University of California

Effect of downy mildew on productivity of sugar beets, and selection for resistance


L. D. Leach

Author Affiliations

L. D. Leachs was Associate Professor of Plant Pathology and Associate Plant Pathologist in the Experiment Station.

Publication Information

Hilgardia 16(7):317-334. DOI:10.3733/hilg.v16n07p317. February 1945.

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For many years downy mildew has been recognized as a serious disease of sugar beets in the coastal regions of California during seasons when climatic conditions favored the development of the fungus. Farther inland, before 1935, this disease was considered of only minor importance; but in 1935, 1936, and 1937 there were serious epidemics over wide areas in the lower Sacramento Valley.

This disease, caused by Peronospora schachtii Fuckel, has been known in Europe since 1852, but was first reported in the United States by R. E. Smith and E. H. Smith (7)4 in 1911. During subsequent seasons downy mildew appeared sporadically in the coastal sugar-beet-producing areas. In 1926 and 1927 Bensel5 reported severe outbreaks in the Santa Clara Valley. Since 1930 the disease has appeared regularly in the Salinas Valley of Monterey County, the Santa Maria Valley of Santa Barbara County, and in Ventura and Orange counties. There were destructive outbreaks in the Salinas Valley in 1930, 1937, and 1938; moderate epidemics during other seasons. According to a 1937 survey by Mr. Suttie of the Spreckels Sugar Company, covering 3,721 acres, about 22 per cent of the beets were infected by the middle of June. In 1938, up to 80 per cent of the beets were infected in some fields in the Salinas Valley.

Literature Cited

[1] Abegg F. A. A genetic factor for the annual habit in beets with linkage relationships. Jour. Agr. Res. 1936. 53:493-511.

[2] Brewbaker H. E. Self-fertilization in sugar beets. Jour. Agr. Res. 1934. 48:323-37.

[3] Downs E. E., Lavis C. A. Studies on methods for control of pollination of sugar beets. Jour. Amer. Soc. Agron. 1930. 22:1-9. DOI: 10.2134/agronj1930.00021962002200010001x [CrossRef]

[4] Leach L. D. Downy mildew of the beet caused by Peronospora schachtii Fuckel. Hilgardia. 1931. 6:203-51. DOI: 10.3733/hilg.v06n07p203 [CrossRef]

[5] Leach L. D. Effect of downy mildew on size, sucrose percentage, and purity of sugar beets 1938. pp.64-66. (Mimeo.). Proceedings of First General Meeting, American Society of Sugar Beet Technologists. [Salt Lake City, Utah; Jan. 13, 1938.]

[6] Singalovsky Zehara. Etude—morphologique, cytologique et biologique due Mildiou de la Betterave (Peronospora schachtii Fuckel). Annales des Epiphyties et de Phytogénétique n.s. 1937. 3(4):551-618.

[7] Smith R. E., Smith E. H. California plant diseases. California Agr. Exp. Sta. Bul. 1911. 218:1039-1193. http://www.archive.org/details/californiaplantd218smit

Leach L. 1945. Effect of downy mildew on productivity of sugar beets, and selection for resistance. Hilgardia 16(7):317-334. DOI:10.3733/hilg.v16n07p317
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