ANNUAL REPORT, 1935 47 



Weekly records of flea beetle damage were made in each plot throughout the 

 season. These are summarized in the following table. 



Number of Punctures per Leaf Cluster 



Material 



Average for 

 Maximum Minimum season 



Bordeaux mixture (5-5-50 ) 444 35 143 



*Ku-ba-tox 461 43 151 



*Cubor 229 24 110 



*Derrisol 207 56 101 



*Calrite 204 7 82 



*Dutox 317 58 135 



♦Combined with Bordeaux 5-5-50. 



The addition of calcium arsenate (Calrite) to Bordeaux mixture materially 

 reduced the flea beetle injury, and the constant coating of poison on the 

 leaves gave greater protection than did the contact insecticides where sprays 

 were applied at weekly intervals; although as shown by laboratory tests and 

 supported by observations in the field, the rotenone combinations were more 

 effective in their immediate kill of the beetles. 



Weather conditions were not conducive to high yields. Hot, dry weather 

 from late July to September interfered with the set of tubers so that yields 

 were materially lower than in 1934. The crop .throughout western Massa- 

 chusetts was estimated to have been reduced by about 100 bushels per acre, 

 which was substantially the reduction in the experimental plots. The yield 

 record in the various plots is as follows: 



Yield 

 Material (Bushels 



per acre) 



Bordeaux mixture (5-5-50) 474.56 



*Ku-ba-tox 505.48 



*Cubor 416.76 



*Calrite 404.21 



*Derrisol 392.56 



*Dutox 381.35 



♦Combined with Bordeaux 5-5-50. 



A slight amount of foliage burn was noted in the Dutox and the Calrite plots. 

 The high yield on the Ku-ba-tox and Cubor plots was believed to be due to 

 leafhopper control by these materials. Their superiority in that respect evi- 

 dently outweighed the greater effectiveness of the calcium arsenate against flea 

 beetle. Both of these materials gave increased yields over the Bordeaux plots 

 in 1934, and they appear to be valuable adjuncts to Bordeaux mixture where 

 flea beetle and leafhopper are a real problem, with potato aphids a menace in 

 seasons favorable for their development. It is doubtful whether it would be 

 necessary to add the materials to every application, so their use would not 

 materially increase the cost of the season's spraying. 



Value of Electric Traps against Orchard Insect Pests. (A. I. Bourne.) 

 Beginning April 11, 1935, Professor W. D. Whitcomb operated two electrocutor 

 traps in a large rose house at Thos. Roland, Inc., Revere, where a light infes- 

 tation of the rose leaf roller {Platynota slultana, Wals. ) was present. These 

 traps were hung from ropes at about 10 feet from the ground and were located 

 about 50 feet on each side of a center walk. The traps were equipped with 100- 

 watt lamps: one a clear glass bulb, and the other a blue glass bulb giving a 



