September 27, 1894, 
JOURNAL OF HORTICULTURE AND COTTAGE GARDENER. 
297 
Cost op the Work, 
FIG. 44.— LEAP OP POTATO AFFECTED WITH THE MACROSPORIUM DISEASE 
Potato Scab. —Within recent years this disease has attracted a 
great deal of attention. Its effects on the tuber are so prominent 
and easily recognised that nothing further on this point need be 
said (fig. 45). 
“The cost of the work outlined for Potato blight and 
the Macrosporium disease will depend to a considerable 
extent upon the kind of machinery used and the price paid 
for labour. With suitable apparatus, such as has been 
described, and labour estimated at i’50 dols. per day, 
Potatoes may be sprayed six times for about 6 dols. per 
acre. This estimate is based upon experiments extending 
over several years, and includes the cost of chemicals as 
well as of labour. The cost of treating scab is mainly 
in the labour involved in dipping and drying the seed, and seldom 
exceeds 15 cents per acre. 
Conclusions. 
The disease progresses rather slowly, the spots gradually becoming larger, 
especially along the edges of the leaflets. At the end of ten days 
or^ two weeks half of the leaf surface may be brown, withered, and 
brittle, while the rest is of a pale yellow colour. Three weeks or a 
month may elapse before all the leaves succumb, the stems in the 
meantime remaining green, until they finally perish through lack of 
nourishment. The tubers stop growing almost as soon as the leaves 
are attacked, and as a result the crop is practically worthless. 
is now offered for sale by pump manufacturers and dealers in seeds and 
agricultural implements in various parts of the country. Of course 
where there are only a few plants to treat simple devices for the appli¬ 
cation of the fungicide, such as syringes, watering cans, and even old 
brooms may be used. These makeshifts, however, should be avoided as 
much as possible, as they not only fail to distribute the mixture uniformly, 
but are wasteful. 
“In addition to the line of treatment suggested care must be taken to 
avoid the use of diseased ‘ seed,’ and further, the stems 
and leaves killed by either the blight or Macrosporium 
disease should be mowed or cut off and burned. 
“ Potato scab has been very successfully prevented by 
the use of the corrosive sublimate solution already described, 
very smooth Potatoes having been grown from very scabby 
tubers. The Potatoes to be planted are simply immersed 
in the solution for an hour and a half, then spread out 
to dry, cut, and planted in the usual manner. A large 
barrel offers a convenient receptacle for the solution. 
The Potatoes may be placed in a coarse sack and 
suspended in the liquid, care being taken to wash the 
tubers before dipping, providing they are very dirty. 
The corrosive sublimate is very poisonous, therefore it 
must be used with great care and kept out of the reach 
of children and animals. All treated tubers should be 
Ranted. 
Fungicides or Preventives to be Used for the Diseases. 
“ For blight and the Macrosporium disease nothing so effective as the 
Bordeaux mixture has been found. This should be prepared as follows : 
Pour into a 45-gallon barrel about 30 gallons of clean water, then weigh 
out 6 lbs. of bluestone or copper sulphate, and after tying it in a piece 
of coarse sacking suspend the package just beneath the surface of the 
water by means of a string tied to a stick laid across the top of the 
barrel. In another suitable vessel, such as a tub or half barrel, slack 
4 lbs. of fresh lime. Slack the lime carefully by pouring on small 
quantities of water at a time, the object being to obtain a smooth, 
creamy liquid, free from grit. As soon as the bluestone is dissolved, 
which will require probably less than an hour, pour the lime mUk into 
the bluestone solution, stirring constantly to effect a thorough 
mixing ; add enough water to fill the barrel, stir again, and the 
mixture is then ready for use. 
“ For the treatment of Potato scab a solution of corrosive 
sublimate has given the best results. This should be prepared 
by dissolving 2^ozs. of corrosive sublimate in about 2 gallons 
of hot water and after an interval of ten or twelve hours 
diluting with 13 gallons of water. 
When and How to Apply the Fungicides. 
“For Potato blight and the Macrosporium disease apply 
the Bordeaux mixture, beginning when the plants are about 
6 inches high, and continuing at intervals of twelve or fourteen 
days, until five or six applications in all have been made. If 
the season is rainy it would probably be beat to make the 
treatments every ten days, the object being to keep the plants 
at all times covered loith the fungicide. By adding 4 ozs. of 
Paris green to each barrel of the Bordeaux mixture the treat¬ 
ments will not only prevent the diseases under consideration, 
but keep in check the Colorado Potato beetle and other insects 
as well. Before adding the Paris green to the Bordeaux mix¬ 
ture the former should be made into a thin paste by mixing 
with a small quantity of water. 
“The successof this work depends in large measure upon the thorough¬ 
ness with which the fungicides are applied. To reach all parts of the 
plants above ground with a fine spray requires a good force pump and 
a suitable nozzle. The knapsack sprayer now on sale in nearly every 
section of the country will be found one of the most useful machines 
for spraying fields of 5 acres or less. For larger plantations more 
powerful machines should be used. A cheap and serviceable apparatus 
well suited for this work may be made by mounting a good, strong 
force pump on a barrel and then placing the barrel and mounted pump 
in a light wagon. The entire outfit, including barrel, pump, hose, 
nozzles, operator, and boy to drive, may be drawn by one horse. As 
the wagon is drawn slowly between the rows the man in the wagon may 
operate the pump, and at the same time keep the mixture stirred, while 
two others on the ground hold the nozzles and direct the spray over the 
plants. The nozzle found best suited to the work is the Veimorel ; this 
“ The three diseases discussed cause a loss in this country of several 
million dollars annually. It is believed that much of this loss may be 
prevented by following the suggestions made, but it must be borne in 
mind that the treatments are preventive, not curative. The importance, 
therefore, of beginning the work in time cannot be too strongly 
urged. 
“ In the case of blight and the Macrosporium disease the question 
may arise as to the advisability of going to the expense of arranging 
for work that may not be necessary on account of the diseases not 
appearing. In answer to such a question it may be said that there is 
scarcely a section of the country where one or another of the diseases 
mentioned does not occur every year. Furthermore, it is a fact well 
established by experiments that, even if no diseases whatever appear, 
j spraying with the Bordeaux mixture will increase the yield to such an 
extent as to make the work profitable.” 
NUTRITION OF ROOTS. 
One has some compunction in stepping between two controversialists 
who are supposed to be trying to elucidate an abstruse question like 
the one at issue, but we cannot help the conclusion that Mr. Bishop is 
taking us an interminable way round for the short distance accom¬ 
plished. We have had interlocking of pages and paragraphs, learned 
disquisitions on vapour, vaporous moisture, steam condensed, steam 
uncondensed, clouds above and fog below so dense, and the whole 
i so mixed together, that Mr. Bishop even does not distinguish between 
