646 
Journal of Agricultural Research 
Vol. XXIII, No. 8 
LABORATORY TESTS OF THE EFFECT OF FORMALDEHYDE ON SCLE- 
ROTIA AND MYCELIUM 
TREATMENT OF SCLEROTIA 
Some very interesting data were obtained by treating sclerotia of 
►S. libertiana in vitro for different periods of time with different concen¬ 
trations of formaldehyde. Films of air covered portions of the surface 
of the sclerotia when first placed in the solution. This difficulty was 
overcome by vigorous agitation in distilled water for one-half hour im¬ 
mediately preceding treatment. Sclerotia specified as small were 1 mm. 
or less in diameter; those designated as large were over 1 mm. in diameter. 
Sclerotia (Tables I and III) were taken from diseased lettuce plants 
after they had “dropped” in the bed. The sclerotia were grouped into 
lots of nine each according to size . After shaking in distilled water they 
were transferred to 400-cc. air-tight glass jars containing formaldehyde 
solutions of the desired strengths, 4 allowed to remain for different periods, 
after which they were removed under aseptic conditions and thoroughly 
washed three times in sterile distilled water. From this they were trans¬ 
ferred to nutrient agar plates and the results of growth recorded (Tables I 
and III). Under these conditions, in a 1-50 solution the maximum time 
4 1-50,1-100, and 1-200 formaldehyde solutions were made by using one part of 37.3 per cent formaldehyde 
to 49, 99, and 199 parts, respectively, of distilled water. 
