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Emily Hoover, S. McArtney, S. Tustin, M. White, and P. Hirst

Experiments were initiated to document the effect of cultivar, GA4+7, and number of fruit/spur on appendage number and flower bud initiation in apple. `Pacific Rose' is strongly biennial, `Braeburn' and `Fuji' are moderately biennial, and `Royal Gala' is not biennial. In the cultivar study, buds were sampled every 18 days starting at 50 days after full bloom and continuing through until leaf fall to determine the rate of appendage formation and appendage number in relation to doming. Because of the tendency for `Pacific Rose' to exhibit biennial bearing, the rate of appendage formation and the timing of doming were compared on nonfruiting trees, trees carrying a commercial crop, and trees sprayed with 300 PPM GA4+7 applied 14 days after full bloom. Number of appendages for the treatments were similar up to 100 days after full bloom. Presence of fruit on a spur has been demonstrated to inhibit flowering of apple. Spurs of `Pacific Rose', `Splendor', and `Royal Gala' were labeled with zero, one, two, and three fruit per spur and sampled three times during the season. As buds were harvested to count appendage number, the number of fruit per spur and the number of total seeds per spur were recorded. Correlation between number of seeds per spur and rate of appendage formation were done.

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David Shupert, Aaron P. Smith, Jules Janick, Peter B. Goldsbrough, and Peter M. Hirst

The codominant PCR marker AL07-SCAR closely linked to the Vf gene for scab resistance was used to genotype seedlings in three apple populations in which each parent (`GoldRush', `Enterprise', `Pristine', and CQR10T17) was resistant to apple scab. The marker was used to predict the genotype at the Vf locus. Each parent was heterozygous. In two populations (CQR10T17 × `GoldRush' and `Pristine' × `GoldRush') seedlings segregated 1:2:1 for fragments associated with VfVf:Vfvf:vfvf as predicted by Mendelian segregation. However, in another population (`GoldRush' × `Enterprise') the ratio was 1.5:1:1.5, suggesting some type of selection against heterozygotes. Fruiting seedlings were rated for the presence of fruit scab. No scab was observed on seedlings homozygous for the PCR marker linked to Vf, a small amount of scab was observed on one heterozygous seedling out of 35, and 22 of 26 seedlings that were homozygous recessive, had fruit scab.

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Emily E. Hoover, Richard P. Marini, Emily Tepe, Wesley R. Autio, Alan R. Biggs, Jon M. Clements, Robert M. Crassweller, Daniel D. Foster, Melanie J. Foster, Peter M. Hirst, Diane Doud Miller, Michael L. Parker, Gregory M. Peck, Jozsef Racsko, Terence L. Robinson, and Michele R. Warmund

Researchers have collected a considerable amount of data relating to apple (Malus ×domestica) cultivars and rootstocks over the past 30 years, but much of this information is not easily accessible. The long-term goal of our working group is to increase access to this information using online technology available through eXtension. In eXtension, researchers and extension personnel are developing a community of practice (CoP) to increase the quality and amount of online information for individuals interested in our work [referred to as a community of interest (CoI)]. For this project, our CoI is broadly defined as commercial apple producers, nursery professionals, county extension educators, Extension Master Gardeners, home gardeners, and consumers. Our CoP is developing diverse educational tools, with the goals of increasing productivity, profitability, and sustainability for commercial apple production. Additionally, we will provide other members of our CoI access to research-based, reliable information on the culture of apples. We chose to begin our focus on cultivars and rootstocks adapted to the eastern United States and will add other U.S. regions as our resources and interest in our project grows.