2G UNIV. OF N. H. AC.R. EXPERIMENT STATION [Bulletin 238 



]:)roduccd no more cabbage than the unlimed. In some supplementary tests 

 different forms of nitro^^en to the equivalent of that contained in an appli- 

 cation of 500 pounds nitrate of soda per acre were applied to several plots 

 of carrots. The results indicate that nitrate of soda, urea, ammonium 

 sulphate, ])otassium nitrate, Leuna saltpeter, and calurea are equally desir- 

 able as sources of nitrogen for this crop. A slightly increased yield, 

 possibly not significant, w^as obtained in the plots in vv^hich calcium nitrate 

 and nitrophoska were used. (Hatch Fund.) 



SPRAY SERVICE 



Tests were made this season by E. J. Rasmussen on the feasibility of 

 determining more definitely the proper time to spray for apple scab and 

 codling moth. Efforts were made to determine the stage of development 

 of the apple sc?b fungus, and the date when ascospores would first be ready 

 to discharge. The variation in development of the fungus in the various 

 orchard locations on the rolling hills of southern New Hampshire appears 

 so great that further study will be necessary before trustworthy informa- 

 tion can be furnished to fruit growers. 



Tests were made of the feasibility of determining the date of egg laying 

 by codling moth through the use of bait traps. All told, 1,115 moths were 

 caught between June 15 and August 15 in 110 traps placed in eleven 

 orchards in four counties. The experience thus far indicates that this 

 method gives a rather reliable indication of the time that the eggs are 

 deposited, which in 1928 was considerably later in the season than previous 

 investigations had indicated. The tests indicated that the commercial 

 product Diamalt is much superior to fermented glucose syrup for the pur- 

 pose of attracting the moths. (State Fund.) 



FOREST STUDIES SHOW RESULTS 



Studies with forest plots at the Station have shown the following facts, 

 reports K. W. Woodward : 



(1) That white pine on heavy clay soils is overtopped and crowded out 

 by hardwoods within ten years after seeding. 



(2) That Scotch pine is in every way inferior to white and red pine. 

 It does not grow any more rapidly and produces much inferior wood. 

 Besides, seed of suitable origin is difificult to obtain. 



(3) That pure white pine stands will yield a cord per acre per annum in 

 thinnings between 30 and 50 years. 



(4) That thinning white pine stands produces better quality and bigger 

 trees, and more volume per acre in a given time. (Hatch Fund.) 



THE EFFECT OF POTASSIUM DEFICIENCY ON 

 METABOLISM IN PLANTS 



In an effort to find the effect a lack of potassium in the nutrient solution 

 has on plant growth, T. G. Phillips and T. O. Smith grew tomato and 

 radish plants in sand cultures of three types : a complete nutrient solution ; 

 a solution containing one-tenth the amount of potassium in the first ; and a 

 solution wholly lacking in potassium. In the radishes a soluble carbohy- 

 drate was discovered which is easily hydrolyzed by acids but is not sucrose. 

 The plants grown in the complete nutrient solution contained an abundance 



