Please review this message and get back to me if you have any suggestions, particularly if you would like to include new rootstock cultivars in evaluations. If you would like to be placed on an email mailing list to receive updates automatically, please send me a message at wcj4@cornell.edu>.

Topics:

1. Attention Nurseries: Inclusion of new rootstock cultivars evaluations
2. Scion variety choices for NE and NW intermediate & advanced trials
3. G.16 and latent virus hypersensitivity
4. Website improvements - new info in late August

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1. There are a number of new, promising rootstock cultivars that will be becoming available or are presently available to US growers from breeding programs in England, Poland, Russia, the Czech Republic, Japan, New Zealand, Romania, Italy, and Germany. Typically these are introduced to US consumers by the larger rootstock nurseries, and often these nurseries can obtain and commercialize new genotypes before they are evaluated thoroughly. As a service to both these nurseries and to domestic growers, I plan to begin including each of these in our rootstock variety evaluations. As part of the evaluation process, we measure the level of resistance to various pests and pathogens, determine the tolerance a genotype exhibits to abiotic stresses, and include the new rootstock genotypes in standardized orchard trials. Because of the proprietary interests nurseries have in these new rootstock cultivars, it will be necessary for them to provide the plant material and research exemptions to allow inclusion of new varieties in the evaluation process. I do not propose that inclusion of novel rootstock genotypes in the Geneva rootstock evaluation program be a prerequisite for commercialization, but for nurseries expecting to commercialize a new rootstock I believe that the objective, impartial evaluations that we can conduct here in Geneva can be valuable to when making claims regarding the performance of their new varieties. Please contact me if you are introducing new rootstock cultivars to the US market or would like to. I write this at this time in case their are any new introductions with limited plant material available so that we can do the budding this August to begin bulking up the material asap. Nurseries do not need to be a part of the Cornell-Geneva rootstock licensee group to participate in this service.

2. I am in the process of establishing a budwood block to be used in our Geneva nursery where we produce trees for rootstock trials. I would like to establish a limited number of genotypes that we will use for intermediate and advanced stage trials with promising rootstock cultivars. The scion varieties I am proposing to have available for trials are Empire, Macintosh, Royal Gala, Empire, Gingergold, Golden Delicious, Jonagold, Granny Smith, Spur Red Delicious, and Pink Lady. The strategy here is to have the ability to provide trees of economically important varieties with a range of scion vigor levels and growth characteristics for trials in a wide range of environments, but without generating an excessive number of new variables to evaluate in trials (scion variety being an important variable). Intermediate stage trials (approximately 10 trees X 10 new rootstock genotypes per year trialled in NY and WA) will be performed with Golden Delicious in Washington and Empire in New York.

3. As the budding season quickly approaches, please remember that if you are growing the G.16 rootstock (M.9 size, productive, very fireblight resistant) you need to use virus free budwood. This cultivar is hypersensitive to at least one of the common latent viruses (I expect to be able to tell you which one within several months) and the trees will decline and die approximately 10 months after an August budding if infected budwood is used (sooner for dormant bench grafts). Similarly, the G.65 rootstock (M.27 size, productive, very fireblight resistant) is susceptible to the Apple Stem Grooving Virus (ASGV) and the same precautions should be employed. If you have any questions about your choice of budwood, please feel free to contact me. I have attempted to contact all the G.16 recipients this year, but there are several, particularly in the Midwest, that I have been unable to contact because the secondary nursery supplier did not keep records of his customers and chose not to inform them of this problem at the time of sale.

4. I expect to have several new additions to the website by the end of August. I plan to include images of elite rootstock genotypes and of field trials, and summaries of important characteristics for elite rootstock genotypes. Please check back in approximately one month to view these at your leisure. I am hoping that one use of these images will be to serve as a reference point for cooperators who are growing new rootstock cultivars so that they can cross check the phenotypes of their plant material with the standards we maintain locally.

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