62 MASS. EXPERIMENT STATION BULLETIN 436 



may have been leached from the soil by the heavy rains of May and June, 1945, 

 and that soil moisture continued ample through July and August so that little 

 leaf scorch appeared. The problem of correcting magnesium deficiency is dififii- 

 cult, particularly with mature trees. We continue to recommend the use of 

 magnesium sulfate in three or four sprays in early summer for immediate results 

 and dolomitic limestone for more lasting effect. An enlarged program of study 

 of this problem is under way. 



Thinning Apples with Sprays. (J. K. Shaw.) In 1946 as in 1945, spring freezes 

 interfered with attempts to thin apples by spraying in bloom, yet some results 

 were obtained. Dowax, 1 gallon to 100, seemed to reduce set of Macoun but 

 had little or no effect on five other varieties, including Mcintosh. A commercial 

 preparation of naphthalene acetic acid, 20 p. p.m., was more or less effective on 

 several varieties and thinned certain crab varieties and Stark excessively. Ap- 

 plied at 30 p. p.m., it reduced the set of Wealthy about one third; not enough to 

 eliminate some hand thinning. It caused considerable dwarfing and distortion 

 of the leaves. 



Two DN powders were used, both of which thinned several varieties quite 

 effectively and caused much less leaf burning than did Elgetol used in 1944. 

 There were generally not effective on Mcintosh. It will not usually be neces- 

 sary to thin Mcintosh, but the unusually heavy bloom this year seemed to offer 

 an opportunity to study this variety. It is evidently not easily influenced by 

 blossom-thinning sprays. Naphthalene acetic acid was partially effective and 

 caused little leaf distortion. 



Because of the abnormally cold spring, it is not safe to draw many conclusions 

 as to the value of blossom-thinning sprays. They are being used in commercial 

 orchards and it seems probable that they will find increasing use as we learn 

 more about them. Evidently the variety, stage of bloom, and possibly condition 

 of the tree must be carefully considered. 



Applications of naphthalene acetic acid and 2, 4-D at heavy concentrations in 

 August to delay blossoming the following spring and thus escape frost damage 

 seemed to have no certain effect. Applied at the time of fruit bud formation in 

 May, it affected the leaves in the usual way and destroyed many fruit buds of 

 Duchess but did not noticeably affect the buds of Mcintosh and Wealthy. 

 Neither material seemed to hasten the ripening and development of yellow color 

 in Golden Delicious and Mcintosh when the apples were dipped in various con- 

 centrations of the material in water. 



Chemical Control of Poison Ivy and Other Weeds. (J. S. Bailey.) Several 

 chemicals, including ammonium sulfamate and three formulations of 2, 4-D and 

 some oils, were tried as herbicides for poison ivy, chokecherries, and American 

 bamboo (Polygonum Seiboldii De Vriese). For poison ivy and chokecherry, 

 ammonium sulfamate was superior to anything else tried. Nothing was effective 

 on American bamboo. Ammonium sulfamate sprayed around young peach 

 trees to eliminate grass and weeds killed the peach trees. 



DEPARTMENT OF POULTRY HUSBANDRY 

 F. P. Jeffrey in Charge 



Broodiness in Poultry. (F. A. Hays and Ruby Sanborn.) The chief objective 

 has been to develop a line of Rhode Island Reds entirely free from the broody 

 instinct. This goal has not yet been attained, largely because of the problem of 

 deferred broodiness and the difficulties of adequate progeny testing of the breed- 



