Development of Sclerotinia Stem Rot in Potato Fields in South-Central Washington.

Sclerotinia stem rot, caused by Sclerotinia sclerotiorum, is a recurrent disease on potato in the Columbia Basin of Washington. The role of ascospores in association with disease onset and stem rot incidence in commercial fields and the role of flower blossoms on plant infection were investigated in 10 fields over 2 years. Ascospores of S. sclerotiorum were detected on a semiselective medium over several weeks, with a peak in number of ascospores near initial full bloom. A high proportion of blossoms at initial full bloom were contaminated with S. sclerotiorum prior to blossom fall in most fields. Stem lesions occurred after row closure and blossom drop, and were associated with mycelial mats growing from contaminated blossoms that had dropped on plant stems in the plant canopy or blossoms that dropped on the ground and stems contacting the ground. Incidence of Sclerotinia stem rot was reduced significantly when blossoms were removed from plants before blossom drop. Flower blossoms were shown to be a paramount bridge between airborne ascospores of S. sclerotiorum and stem infection in the potato canopy.

[1]  H. Shew,et al.  Evaluation of Wounds as a Factor to Infection of Cabbage by Ascospores of Sclerotinia sclerotiorum. , 2000, Plant disease.

[2]  H. Shew,et al.  Identification and Quantification of Ascospores as the Primary Inoculum for Collar Rot of Greenhouse-Produced Tobacco Seedlings. , 1998, Plant disease.

[3]  C. Lefol,et al.  Immunofluorescent staining of sclerotinia ascospores on canola petals , 1996 .

[4]  J. Steadman,et al.  A Semi-Selective Medium for Isolation of Sclerotinia Sclerotiorum , 1994 .

[5]  T. Turkington,et al.  Use of petal infestation to forecast Sclerotinia stem rot of canola: the influence of inoculum variation over the flowering period and canopy density. , 1993 .

[6]  M. E. Lacey,et al.  Release and dispersal of Sclerotinia ascospores in relation to infection , 1992 .

[7]  J. G. Morton,et al.  Factors determining the efficacy of chemical control of white mold in white bean , 1989 .

[8]  G. Boland,et al.  Epidemiology of Sclerotinia stem rot of soybean in Ontario , 1988 .

[9]  C. Grau,et al.  Effects of cultivars and cultural practices on Sclerotinia stem rot of soybean. , 1984 .

[10]  J. Steadman.  White mold -- a serious yield-limiting disease of bean. , 1983 .

[11]  J. Dueck,et al.  Wilt of sunflower from infection by mycelial-germinating sclerotia of Sclerotinia sclerotiorum , 1980 .

[12]  H. C. Huang,et al.  Control of sclerolinia wilt of sunflower by hyper parasites , 1980 .

[13]  L. H. Purdy.  Sclerotinia sclerotiorum: history, diseases and symptomatology, host range, geographic distribution, and impact. , 1979 .

[14]  J. Williams,et al.  Dispersal of ascospores of Sclerotinia sclerotiorum in relation to Sclerotinia stem rot of rapeseed. , 1979 .

[15]  G. Abawi,et al.  Infection of bean by ascospores of Whetzelinia sclerotiorum. , 1975 .

[16]  J. J. Natti.  Epidemiology and Control of Bean White Mold , 1971 .

[17]  Margaret A. Keay.  A STUDY OF CERTAIN SPECIES OF THE GENUS SCLEROTINIA , 1939 .