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sources. Technical conunittee members elected from each region as 

 well as their administrative advisors formed a working advisory 

 board for the IR-2 fruit tree repository. At first, emphasis was 

 given to stone fruit problems only and the repository had received 

 up to I960 a total of 472 candidate clones submitted for consider- 

 ation. The spring of 1960 saw 13 virus free clones planted in iso- 

 lation at the Moxee site. Extensive therapy of budwood of varie- 

 ties in which no clean propagating material could be found was be- 

 gun in 1960-61. In 1964, initial release of several Prunus selec- 

 tions was authorized as a result of this work. 



Starting in 1963, work en pome fruit viruses was included in 

 the interregional and regional projects. A subcommittee was set 

 up for the new apple and pear work and they immediately reported 

 out a project to find suitable indicators for virus indexing. An- 

 nual reports of 1964 revealed that 15 indicators and 92 sources of 

 virus-infected and healthy apple collections were being tested at 

 the Indiana and the New York (Geneva) Experiment Stations. These 

 tests were undertaken to find more sensitive indicators to both 

 the latent and fruit distorting virus entities. Also included at 

 that time were indicators such as the Russian indicator R-127407, 



Mai us platycarpa and Virginia Crab. Mechanically inoculated her- 

 baceous indicators were also used to identify and screen out other 

 possible contaminating entities in apple and pear budwood sources. 

 In the meantime, work with pome fruits had already been initiated 

 at several stations and became dovetailed with the IR-2 endeavors. 

 The consent to officially start work at the IR-2 repository on pome 

 fruits was given in 1965 and at that time 37 candidate clones were 

 assembled for further testing in screenhouse tests at the Washing- 

 ton Station. Additional Malus clones w^ere also received at the 

 repository that had been initially screened at individual cooperat- 

 ing stations, and by other workers concerned with maintaining a 

 virus-free repository of budwood. Thus, after 10 years of work on 

 Prunus , 1965 also saw the beginnings of a collection of virus in- 

 dexed apple clones established in the interregional repository. 

 In response to the U.S. success of the IR-2 project in establishing 

 screenhouse nuclear stocks and isolated fruit tree plantings, other 

 countries initiated similar repositories modeled after the IR-2 

 development . 



By 1969, provisions were made to include patented cultivar 

 selections in the repository along with proper restrictions and 

 permission from the patent holder allowing experimental manipula- 

 tion and incorporation of the cultivar in the repository. This 

 was deemed necessary because many of the newer and most important 

 commercial apple cultivars used were the patented ones. In 1971, 

 the release of indexed apple budwood under the regional and IR-2 

 project working groups was started. A distribution list of 66 

 clones was available and 900 buds of 59 selections were formally 

 released to 9 research and regulatory scientists. At the time, a 

 number of states including Maine, made use of this indexed IR-2 

 budwood to form mother block trees for use in orchard and nursery 

 improvement projects. 



