significant differences were observed (data not shown), indicating that availability of new plant tissues for infection was similar for each cultivar. The terminal bud of the plant may become infected before the development of the stipules, with subsequent development occurring during internode extension. As disease needs specific climatic conditions to develop, this subsequent disease development will then be dependant from the development of the microclimate. This observation is particularly important for breeders trying to compare genotypes with unaffected terminal green tissue of different sizes. The size of this non-diseased area may reflect differences in internode length between cultivars, rather than differences in the resistance or susceptibility of the cultivar to disease.