ANNUAL REPORT, 1935 81 



320 Pruning Bearing Apple Trees. J. K. Shaw. 16 pp. illus. June 1935. 



Few careful experiments have been made to determine whether current beliefs and 

 practices in regard to pruning bearing apple trees are sound. For the last eight years this 

 Station has carried on experiments directed toward this end. With younger bearing trees 

 in full vigor of growth, pruning has less effect in improving size and quality of fruit than 

 has been commonly believed Other factors were found to be of much greater importance 

 than pruning. Cutting out weak and declining wood will not decrease the size of the crop, 

 but will eliminate much of the low-grade fruit that scarcely pays for the handling. The 

 sooner such wood is removed, the better. Well-cared-for bearing trees should be gone over 

 annually if possible, but at least every two or three years, and this type of wood removed. 

 Water sprouts should also be removed unless needed to maintain or renew the top. How- 

 ever, if one is forced to economize on labor, it is less injurious to neglect pruning than to cut 

 down on spraying or neglect proper cultural treatment. 



321 Tankage as a Source of Protein for Dairy Cows. J. G. Archibald. 8 pp. 

 July 1935. 



Tankage, especially the better grades, has a common use as poultry and hog feed, but 

 interest in its use as a source of protein for dairy cattle is of very recent development. 

 Investigations of the value of tankage for milk production showed that high-grade tankage 

 can be safely added to the list of protein feeds for dairy cows, provided the usual precautions 

 for feeding protein concentrates are observed. 



322 The Effect of Fertilizers on the Longevity of Mowings. A. B. Beaumont, 

 R. W. Donaldson, and M. E. Snell. 8 pp. July 1935. 



There are several good reasons why it is desirable to prolong the life of mowings in 

 Massachusetts. In the first place, much of the land used for hay in this State is so stony 

 as to make plowing difficult. Secondly, since under ordinary conditions it is more economi- 

 cal for the Massachusetts dairyman to purchase his grain than to produce it, a relatively 

 large acreage must be kept in forage crops. Finally, farm labor is relatively more expensive 

 in Massachusetts than in less industrialized regions, and any method of farming which re- 

 duces labor expenditures is desirable. The two experiments reported in this bulletin 

 showed that quality and yield of hay can be improved and the life of the mowing prolonged 

 by the use of fertilizers. However, the quality of mixed grass mowings will deteriorate 

 to such an extent in six to eight years that reseeding is desirable, even when fertilizers 

 are used at fairly high rates. 



323 The Whole Blood Agglutination Test for Pullorum Disease. H. Van 

 Roekel and M. K. Clarke. 24 pp. illus. July 1935. 



The whole blood test was introduced several years ago in response to a demand for a 

 method of testing less expensive than the standard tube test. It has not, however, proved 

 entirely satisfactory, and this study was undertaken in the interests of increasing its 

 efficiency and reliability. Factors such as proper and constant incubation temperature, 

 incubation time, adequate light for reading the agglutination reaction, and an effective 

 and constant whole blood-antigen dilution influence the sensitivity and efficiency of the 

 whole blood agglutination test. The great variation observed in the whole blood-antigen 

 dilution exerted a perceptible influence on the degree of agglutination and played an im- 

 portant role in detecting low-titre birds. Delayed weak reactions were encountered in 

 blood from birds that harbored the infection. The standard tube test detected infected 

 birds which failed to react with the whole blood method. The adoption of the whole blood 

 test as the sole diagnostic means for establishing and identifying pullorum disease-free 

 flocks seems inexpedient at the present time. 



324 Potash in Massachusetts Soils: Its Availability for Crops. F. W. Morse. 

 16 pp. August 1935. 



This bulletin brings together results from soil surveys, soil analyses, and general investi- 

 gational work in Massachusetts with the aim of promoting the more efficient use of potas- 

 sium as a plant-food element. The soils of this State are derived from glacial drift, which 

 consists principally of material from potash-bearing rocks. Fertilizer experiments have 

 shown that the lighter soils required potash, while heavy clay soils did not. Characteristic 

 soils were separated into two groups of soil particles, sands and silt-clay. Chemical analyses 

 showed clay to contain slightly more potash than sand. Clay holds more soil water than 

 is held by sand, and its fine particles are more readily dissolved than the sand grains. 

 Therefore, clay soils of this State will supply more available potash than sandy soils of 

 similar origin. Efficient use of potash fertilizer should include the available soil potash as 

 part of the supply for the crop. 



