Cucurbit Genetics Cooperative Report 1:16 (article 15) 1978
Screening Cucumbers for Resistance to Pickleworm
E. V. Wann, J. F. Robinson, R. L. Lower, J. M. Schalk and Terry L. Pulliam
US Vegetable Laboratory, USDA, SEA, Charleston, SC 29407 and Department of Horticultural Science, North Carolina State University, Raleigh, NC 27650
We have developed procedures for rearing and artificially infesting cucumber plants with neonate pickleworm larvae and for visually rating the plant feeding damage. We found that a minimum of ca 100 larvae per plant were required to give a susceptible rating of 4 on a 1-5 scale (1 = no visible damage; 5 = severe damage) using 6-week-old 'Addis' plants and 9 days feeding time when the average daily temperature was 29°C. Survival of the larvae on plants grown inside a screened enclosure ranged from 24 to 57 percent. The movement of laboratory reared larvae on mature host plants and their feeding response were similar to that of natural populations.
More than 300 plant introductions and cultivars were evaluated for resistance under natural populations and those showing least susceptibility were reevaluated with artificial infestations. Significant differences among lines were found for plant feeding damage and weight of surviving larvae. Differences were inconsistent on some entries; others, especially PI 390254, were lower than 'Addis' for damage rating and weight of surviving larvae. Further tests are underway to assess the resistance found in PI 390254 and to identify other sources of resistance.