1920 ENTOMOLOGICAL SOCIETY. (;: 



Trial Plots, 1910. 



For trial of treatments not previously tested in our experiments, we had iit 

 oiir disposal a section of land 170 ft. wide by 60 ft. long. With the rows of Cahbiiiie 

 2 ft. apart, there was thus space for 85 rows of cabbage, and with the plnnts 

 J 8 inches apart in the rows, 40 plants for each row. With seventeen different 

 treatments including checks, this gave us 300 plants (Copenhagen Market) for 

 each plot. Instead of having all the 200 plants for each plot together, however, 

 we divided the piece iiito five sections, one row i.e., 40 plants in each section 

 being devoted to eacli of the different treatments. We thus had on this piece of 

 ground five repeatings of each treatment, this method tending to equalize variations 

 in intensity of maggot infestation and any in equalities of the soil that miglit 

 affect the final weight of heads from each plot. 



It will be seen that there are four check plots, each receiving a different horti- 

 cultural treatment, but none protected from the maggot. All the other treatments 

 with the exception of the salt solution were in the form of. dry powder and were 

 applied at the rate of 700 lbs. per acre. In the case of the salt, a saturated solution 

 was first made and this then diluted with an equal quantity of water. 



Three of the sections were planted May olst, the remaining two, June 8iid. 

 An exception to this were the plants on Check Plot D, which were planted a week 

 earlier than the others. It was intended to plant them all on the same date, l>ut 

 conditions arose which made this impossible. Normal applications of nitrate of 

 [ soda, i.e., 250 lbs. per acre, applied in two equal sowings on June 11th and June 

 ' 28th were made. On Check B, an extra application was applied on July 12th. 

 this plot receiving a total amount equal to an application of 500 lbs. per acre. 

 All the treated plots received two applications of the material used, the first at 

 planting, the second on June 13th. The first brood flies were actively ovipositing 

 at the time of planting. 



Discussion of Eesults. 



Had it been possible to set out these plots two weeks earlier, it would naturally 

 have been a more severe test of the different materials, since they would have 



': been exposed for a longer period during the height of the oviposition period. 

 At the same time the number lost in the check rows enables us to make sufficiently 

 striking comparisons. 



A consideration of the results from the cheek plots shows that " A " and " B " 

 are equal as regards the number of plants killed, but the acceleration of the head- 

 ing process and the greater weight of head, owing to the extra application of 

 nitrate, have given us a much larger price per acre in the case of '"' B." Obviously, 

 the results of this treatment would depend upon the chemical requirements of 



f the soil. Plot " C " shows n lower rate of infestation, due doubtless to the fact 

 that it escaped the period of most active oviposition. It also missed the higli 



_ liri(-es obtained for the early crop. Check Plot " D " liaving been planted earlier 

 than the others, cannot, uufortunatel_y, be coni])ared with them on an equal basis. 

 Exposed during a longer period of active oviposition, more plants su'ccumbed than 

 in the other check plot. Had conditions been different it is not likely that this 

 would have occurred. As it is, the greater average weight of the heads which 

 survived and the earlier heading up of tlie plants, gives us the largest financial 

 returns of any of the check plots. 



