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Pollination of the half-high blueberry (Vaccinium corymbosum L./V. anugustifolium Ait.) cultivars St. Cloud, Northsky, Northcountry, and Northblue with self, outcross, and outcross/self pollen mixtures suggests that outcross fertilization maximizes percent fruit set, berry weight, seeds per berry, and seeds per pollination while minimizing days to harvest. Based on these results, mixed plantings of at least two blueberry cultivars are recommended for these cultivars. Fruit and seed set were negatively associated with increased percentages of self pollen in outcross/self pollen mixtures. These responses were linear for `Northblue' due to a tendency to parthenocarpy, and nonlinear for `St. Cloud', `Northsky', and `Northcountry', due to low fruit set following self-pollination. These data indicate that post-fertilization abortion affected seed formation, which was, in turn, correlated positively with fruit set.

The blueberry cultivar situation in North America is undergoing rapid change. Attempts to grow blueberries in non-traditional areas, and increased biotic and abiotic challenges in traditional production areas, are fueling the search for superior, adapted cultivars. This survey of all blueberry-producing states/provinces in the United States and Canada provides the current status and projected trends in blueberry cultivar use in North America. Most (86%) of current hectarage is comprised of 25 northern highbush, 10 rabbiteye, and two southern highbush cultivars. `Bluecrop' is the dominant northern highbush cultivar, with 35% of the highbush area, while `Tifblue' occupies 40% of the rabbiteye area. Some historically important cultivars, such as `Jersey', `Weymouth', and `Woodard' are in decline. New cultivars of all blueberry types are beginning to have a positive impact on the blueberry industry.

Potted plants of 53 highbush and half-high blueberry cultivars were screened for resistance to the blighting phase of mummyberry, Monilinia vaccini-corymbosii under controlled nursery conditions over an 18 day infection period. Significant differences were observed in the susceptibility of different cultivars, with `Bluehaven', `Bluegold', and `Blueray' being among the most susceptible, and `Bluejay', `Jersey', and `Duke' being among the most resistant. Differences were also observed in the latent periods and rate of disease progress which may have a bearing on the severity of the secondary fruit infection phase. Preliminary observations suggest that shoot blighting and fruit infection frequencies are not strongly correlated under high inoculum conditions.