Summary
1.
Treated potato tubers were planted in five successive years in soil where potatoes apparently never were grown before, to study the infection of potato plants withRhizoctonia.
2.
Potato tubers had only a very small percentage of infection withRhizoctonia in the first year and this infection increased considerably the second year and remained until the end of this investigation.
3.
Potato stems, stolons, and roots showed a small percentage of infection during the first two years and this infection increased considerably for stems and stolons and moderately for roots during the third year of the study and remained at the same level until the end of the investigation.
4.
Potato stems, stolons, and tubers are very susceptible and potato roots are somewhat resistant to infection withRhizoctonia.
5.
It appears that a period of only one or two years is necessary under favorable conditions to build up theRhizoctonia inoculum in the soil to produce maximum infection on potatoes.
6.
In controlling this disease it appears it is necessary besides treating tubers, to use long rotations.