A Technique for Screening Sugarcane Cultivars for Resistance to Pachymetra Root Rot. B. J. Croft, Bureau of Sugar Experiment Stations, Tully, Queensland 4854, Australia. . Plant Dis. 73:651-654. Accepted for publication 3 January 1989. Copyright 1989 The American Phytopathological Society. DOI: 10.1094/PD-73-0651.

A glasshouse technique for screening sugarcane cultivars for resistance to root rot caused by Pachymetra chaunorhiza was developed. University of California potting mixture was infested with oospores of the fungus produced on cornmeal agar, at 2 × 10⁴ or 1 × 10⁵ oospores per kilogram, and pregerminated single-eye cuttings were grown in the potting mixture for 6–8 wk. The numbers of healthy and diseased primary roots were then determined. The cultivars Q78, Q114, Q138, 77N631, 77N636, and H55-3426 were highly resistant to Pachymetra root rot. The correlation between glasshouse infection levels and field reactions was highly significant (P < 0.01), and the glasshouse infection levels of 27 cultivars tested at three seasons of the year at two inoculum levels were significantly correlated (P < 0.05). A highly significant correlation was found between the percentage of rotted roots (probits) of the susceptible cultivar Q90 and the logarithm of the number of oospores per kilogram.