88 MASS. EXPERIMENT STATION BULLETIN 369 



Since the 1939 season was a dry one, the berries were considerably smaller than 

 normal. Winter injury and the dry season reduced the crop about 50 percent. 



Buds of two new U. S. D. A. seedlings, GN-45 and GN-87, were obtained from 

 New Jersey by permission of Dr. George M. Darrow of the U. S. D. A. They 

 were budded into several bushes in row A, blueberry plot C. Buds of the U. S. 

 D. A. seedling FI-66, which we have had for several years, and of the variety 

 Dixi, were budded into bushes in this same row to increase the supply of propa- 

 gating wood. 



In the fall of 1939 an experiment was started in blueberry plot D to try a com- 

 bination of mulching and cultivation. Various mulches, such as sawdust and 

 waste hay are being used in the rows under the plants. The space between the 

 rows will be cultivated. 



In the spring of 1939 nine plants of a new seedling. No. 73, were planted in 

 blueberry plot B. 



In the spring of 1939 all of the blueberry plants in blueberry plot A were re- 

 moved with the exception of a few diseased bushes. These diseased bushes will 

 be retained for a short time for further observation. 



On June 22 two blueberry plants each of the varieties Rubel, Cabot, and 

 Pioneer were heavily dusted with sulfur at 3 p. m. when the sun was bright and 

 the temperature 80° F. On July 7 there was no sign of injury on any of the plants. 

 At 4 p. m. on that day, which was slightly cloudy, with a temperature of 92° F., 

 these plants were redusted. By July 10 the two Pioneer plants showed severe 

 burning along the edges of the leaves on some of the branches. The other varie- 

 ties showed no injury at that time or later in the season. 



About 350 bushes were removed from the east and south side of blueberry 

 plot D in the spring of 1939. This was done for two reasons: (1) to reduce the 

 size of the planting and thereby reduce the cost of maintenance, and (2) to remove 

 the blueberry bushes from parts of the field not well suited to blueberry growing. 



Premature Dropping of the Mcintosh Apple. (L. Southwick.) Further evidence 

 of the significance of seeds in influencing premature drop of Mcintosh apples 

 was obtained. Using the total crops of two trees, correlation coefificients above 

 -j-.SOO indicate considerable association between the number of seeds in an apple 

 and its date of drop and suggest the importance of adequate cross pollination 

 for Mcintosh. 



Pollen from seven varieties was used on a tented Mcintosh tree to check on 

 pollination success. The results indicate that of the varieties commonly con- 

 sidered good pollinators for Mcintosh, some are better than others based on the 

 seed counts in this experiment. In general, the severity of pre-harvest dropping 

 seemed to vary with the variety of pollen used on the basis of the number of seeds 

 which developed. 



Limb injections of chemical nutrients gave further evidence that abundant 

 nitrogen in the tree tissues hastens Mcintosh fruit drop. The mean date of drop 

 of a nitrogen (urea) injected limb was advanced fully four days ahead of similar 

 untreated limbs or limbs injected with non-nitrogenous materials. A potassium 

 sulfate injected limb likewise dropped its fruit relatively early but this probably 

 was due in part at least to rather severe leaf injury. In another single tree test, 

 both the nitrogen injected limbs and the potassium-phosphorus injected limbs 

 dropped their fruit a little earlier on the average than similar untreated branches. 

 However, the differences here were small and conceivably may have been due to 

 the injection procedure itself rather than to the particular materials used. All 

 of these preliminary results are suggestive only, as the data are few and present 

 only one year's observations. 



Some Mcintosh trees in the Station blocks showed a peculiarly large amount 

 of leaf browning early in September which was followed by severe pre-harvest 



