Nov. 6 , 1916 
Host Plants of Thielavia basicola 
291 
Gilbert (7) in 1909 added three new hosts: Linaria canadensis , Oxalis 
corniculata , var. stricia , and Trifolium repens . Chittenden (5) in 1912 
reported T. basicola as a parasite of sweet peas. Massee (11) in the same 
year added to the list of host plants a species of Cypridpedium, Aster spp., 
and Capsella bursa-pastoris. 
Rosenbaum (14) published in 1912 on infection experiments with 
T. basicola , and by cross-inoculation experiments found that the species 
of Thielavia on tobacco, cotton, and ginseng were identical. 
O’Gara (12) in 1915 found T. basicola causing a disease of Citridlus 
vulgaris in Utah. This is the first report of the fungus on a member of 
the cucurbit family. Recently Burkholder (3) has noted the fungus on 
Trifolium pratense , Trtfolium hybridum , and Medicago sativa . 
METHOD OF WORK 
The investigation of the host plants of 7 \ basicola was undertaken 
primarily to corroborate, so far as possible* the hosts reported by earlier 
investigators, as in the majority of instances this had not been done. As 
it was deemed important to know something of the possible relation of 
the fungus to our agricultural plants, these were for the most part included 
in the earlier tests; but later the trials were made to include as many 
species as obtainable of the more susceptible families of plants. In this 
way about 200 species of plants have been grown on infected soil. The 
work was carried on almost entirely in the greenhouse. The seeds or 
plants were sown or transplanted into the infected soil, and optimum 
conditions maintained, so far as possible, especially as regarded the mois¬ 
ture content of the soil. The work was done partly at Arlington, Va., in 
cooperation with the Office of Tobacco Investigations, Bureau of Plant 
Industry, and partly at the Wisconsin Agricultural Experiment Station 
at Madison. In the Arlington greenhouses a fairly heavy clay loam soil 
from a tobacco field on the farm was used. This soil was taken from a 
spot in the field known to be badly infected with the rootrot caused by 
T. basicola . At Madison a greenhouse soil containing considerable vege¬ 
table matter was infected with soil from a tobacco field, where this 
rootrot had been occurring annually in recent years. On the whole, 
the conditions were such as might occur outdoors during a season of 
high precipitation. Recording soil and air thermometers showed tem¬ 
peratures ranging ordinarily between 18 0 and 25 0 C. in the soil and 20° 
to 30° C. in the air. The data were taken largely from infection on 
seedlings, as this was naturally an advantage in examining minutely the 
root system of a large number of plants. Since the age of the individual 
roots is considered a greater factor than that of the entire plant in deter¬ 
mining the occurrence of infection, it is believed the results would be 
comparable if older plants were used. 
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