Dec. 3. 1917 
Podblight of Lima Bean 
491 
the stomatal pore and the spore of the fungus, it is quite reasonable to 
conceive of an infection even during dry times, an event which actually 
does sometimes take place. It must of course be admitted, and the ob¬ 
served fact supports such a conclusion, that the number of infections by 
a fungus of this type during dry weather is relatively small compared 
with those during a period of rainfall or damp weather. Jones, Giddings, 
and Lutman (23) pointed out that moist, damp weather was conducive 
to the germination of the spores of Phytophthora infesians and made the 
interesting observation that the germ tube penetrated the leaf of an 
Irish potato through the epidermis as well as through the stomata. 
Similar observations were made by Jones (24), who found that the germ 
tube of Macrosporium solani E. and M. may penetrate the epidermis, as 
well as the stomata of Irish potatoes. The writer found no instance of 
penetration of Lima bean pods except through the stomata, and Pool 
and McKay (28) make a similar statement for Cercospora beticola. 
The inoculation experiments already described have shown that 
infection takes place readily through wounds, perhaps made chiefly 
by wind, and by means of pickers. In ordinary farm practice the pole 
Lima bean is usually trained up several feet above the ground. Exposed 
thus to the wind, the vines are whipped around and the pods wounded 
by rubbing against the stems, poles, or wires on which they are trained. 
A careful examination will readily show the bruised spots on pods ex¬ 
posed to such conditions. Pickers also, in searching through the foliage, 
may likewise brush or press the immature pods against stems or poles, 
bruising them in a similar manner. The reddish, streaked appearance 
in localized spots often observed on bean pods is characteristic of wounds 
made by constant brushing or rubbing of the pod against a hard surface. 
It is in such areas that infections are frequently found. 
The relation of insects to infection has not been studied. 
DISSEMINATION 
The dissemination of the podblight of Lima beans must be considered 
from two standpoints: (1) Over short distances, and (2) over long dis¬ 
tances, as from one district or State to another. As to the first of these, 
there are several ways in which the spores may be carried from plant 
to plant or from one field to another. It is not unlikely that insects, 
whether they feed on the pods or not, play an important part in the 
distribution of the spores. During wet periods the spores are exuded 
from the pycnidium, and any insect frequenting the diseased pods is 
likely to carry the spores about on its body. Pickers, too, in searching 
through the foliage for mature fruit, are likely also to distribute the 
spores to unpicked pods, where, under favorable conditions, new infec¬ 
tions will start. It is interesting to note in this connection that this 
and certain diseases of othei; crops seldom become serious until about 
picking time. There are two possible explanations for this. One is 
