Plant Disease (2010) 94, 557-562

C.A. Gallup and H.D. Shew (2010)
Occurrence of race 3 of Phytophthora nicotianae in North Carolina, the causal agent of black shank of tobacco
Plant Disease 94 (5), 557-562
Abstract: Black shank, caused by the oomycete Phytophthora nicotianae, causes significant annual yield losses in tobacco. Race 3 of P. nicotianae is reported here for the first time from North Carolina. It was identified from a North Carolina tobacco field with a history of tobacco varieties with Phl gene resistance and numerous field sites with no known deployment of varieties with the Phl gene. Race 3 was originally described from cigar-wrapper tobacco in Connecticut in the 1970s, but has not been reported in any other location since. Race 3 was defined as overcoming the Phl gene from Nicotiana longiflora but not the Php gene from N. plumbaginifolia. Stem and root inoculations were conducted on a set of host differentials to determine the virulence of North Carolina isolates. Stem inoculation was unable to distinguish between races 0 and 3 of P. nicotianae and is not a reliable method of identifying these virulence types. Race 1 gave a unique phenotype using stem inoculation. Root inoculation was the only reliable means of distinguishing between races 0 and 3. This is the first report of race 3 in North Carolina and the first report of damage to seedlings from root inoculations and to plants containing the Phl gene in naturally infested soil.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Full text of article
Database assignments for author(s): Courtney A. Gallup, David Shew

Research topic(s) for pests/diseases/weeds:
surveys/sampling/distribution

---

Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Phytophthora nicotianae	Tobacco (Nicotiana tabacum)	U.S.A. (SE)