1897.] PUBLIC DOCUMENT — No. 33. 71 



While this is not a disease in any sense of the word, still, 

 the etFect of the fungus on roses is of course disastrous to 

 their beauty and salability. Knowing that the disfiguring 

 sporangia come from the manure, where they can readily be 

 seen in the morning in process of development, it would seem 

 a comparatively simple matter to destroy them at that stage, 

 either by mechanical means or by spraying with a fungicide. 



A^ Leaf Blight or Anthracnose of the Cucumber. 

 {Colletotrkhrmi Lagenarium (Pass.), E. and Hals.) 

 During the past summer we have received specimens of 

 cucumber leaves from several different parts of the State, 

 which were infested with a very destructive blight. In 

 Arlington and Leominster, where the raising of hot-house 

 cucumbers is carried on extensivel}, the disease was reported 

 as doino- great damage. The fung-us which causes this trouble 

 grows wdthin the tissues of the leaf, and by sapping its 

 vitality causes its death. Under favorable conditions it is 

 very quick acting and extremely destructive. The infested 

 leaf first shows yellowish spots upon its surface, which rapidly 

 increase in size and become dry and dead. Various moulds 

 often develop upon the dead areas, and, being more promi- 

 nent than the fungus which really produces the disease, 

 appear to be the cause of the trouble. A dark-brown, luxu- 

 riantly growing species of Macrosporium or Alternaria was 

 particularly abundant upon the specimens received this sum- 

 mer, and had evidently been taken to be the cause of the 

 disease, which was referred to as the "brown mildew," 

 " brown leaf blight," etc. Such growths undoubtedly hasten 

 the destruction of the leaf, but they are al)le to develop only 

 upon leaf tissue which has been killed or greatly weakened 

 by the other more strictly parasitic fungus which is invisible 

 to the eye. The dead areas gradually fall away, leaving 

 large irregular holes in the leaf, which in a short time be- 

 comes entirely dead. The same fungus often attacks the fruit, 

 causing it to rot badly, and has been proven to be the cause 

 of the well-known " rust," so called, of the pods and leaves 

 of the bean. It also attacks the watermelon, musk-melon, 

 citron, squash and pumpkin, affecting both leaves and fruit. 

 We have recommended spraying every week or two with the 



