80 Report <ni a Trinl of Tarred Felt ''Discs" 



Some alterations in the discs themselves were made and the method 

 of placing them on the plants was also varied, as follows. On one row 

 all the discs used were perforated with a sn\all hole in the centre where 

 the two slits cross, in order to obtain a closer fit ronnd the stems of 

 the plants. On another row two discs were applied to each plant, the 

 discs being crossed so that when the slits are forced open by the stem 

 thickening during growth, the soil is not exposed, as it is to some extent 

 when single discs alone are used. Where two discs were used it was 

 surmised that female flies would be absolutely prevented from gaining 

 access to the soil near the plants so protected. As will be seen from the 

 results obtained the single discs gave quite adequate protection and no 

 corresponding advantage was gained by using either perforated discs 

 or double ones to compensate for the additional expense and trouble 

 entailed. 



(b) With Cauliflowers. 



The land on which the cauliflowers were planted was similar in 

 character to that on which the cabbages were grown; it was prepared 

 in the same manner and was cropped with sage the previous season. 

 The seedlings (variety Autumn Giant) were planted out on May 27th 

 and the discs were placed round the plants immediately after planting. 

 The latter were planted in four rows, each row containing 233 plants, 

 i.e. 932 plants altogether. The protected rows alternated with the 

 unprotected ones : rows I and III being protected, rows II and IV were 

 unprotected. 



The first count was made on June 23rd with the following result. 

 On row I adjoining the field (see Fig. 1) no plants showed signs of maggot 

 infestation ; row II, sixty- two plants attacked ; row III one plant 

 infected; row IV, ten plants had succumbed. 



Altogether seventy-two of the 466 unprotected plants were attacked, 

 equal to 15-4 per cent., whilst only one of the protected plants was 

 attacked up to that date. 



On July 4th the plants weie again counted when considerably further 

 losses had occurred; a photograph (Fig. 1) was taken on this date. 



The results of the countings are given in tabular form; a table 

 showing the results obtained with the cabbages is also given for com- 

 parison. 



No further cabbage jjlants were destroyed by maggots on this plot 

 after July 8th. 768 cabbages, out of a total of 816 planted, had been 



