Feb. i, 1921 



Onion Smudge 



715 



Economically this factor has considerable value, since bulbs which 

 sprout before the end of the storage period are usually a total loss. 



RELATION OP SMUDGE TO SHRINKAGE OP SETS IN STORAGE 



In order to secure bulbs as nearly comparable as possible except for 

 presence or absence of smudge, healthy and diseased sets averaging 

 about 1 inch in diameter were selected from a general lot of white sets 

 which had been harvested in early August, properly field-cured, and 

 placed in storage on August 22, 191 8. Four lots of 25 bulbs each were 

 secured which showed heavy smudge infection but no signs of any other 

 disease. Three lots of 25 each were selected which appeared to be per- 

 fectly healthy. All lots were weighed on October 15. Two diseased lots 

 and one healthy lot were kept in the warehouse throughout the experi- 

 ment under conditions previously described. In order to secure a high 

 relative humidity a special temporary chamber was made in the ware- 

 house and lined with moistened burlap. Thus, a relative humidity of 

 90 to 95 per cent was maintained at a temperature close to that of the 

 main warehouse. Two diseased and two healthy lots were placed in this 

 chamber for approximately four weeks and then removed to the main 

 warehouse room. The several lots were weighed on December 30, 191 8, 

 and on February 18, 191 9. The results of the experiment are given 

 in Table VIII. A constant increase in shrinkage of diseased sets over 

 healthy sets was to be noted. Before the end of the experiment sprouting 

 had occurred in most of the lots, and, as was to be expected, was more 

 prevalent in diseased than in healthy lots. Sprouting and the complica- 

 tion of contaminating parasites should be considered; but, since the 

 former is seemingly enhanced by the disease and the latter is not serious 

 in these cases, there is reason to believe that smudge is responsible in 

 large measure for the increase in shrinkage. 



Table VIII. — Relation of smudge to shrinkage of onion sets in storage 



Lot 



No. 



Condition of bulbs. 



Environment. 



Num 



ber 



of 



bulbs 



used 



Origi- 

 nal 

 weight, 

 Oct. i S> 

 1918. 



Percentage of 

 shrinkage. 



Dee. 30, 

 1918. 



Feb. 18 

 1919. 



Condition at end 

 of experiment. 



Diseased. 



do... 



Healthy . 



Diseased. 



.do. 



Healthy 



do 



Average shrinkage of dis- 

 eased lots 



Average shrinkage of 

 healthy lots 



Ordinary storage. 



.do. 

 do. 



Exposure to high rela- 

 tive humidity for 4 

 weeks, followed by or- 

 dinary storage. 



....do 



do. 



.do. 



Gm. 



291.8 



277- S 

 319-3 



324-3 

 284.5 



6-S 



7-4 

 2-5 



8.9 



19. o 

 II- 3 



9. I 



11.4 



22. 4 



12 sprouting; 1 in- 

 fected with neck- 

 rot. 



is sprouting. 



8 sprouting; 1 in- 

 fected with blue 

 mold. 



16 sprouting; 3 in- 

 fected with neck- 

 rot. 



7 sprouting. 



5 sprouting. 



