62 MASS. EXPERIMENT STATION BULLETIN 417 



Preharvest Dropping of Apples. (L. Southwick.) Comparative tests with 

 sprays and dusts for controlling the preharvest drop of apples were conducted 

 in the late summer and fall of 1943. For the first time, dusts were used which 

 contained higher percentages of active ingredients than the usual commercial 

 dusts. The "regular" strength dusts were prepared so that one pound of dust 

 was equivalent to ten gallons of a standard (.001 percent) spray in amount of 

 active ingredient, while most of the more concentrated dusts used contained 

 twice the amount. Standard and double strength sprays were included in the 

 tests, and both dusts and sprays were used in single and in duplicate applications. 



The fairly uniform success from all treatments in lessening preharvest drop 

 of Mcintosh was not entirely consistent with previous results which have shown 

 better success with stronger sprays as well as with duplicate applications. Wider 

 differences might have appeared had the harvest been delayed. Nevertheless, 

 some of the data showed a slight trend toward better drop control with the 

 double strength and the duplicate applications of both dust and spray. There- 

 fore, further work is planned for the 1944 season. A report of the 1943 experi- 

 ments will appear in Volume 44 of the Proceedings of the American Society for 

 Horticultural Science. 



Five new chemical compounds were tried in small-scale tests to determine 

 their possible usefulness in controlling preharvest fruit drop. However, none of 

 these materials in spray applications was comparable to napthalene acetic acid 

 in effectiveness. 



Beach Plum Culture. (J. S. Bailey.) A cooperative experiment was carried 

 out with W. L. Doran of the Department of Botany on the propagation of beach 

 plums by softwood cuttings. See the report of this work given on page 20. 



As a result of the experience in 1942, the spray program was modified to get 

 better control of the various diseases and insects. Slightly better results were 

 obtained but the control of plum gouger was still poor. Careful search was made 

 during the blooming seasons of 1942, '43, and '44, but no gougers were found. 

 It is evident that this insect does not appear as early as had been reported. 

 Limited preliminary tests of cryolite and of calcium arsenate sprays on beach 

 plums were made in Amherst in the spring and early summer of 1944. No burn- 

 ing of the foliage has as yet resulted from the use of either material. 



The failure of nearly the entire beach plum crop on the Cape in both 1941 

 and 1942 made it difficult to evaluate the effects of fertilizer treatments. Judging 

 by the appearance of the plants and set of fruit (which later dropped off because 

 of dry weather), a single application of 400 pounds per acre of a 5-6-4 cranberry 

 fertilizer was better than the same amount split into 3 applications or than no 

 fertilizer, although this application is probably too light to be very effective. 

 Cottonseed meal used alone in 1943 gave slight evidence of benefit. 



Because of lack of trained personnel to supervise the work, these experiments 

 had to be discontinued in 1944. In their place outlines were prepared for grower 

 cooperative experiments. These were distributed through the office of the 

 County Agent, Mr. Bertram Tomlinson. 



A more complete report of the beach plum work is in preparation. 



Magnesium Deficiency in Massachusetts Apple Orchards. (L. Southwick.) 

 It is now recognized that magnesium deficiency in apple orchards in Massachu- 

 setts is not limited to a few cases. Since the deficiency was positively diagnosed 

 in 1942, it has been reported from most orchard sections in the state. Growth 

 records in our young clonal stock orchard indicate the seriousness of this nutrient 

 deficiency. The average increase in trunk cross-sectional area over a 4-year 



