Mar. 19,1917 
Dissemination of Angular Leaf spot of Cotton 
459 
the air * * * Inasmuch as this [infection through the water pores] is by far the 
most common gate of entrance for the disease organism, it is highly probable that the 
disease is disseminated by means of the wind more than in any other way. 
Smith discusses the wilt of cucurbits in the same volume and presents 
evidence of the dissemination of that disease by insects, especially one 
Diabrotica vittata. Concerning Cobb’s disease of sugar cane, this author, 
in his third volume (1914) writes (p. 48): 
We can well imagine, however, that under ordinary field conditions, with an abund¬ 
ance of dew or rainfall, and plenty of insect depredators, diseased plants might readily 
infect neighboring healthy ones, especially when young. 
In the chapter on Stewart’s disease of sweet corn, which is also in the 
third volume, the author states (p. 124), in the discussion of an experi¬ 
ment relating to seed infection: 
If the disease was actually derived from the seed-corn there probably would have 
been some cases during the seedling stage, and fragments of these soft plants full of 
the bacteria would have been blown upon neighboring plants, or dragged by culti¬ 
vators, or carried on the feet of men and horses, or bitten into by insects, or washed 
about by rains and dews. There are ways enough to account for the dissemination 
of the bacteria in the infection of a few plants when the distance is only a matter of 
a few feet. 
In an address before the Massachusetts Horticultural Society (1897) 
Smith discussed the subject under the headings: (1) Spread by insects; 
(2) spread by snails and slugs; (3) spread through manure pile; (4) 
spread by way of the soil; (5) spread by way of seeds, seedlings, buds, 
tubers, cuttings, and nursery stock. 
Macchiati (1891) and Boyer and Lambert (1893) describe a leaf and 
twig disease of mulberry caused by bacteria. Both claim to have iso¬ 
lated the organism, and the latter authors report successful inoculations 
with a bacterium named by them il Bacterium mori E. F. Smith (1910) 
uses this name 1 for an organism which he determined to be the cause of 
the same disease in Georgia, though it differed from that of Boyer and 
Lambert. In no case, however, is an explanation of the method of dis¬ 
semination offered. 
Manns (1909) concluded that the bladeblight of oats was caused by 
two bacteria to which he assigned the names “Pseudomonas avenae ” and 
“ Bacillus avenae ,” and that these bacteria were present in the soil 
reaching the host through “spattering rains.” Manns and Taubenhaus 
(1913) report their studies of the streak disease of sweet peas and clovers 
which they found caused by a bacterium named by them “Bacillus 
lathyri Later, Manns (1915) discusses this disease and considers more 
fully the subject of dissemination, saying (p. 12) that the disease attacks 
the plants about the beginning of the blooming period— 
having its origin usually near the ground, indicating distribution by spattering rain 
and infections through the stomata. 
Neither of them states by what means the upper parts of the plants 
become infected. 
1 According to Migula’s system of classification this name would be “ Pseudomonas mori.” 
