Increased yield and disease resistance of giant hill potatoes

Summary

In the San Juan district of San Benito county, California, nearly all plantings of potatoes show a dying of the vines in 70 to 100 days from planting, associated with heavy infection of Verticillium and Rhizoctonia. Longer lived selections proved to be giant hill. These have lived up to 136 days, have been relatively free of Verticillium, and have yielded an average of 63 per cent greater gross weight of tubers at 123 to 136 days from planting than normal plants. Tubers from giant hill plants have the disadvantage of more overgrowths, larger size, are more spindle shaped, and have deeper eyes. Other characteristics by which giant hill plants differ from normal are: longer, heavier, and more branched vines, fewer stems per hill, increased number and length of stolons, more cracking of stem surface in soil, indeterminate type of stem growth, smaller leaves with a tendency to curl up, longer dormant period of tubers, less yield of tubers up to go days from planting, slower rate of seed piece decay, less susceptibility of stems and tubers to Rhizoctonia, less susceptibility of foliage to early and late blight, and perhaps greater drought and frost resistance. Strains of giant hill appear to differ greatly with respect to most if not all characteristics observed.