Dec. 3, 191? 
Podblighi of Lima Bean 
485 
The ascospores germinate readily in most any nutrient medium in 
about six to eight hours by the development of a single germ tube from 
one or both cells (fig. 9). The hyphae branch is 12 to 24 hours, and septa 
are laid down at about the same time. Growth is very rapid. At ordi¬ 
nary room temperature a colony from a single spore becomes visible 
to the naked eye in about five days. The ascogenous stage has not been 
t^todu.ced vtl culture. The transfer of a colony from a single ascospore 
resulted after 7 to 10 days in the production of the pycnidial stage on 
the same culture media on which pycnidia were developed by a transfer 
of pycnospores in the same length of time. In other words, there is 
no difference between the growth of the ascogenous strains and pycnidial 
strains on the same culture media. 
INOCULATION EXPERIMENTS 
The inoculation experiments on which the conclusions of the parasitism 
of the organism have been drawn were made in the greenhouse. It was 
found that Lima beans grow normally and produce fruit as well under 
greenhouse conditions as in the open field. Opportunities 
were therefore afforded to study the parasitism of this dis¬ 
ease under controllable conditions and at any time of the 
year most suited to the needs of the work. 
Controls were held with each experiment, the number 
and results of which are shown in Table I following a dis- Fig. g.—Diapor- 
cussion of the inoculation experiments. The pods unless f* m: P ofrmi- 
otherwise stated were inoculated by inserting spores and mating asco- 
hyphse into a wound made by a sterile needle. While sp ° res ' Xs °°* 
later evidence will show that under suitable conditions infection may 
take place without wounding, the relative humidity of a greenhouse is 
usually so low that spores smeared on the surface often fail to germi¬ 
nate. It was necessary, therefore, to protect the spores from drying out 
by inserting them under the epidermis or by other means. In most 
cases it was impossible to protect the spores against drying, owing to 
the fact that when a Lima bean plant is fruiting abundantly it is gener¬ 
ally too large to confine in an infection cage, though this was done with 
some smaller plants (see p. 486). 
All inoculations were made from cultures grown on stems of MelUotus 
alba . The age of the culture was not considered or found important 
further than that the culture should be vigorous and fruiting abundantly. 
Spores were exuded from the pycnidium in about seven days after the 
culture was inoculated and continued to do so for 30 to 40 days there¬ 
after or until the culture was dried. Spores were well suited for inocu¬ 
lation purposes until the culture medium was dried out. 
Inoculations were made with six different strains. By a strain is here 
meant a difference in the source and not a difference in morphology or 
