538 EXPERIMENT STATION RECORD. [Vol. 43 



variations in manurial or fertilizer treatments. A number of the varieties pro- 

 duced by Norton in the cooperative breeding experiments conducted in Concord 

 appear to have to an exceptional degree the character of relative immunity from 

 rust (E. S. R., 40, p. 538). The season of application of nitrate of soda appears 

 to influence the susceptibility of asparagus to rust, which Is reduced by the 

 jipplication of at least a portion of the nitrate of soda at the close of the cut- 

 ting season. The character of tlie season, especially the amount and distribu- 

 tion of rainfall, appears to affect the probability of a serious attack of rust to 

 a considerable degree, such attacks being more common in dry seasons than in j 

 those characterized by normal or abundant and well-distributed rainfall. 



In commercial asparagus growing as usually carried on in Massachusetts, it i 

 is a common practice to apply what appear to be excessive quantities of fer- 

 tilizers. Applications of 460 lbs. of nitrate of soda, 300 lbs. of acid phosphate, 

 and 2G0 lbs. of muriate of potash per acre appear to be as large quantities of 

 these elements as could be utilized by the crop. Nitrate of soda at the rate of' 

 about 400 lbs. per acre in connection with manure at the rate of 10 tons per acre 

 increased the crop, and appears to be the maximum amount which proved bene- 

 ficial. The application of either acid phosphate or muriate of potash with] 

 manure at the rate of 10 tons per acre appears not to have increased the crop. 

 Generally speaking, chemical fertilizers upon this sandy soil give as good results 1 

 as manure. The season of application of nitrate of soda does not appear to 

 affect the relative yield of commercial asparagus in successive 10-day periods 

 throughout the season. In other words, the cut of commercial asparagus dur- 

 ing the early part of the season is not increased by either small or large appli- 

 cations of nitrate made as eai'ly as the soil can be worked. The lack of benefit 

 from humus furnished by the manure is explained in part by tlie practice of 

 working the t<ips grown subsequent to the cutting season into the soil and in 

 part to the yearly replacement and decay of a portion of the asparagus roots, 

 thus adding to the organic matter of the soil. 



[Report on pomological investigations], J. P. Stewart and W. C. Gil-i 

 LESPiE {Pennsylvania Sta. Rpt. 1916, pp. 52-56). — A progress report on projects ■ 

 under way In 1916. 



Experiments on the fertilization of apple orchards have been summed up for | 

 a 10-year period in a sub.sequent bulletin of the station (E. S. R., 39, p. 445).' 

 Summing up to date the results on cultural methods and cover crops in apple 

 orchards (B. S. R., 35, p. 644), it is concluded that In the absence of fertiliza- 

 tion, the mulch method gives the largest growth and most fruit in young 

 orchards, while the tillage and cover-crop method has done slightly better in 

 mature orchards. In tlie presence of fertilization, there was usually compara- 

 tively little difference between tillage, tillage and cover crops, and sod mulch. 

 Even sod, plus proper fertilization, has not been far behind. The greater etli- 

 ciency of the mulch on the younger trees appears to be connected with its 

 greater moisture-conserving effects. 



Among the annual cover crops, hairy vetch, soy beans, millet, medium red 

 clover, and the combination of oats and Canada peas have shown the best re- 

 sults. The addition of cover crops, however, appears to be of little value, 

 excepting possibly in seasons of abundant rainfall. The use of tilled intercrops, 

 with ajiproprlate fei-tilization and with a subsequent winter cover of rye, or 

 rye and vetch, has proved very satisfactory in the development of young or- 

 chards, and has resulted in no apparent injury during the first eight years. 

 Potatoes have done .specially well in this connection. 



Nearly all of the experiments show a marked correlation between yield and 

 growth under all normal conditions. It is only when one of these characters 



