1920 ENTOMOLOGICAL SOCIETY. 69 



70 to 210 plants to a block. Three control untreated blocks were interspaced 

 between the treated blocks and they, with the tar-paper blocks, only received 

 applications of ordinary water on the same occasions as the treatments of corrosive 

 sublimate were made. Six tar-paper-disc blocks, consisting in all of 611 plants 

 were employed in the experiment, interspaced between the other blocks, and three 

 corrosive sublimate blocks on which various strengths were used, at 1 oz. to 6 

 gallons, 1 oz. to 8 gallons and 1 oz. to 10 gallons of water. The con'osive sub- 

 limate blocks were in turn divided into three parts, which received respectively 

 1. 2 and 3 applications in the season. Observations were made on cabbages and 

 caulitiowers. The following notes deal with cauliflowers in particular and, inas- 

 niuc-h as the cauliflower is more susceptible to injury than the cabbage, it would 

 necessarily follow that what was shown to be the ea<e with the cauliflower Avould 

 also be so with the cabbage. Cauliflowers were transplanted on May 3rd and set 

 in their permanent positions in the field, and tar-])a])er discs were placed around 

 the ])lants at this time. Apjilications of eorrosixe sublimate were made on May 

 :th. May 13th and May 23rd: the first application requiring the use of 1 gallon 

 of diluted mixture, the second application IJ/. gallons and the third nearly 2 

 gallons per 100 plants. One cultivation was given the entire plantation after 

 Transplanting between ^lay 3rd and May 23rd. 



In checking results a great deal of care was exercised to determine exactly 

 what caused the plants to die or sufi'er, and observations were made on the vege- 

 tative growth and development of the root system. ]^]very plant received a 

 separate number and each was cheeked weekly throughout the period of the 

 experiment. 



TiESULTS OF EXPEItlMEXT. 



The untreated blocks ol' cauliflowers showed considerable (76.5 per cent.) 

 characteristic injury from maggots and stood out very clearly in the plantation. 

 The tar-paper-disc blocks showed pronounced injury but only 25.3 per cent, of 

 tlie injury caused was due to maggot attack. Fully 36 per cent, was caused by 

 a '"wilt" produced l)y the presence of the disc. ]t would be well to mention 

 clearly at this point, that the field chosen for the experiments was a low-lyim^ 

 one with a large quantity of vegetable matter in the soil composition, with a 

 ten<len(y to remain cold for a long time in the spring months. The sun is usually 

 ^ery warm in the Okanagan Valley during May and this last year was no exception 

 in this regard. Consequently with conditions such as these, on cauliflowers, the 

 influence of heat acting on and in association with the subsoil moisture produced 

 a condensation of moisture beneath the disc below the soil surface. Thi- condi- 

 tion was not observed in the case of the cabbages, for the reason that the growth 

 of a cabbage is sufficiently strong to outgrow numy adverse conditions. Any check 

 in the growth of cauliflowers is serious in commercial growing, as a proccBs known 

 as -'^buttoning" takes place. This "wilt" condition was not observed in any case 

 Avith the plants treated with corrosive sublimate, but some plants were injured 

 by the proximity of fresh manure to the roots, causing the loss '"'from other 

 causes" shown in the table given below. In fact after three treatments with 

 corrosive sublimate at all three strengths the loss due to maggot attack was less 

 than 2 per cent., and the growth of the plants in "top" and '"root" was double 

 the growth on any other block. The results clearly showed that under " bottom " 

 land conditions, with cauliflowers, tar-paper discs were unsatisfactory and that 

 corrosive sublimate in three treatments at 1 oz. to S or 10 gallons o-avc eminentlv 



