Vol. LX XIV, No. 4314. 
NEW YORK, JULY 10, 1015. 
WEEKLY $1.00 PER YEAR. 
Some Common Potato Diseases. 
To be Seen at Blooming Time. 
U nsuspected troubles.—F ew farmers 
realize what there is to be seen in their potato 
field, if they examine the plants carefully, while 
they are in blossom. The field may look green, 
thrifty and free from disease, yet, if the plant path¬ 
ologist from the State Experiment Station should 
walk through our fields with us, he would probably 
show us at least half a dozen diseases within a few 
minutes. It is the purpose of this article to explain 
the symptoms of a few of the common diseases and 
that some of the plants, while they have a good 
color, will have undersized leaves, somewhat 
crinkled and closely clustered upon the branches. 
Later in the season the plants may again produce 
normal-sized leaves at the tops of the branches. 
The grower may easily imagine that the plant is 
growing out of the disease; however, the yield will 
surely be small. Upon looking below the foliage, 
little green swellings may be observed in the axils 
of the leaves. These swellings may be the size of 
peas, or in some cases as large as strawberries. These 
swellings are actually aerial potatoes. Many more 
real potatoes may lie found near the surface of the 
This disease frequently comes on so gradually and 
inconspicuously that the farmer may think his crop 
is getting ripe in the natural way. However, the 
yield is seriously affected by this disease, because it 
cuts short the growing season just when the tubers 
should be gaining size rapidly. Early blight is effi¬ 
ciently held in control by spraying with Bordeaux. 
POISON INJURY.—The poisons, which are ap¬ 
plied to kill the Colorado potato beetle frequently 
burn and destroy the leaves. An example of this 
is the burning so often caused by the use of Paris 
green. The fungus of early blight develops very 
fast in the leaf tissue injured by spray. Also, even 
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teach the farmer to pick them out in his own field 
ami eventually avoid having the diseases. 
BLACK-LEG.—Upon going to the field the first 
thing that might attract attention is an undersized, 
pale colored plant with the leaves having a ten¬ 
dency to curl upward. Upon pulling up this plant 
it may be found that the main root has turned black 
and may be partly decayed. This disease is com¬ 
monly known as “black-leg” and is very prevalei 
tins season. If potatoes have developed on such 
plant., they may be found to have a decayed cent 
due to the disease. It is claimed that this disea: 
does not persist in the soil in Northern States, bi 
is carried over in the seed. Treating the seed befoi 
planting with formaldehyde or corrosive subliina 
IS quite effective against the disease. 
ABNORMAL GROWTH.—Another thing tin 
will perhaps be noticed when looking carefully 
ground, closely clustered round the stem. These 
diseased tubers show white spots, which are masses 
of the disease itself. The spots turn black in stor¬ 
age and infect the next year’s crop if used for seed. 
Corrosive sublimate is more effective against this 
disease than formaldehyde, yet neither is thorough¬ 
ly effective. 
EARLY BLIGHT.—Along the sandier and lighter 
ridges of the potato field, the first grayish brown 
spots of the early blight may lie noticed upon the 
leaves. At first these spots may be about a quarter 
of an inch in diameter. If these brittle, irregularly 
circular spots contain one delicate little circular 
marking within another, we have the characteristic 
feature of this early blight disease. These grayish 
brown spots slowly but surely increase in size and 
number, causing the entire plant to defoliate within 
three or four weeks, leaving the stems still green. 
though the foliage may not be destroyed outright 
or visibly by the poison, the texture of the leaves 
may be injured enough to induce or permit the early 
appearance and development of the early blight. 
Arsenate of lead is less apt to burn, and sticks to 
the foliage better, but it works slower than Paris 
green. Therefore, in cases of many bugs, it may 
be advisable to use the quicker acting material. If 
Paris green must be used, mix with it equal parts 
of air-slaked lime, as this material will help to pre¬ 
vent burning. 
SUNSCALD.—Sometimes, dead blackened leaves 
are found in fields, which have never received a 
drop of injurious spray material. This trouble is 
frequently caused by extreme hot sun, especially fol¬ 
lowing a few cloudy days or a shower at mid-day. 
If the moisture content of the soil becomes low, the 
roots cannot furnish enough water properly to sup- 
