654 
Journal of Agricultural Research 
Vol. XXHT, No. 8 
Approximately the same length of time was required to kill sclerotia 
in both the 1-50 and the 1-100 solutions of formaldehyde; the same was 
true of mycelium. 
Aspirating sclerotia for one-half hour in water and subsequent treat¬ 
ment in a formaldehyde solution in vitro failed to shorten the time 
in which they were killed. 
Formaldehyde solutions are much more effective if the sclerotia are 
not in a desiccated condition. For this reason, the soil of commercial 
greenhouses should be maintained in a moist condition for 5 to 10 days 
immediately previous to the formaldehyde treatment. 
The formaldehyde solutions greatly checked subsequent colony growth 
on nutrient agar of the sclerotia and the particles of mycelium which 
were treated in them. 
In most cases the 1-100 formaldehyde solution killed sclerotia and 
mycelium 20 inches below the soil surface. 
A 4-year test has demonstrated that a 1-100 formaldehyde solution 
is an effective soil fungicide when used to control S. libertiana in green¬ 
house soils. Sterilization is not always complete. In both experi¬ 
mental and commercial greenhouses the treated portions have not aver¬ 
aged over 2 to 4 per cent drop, whereas the unsterilized portions have 
averaged over 50 per cent drop. 
In greenhouses that show only scattered cases of drop it is advisable 
to remove the diseased plants, mark their locations, and after harvest 
treat the infected area with a liberal application of a 1-100 formaldehyde 
solution. This will not delay work in the house, as the soil may be worked 
and planted the day following such treatment. 
LITERATURE CITED 
(1) Anonymous. 
1920. WAR is BEING WAGED on “LETTUCE DROP. ,, In N. J. Agr., v. 2, no. I, 
p. 6-7. 
(2) beach, W. S. 
1921. THE LETTUCE “DROP** DUE TO SCLEROTINIA minor. Pa. Agr. Exp. Sta. 
Bui. 165, 27 p., 3 fig., 3 pi. (in text), Bibliography, p. 26. 
(3) Buddin, Walter. 
1914. PARTIAL STERILIZATION OP SOIL BY VOLATILE AND NON-VOLATILE ANTI¬ 
SEPTICS. In Jour. Agr. Sci., v. 6, pt. 4, p. 417-451, 4 fig. 
(4) Clinton, G. P. 
1908. NOTES ON PUNGOUS DISEASES, ETC., POR 1908. LETTUCE (LACTUCA 
sativa). In 3ist/32d Ann. Rpt. Conn. State Agr. Exp. Sta., [i9o6]/o8, 
p. 863-864, pi. 63. 
(5) Smith, Clayton O. 
1916. COTTONY ROT OP LEMONS IN CALIFORNIA. Calif. Agr. Exp. Sta. Bui. 265, 
237-258, 11 fig. 
(6) Stevens, F. L. 
1911. A SERIOUS LETTUCE DISEASE (LETTUCE SCLEROTINIOSE). N. C. Agr. Exp. 
Sta. Bui. 217, 21 p., 8 fig. 
(7) Stone, G. E. and Smith, R. E. 
1900. the rotting op greenhouse lettuce. Mass. Agr. Exp. Sta. Bui. 69, 
40 p., 10 fig. (in text and on pi.) 
(8) Reddick, Donald, et al. 
[1913]. vegetable diseases, round table. In N. Y. Veg. Growers’ Assoc. 
Rpt., 1911/13, p. 194-205. 
