RELATIONSHIP BETWEEN RESISTANCE TO LATE BLIGHT IN POTATO FOLIAGE AND TUBERS OF CULTIVARS AND BREEDING SELECTIONS WITH DIFFERENT RESISTANCE LEVELS

Due to changes in the pathogen population, late blight of potatoes cau sed by Phytophthora infestans has become a more difficult disease to m anage and there is a need for new potato cultivars with greater and mo re stable disease resistance. Field studies are required to identify a nd characterize host resistance to late blight in both foliage and tub ers but, as epidemics vary from year to year, combining multi-year res ults can be difficult. Residual maximum likelihood (REML) was successf ully used to analyze data which demonstrated good correlations between foliar and tuber responses to late blight (US-1 genotype). In additio n, studies on post-harvest inoculated tubers provided more reliable di sease responses than field studies, and the disease resistance with th is method correlated well with foliar disease responses. This tuber te st would be a useful method of pre-screening selections for disease re sponse prior to testing in the field.