MSpace - DSpace at UofM >
Faculty of Graduate Studies (Electronic Theses and Dissertations) >
FGS - Electronic Theses & Dissertations (Public) >

Please use this identifier to cite or link to this item: http://hdl.handle.net/1993/119

Title: Effect of preharvest management on yield, process quality, and disease development in Russet Burbank potatoes
Authors: Ronald, Andrew
Supervisor: Pritchard, Mervyn (Plant Science)
Examining Committee: Lamari, Lakhdar (Plant Science) Punter, David (Botany)
Graduation Date: February 2005
Keywords: potato
potatoes
late blight
Phytophthora infestans
desiccation
vine killing
diquat
fungicide
yield
process quality
tuber rot
sugars
specific gravity
preharvest
Issue Date: 19-May-2005
Abstract: Phytophthora infestans (Mont) de Bary is a devastating pathogen in potato producing regions around the world. Populations of the organism in Canada shifted during the mid-1990’s as the US-1 strain (A1, metalaxyl-sensitive) was displaced by the highly aggressive, US-8 strain (A2, metalaxyl-insensitive). An increase in the incidence and severity of late blight has followed. Late blight is controlled by cultural practices aimed at eliminating disease sources and by the application of foliar fungicides. Tubers can become infected at harvest from contact with blighted vines leading to severe losses in storage. In many production areas, growers desiccate vines two to three weeks prior to harvest to reduce late blight tuber rot. However, in Manitoba, because of the loss of potential yield that results from vine killing prior to harvest in a late maturing cultivar such as Russet Burbank, growers are reluctant to adopt this practice. The objective of this study was to develop recommendations for preharvest management practices that reduce storage losses due to late blight. Field trials were conducted in 1997 and 1998 to investigate the effect of vine desiccation with diquat and/or a late season application of chlorothalonil and copper hydroxide on yield, processing quality, and disease development in storage. Desiccating vines with diquat two weeks prior to harvest reduced yield and tuber size. Compared to the untreated control, the largest reductions in marketable yield were observed for the early September harvest. By the late September harvest, however, the effect of vine killing in reducing marketable yield was less apparent. Specific gravity was lower in the vine killed treatment for all harvest dates in 1997 and in the early and mid September harvests in 1998. Vine killing did not contribute to elevated levels of reducing sugars or consistently darker fry colour at harvest or during storage. Skin-set was improved when vines were desiccated for all harvest dates in 1997 and at the early September harvest date in 1998. Vine killing reduced tuber rot in storage caused by Fusarium dry rot and Pythium leak for the early and mid September harvest dates in 1997. The incidence of late blight tuber rot was reduced in storage for the early September harvest in 1998 when vines were desiccated. The late-season application of chlorothalonil and copper hydroxide did not reduce tuber rot in storage in storage either year. Results from this study indicate that vine killing two weeks before an early to mid- September harvest is not recommended in Manitoba because of reductions in yield and specific gravity. Alternative management practices to reduce late blight tuber rot in storage should be investigated.
URI: http://hdl.handle.net/1993/119
Type: Electronic Thesis or Dissertation
Appears in Collection(s):FGS - Electronic Theses & Dissertations (Public)

Files in This Item:

File Description SizeFormat
Andrew Ronald MSc v2.pdf1.84 MBAdobe PDFView/Open
View Statistics

Items in MSpace are protected by copyright, with all rights reserved, unless otherwise indicated.

 

Valid XHTML 1.0! MSpace Software Copyright © 2002-2010  Duraspace - Feedback