-16- 



The trees were slow in coming into production partly due to 

 poor tree quality at planting and poor growth in the orchard. The 

 first crop was harvested from the Empire, Macspur, and Mcintosh 

 trees in 1980 and from Oregon Red Spur Delicious in 1981. Thus, 

 the yield data was still inadequate at the completion of the study 

 in 1982 for a good evaluation of the influences of planting depth 

 on yield and this problem was confounded by the fact that the 

 orchardist inadvertently harvested the Macspur and Mcintosh in 

 1982, Preliminary data for the Empire and Delicious show that 

 trees with the stempiece exposed have produced less per TCA than 

 those with the stempiece buried. Yield efficiency of trees with 

 the stempiece partially exposed was not different from the others. 

 Both the growth and limited yield data support the suggestion that 

 interstem trees will be weakened and bear less if the stempiece is 

 above the soil line. 



The rootstock and/or cultivar had more effect than planting 

 depth on several factors. Tree spread was greater for trees on 

 M9/MM106 than on M9/MM111. Delicious trees were smaller and had 

 less bloom than the other cultivars. Macspur had less branch spread 

 than Mcintosh or Empire. 



Roots from burrknots were present on all but 3 trees with the 

 stempiece buried. Conditions were considered very favorable for 

 rooting from the burrknots because the soil had been heavily mulched 

 with hay since 1980 and rain was ample for optimum grov;th. Never- 

 theless, 26% of the stempieces had only short, fibrous roots less 

 than 18 cm in length. Since the trees were not dug up, the original 

 roots could not be observed but it does seem that this rooting may 

 be too limited to entirely replace the original roots as was 

 observed by Rogers and Parry in England. Rootstock and cultivar had 

 no influence on the amount of rooting. 



After 7 growing seasons, interstem trees of Oregon Spur Red 

 Delicious are smaller and less productive than similar trees of 

 Empire, Macspur and Rogers Mcintosh. It appears that because of 

 the upright branching nature and small leaf surface, the spur-type 

 Delicious strain is slow to develop. 



Summary 



Production of root suckers by interstem trees can be reduced 

 by deeper planting. Our limited observations lead us to conclude 

 that interstem trees will require more care than those on vigorous 

 size-controlling rootstocks and that the stempiece is a site for 

 possible difficulty with weather, rodents, insects and disease. 

 Further testing is needed before we can recommend planting of inter- 

 stem trees other than for trial. 



