1 Jury, 1899.] QUEENSLAND AGRICULTURAL JOURNAL. 61 
field, care being taken to leave no part behind, whether tuber, root, stem, 
or foliage. (Thus by no means should the common practice of pulling up the 
haulm and casting it on one side be persisted in.) Such action should be taken 
as soon as the first symptoms of the disease are recognised, since an affected 
plant never recovers, and whilst it remains in the field it is an immediate 
source of disease for other plants around and will also, in due course, infect 
the soil in which it grows. 
2. The ground in which the plant has grown should then be opened out, so 
as to expose the soil that has been adjacent to the roots to the influence of 
sunshine and the drying action of the atmosphere. A little lime applied at the 
same time will contribute to the result to be derived from these influences—viz., 
that of killing the plant-microbe. 
8. In lifting the crop endeavour, as far as practicable, to deal separately 
with those plants that do not evince disease, and by no means mix sound and 
diseased potatoes in the same heap, bag, or other receptacle. Especially is this 
necessary if any of the crop is intended for subsequent use as seed. Whenever 
racticable, however, procure fresh seed from some outside source, though even 
in this case care should be taken that the disease be not present in connection 
with it, either latent or undeveloped. 
4, In ploughing and subsequently cultivating, avoid as far as possible 
carrying the soil forward with the implements or teams from ground in which 
a diseased crop or diseased plants have grown to that in which such has not 
occurred ; and, generally speaking, mixing together presumably uncontaminated 
and contaminated soil. 
5. When the crop has been lifted and the preceding measures have as far 
as possible been complied with, the ground should be kept in a state of clean 
fallow, so that by frequent tillage as much of the soil as possible may be exposed 
to heat and sunlight. ; 
6. Moreover (as there are some grounds for concluding), benefit may be 
derived from applying to the soil that has already become infected by the germs 
‘of the disease, and before replanting it afresh with potatoes, some chemical 
substance which, whilst acting as a mineral fertiliser, will at the same time 
destroy its powers of communicating the malady to the creRe grown in it. At 
-present, however, there is not sufficient evidence derived from experiment to 
“warrant any specific recommendation in this connection. 
7. The two preceding recommendations contemplate cases in which the 
entire soil of a farm is disease-infected, and it is necessary to plant potatoes 
afresh in ground wherein it has already manifested its presence. But as a 
general rule an effort should be made to provide that one crop of potatoes 
‘does not succeed another upon the same soil, if the malady has once 
-shown itself. Even a single intervening crop of an entirely different deseription— 
eg., maize or broom millet, &¢.—will not always meet the requirements of the 
case, but two or more will need: be raised. Otherwise persistence of the disease 
with increased virulence and more general occurrence is almost inevitable. But, 
-of course, plants that belong to the same natural order as does the potato (i.e., 
Solanacex), and which are also-addicted to the presence of the same malady, are 
not admissible for intervening crops—a remark that especially applies to the 
tomato. 
Norr.—Justification for advocating this procedure is found in the experience of 
-other districts. One person to whom it was recommended for adoption in March, 
1894, writes in May of the present year as follows :—I have tried many remedies with 
little success, with one exception, for I have found that, after planting two successive 
crops of oats, barley, or rye, the disease disappears altogether. Many of the farmers 
-of . . . are adopting the same course. 
8. In any fresh planting, especial attention should be given to the condition 
of the seed. If there be any history of the occurrence of the disease in the crop 
from which it has been derived, or there is any probability of its haying been 
subjected to the action of the infecting germ, it should, prior to being planted, 
sbe passed through a weak solution of sulphate of iron, containing not less than 
x 
