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the last decade with trickle irrigation, herbicides, frost pre- 

 vention, and virus-free rootstocks, behoove us to take another 

 look at the M.9 rootstock! 



Needed research on M.9 . The creosote-impregnated posts used to 

 support trees on M.9 in the Netherlands are much smaller in diameter 

 than those commonly used in New England, being only 2 to 2-1/2 inches 

 at the base. The use of creosote-impregnated posts (if economical) 

 or substitutes for wood appears to need investigation under our con- 

 ditions. 



There are 4 virus-free sources of M.9 in the Netherlands which 

 may or may not be different. Growth of trees on these virus-free 

 rootstocks is considerably greater than those budded to virus-infec- 

 ted M.9 rootstocks. The need to evaluate virus-free rootstocks of 

 M.9 under our conditions is obvious. 



Slender-spindle techniques need investigation for individually- 

 staked trees on M.9 in Massachusetts. These techniques may induce 

 earlier heavy yields and reduce pruning time in comparison to cur- 

 rent pruning practices. 



Budding height . Budding height and its effect on tree performance 

 is being investigated in the Netherlands. It is now suggested that 

 budding height on M.9 rootstock be increased by 2 inches Cfi^om 4 

 inches to 6 inches in height) . This will reduce the incidence of 

 scion rooting and decrease tree vigor. Budding M.9 and M.26 at 

 heights of 8 inches to 20 inches will cause even greater reduction 

 in tree size than by budding at 6 inches. However, tree variabil- 

 ity is increased because of burr knots (adventitious roots on trunks 

 of trees) on M.9 and M.26 rootstocks and variation among rootstocks 

 in form. The burr knots restrict carbohydrate transport to the 

 roots which leads to tree decline. Deeper plantings would allow 

 the burr knots to develop into roots and thus improve anchorage. 

 However, tree vigor is increased. High budding of MM 106 and M.2 

 rootstocks is of little value for growth suppression in the Nether- 

 lands but it does induce better branching. Certainly somewhat 

 higher budding, as being advocated in the Netherlands or more care 

 at planting, should help reduce the incidence of scion rooting in 

 our orchards. 



Interstem trees . At present, there is little interest in using M.9 

 as an interstem in the Netherlands because the trees would be more 

 costly and burr knots on M.9 and variable rootstock form increases 

 tree variability. However, there seems to be considerable interest 

 in the United States in interstem trees and we should evaluate them 

 in Massachusetts. 



Pruning . The statement heard in the Netherlands that continually 

 comes to mind is -- orchard size should be g6verned by the number 

 of skilled pruners available on the farm. Those considering high 

 density plantings or even medium density plantings of more than 



