24 CRANBERRY DISEASES. 



Fresh pycnospores have been placed in drops of water upon fruit 

 kept in sterile moist chambers, but without any noticeable result. 

 The spores germinate, but are apparently unable to penetrate the 

 epidermis of the fruit. That infection of the foliage and fruit in- 

 stead of taking place in whole or in part by way of the roots and up 

 through the stems, as supposed by Doctor Halsted, arises from exter- 

 nal sources seems to be proved by the very satisfactory results of 

 spraying experiments and by the observations already recorded. Sev- 

 eral tips of vines bearing leaves, collected September 15, which had 

 been thoroughly sprayed during the season, were carefully washed 

 with corrosive sublimate and placed in sterile moist chambers. A 

 few fungi developed in a very few of these leaves. Other leaves, 

 collected at the same time from adjacent vines which had not been 

 sprayed, were treated in the same manner. These were found to be 

 completely infested with fungi, and the pycnidia of Guignardia de- 

 veloped in abundance on almost every leaf. 



A considerable quantity of fruit which had been sprayed was 

 treated in the same manner as the leaves already mentioned. As a 

 result, 1,200 sprayed berries picked on September 18 showed on 

 October 18 but 9.8 per cent of diseased fruit, while the same number 

 of unsprayed berries from the same source kept under the same con- 

 ditions in the laboratory for the same period showed 38.1 per cent 

 of diseased fruit. The only explanation of these results in the light 

 of our present knowledge of the effect of Bordeaux mixture is that 

 most of the spores of the fungus had been destroyed by the spraying 

 and therefore did not gain entrance to the leaves and fruit. 



TREATMENT. 



Applications to the soil. Acting upon the supposition that the 

 cranberry- scald was primarily due to unfavorable soil conditions or 

 to fungi attacking the plant by way of the root system, chemicals 

 or fungicides to be applied to the soil were suggested as a remedy 

 by Doctor Taylor, 4 and later they w r ere tried by Doctor Halsted. 11 

 Lime, plaster, salt, sulphur, copper sulphate, and iron sulphate were 

 tried in different quantities. No decided benefit is reported to have 

 resulted from these applications. 



Improving the condition of the plants. It is a' matter of general 

 observation that the cranberry scald is much more serious on certain 

 bogs or portions of bogs than on others. The conditions obtaining in 

 the soil and water of these diseased areas no doubt have much to do 

 with the prevalence of the disease. The factors concerned are so 

 complex, however, that it is difficult to demonstrate satisfactorily 

 exactly what they are and which are of greatest importance. The 

 experience of various growers appears to show that the control of the 

 no 



