BACTERIAL DISEASE OF TOBACCO. 437 
appears year after year. In 1917 I had two interesting 
illustrations of the way in which the disease may be trans- 
ported. At Tamworth some Chinamen had tobacco seed- 
beds on high land on virgin soil on a spur of the Moonbi 
Ranges, many miles from other tobacco growing land. The 
crop was free from “‘ Blue Mould”’ until the owners visited 
some of the gardens of their compatriots where the disease 
was rampant and then returned. At Tumut, one grower 
in an isolated spot made a handsome return by supplying 
seedlings to those whose beds had been destroyed by “‘ Blue 
mould.’’ But he got tired of lifting and delivering the 
seedlings himself, and those who wanted them had to come 
and get them themselves. Shortly after this his beds also 
were attacked by “‘ Blue Mould.”’ 
A Bacterial Disease of Tobacco.—Seedlings that have 
been attacked by Peronospora hyoscyami may die out 
completely or they may exhibit a partial recovery, sufficient 
to induce the grower to transplant them. Such plants may 
grow in the field and almost completely recover, or they may 
attain a certain size and then wilt. They seldom have the 
appearance of normal healthy vigorous plants, and are very 
liable to develop brittle stems that break off in a very 
moderate breeze. The stems of all such plants when cut 
sharply across, just above the root, show aring of vascular 
tissue that is discoloured—it is brown or black. Cutting 
the stem across at intervals, this discoloured tissue may 
be traced upwards towards the apex. The colour becomes 
fainter, but it can be traced even with the naked eye into 
the veins of the big leaves. 
The distribution of this colour in the vascular tissue of 
the stems and leaves is very similar to the distribution of 
the black pigment in cabbages affected with ‘‘Black Rot.”’ 
This disease occurs in New South Wales, and the organism 
Pseudomonas campestris (Pammel) Erw. Smith, has been 
isolated from diseased specimens. | 
