July
2007
, Volume
91
, Number
7
Pages
835
-
841
Authors
L. D.
Porter
,
USDA-ARS, Vegetable and Forage Crops Research Unit, Prosser, WA 99350
; and
D. A.
Johnson
,
Department of Plant Pathology, Washington State University, Pullman 99164-6430
Affiliations
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RelatedArticle
Accepted for publication 5 February 2007.
Abstract
ABSTRACT
Currently, there is no information on the viability of sporangia in soil of the new metalaxyl-resistant genotypes of Phytophthora infestans in the semiarid Columbia Basin of Washington and potato-growing regions throughout the world. Sporangia of metalaxyl-resistant US-8 and US-11 clonal lineages of P. infestans survived a maximum of 23 to 30 days in a Shano silt loam and a Quincy loamy fine sand. There were no significant differences between soil types in area under the spore survival curve (AUSSC) in two trials, however, sporangia of P. infestans in the Quincy sand had a significantly greater mean maximum days of sporangia survival (MDSS) than did the Shano silt loam in one of two trials. AUSSC and MDSS were significantly greater (P < 0.05) for sporangia in wet soil than in dry soil under shaded conditions. Mean AUSSC and MDSS significantly decreased (P < 0.01) under nonshaded conditions versus shaded conditions. Three metalaxyl-resistant isolates (two US-8 and one US-11) of P. infestans did not significantly differ (P < 0.05) in AUSSC and MDSS.
JnArticleKeywords
Additional keywords:
late blight
,
solar radiation
Page Content
ArticleCopyright
The American Phytopathological Society, 2007