregon have observed a late season wilt in their seed fields. Twenty-two fields were surveyed for wilt in the Willamette Valley during June through August 2012 and 2013. Plants exhibiting wilt symptoms were collected from the fields and examined for vascular...
A necrosis at the tip of cones was observed on hop (Humulus lupulus), cultivar "Nugget", grown in Oregon in the early 1990's. Fusarium sambucinum and F. avenaceum were recovered from symptomatic cones in 1998 and preliminary inoculation experiments suggested both Fusarium species could cause hop cone necrosis. Studies were carried...
After an unusually high incidence of Fusarium canker was observed in commercial hop fields of the Pacific Northwest, field surveys were conducted and revealed that canker incidence ranged from 20 to 60% of bines sampled in six commercial fields, as well as wide-spread Hop stunt viroid infection in these six...
The Pacific Northwest is an internationally important region for the production of Brassica seed and other seed crops including grass seed. Oregon lawmakers mandated research into the co-existence of canola (Brassica napus) with other Brassica production in the Willamette Valley and House Bill 2427 was signed into law in 2013,...
The two most economically important plant pathogens in the Pseudoperonospora (Peronosporaceae) genus are P. cubensis, causal agent of cucurbit downy mildew, and P. humuli, causal agent of hop downy mildew. These organisms have been shown to be very closely related phylogenetically and morphologically. In 2005, researchers in Korea proposed that...
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David. H. Gent Cynthia M. Ocamb
The two most economically important plant pathogens in