Fig. 2. Mean C. obstrictus exit holes per pod for 21 S. alba x B. napus hybrid genotypes compared with B. napus cv. Q2 in field evaluations conducted near Lethbridge, AB, in 2002. Gray histograms indicate genotypes considered to have high susceptibility to attack by C. obstrictus (5% of pods with larval exit holes) and were excluded from further testing. White histograms were genotypes considered to have low susceptibility to C. obstrictus infestation (<5% of pods with larval exit holes) and were selected for further evaluations. The dotted line indicates the arbitrary cutoff between susceptible and resistant genotypes.