Some factors influencing infection byCorynebacterium sepedonicum in potato plants
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Great variations have been observed in the severity of potato ring rot symptoms even when the tubers are inoculated in a presumably uniform manner. Several factors are responsible for this variation, some of which are treated in this paper.
When potato seed-pieces were cut directly through one or more eyes with a contaminated knife or inoculated in a bacterial suspension, the subsequent ring rot symptoms produced in the plant were more prevalent and more severe than those caused by cutting similar tubers between the eyes.
The repeated use of the bacterial suspension in which lots of potatoes were inoculated one after the other, drastically reduced the severity and prevalence of ring rot, particularly with the third lot treated. The fourth lot and all subsequent lots produced no plant symptoms whatsoever. p]The kind of inoculum, whether from a resistant or a susceptible variety, varied somewhat in virulence from year to year but over a period of five years the averages were very similar. In other words, the bacteria from resistant Teton tubers were no more pathogenic than the bacteria from susceptible Bliss Triumph tubers.
During the period from 1946–1949, ring rot symptoms never developed in potato plants at Laramie when the inoculum was diluted more than 1:1,000; however, in 1950 plant symptoms were found in all dilutionseries, even in the 1:1,000,000. Moreover, several potato lots produced ring rot symptoms when inoculated with trace amounts of bacteria the previous season or earlier.
KeywordsBacterial Suspension Potato Plant Seed Piece Susceptible Variety Disease Index
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