REPORT OF CRANBERRY SUBSTATION FOR 1916. 223 



Plots 1, 5, 9, 13, 17 and 21 are all untreated checks. The meanings of 

 the symbols used in the table are as follows: — 



= Nothing. 



N = 100 pounds nitrate of soda per acre. 



P =400 pounds acid phosphate per acre. 



K =200 pounds high-grade sulfate of potash per acre. 



L = 1 ton of (slaked) lime per acre. 

 Kcl =200 pounds muriate of potash per acre. 

 Nij =150 pounds nitrate of soda per acre. 

 Nj =200 pounds nitrate of soda per acre. 

 Pi;^ =600 pounds acid phosphate per acre. 

 P2=800 pounds acid phosphate per acre. 



In combination they mean, for example, as follows: N2PK = 200 

 pounds of nitrate of soda + 400 pounds of acid phosphate + 200 pounds 

 of high-grade sulfate of potash per acre. 



As the table shows, the fruit of the fertilized areas this season was, as 

 a rule, much inferior in both quantity and keeping quality to that of the 

 checks, this being especially marked with the plots treated with lime and 

 with the maximum amount of nitrate of soda. Considering all the expe- 

 rience with these plots since they were started in 1911, it is the writer's 

 judgment that, in general, whatever slight advantage in yield has been 

 gained by the use of the fertilizers has been balanced by the cost of the 

 treatment, the deterioration in the quality of the fruit and the greater 

 cost of picking due to the increased vine growth. 



Insects. 

 The Cranberry Rootworm (Rhabdopterus picipes (Oliv.)). 



The rearing of the beetles definitely identified the mfestation by the 

 cranberry rootworm {Rhabdopterus picipes (Oliv.)) tentatively recorded in 

 last year's report (pages 32 and 33). By the beginning of winter the grubs 

 of this insect nearly complete their growth. They are then, except the 

 head, for the most part nearly white in color and somewhat over a quarter 

 of an inch long. They hibernate without growing larger. They do some 

 feeding in the spring and change into pupa? in June. No beetles of the 

 infestation under observation had yet emerged on June 30, this season, a 

 collection of the insects taken that day consisting of 4 grubs and 32 pupse. 

 One beetle was found on July 1, and during the following two weeks they 

 practically all came out, the period of most rapid emergence extending 

 from the 3d to the 11th of the month. 



It was anticipated that the adults might feed freely on the cranberry 

 foliage, and at the WTiter's suggestion an arsenical spray was applied to the 

 infested area on July 3 and repeated on the 11th and 18th. In the first 

 two applications, 2j pounds of "Corona" arsenate of lead and 1 heaping 

 teaspoonful of white arsenic to 40 gallons of water were used. For the last 

 treatment the mixture was the same, except that the arsenic was increased 



