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more serious is this effect on the crop. _In most years 
potato plants which are attacked by Late-Blight, die down 
much earlier than they would normally. . 
When a field has been badly attacked by Late-Blight 
the tubers almost invariably become infected. This either 
takes place by spores being washed down into the soil 
and directly infecting tubers near the surface, or by the 
growth of the fungus down the tissues of the dying stalks 
into the tubers. Potato tubers infected by this disease 
can readily be recognised by the purplish discoloration 
and rather sunken appearance of the skin in diseased 
parts. These features are caused by the brown colour 
of the cells immediately under the skin. Living filaments 
of the fungus infest the discoloured cells, and if such 
tubers are stored the fungus slowly invades healthy cells, 
often producing the so-called dry rot of the tuber. In 
addition to this, the presence of the fungus in the potatoes 
renders them extremely susceptible to the attacks of 
secondary rotting fungi and also of bacteria. In some 
such cases the potato shows the characters of the winter 
rot disease caused by Fusarium solani. The tuber 
gradually shrivels and at a late stage small white tufts 
of that fungus appear over the sunken parts. In other 
cases the potato becomes changed into a moist, putrid 
mass infested by bacteria and mites. These diseases are 
extremely likely to appear in stored tubers that are, to 
any degree infected by Phytophthora. Much, however, 
can be done to prevent healthy tubers developing these 
rots by careful attention to the method of storage. It 
is well known that the favourable conditions for the 
growth of most fungi are a moist, warm atmosphere 
and absence of light. If, therefore, the storage clamp is 
not carefully made, it is possible that very favourable 
conditions for the growth of fungi will be provided. If 
the tubers are stored moist, or if they are too closely 
covered, and if no provision is made for adequate access 
of air to all parts of the “pie,” the temperature will rise 
and harmful fungi will become rampant. To avoid these 
dangers then, potatoes should be stored in a dry, well- 
ventilated shed ; or, failing that, the “ pie” or clamp should 
be in a dry situation and well ventilated. By such pre- 
cautions the conditions are rendered unfavourable for the 
growth of rotting organisms; and even though a few of 
the tubers are diseased the trouble is then unlikely to 
