162 
WISCONSIN HORTICULTURE 
August, 1919 
TOMATO DISEASES 
J. E. Howitt, Guelph, Canada in 
Canadian Horticulturist. 
The tomato is a comparatively 
healthy crop, but nevertheless it 
is subject to several diseases which 
are serious enough to cause appre- 
ciable financial loss to the growers. 
Chief among these are Blossom-end 
or Point Rot, Leaf Spot or Blight 
and Tomato Mosaic. 
Blossom- end or Point Rot was 
very prevalent during the summers 
of 1917 and 1918. Many growers 
lost from 10 per cent to 50 per 
cent of their crop from it. The 
first symptom of the trouble is the 
appearance of irregular water- 
soaked areas near the tip of the 
fruit, usually when it is about 
half grown. These areas later 
become flattened or sunken and 
dark gray to dark brown in color 
and hard and leathery in texture. 
Later, fungi and bacteria may gain 
entrance through these injured 
spots and induce a rot which may 
destroy the whole fruit. 
Blossom-end or Point Rot is a so 
called physiological disease, not 
being due to any organism but to 
some condition within the plant it- 
self probably induced by its en- 
vironment. It appears to be due 
to an intermittent food and water 
supply and is worse in summers 
when we have prolonged heavy 
rains followed by periods of severe 
drouth. There is very little exact 
knowledge concerning the control 
of this disease. Observations, 
however, would lead the writer to 
believe that the following precau- 
tions will reduce the loss from this 
trouble : 
1. Avoid over-forcing the plants, 
especially in the early stages of 
their development. 
2. If possible water regularly 
throughout the growing season so 
the tomato plants are never al- 
lowed to become thoroughly dried 
out. Such regular watering is 
possible on small garden lots but 
is not possible in large plantations 
unless some system of irrigation, 
such as the Skinner System, is in- 
stalled. 
3. Avoid heavy applications of 
farmyard manure if the crop has 
suffered from Blossom- end Rot the 
previous year. 
Leaf Spot or Blight 
Leaf spot or blight is the most 
destructive fungus disease of toma- 
toes in Ontario. Tt attacks the 
leaves and stems of tomatoes and is 
extremely hard to control. Small, 
grayish-brown, angular spots, con 
taining minute black specks, ap- 
pear upon the leaves and stems. 
The lower leaves are first affected 
and the disease spreads upwards, 
almost completely destroying the 
foliage of the plants. The organ- 
ism which causes the disease is car- 
ried over the winter in rubbish in 
the soil of the field, greenhouse or 
hotbed. 
Leaf spot or blight can be pre- 
vented by spraying with bordeaux 
mixture, 4.4.40 formula. Com- 
mence spraying when the plants 
are in the seed beds and repeat at 
intervals of ten days or two weeks 
until there is danger of staining 
the fruit. With small patches of 
tomatoes it is often advisable to 
prune, stake and tie up the plants 
for greater convenience in spray 
ing. The diseased tops should be 
reaked up and burned in the fall il 
practicable tomatoes should not be 
oftener than once in three or four 
grown on the same piece of ground 
years. 
The Practical Efficiency of Our 
Common Insecticides 
Prof. II. F. Wilson, College of 
Agriculture. 
Spraying is now a very neces- 
sary part of farm practice for the 
control of insects on orchard, farm 
and garden crops. A cheap and 
efficient spray, easy tu handle and 
easy to apply is the desire of both 
grower and manufacturer. In other 
words what we need is a spray 
material that will kill quickly and 
at the same time involve a mini- 
mum of labor and expense for its 
application. Spraying is especi- 
ally desirable at this time when a 
maximum crop is needed in order 
to help feed the European nations. 
The value of an insecticide is 
based on its power to kill or to re- 
pel insects. An ideal insecticide 
may be said to have the following 
qualities. 
1. It must kill the insect before 
the latter can seriously damage the 
plant. 
2. It must not possess any prop- 
erties which will cause injury to 
the plant. 
3. Its cost must be sufficiently 
low to permit its use in large quan- 
tities. 
4. It must spread and stick well 
to the surface to which it is ap- 
plied. 
5. It must remain sufficientlv 
well in suspension to permit of a 
uniform coating of poison on the 
sprayed parts. 
Arsenic, the base of all impor- 
tant insecticides now used against 
chewing insects, is a substance 
which cannot by itself be used 
with safety on plants because of its 
tendency to burn the foliage. In 
combination with other substances, 
it acts as a poison to insects but 
does not cause harm to plants un- 
less in a liberated form as arsenic 
