A SERIOUS LETTUCE DISEASE. 
141 
The record is presented in Table XIX and in Diagram II (Fig. 31). 
TABLE XIX.—DAILY RECORDS OF DEATHS FROM SCLEROTINIOSE, 1909-1910. 
Number 
Date of Plants 
Diseased 
Feb. 18.______ 1 
March 4........ 1 
22 ...__..___ 1 
28____ 1 
31. 2 
Total. 7 
It will be noted that no plants died of sclerotiniose prior to Feb¬ 
ruary 18, 1910, and none after March 31, and that in all only seven 
plants or one-half of one per cent, of the crop died. 
This very large decrease in disease under one year of hygienic 
treatment—about 99 per cent, of' the disease bad been removed—was 
more than was anticipated and indicates even shorter life of the Sclero- 
tia and greater loss of sclerotia from rotting than was predicated for 
them. 
The beds were again set with lettuce in December, 1910. 
This year approximately the usual number of plants, or to be exact, 
1,113 in all, were set. The crop was raised to maturity, cut and sold. 
The record of disease is shown in Table XXI and in Diagram III 
(Fig. 31). 
TABLE XX.— DAILY RECORDS OF DEATHS FROM SCLEROTINIOSE, 1910-1911. 
Date 
April 18 
19 
20 
29 
Number 
of Plants 
Diseased 
... 1 
... 1 
... 3 
1 
May 1......1 
15.......I 
Whatever may be thought of the theoretical questions involved, cer¬ 
tain practical conclusions stand forth clearly and unmistakably. 
1. The lettuce beds were very thoroughly infected. See record of 
1908-09, Table XVIII and Diagram I. 
2. Under usual conditions and usual mode of handling this disease 
would not have decreased but would have increased or at least remained. 
destructive during following years. 
3. Under the treatment that was followed, which had been indicated 
as the proper one by our laboratory and field studies, the disease de¬ 
creased very markedly after one year and remained unimportant during 
the second year. 
