Breeding a potato resistant to the potato leafhopper

Summary

A number of progenies segregated for various degrees of resistance and of tolerance to the potato leafhopper.

Of 14 progenies tested three showed a small but significant positive correlation, and one showed a negative correlation between resistance to late blight and resistance to attack by the potato leaf-hopper.

Nymphal populations were significantly larger on some seedlings than on others. Correlations calculated between nymphal populations in 1938 and 1939 on 5 progenies did not reach the 5 per cent level of significance.

The correlations between nymphal populations and the degrees of hopperburn, with one exception, were not significant. This fact indicates that the variations between seedlings as to the amount of hopperburn were not because of differences in leafhopper populations.

The analysis of the 1940 data shows that there were highly significant differences between the varieties and seedlings in nymphal populations and in the amount of hopperburn. Sebago, Sequoia, Katahdin, Rural New Yorker No. 2, and 61 numbered seedlings were significantly more resistant to the potato leafhopper than Irish Cobbler, Warba, Red Warba, Bliss Triumph, Earlaine, and Pontiac.

A number of the seedlings were much more resistant and some were more tolerant to attack by the potato leafhopper than were any of the old commercial varieties.