Ottawa 3: A Summary of Twenty 

 Years of Trial 



Wesley R. Autio 



Department of Plant & Soil Sciences, University of Massachusetts 



This article is the second in a series summarizing 

 the data collected in Massachusetts on specific apple 

 rootstocks over a number of years. Ottawa 3 (0.3) is 

 the focus of this installment. The Ottawa series of 

 rootstocks dates back to the 1950's and 1960's. They 

 were selected at the Ottawa Research Station. 0.3 

 resulted from a cross of Robin (a hardy crab apple) and 



M.9. It is more resistant to collar rot than M.26 and 

 somewhat less resistant than M.9. It is sensitive to 

 fireblight. Propagation has been a problem, but Traas 

 Nurseries in Canada have been relatively successful 

 with tissue culturing of 0.3, providing most rootstock 

 liners for nurseries producing finished trees on 0.3. 

 In Massachusetts, the first planting including 0.3 



Table 1 . Characteristics of trees of various cultivars on 0.3 in comparison to M.9 and M.26. These data were 

 exuacted from several replicated trials, and represent conditions through the end of the 1999 growing season for 

 Golden Delicious, Empire, Rome, and Gala, through 1994 for Mcintosh, and through 1993 for Delicious. Fruit 

 size is the average over all fruiting years for each trial. 



Tree 



age 



(years) Cultivar 



Rootstock 



Trunk 



cross- 

 sectional 

 area (in^) 



Cumulative 

 yield per 

 tree (bu) 



Cumulative 



yield 



efficiency 



(lbs/in' 



TCA) 



Fruit size 

 (no./42- 

 Ib box) 



14 



10 



Delicious 



Mcintosh 



Golden Delicious 



Empire 



Rome 



Gala 



M.26 EMLA 

 M.9 EMLA 

 0.3 



M.26 EMLA 

 0.3 



M.26 EMLA 

 M.9 EMLA 

 0.3 



M.26 EMLA 

 M.9 EMLA 

 0.3 



12.7 

 5.2 

 8.8 



10.2 

 6.9 



8.4 

 6.5 

 8.0 



10.9 

 4.9 



7.3 



27 

 18 

 23 



13 

 13 



9 

 8 

 12 



8 



10 



10 



94 

 143 

 110 



57 

 77 



45 

 48 

 62 



34 

 80 

 63 



91 

 86 

 88 



115 

 115 



97 

 101 

 95 



108 

 99 

 102 



12 



Fruit Notes, Volume 64 (Number 2), Spring, 1999 



