RANKING AND EVALUATION OF FIELD CORN HYBRIDS FOR RESISTANCE TO BLACKBIRD DAMAGE

We measured husk characteristics for a sample of ears from each of 229 hybrids grown in a performance test in Ohio in 1987 and ranked these hybrids for potential resistance to bird damage. Hybrids predicted to be resistant (i.e. with heavier husks) tended to mature later and have lower yields in the 1987 performance test than did the lighter-husked hybrids. We selected three hybrids from the 10 predicted to be most r esistant, three from the 10 predicted to be least resistant and two in termediate hybrids to be evaluated in a free-choice aviary test with r ed-winged blackbirds (Agelaius phoeniceus L.) in 1988. The three resis tant hybrids averaged 2.5% corn loss, significantly (P < 0.01) less th an the 26.1% loss for the three susceptible hybrids. The two intermedi ate hybrids had intermediate damage levels. In a 1989 field evaluation in New York, damage was substantial in all hybrids although the three predicted-resistant hybrids still averaged significantly (P < 0.05) l ess loss (20.5 bu/ac) than did the predicted-susceptible hybrids (27.4 bu/ac). Final yield was not significantly different between the two h ybrid groups. The ranking system accurately predicted resistance but a dditional evaluation is recommended regarding within-hybrid variation in husk characteristics among planting sites and years.