Response of potato tuber yield to stem injury by European corn borer (Lepidoptera : Crambidae) in the Mid-Atlantic United States

The response of potato,Solanum tuberosum L., tuber yield to stem injury by European corn borer, Ostrinia nubilalis (Hubner), larvae was investigated i n the Mid-Atlantic region of the United States for 3 yr. This, response was described for 'Superior', 'Atlantic', and 'Snowden' potato, which are earl y-season, midseason, and late-season maturing cultivars, respectively. To m odel the yield/injury relationship, a range of corn borer injury levels was established in the field by augmenting the natural infestation with varyin g densities of laboratory-reared larvae. Linear and nonlinear regression an alyses (plateau and second-order polynomial models) were used to describe t he relationship between yield of US. No. 1 grade tubers and the percentage of stems injured by corn borer larvae.. The maturity of the cultivar did no t affect the response of potato yield to stem injury. In nine of 14 experim ents, potato tolerated high levels of corn borer injury (55-90% of stems in jured) without yield loss, suggesting that control of corn borer may not be necessary. Yet, in one of five Superior tests, in two of four Atlantic tes ts and in two of five Snowden tests corn borer injury significantly reduced yield. Of the five data sets in which corn borer injury reduced yield, the plateau model fit two data sets and the quadratic model fit one data set. In two of the three cases, these models accounted for nearly identical amou nts of total variation in yield as that accounted for by the linear model. The linear model fit four of the five data sets, but the R values were low for three of the four tests (0.10, 0.18, and 0.31). The parameter or parame ters that interact with corn borer injury to cause tuber yield reduction sh ould be identified before economic injury levels and thresholds are develop ed.