APPLE DISEASES 139 
apparatus has been suggested as a causal factor. It has been 
acceptably demonstrated that arsenate of lead is not the cause 
of the Jonathan-spot. Spots are found on unsprayed as well as 
on sprayed fruits. While the cause is yet somewhat obscure it 
is known that the spotting is more common subsequent to a 
dry season. The disease was severe following the dry summers 
of 1910, 1911 and 1914; while after the relatively wet season of 
1912 it was less serious. In storage the disease is found most 
commonly where the fruit is kept in ordinary storage for some 
time before being placed in cold storage. It also is favored by 
poor storage ventilation and by improper storage temperatures. 
Where a relatively high temperature prevails, spots develop 
abundantly. Under such conditions the fruit often “sweats” 
and rapidly respires. Apparently the causal factor comes from 
an external source and gains entrance through the lenticels and 
through other small fruit cracks as evidenced by the fact that 
such points serve as centers of all lesions. Since investigators 
are not generally agreed as to the causal agent, and since the 
possibility that two or more diseases are confused under the 
same name, the cause of Jonathan-spot remains to be further 
investigated. 
Control. 
Fruits which hang on the tree too long show the disease more 
commonly than in cases where. they are harvested at the proper 
time. Fruits picked at maturity, rushed to storage, and con- 
sumed within a few days after removal from cold storage will 
not develop the disease to any serious extent. Susceptible 
varieties like the Jonathan are likely to be severely spotted if the 
apples are withheld from cold storage, or are merely placed in 
common storage. It has been estimated that the trouble is 
quadrupled under conditions of cellar storage as opposed to the 
amount developed in cold storage. In cold storage the spots 
which do appear are smaller and less conspicuous. It is to be 
noted, of course, that the cold storage should be properly 
ventilated and the temperature should be standard (32° Fahr.). 
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