Performance Over Five Years of Five 

 Rootstock Cultivars in Combination witli 

 Five Scion Cultivars in l\/lassachusetts 

 and l\/iaine 



Wesley R. Autio 



Department of Plant & Soil Sciences, University of Massachusetts 



James R. Schupp 



Highmoor Farm, University of Maine 



Clearly, the future of the New England apple in- 

 dustry rests with dwarfing rootstocks and high-density 

 plantings, and a major decision that each grower must 

 make is the appropriate dwarfing rootstock to use. To 

 aid in this decision, much research has been conducted 

 on dwarfing rootstocks, particularly by the NC-140 

 Technical Committee on Tree-fruit Rootstocks. How- 

 ever, much of this research has utilized a relatively small 

 number of scion cultivars, and before selecting a par- 

 ticular rootstock, it is important to understand its per- 

 formance with the particular scion cultivar of interest. 

 To this end, the NC- 1 40 Committee established in 1 990 

 a trial at 18 locations in the U.S. and southern Canada 

 to study the performance of five dwarfing rootstocks 

 and a number of scion cultivars. In this article, we will 

 detail the results to date from the plantings in Massa- 

 chusetts and Maine. 



Materials & Methods 



In May 1990, Smoothee Golden Delicious, Nicobel 

 Jonagold, Empire, and nonspur Law Rome in all com- 

 binations on M.9 EMLA, B.9. Mark, 0.3, and M.26 

 EMLA were planted at the University of Massachu- 

 setts Horticultural Research Center in Belchertown, 

 Mass. Jonagold on 0.3 was missing from the plant- 

 ing. A similar planting was established at the Univer- 

 sity of Maine Highmoor Farm in Monmouth, Me., ex- 

 cept Marshall Mcintosh was included as one of the scion 

 cultivars and no trees on M.9 EMLA were planted. 

 Additionally, Golden Delicious on B.9 and Jonagold and 



Mcintosh on 0.3 were missing from the Maine plant- 

 ing. Each planting included five replications in a ran- 

 domized complete block/split plot design. Additional 

 trees were planted at the ends of rows and as guard 

 rows on both sides of the plantings. In Massachusetts, 

 Marshall Mcintosh trees on M.9 EMLA, B.9, or M.26 

 EMLA were planted as a trial with five replications in 

 the guard rows of the larger planting. All trees were 

 staked at planting and were maintained as slender 

 spindles. All developing fruit were removed during the 

 first two growing seasons. All fruit were harvested and 

 weighed in the third through the fifth growing seasons. 

 Trunk circumference was measured each October and 

 used to calculate trunk cross-sectional area. At the end 

 of the fifth growing season, tree height and canopy 

 spread were measured. 



Results 



In general at these two locations, the effects of root- 

 stock did not vary with scion cultivar; therefore, we 

 will discuss only the overall effects of rootstock or scion 

 cultivar. 



Trunk growth varied with rootstock at both loca- 

 tions (Figure 1 ). After five growing seasons in Massa- 

 chusetts, trees on M.26 EMLA had the greatest trunk 

 cross-sectional area and those on Mark or B.9 had the 

 smallest. Trees on Mark experienced similar changes 

 in growth rate to those that we have observed previ- 

 ously, i.e. they grew rapidly in the first two seasons 

 when they were not allowed to fruit, after which their 



Fruit Notes, Spring, 1995 



15 



