342 MASS. EXPERIMENT STATION BULLETIN 247 



It is quite evident from these tests, together with observations through- 

 out the Valley, that brown root-rot is, in the great majority of cases, the 

 result of some crop eifect. This would indicate that cellulose decomposi- 

 tion might play a part in bringing about such a condition on tobacco roots. 

 However, cellulose decomposition, as such, does not appear to be respons- 

 ible for the occurrence of brown root-rot. Practically pure cellulose was 

 applied to the extent of one per cent of the weight of the soil in com- 

 bination with ample nitrate nitrogen, and this amount of cellulose was 

 also applied on unfertilized field plots, but no symptoms of brown root- 

 rot were present on the roots at harvest. The tests have also demonstrated 

 that ordinary applications of fertilizers have little or no effect on brown 

 root-rot. Twice the ordinary application of a commercial tobacco fer- 

 tilizer, or heavy applications of nitrate nitrogen have failed to iiTii)rove 

 the yield of tobacco on infested soil. 



In summarizing, no crop under investigation, with the exception of oats, 

 has proven beneficial to a following crop of tobacco either on infested or 

 healthy soil. The data on oats as a preceding crop or as a crop to be 

 grown on infested soil to eliminate this brown root-rot condition are not 

 suft'icient, to date, to warrant recommendation for such purposes. With 

 these facts in mind, the practical solution at present appears to be the 

 continuous culture of tobacco, avoiding rotation when it is not necessary 

 for other reasons. 



PUBLICATIONS 



General Bulletins 



231 The Market Outlet for Massachusetts Apples^ Jefferson, Lorian P. 

 40 p. January, 1927. 



This deals with the wholesale an<i retail distribution in domestic markets, with 

 some discussion of the character of the demand. The world crop and international 

 trade are also discussed, and the costs and problems of exporting. Seasonal fluctua- 

 tions in Baldwin apple prices, 1889-1925, and comparisons of Baldwin and Mcintosh 

 prices are included, with a discussion of the relation between price and size of the 

 apple crop. The chief conclusions are that the demand for New England apples is 

 increasing in New England markets, and that the demand for good quality and 

 larger sizes is increasing. 



232 Effect of Potash Salts on Crop Yields. Haskell, Sidney B. 10 p. 



February, 1927. 



Among the more important results of long-continued experiments comparing chem- 

 ical forms of fertilizer potash are the following: occasionally better table quality of 

 potatoes, but seldom any significant difference in yields : variations in the stand of 

 grass and clover, but surprising similarity in yields of hay ; a distinct difference 

 in the winterkilling of cane fruits, with consequent large differences in yield ; no 

 indication of sulfur shortage even aftel- thirty years of treatment with little or no 

 sulfur in the fertilizer, and a similar result with magnesium. 



233 The Codling Moth in Massachusetts. Bourne, A. I. and Whitcomb, 

 W. D. 19 p. March, 1927. 



The life history of the codling moth in Massachusetts was studied for three con- 

 secutive seasons. The codling moth has one complete generation and a partial 

 second annually in this State. There is a slight overlapping of the two genera- 

 tions, so that from the time the fruit is set until harvest there are but few days 

 when infestation may not take place. Spraying is the most important phase of 

 codling moth control and should be thorough and timely. The calyx spray and the 

 post calyx sprays are the most important in the control of this insect. The mate- 

 rial most effective against the codling moth is arsenate of lead, and its use is 

 recommended at the rate of IV^ pounds of the powder in 50 gallons of water. 



