-13- 



Table 2. Mean percentage of root penetration by Glomus epigaeus 

 in two clonal apple rootstocks (St-Jean, Quebec, 1981)^. 



Tree No. MMlll rootstock M7 rootstock 



1 17y 70 



2 23 32 



3 31 47 



4 30 67 



5 48 23 



6 61 31 



7 16 93 



8 62 39 



9 0.7 47 



X 33 50 



z 

 No mycorrhizal colonization was observed on the control trees. 



y 



Each mean represents 90 systematic microscope scannings. 



These findings indicate that apple clones do not respond uni- 

 formly to a given species of mycorrhizae. This phenomenon may 

 reflect the different phosphorus requirements of each clone since 

 mycorrhizae increase availability of P to roots. In vitro pro- 

 pagation apple trees might benefit greatly from mycorrhizal treat- 

 ments provided their genetic make-up allows for the mycorrhizal 

 symbiosis along with the appropriate mineral nutrition regime. 



Training and density studies on compact apple trees : The Spartan 

 and Mcintosh cultivars, grafted on M9, M7 , Ott . 3 and M26, were 

 planted at 296, 592, and 984 trees/acre and trained as slender bell, 

 oblique palmette, Van Roechoudt palmette and free standing trees. 

 1980 was the fourth cropping year for the trees of this trial. 



The highest yields came from the Spartan/Ott . 3 trees planted 

 at a density of 984/acre and trained as slender bell. With a net 

 profit of $1379/acre this combination almost reached the break-even 

 point in 1980 and yielded 20,455 lbs/acre. The second most profit- 

 able combination was that of Spartan/M9 planted at 484 trees/acre 

 and trained intheslender bell system. It yielded 18,567 lbs/acre. 

 The McIntosh/M9 trained in the Van Roechoudt palmette system was 

 the poorest combination, producing only 506 lbs/acre. The free 



