60 MASS. EXPERIMENT STATION BULLETIN 428 



With Mcintosh, the September 14-15 hurricane wind terininated the tests 

 too early for best results. However, in many cases, control of drop was better 

 with the stronger sprays and dusts. Since the wind broke many spurs, the 

 "hormone" applications were not effective in reducing drop during the hurricane. 



The data show benefits from stronger sprays and dusts, but whether the bene- 

 fits would warrant the increased cost of material is not proven. In any case, 

 with Mcintosh and Wealthy, it would seem unwiSe to use less than standard 

 amounts of commercial materials; in many cases, increased concentrations are 

 justifiable on the basis of insurance alone. 



A small test on Duchess showed good results with lower than standard con- 

 centrations. This variety is much more easily influenced by "hormone" drop 

 control applications than many varieties including Mcintosh. 



Plans for using a promising, newly exploited chemical in drop-control tests 

 are underway. It is very possible that more effective materials than naphthalene 

 acetic acid will be found. 



Beach Plum Culture. (J. S. Bailey.) This project was concluded and the re- 

 sults published in Experiment Station Bulletin 422, "The Beach Plum in Mass- 

 achusetts." 



Control of the Peach Tree Borer. (J. S. Bailey.) Paradichlorobenzene, ethylene 

 dichloride, and propylene dichloride were applied to peach trees according to 

 standard directions for each. There were so few borers even in the untreated 

 trees, that no indication of their relative effectiveness for borer control was ob- 

 tained. It is worth noting that none of these materials properly applied caused 

 any injury to the trees. 



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

 The inclusion of 20 pounds of Epsom salts per 100 gallons of spray solution in 3 

 early-season applications was rather effective in preventing the appearance of 

 magnesiutii deficienc^^ leaf scorch in the year of application. This treatment 

 seems especially valuable for trees which may be slow in responding to soil appli- 

 cations of magnesium materials. As a temporary measure for controlling scorch, 

 it has a definite place, particularly in mature orchards. 



Soil applications of Epsom salts and kieserite were beneficial in young, mulched 

 blocks; but one application of dolomite, kieserite, or Epsom salts was rather 

 ineffective in a seriously deficient bearing orchard under sod culture. The 

 application of commercial magnesium oxide (^2 percent MgO) appeared to result 

 in greater increases of magnesium in apple leaves on young trees than the use of 

 Epsom salts applied in similar amounts by weight. Results with magnesium 

 oxide on older trees have not been obtained. Commercial dolomite (magnesium 

 limestone) has seemed to be less beneficial than other materials, even when used 

 in relatively large amounts. 



Although some time may elapse before applications become effective, the use 

 of magnesium lime is recommended in most orchards where magnesium deficiency 

 symptoms have appeared. Its use in other orchards is suggested as a means of 

 preventing the deficiency. Prevention is possible and is preferable to allowing 

 the trouble to appear and then trying to correct it. A report of several field 

 experiments will be published in Volume 46 of the Proceedings of the American 

 Society for Horticultural Science. 



Thinning Apples with Caustic Sprays. (J. K. Shaw.) Attempts to thin apples 

 in 1944 by spraying with Elgetol at blooming time were partially successful. 

 The trees receiving a second application and those receiving the stronger con- 

 centration required less thinning. The apple bloom in 1945 was light, and most 



