Oct. 1, 1925 
Sclerotinia Species Causing Decay of Vegetables 
629 
at shipping time in vegetables which are not precooled may therefore 
develop considerable decay during the first few days of transit in 
spite of the fact that the car may show a perfect icing record and a 
temperature of 40° to 45° F. on arrival at market. 
It is rather difficult to control Sclerotinia decay in the field on 
account of the fact that the soil soon becomes heavily seeded with 
sclerotia if the same crop is planted year after year, and it is often 
difficult to find profitable truck crops to rotate which are not also 
subject to attack by this fungus. The soil may be sterilized by means 
of heat or chemicals, but this is practicable for only small plots and 
greenhouses. The selection of the more upright varieties of lettuce 
and the practice of general field sanitation, together with two or three 
year crop rotation system, seems to be the best recommendation for 
the control of Sclerotinia diseases in the field. 
In summarizing all studies and experiments made upon the various 
Sclerotinia cultures isolated from vegetable produce on the market, 
with the exception of S. intermedia , which was discovered during the 
progress of these investigations, and one other undetermined strain, 
all cultures have shown morphological as well as physiological char¬ 
acteristics of Sclerotinia libertiana Fckl. More than 90 per cent of all 
Sclerotinia cultures isolated by the writer in the last four years be¬ 
long to this species. 
SUMMARY AND CONCLUSIONS 
Sclerotinia libertiana Fckl. and related species cause great damage 
to truck crops during transit and storage, as well as in the field. 
All strains of Sclerotinia under observation produce a soft, watery, 
odorless type of decay of the host plants. 
Observations on the market indicate that produce harvested dur¬ 
ing wet weather is especially susceptible to Sclerotinia infection and 
decay during transit. 
Vegetable produce having little or no visible decay at time of ship¬ 
ment may show a high percentage of infection and decay upon arrival 
at market. 
S. libertiana is not limited to vegetable crops, but may also attack 
fruits. The manner of growth of the host and the opportunities for 
infection seem to be the important limiting factors. 
From 20 to 50 per cent of the cars of carrots, lettuce, and celery 
which the Bureau of Agricultural Economics, United States De- 
E artment of Agriculture, is called upon to inspect show decay caused 
y Sclerotinia. The amount of infection often averages higher 
than 50 per cent, and in some instances 100 per cent of the shipment 
is affected. 
Morphological and cultural studies show that there is no difference 
between cultures arising from sclerotial and mycelial plantings, 
other than variations in rate of growth. 
Cultural studies on agar indicate that at. temperatures approach¬ 
ing the minimum for the strain, the sclerotia formed are likely to be 
larger than normal for ropm temperature.- At temperatures nearing 
the maximum for the fungus the sclerotia formed are often smaller 
than normal. 
On media favorable for the development of the fungus the sclerotia 
formed are larger than those formed on unfavorable media. 
71486—261-3 
