446 



The Contkol of Onion Smut. 



[Aug., 



Seed Treatments, 1919. — The following treatments were 

 carried out. The very susceptible variety " White Lisbon " 

 was used throughout, and the seed was drilled on May 1st. 



Plot 1 (Rows 1 to 4). Soot and salt applied to land on May 1st, and 



thoroughly worked in. 

 Plot 2 (Rows 5 to 8). Untreated control. 



Plot 3 (Rows 9 to 12). Row 9. Soil untreated, seed soaked for two days 



in O'l per cent, sulphuric acid, washed 

 and dried. 



Row 10. As in row 9 but 0*5 per cent, acid used. 

 Row 11. As in row 9 but 1 per cent, acid used. 

 Row 12. As in row 9 but 2'5 per cent, acid used. 

 Plot 4 (Rows 13 to 20). Row 13. Seed treated with 0-5 per cent, acid 



as in row 9 and afterwards shaken 

 up with 0*07 grammes of paraform, 

 just before sowing. 

 Row 14. 0*5 per cent, acid treatment and 0"28 grms. of paraform. 

 Row 15. 0-5 per cent, acid treatment and 0-56 grms. of paraform. 

 Row 16. 0*5 per cent, acid treatment and 1-4 grms. of paraform. 

 Row 17. No acid treatment but treated with 1*4 grms of paraform. 

 Row 18. No acid treatment but treated with 0*56 grms. of paraform. 

 Row 19. No acid treatment but treated with 0'28 grms. of paraform. 

 Row 20. No acid treatment but treated with 0*07 grms. of paraform. 

 The seed for Plot 4, i.e., rows 13 to 20 inclusive was, in each case, 

 shaken up with the proper quantity of paraform immediately before 

 sowing. It was found, however, that the seed hopper became dusted 

 inside with paraform, so that the last four rows probably received a 

 heavier dressing than was intended. 



Note. — A small plot (8 sq. yd.) along the edge of Plots 1 to 3 in- 

 clusive had about ^ lb. of paraform worked in on Feb. 21st. This plot 

 produced but a scanty crop and many of the plants were diseased. 



In addition to the White Lisbon seed used throughout Plots 

 1 to 4, seven other varieties were tested. 



Taking a full crop as 33 plants, a count gave the percentage 

 of healthy plants in one foot of each row as follow^s : — 



Row (1) 54-5 ; row (2) 21-2 ; row (3) 60-6 ; row (4) 12-1 ; row (5) 9 ; 

 row (6) 12-1 ; row (7) 6 ; row (8) 15-1 ; row (9) 3 ; row (10) 3 ; 

 row (11) 6 ; row (12) ; row (13) 3 ; row (14) 3 ; row (15) ; row (16) 3 ; 

 row (17) 12-1 ; row (18) 6 ; row (19) 6 ; row (20) 12*1. 



All the varieties tested proved to be susceptible ; the best one 

 (Red Garganus) giving only 36 per cent, of healthy plants. 



Soil Treatments, 1919. — In the autumn nine plots, each 

 one yard wide, and extending across the whole trial ground, 

 w^ere treated as follows : — 



Plot (1) ^Ib. of paraform worked into the land on Aug. 25th. 

 Plot (2) 2 lb. of bleaching powder applied as in plot (1). 

 Plot (3) 21b of soot worked in on Sept. 1st. 



