In a general sense, the answer to both queries is in the negative. It has not been proved possible to transmit the disease from one piece of crepe to another, except by the closest possible contact and in the presence of an abundance of moisture.
A dry crepe, even when in close contact with an infected dry specimen, has not been found to be affected.
Unless, therefore, pieces of rubber are pressed together, under favourable conditions as to moisture, there has been observed no transfer of disease.
Similarly it has not been found that the presence of spotted rubber in one part of the drying-house has been responsible for an outbreak of disease in another part of the same building. Furthermore, after the removal of diseased rubber from the drying-shed, freshly prepared rubber may be hung on the same supports without becoming affected, and without any intermediate treatment of the wooden bars, providing the crepe is thin and weather conditions are good. In our experience, no case has been observed in which the disease has been communicated to freshly prepared rubber by reason of the previous presence of affected rubber. In our opinion, therefore, any scheme for disinfecting the interior of a drying-house, as a preventive measure against the spread of “spot” disease, is unnecessary.
All other things being equal, it is plain that much will depend, as to the incidence of coloured spots, upon the design and situation of the drying-house. Sufficient has been written in previous chapters to indicate the importance of these points as affecting the rate of drying, upon which hinges the possibility of the appearance of “spot” disease.
In conclusion, the chief points in any discussion of this subject may be summarised thus:
1. No coagulum should be left without working for longer than the ordinary period. Otherwise, the prevailing conditions are very favourable for the development of the disease.
2. Thin crepe only should be made. The quicker the rate of drying the less possibility is there of the coloured spots appearing.
3. Crepe should never be allowed to remain folded overnight, and batches of folded wet crepe should be placed on edge to drain off surface moisture. The rubber should be hung to dry as soon as possible.
4. Several species of fungi causing coloured spots have been recognised, and it has been proved conclusively that it is possible to infect latex and also fresh coagulum.