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ROOTSTOCK TESTING ON AN INTERNATIONAL BASIS 



William J. Lord 

 Department of Plant and Soil Sciences 



In the past, rootstock studies were uncoordinated efforts and 

 results have varied from state to state with little chance of iso- 

 lating the influences due to climate and soil differences. In 1976 

 the North Central Regional Cooperative Project NC-140 entitled 

 "Scion/Rootstock and Interstem Effects on Apple Tree Growth and 

 Fruiting" was initiated with the following objectives. 



Objectives : 



1. To evaluate the production efficiency of available and 

 potentially useful rootstocks or interstems for fruit 

 trees which are potentially precocious, dwarfing, free 

 standing, easy to propagate and adapted over a wide range 

 of climatic conditions in the North Central Region. 



2. To determine the propagation practicability of new root- 

 stocks and interstem material and ascertain the anatomical 

 and physiological factors in graft unions that determine 

 compatibility. 



3. To ascertain the cause and prevention of the decline of 

 new and existing rootstocks and interstems and evaluate 

 the influence of various cultural practices on rootstock 

 survival and performance. 



Under Objective 1, a uniform interstem planting was establish- 

 ed in 1976 in Illinois, Indiana, Iowa, Kansas, Massachusetts, Mich- 

 igan, Missouri, Ohio, and Wisconsin, and a partial planting was 

 established in Kentucky. 'Millerspur Delicious' and ' Empire ', with 

 8-inch interstem of M.9 on either Antonovka, MM. Ill or Ottawa 11 

 rootstock, are being evaluated. 



Currently, NC-140 is being expanded so that a 1980 rootstock 

 planting will be established by at least 20 cooperators in U.S.A. 

 and Canada. At each location a planting of 'Redchief Delicious' 

 (spur- type) on M.9, Ottawa 3, EMLA27, EMLA9 , EMLA7 , EMLA26, MAC9, 

 MAC24, and OARl will be established. (The EMLA's are virus-free 

 clones of M.9, M.7, etc., the MAC's are Michigan State apple clones, 

 and the OARl is a clone introduced by Oregon State Agricultural 

 Experiment Station.) 



Other Cooperative Rootstock Plantings will be established 



later in the 1980's. Hopefully, our NC-140 project will prove to 



be a benefit to growers and apple tree nurserymen, since coordinated 



research should lead to clearer information about apple rootstock 



performance . 



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