11. 



growth restricting layers on the performance of apple trees on 

 clonal rootstocks. This is accomplished by a newly developed 

 testing procedure under controlled conditions in a greenhouse. 



The effect of a hardpan will be simulated by using growth 

 containers with different heights. The bottoms of the containers 

 will limit expansion of the root system and thus are limiting 

 growth in the same fashion as actual hardpans. Massachusetts 

 orchard soils often have growth restricting layers at 2-3 ft. 

 and the growth containers in this trial are, therefore, either 

 2 or 3 ft. deep. The containers are equipped with a specially 

 designed bottom which permits control of the soil moisture regime, 

 Three moisture conditions are possible: dry, moist, or wet. 

 Growth performance of each rootstock will be evaluated over a 

 period of time until differences become evident. 



A greenhouse was erected in the fall of 1980 at the Horti- 

 cultural Research Center in Belchertown. The necessary experi- 

 mental equipment was assembled over the 1980 summer and the 

 current set-up allows for the simultaneous evaluation of 8 differ- 

 ent rootstocks. However, the greenhouse roof has yet to be 

 installed because of adverse weather conditions, but it is hoped 

 that an evaluation cycle can be started in January. That test- 

 ing cycle will compare the growth of 'Mcintosh' apple trees on 

 M7, M9, M26, MM106, MMlll and standard rootstocks. 



AAA******** 



AN UPDATE ON FRUIT TREES INJURED IN 1978-1979. 



William J. Lord 

 Department of Plant and Soil Sciences 



Winter injury to fruit trees in 1978-1979 was predominantly 

 damage to roots. The cause and factors influencing the injury, 

 and symptoms of the injury were discussed in the JANUARY/ FEBRUARY 

 1980 issue of FRUIT NOTES. The majority of the weakened peach 

 trees were removed during the summer of 1979, but not the apple 

 trees. In late-summer we tagged individual limbs and whole apple 

 trees at the Horticultural Research Center in Belchertown after 

 rating the severity of winter injury. This was done to enable 

 us to determine the degree of tree recovery in 1980. 



Lack of snow cover and relatively mild temperatures character- 

 ized the winter of 1979-1980. No injured limbs or trees died dur- 

 ing the winter. Bloom was heavy on many of the injured trees but 

 fruit set was very light. Nevertheless, the fruits were removed 

 chemically and by follow-up hand thinning. 



