captured on a sphere did increase. This result 

 indicates that for greatest effectiveness in con- 

 troUing AMF, baited sticky red spheres should 

 be hung very early in the fly season, before 

 immigrating AMF have reached maturity. In 

 addition, our findings suggest that while green 

 apples may receive fewer visits by AMF than red 

 apples, green apples may be more susceptible to 

 oviposition by arriving AMF. This result again 

 affirms the need to hang baited sticky red 



spheres early in the fly season for greatest 

 effectiveness in avoiding finiit injury by immi- 

 grating AMF. 



Acknowledgements 



This work was supported by the Science and 

 Education Administration of the U.S.D.A, im- 

 der grant 8900901 from the Cooperative Re- 

 search Grants OfBce and by a USDA grant 

 under the NE-156 Apple IPM project. 



^% %% %% ^10 «^ 



rf* •^ rf% #J% rj% 



Evaluation of Four Rootstocks and 

 Two Mcintosh Strains 



Wesley R. Autio and Franklin W. Southwick 



Department of Plant & Soil Sciences, University of Massachusetts 



Through the 1960's and 1970's, the trend 

 in the New England apple industry was from 

 seedling-rooted trees to trees on M.7 or similar 

 sized rootstocks. In the latter part of the 1980's, 

 the trend shifted toward smaller trees. In the 

 1990's, growers are planting significant num- 

 bers of dwarf trees, mostly on M.9 and Mark 

 rootstocks. In 1979, a planting was established 

 at the University of Massachusetts Horticul- 

 tural Research Center to assess rootstocks in 

 the size range from M.7 to M.9. 



The planting included Rogers Red Mcin- 

 tosh and Macspur Mcintosh on M.7A, M.26, M.9 

 (trained either to a post or on a 4- wire vertical 

 trelhs, seven-feet tall), andM.9/MM. 111. Seven 

 replications were planted, and each replication 

 had four trees of each cultivar/rootstock combi- 

 nation. Two trees of each group were used for 

 data collection, and any Macspur that reverted 

 to a nonspur habit was eliminated from the 

 experiment. Normal fertilization and pest man- 



agement practices were used. All trees were 

 maintained as central leaders. With the excep- 

 tion of tjdng branches to the wires in the trellis 

 treatment, very Uttle limb positioning was per- 

 formed in the planting. 



After 10 growing seasons, trees on M.7A 

 were the tallest, regardless of Mcintosh strain 

 (Table 1). Trees on M.26 and M.9/MM.1 1 1 were 

 similar in size and intermediate. Trees on M.9 

 were the shortest. Rogers trees were signifi- 

 cantly taUer than Macspur trees. Tree spread 

 followed a similar trend (Table 1); however, 

 trees on M.9 trained to a trellis had a greater 

 tree spread after 10 seasons than those trained 

 to a post. Clearly, this difference related to the 

 support provided to lateral branches by the 

 trelhs wires. 



Tree spread was used to calculate poten- 

 tial tree density (Table 1). It was assumed that 

 trees could be planted 1 percent closer than the 

 spread measured after 10 seasons. Seven feet 



Fruit Notes, Winter, 1993 



