458 
Journal of Agricultural Research 
Vol. VIII, No. 12 
Ramsey (1912) agree that the uninjured host is susceptible, and conclude 
that water is apparently the principal agent in conveying the bacteria 
from the existing lesions to younger leaves and small nuts lower down 
on the tree. They state (p. 338) that— 
During one of these [before mentioned] fogs the trees became saturated, water 
dripping from one portion of the tree to another which could easily carry the disease 
organisms to healthy tissue. Observations go to show that secondary infection in 
which large numbers of the small nuts become diseased is very likely to follow one 
of these foggy periods. 
Arthur and Bolley (1896) suggest that wound-producing insects are 
probably an important factor in the spread of the carnation disease caused 
by Bacterium dianthi , though infections can also take place through the 
stomata. They recommend a method of watering the plants in which 
the foliage is kept dry, and experience has shown the efficacy of it. In 
their conclusion (p. 34) the authors state that— 
As there must be moisture upon the leaves sufficient to enable the bacteria to move 
about and enter the stomata in order that they may gain access to the interior of the 
leaf, it is evident that keeping the foliage dry will prevent the disease. 
It apparently does not occur to them that the water under pressure, 
being dashed from plant to plant, might serve as a means of dissemination. 
Lewis (1914) describes a disease of Erodium spp. and Pelargonium 
spp. caused by Bacterium erodii, which, he says (p. 230),— 
is more prevalent in crowded beds where the plants remain moist and light is not 
so dense. 
Sprinkling is suggested as the most probable method of dissemination. 
Sackett (1910) discusses a disease of the stems of alfalfa caused by 
Pseudomonas medicaginis . The organism is probably carried from place 
to place on wind-blown dust particles. O’Gara (1914) describes more 
fully the characteristic appearance of the affected parts, and adds that 
stomatal infections may occur, though by far the greatest infection takes 
place through openings produced by insect puncture and severe frost 
injury. 
E. P. Smith, in the second volume of his work on Bacteria in relation 
to plant disease (1911), summarizes the data relating to water-pore 
inoculation of cruciferous plants with Bacterium campestris , and, in 
discussing Fischer’s objections to this conclusion, writes (p. 308)— 
* * * (2) the hypothetical, dust-dry, wind-borne bacterium requiring a half day or 
more to moisten it, is probably not the one that usually enters the water-pores and in¬ 
duces the disease, but rather a fresh germ recently come from the interior of some 
affected leaf as an extrusion from some water-pore already diseased, or left in the 
vicinity of the water-pore by some wandering insect. * * * such a bacterium would 
be ready to grow as soon as it found lodgment in a moist place. 
The disease progresses most in periods of frequent rains. Russell 
(1898, p. 31-32), writing on the same subject, states: 
One direct agent by which the disease is spread is the wind. Whether the disease 
germ is present in the soil or in decaying plants, the dried bacilli can be carried through 
