Date of this Version
Thesis (M.S.)—University of Nebraska—Lincoln, 1951. Department of Entomology.
Results of potato varietal tests at Scottsbluff Experimental Station, Mitchell, Nebraska have indicated that certain varieties are less susceptible than other varieties to tuber injury caused by the tuber flea beetle, Epitrex tuberis Gentner.
In 1949 and 1950, field tests were conducted to determine the nature of this degree of susceptibility and to determine what factors might be responsible for differences in tuber injury between varieties.Five potato varieties, Houma, Progress, Yampa, Doe Bay Red and a numbered line, 8.38-8, were grown and studied in these tests.
Data were taken on time of plant emergence, leaf area, leaf injury, stolon growth, stolon injury, time of tuber development, tuber growth habits and nutritive chemical composition of the tubers.Also, the seasonal cycle of the flea beetle in relation to the plants was studied.
Earliness of emergence did not seem to be important with respect to the number of feeding holes per square inch of foliage area.This is apparent from the data which shows that the number of holes per square inch for all varieties was more or less the same.
Doe Bay Red had a significantly lower, statistically, average per cent of infested stolons which could not be correlated to the lower average number of beetle forms per stolon.
In 1949 Doe Bay Red had significantly fewer, statistically, larval tracks per tuber than Houma or Yampa, but this was not true in 1950.Also, mature tubers of Doe Bay Red had fewer “slivers” per gram or surface area than the other varieties.
Although there was a significant difference, statistically, in sucrose content between Houma and Doe Bay Red, no definite statement can be made concerning this factor in relation to larval feeding.
The relationship of tuber development to the period of larval activity seems to be the important factor to the susceptibility to tuber injury of these potato varieties.However, many other factors such as oviposition, feeding preference and feeding habits were not investigated.
According to the data in this thesis, it appears that the susceptibility of Doe Bay Red to tuber injury is not based on physiological or morphological characteristics of the plant, but on ecological factors involving the seasonal habits of the tuber flea beetle.Perhaps, if Doe Bay Red plants were planted so as to develop at a time coincidental to the time of peak larval development, the tubers would be injured to the same extent as tubers of other varieties.
Advisor:R. E. Hill